Alan Friedlander 

A Marine Biogeographic Assessment 

of the Northwestern Hawaiian Islands 

NOAA Center for Coastal Monitoring and Assessment

Biogeography Branch 

Kaylene Keller

NOAA Office of National Marine Sanctuaries 

Papahanaumokuakea Marine National Monument 

Lisa Wedding

NOAA Center for Coastal Monitoring and Assessment

Biogeography Branch 

University of Hawaii at Manoa 

Alicia Clarke 

NOAA Center for Coastal Monitoring and Assessment

Biogeography Branch 

Mark Monaco 

NOAA Center for Coastal Monitoring and Assessment

Biogeography Branch 

NOAA TECHNICAL MEMORANDUM NOS NCCOS 84 
 
Citations 

Citation for entire document: 

Friedlander, A., K. Keller, L. Wedding, A. Clarke, M. Monaco (eds.). 2009. A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands. NOAA Technical Memorandum NOS NCCOS 84. Prepared by 

NCCOS’s Biogeography Branch in cooperation with the Office of National Marine Sanctuaries Papahanaumokuakea Marine National Monument. Silver Spring, MD. 363 pp. 

Example citation for an individual chapter (example of Oceanographic and Physical Setting chapter): 

Desch, A., T. Wynne, R. Brainard, A. Friedlander, J. Christensen. 2009. Oceanographic and Physical Setting. 

pp. 17-63. In: Friedlander, A., K. Keller, L. Wedding, A. Clarke, M. Monaco (eds.). 2009. A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands. NOAA Technical Memorandum NOS NCCOS 

84. Prepared by NCCOS’s Biogeography Branch in cooperation with the Office of National Marine Sanctuaries Papahanaumokuakea Marine National Monument. Silver Spring, MD. 363 pp. 

Acknowledgements 

Project funding was provided by the Office of National Marine Sanctuaries Papahanaumokuakea Marine 

National Monument, the National Centers for Coastal Ocean Science and the Coral Reef Conservation 

Program. 

The completion of this document would not have been possible without the participation of the people recognized below. Their efforts to compose, format, review and edit the document are very much appreciated. 

Particular recognition and thanks is extended to Jamison Higgins for her assistance with the layout and 

production of this publication. 

In addition to chapter authors, the editors would like to acknowledge the following contributors and 

reviewers: 

George “Bud” Antonelis, Jay Barlow, Jamison Gove, Francine Fiust, Sarah Hile, David Hyrenbach, John 

Klavitter, Kevin McMahon, Gustav Paulay, Audrey Rivero, Jenny Waddell, Susan White and Lee Ann Woodward. 

For more information 

For more information about this report, please contact CCMA’s Biogeography Branch Chief Mark Monaco 

Ph.D, at (301) 713-3028 or visit http://ccma.nos.noaa.gov/about/biogeography/. 

Cover 

The covers were designed and created by Gini Kennedy (NOAA). Cover photos by James Watt (NOAA), 

James Maragos (U.S. Fish and Wildlife Service) and the Hawaii Volcano National Park. 

Mention of trade names or commercial products does not constitute endorsement or recommendation for 

their use by the United States government. 
 

 

 

 

A Marine Biogeographic Assessment of the 

Northwestern Hawaiian Islands 

Prepared for NOAA’s Office of National Marine Sanctuaries (ONMS) 

Papahanaumokuakea Marine National Monument 

Biogeography Branch
 

Center for Coastal Monitoring and Assessment (CCMA)
 

National Centers for Coastal Ocean Science (NCCOS)
 

NOAA’s National Ocean Service
 

1305 East West Highway (SSMC-IV, N/SCI-1)
 

Silver Spring, MD 20910
 

USA
 

NOAA Technical Memorandum NOS NCCOS 84
 

March 2009
 

Editors
 

Alan Friedlander, CCMA Biogeography Branch
 

Kaylene Keller, ONMS Papahanaumokuakea Marine National Monument 

Lisa Wedding, CCMA Biogeography Branch; University of Hawaii at Manoa
 

Alicia Clarke, CCMA Biogeography Branch
 

Mark Monaco, CCMA Biogeography Branch
 

National Oceanic and National Ocean Service 

Atmospheric Administration 

Mary M. Glackin John H. Dunnigan 

Deputy Under Secretary Assistant Administrator 

 

 

 

 

	 	 	

Table of Contents 

Executive Summary i
 

Chapter 1: Introduction 1
 Alan Friedlander, Kaylene E. Keller and Mark Monaco 

Background 1
 

The Northwestern Hawaiian Islands Biogeographic Assessment 2
 

The Region’s Unique Natural Environment 6
 

Major Taxa of Marine Resources 8
 

History of Use and Management 10
 

References 12
 

Chapter 2: Oceanographic and Physical Setting 17
 

Arthur Desch, Timothy Wynne, Russell Brainard, Alan Friedlander and John Christensen 

Introduction 17
 

Regional Summary 18
 

Ocean Remote Sensing Analysis: Data and Methods 22
 

Ocean Remote Sensing Analysis: Results 26
 

Existing Data Gaps 39
 

Conclusions 39
 

Appendix I: Sea Surface Temperature Time Series Plots 41
 

Appendix II: Chlorophyll Time Series Plots 51
 

References 61
 

Chapter 3: Geology and Benthic Habitats 65
 

Jonathan Weiss, Joyce Miller, Emily Hirsch, John Rooney, Lisa Wedding and Alan Friedlander 

Introduction and Origin 65
 

Benthic Habitat Mapping 69
 

Existing Data Gaps 101
 

References 102
 

Chapter 4: Benthic Communities 105
 

James Maragos, Jean Kenyon, Greta Aeby, Peter Vroom, Bernardo Vargas-Angel, Russell Brainard, 

Lisa Wedding, Alan Friedlander, Jacob Asher, Brian Zgliczynski and Daria Siciliano 

Introduction 105
 

Corals 105
 

Algae 139
 

Invertebrates 145
 

Existing Data Gaps 148
 

Appendix 150
 

References 152
 

Chapter 5: Fishes 155
 Alan Friedlander, Edward DeMartini, Lisa Wedding and Randy Clark 

Biogeography of Fishes 155
 

Latitudinal Affinities Among Fishes	 161
 

General Fish Assemblage Structure 165
 

Existing Data Gaps 187
 

References 188
 
 

 

Chapter 6: Marine Protected Species 191
 

Charles Littnan, Marie (Chapla) Hill, Stacy (Kubis) Hargrove, Kaylene E. Keller and Angela D. Anders 

Introduction 191
 

Cetaceans 192
 

Pinnipeds 211
 

Marine Turtles 221
 

Existing Data Gaps 228
 

References 229
 

Chapter 7: Seabirds 235
 

Kaylene E. Keller, Angela D. Anders, Scott A. Shaffer, Michelle A. Kappes, Beth Flint and Alan Friedlander 

Introduction 235
 

Procellariiformes (Albatrosses, Petrels and Shearwaters) 240
 

Pelecaniformes (Boobies, Frigatebirds and Tropicbirds) 249
 

Charadriiformes (Terns and Noddies) 256
 

Population Status and Trends 263
 

Existing Data Gaps 271
 

References 272
 

Chapter 8: Nonindigenous and Invasive Species 275
 

Kevin See, Scott Godwin and Charles Menza 

Introduction 275
 

Marine Algae 278
 

Invertebrates 280
 

Fishes 285
 

Management 287
 

Existing Data Gaps 287
 

References 288
 

Chapter 9: Connectivity and Integrated Ecosystem Studies 291
 

Alan Friedlander, Donald Kobayashi, Brian Bowen, Carl Meyers, Yannis Papastamatiou, Edward DeMartini, 

Frank Parrish, Eric Treml, Carolyn Currin, Anna Hilting, Jonathan Weiss, Chris Kelley, Robert O’Conner, 

Michael Parke, Randy Clark, Rob Toonen and Lisa Wedding 

Introduction 291
 

Large-Scale Population Connectivity Models from Ocean Currents 291
 

Essential Fish Habitat 316
 

Trophic Relationships: Stable Isotope Composition of Primary Producers
 

and Consumer Organisms 320
 

Food Web Models 324 

Existing Data Gaps 326
 

References 328
 

Chapter 10: Management Concerns and Responsibilities 331
 Kaylene E. Keller, Angela D. Anders, Ann Mooney, Randall Kosaki, Malia Chow and Mark Monaco 

Introduction 331
 

Background 331
 

World Heritage Nomination 333
 

Management of Protected Species 334
 

Management of Threats to the Ecosystem 336
 

Management of Human Impacts 349
 

Monument Permit Applications and Permit Issuance 351

 Future Directions and Implications for a Biogeographic Assessment to 

 Support Hawaiian Archipelago Spatial Management 359

 References 361
 
Executive Summary

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

EXECUTIVE SUMMARY
 

The mission of NOAA’s Office of National Marine Sanctuaries (ONMS) is to serve as the trustee for a system of 

marine protected areas, to conserve, protect and enhance biodiversity. To assist in accomplishing this mission, 

the ONMS has developed a partnership with NOAA’s Center for Coastal Monitoring and Assessment’s Biogeography Branch (CCMA-BB) to conduct biogeographic assessments of marine resources within and adjacent 

to the marine waters of NOAA’s National Marine Sanctuaries (Kendall and Monaco, 2003). 

Biogeography is the study of spatial and temporal distributions of organisms, their associated habitats, and 

the historical and biological factors that influence species’ distributions. Biogeography provides a framework to 

integrate species distributions and life history data with information on the habitats of a region to characterize 

and assess living marine resources within a sanctuary. The biogeographic data are integrated in a Geographical Information System (GIS) to enable visualization of species’ spatial and temporal patterns, and to predict 

changes in abundance that may result from a variety of natural and anthropogenic perturbations or management strategies (Monaco et al., 2005; Battista and Monaco, 2004). 

Defining biogeographic patterns of living marine resources found throughout the Northwestern Hawaiian Islands (NWHI) was identified as a priority activity at a May 2003 workshop designed to outline scientifi c and 

management information needs for the NWHI (Alexander et al., 2004). NOAA’s Biogeography Branch and the 

Papahanaumokuakea Marine National Monument (PMNM) under the direction of the ONMS designed and 

implemented this biogeographic assessment to directly support the research and management needs of the 

PMNM by providing a suite of spatially-articulated products in map and tabular formats. The major fi ndings of 

the biogeographic assessment are organized by chapter and listed below. 

The NWHI are home to a wide variety of ecosystems and living marine resources. Photos: J. Maragos. 

Oceanography 

• Sea surface temperature (SST) analyses suggest three latitudinal subunits: 

o North – Kure, Midway, Pearl and Hermes – temperature range 20-27 °C, among the largest 

variation in any coral reef ecosystem; 

o Middle – Lisianski to Gardner; and 

o Southern – French Frigate Shoals to Nihoa, average temperature range 23-27 °C. 

• SST analysis suggest there may have been bleaching events in 1987 and 1991 based on temperature 

anomalies >1 °C during warm period (August-September). 

• Sea surface fronts or eddies are active in the northern region from December to April with a peak in 

March. Few fronts are found in the southern portion and during mid-summer, fronts retreat to the north. 

• Low productivity ocean water is increasing worldwide due to climate change and this water has reached 

the Hawaiian archipelago with major implications for ecosystem productivity. 

i 
Executive Summary

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Geology and Benthic Habitats 

• Only 50% of shallow water habitats (0-30 m) have been mapped with more than one-half of this habitat 

consisting of hardbottom. 

• Nearly complete high resolution bathymetric coverage from 3 to 3,000 m exists for Kure, Midway, Pearl 

and Hermes, Brooks Bank and French Frigate Shoals. 

• Upchain islands (Kure, Midway, Pearl and Hermes and Lisianski) have steeper slopes compared to downchain islands. The highest rugosity (complexity) derived from multibeam data was at Pearl and Hermes. 

Benthic Communities 

• There are approximately 80 morphologically distinct coral "species" in the NWHI, and about 35 are likely 

to be endemic (44%). This represents some of the highest endemism of any coral assemblage found 

on earth. More than 25 NWHI species are still undescribed or unidentified, and once type specimens 

are collected and examined morphologically and genetically, then final determinations can be made on 

which corals are new species and possible endemics. Notwithstanding efforts to date, NWHI explorations 

are still inadequate, and it is likely that additional undescribed coral species will be encountered in the 

future. 

• The highest species richness was observed at French Frigate Shoals and reflects optimal conditions for 

coral growth (optimal temperature, low wave exposure, large open atoll) 

• Coral cover, based on tow board data, was 8% overall. Lisianski (19%) and Maro (15%) had the highest 

cover while Midway (2%) had the lowest. Coral cover on hard bottom only was highest at Maro (39%) 

and Lisianski (37%). 

• No significant differences were found in coral cover at permanent locations between 2002 and 2006. 

• Disease prevalence is low overall, <1%. 

• Algal diversity is similar across the chain but brown algae are more abundant at the northern end of the 

chain (Midway and Kure). Algal endemism was calculated at 11% for French Frigate Shoals, and 7% for 

Gardner Pinnacles, however recent molecular evidence coupled with more detailed morphological observations are finding that a large percentage of the Hawaiian algal flora are likely incorrectly identifi ed and 

may be species new to science. 

Fishes 

• Endemism based on numbers is 52% and 21% based on species richness. 

• Fish assemblages showed latitudinal affinities with more subtropical and temperate species found to the 

north and more tropical species to the south. The major faunal break occurs around Maro and Laysan. 

• Midway and Kure have a distinct fish assemblage based on biomass as does Nihoa and Mokumanamana. These distinct assemblages at the extremes of the chain are likely the result of temperature and 

habitat. 

• Grey reef sharks are more common downchain while Galapagos sharks are more common to the north. 

The transition occurred around Gardner and Maro. 

• Ranking of fish assemblages (based on endemism, species richness, number of individuals, biomass, 

apex predator biomass and recruitment) show Pearl and Hermes with the highest rank, followed by Midway, and French Frigate Shoals, respectively. 

Protected Species 

• Fifteen cetacean species have been observed within the Monument boundaries. This group of organisms 

has not been well studied in the NWHI and it may represent an important area for these species. 

ii 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

iii Executive Summary

•	 Hawaiian monk seals have shown dramatic declines since the late 1990s but these declines differ among 

locations and for various reasons. French Frigate Shoals currently supports the largest colony but has 

also shown the steepest decline (75% since 1989) with low juvenile survival. Laysan and Lisianski have 

remained fairly constant over the past decade. Pearl and Hermes is the only location to have shown an 

increase in the past 10 years. Low population numbers at Midway and Kure are likely the result of long 

histories of human disturbance.

•	 Green turtle populations continue to increase in the NWHI, representing a major conservation success 

story. French Frigate Shoals accounts for over 90% of the nesting population with Laysan, Lisianski, and 

Pearl and Hermes accounting for the remainder. Despite extensive potential beach nesting habitat at 

Midway and Kure, limited nesting has been observed at Midway and none at Kure.

Seabirds

•	 Twenty-two species of seabirds exist in the NWHI, representing one of the most important locations for 

seabirds in the tropics. Despite the importance of this region, long-term data collection has been restricted to a few species at a limited number of locations.

•	 Foraging areas range from only a few kilometers for some species (e.g. Little Terns) to over 1,000 km for 

species like the Laysan Albatross. Wide ranging species will require cooperative management at national 

and international levels.

•	 Changes in SST and primary production will result in changes in seabird populations over time and monitoring of these populations will be important to better understand the impacts of climate change.

Nonindigenous and Invasive Species

•	 The presence of invasive species is currently concentrated in harbors and when man-made objects are 

present.

•	 The blueline snapper (Taape) have spread from Oahu in 1958 to Midway in 1992, a distance of 1,180 nmi 

and observations at other islands in the chain show during this time period show a rate of spread of about 

18-70 nmi/yr. On the other hand the Peacock grouper (Roi) has only made it as far as French Frigate 

Shoals or about 5-17 nmi/year.

•	 The current presence of invasive species is low but data are limited, particularly at deeper depths and 

more systematic sampling is currently being implemented.

Connectivity and Integrated Ecosystem Studies

•	 Advection-diffusion ocean current models show Kure, Midway, and Pearl and Hermes strongly connected. Scale of dispersal is on the order of 50-150 km.

•	 High-resolution ocean current data and computer simulation showed that for organisms with short larval 

duration (15 days – e.g., corals and some invertebrates), a narrow transitional region from Kauai to Nihoa 

included	settlers	from	both	the	Main	Hawaiian	Islands	(MHI)	and	NWHI.	For	typical	fish	larvae	(45	day	larval duration) there appeared to be little exchange between the NWHI and the MHI north of French Frigate 

Shoals.	For	the	few	organisms	with	longer	larval	durations	(eg.,	Bottomfishes,	lobster)	nearly	all	regions	

of the MHI have at least some NWHI settlers where as most of the NWHI is self-seeding.

•	 Giant	trevally	(ulua)	and	jobfish	(uku)	show	no	inter-atoll	movement	over	a	several	year	period.	They	congregate around channels and reef passes and make seasonal, within-atoll movements to spawn.

•	 Genetic connectivity for opihi, the Hawaiian endemic limpet, between the MHI and NWHI is too low (less 

than three migrants per generation) to replenish MHI stocks and one species is not even found in the 

NWHI.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

iv Executive Summary

•	 Barriers to genetic dispersal occur between Pearl and Hermes and Midway, as well as between Niihau 

and French Frigate Shoals for some species however closely related species with similar ecology and 

reproductive biology have dramatically different patterns of connectivity. 

•	 Potential	bottom	fish	habitat	was	calculated	among	islands	based	on	depth	(100-400	m),	slope	(>20%),	

and hardness using available mapping data. Kure (31%) and Maro (30%) had the greatest percentage 

of	potential	bottom	fish	habitat	to	total	area	mapped.	These	results	may	indicate	areas	with	high	populations and therefore greater replenishment potential for other locations. These results may also be useful 

in identifying monk seal forage habitat.

•	 Stable isotope analysis indicates that benthic algae provide the majority of the trophic support for apex 

predators and the entire system consists of short (three to four trophic levels above primary production) 

food chain. These results are very consistent with the Ecopath model estimates of food web supporting 

fisheries	production	in	the	NWHI.

Management

•	 The complex meta-population dynamics observed in the NWHI requires a better understanding of how 

these populations replenish themselves and how they connect to other areas.

•	 The results show some areas of strong linkage and others with clear breaks in connectivity. This will require zoning and other spatial management tools to maintain ecosystem function.

•	 Current and future changes in the environment as a result of climate change will require more comprehensive assessment and monitoring along with the ability to respond in a timely manner to mitigate potential negative impacts to the ecosystem.

•	 The	data	gaps	identified	in	the	report	(e.g.,	shallow-water	maps,	cetaceans,	seabirds,	deeper	habitats,	

etc.) need to be addressed in order to have a better understanding of the entire ecosystem.

•	 A biogeographic assessment that integrates the MHI and NWHI would better help to explain ecosystem 

connectivity and processes. 

For questions or more information, please visit http://ccma.nos.noaa.gov/about/biogeography/ or contact:

Mark E. Monaco, Ph.D.

Biogeography Branch Chief

NOAA/NCCOS/CCMA

1305 East West Highway, N/SCI1

Silver Spring, MD 20910

Email: mark.monaco@noaa.gov

Alan M. Friedlander, Ph.D.

USGS Hawaii Cooperative Fishery Research Unit

Department of Zoology

University of Hawaii

Honolulu, HI 96822

Email: alan.friedlander@hawaii.edu
Executive Summary

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

REFERENCES 

Alexander, C.A., S.R. Gittings, R. Kosaki, and M.S. Tartt. 2004. Information needs for conservation science and management of the Northwestern Hawaiian Islands: a product of the I ke amio o na wa’a workshop. National Oceanic and Atmospheric Administration, Marine Sanctuaries Division. 31 pp. & app. 

Battista, T.A. and M.E. Monaco. 2004. Geographic information systems application in coastal marine fi sheries. Pages 

189-208 In: W.L. Fisher and R.J. Rahel, editors, Geographic information systems in fisheries. American Fisheries Society, 

Bethesda, MD. 

Kendall, M.S., and M.E. Monaco. 2003. Biogeography of the National Marine Sanctuaries: A Partnership between the 

National Marine Sanctuary Program and the National Centers for Coastal Ocean Science Biogeography Program. Unpublished Report. 15 pp. 

Monaco, M., Kendall, M., Higgins, J., Alexander, C., and Tartt, M., (2005) Biogeographic assessments of NOAA National 

Marine Sanctuaries: The integration of ecology and GIS to aid in marine management boundary delineation and assessment, in Wright, D.J. and Scholz, A.J. (Eds.), “Place Matters: Geospatial Tools for Marine Science, Conservation, and 

Management in the Pacific Northwest,” Corvallis, OR: Oregon State University Press, 2005. 

v 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Introduction 

Alan Friedlander1,2, Kaylene E. Keller3 and Mark Monaco1 

BACKGROUND 

The mission of NOAA’s Office of National Marine Sanctuaries (ONMS) is to serve as the trustee for a system of 

marine protected areas, to conserve, protect and enhance biodiversity. To assist in accomplishing this mission, 

the ONMS has developed a partnership with NOAA’s Center for Coastal Monitoring and Assessment’s Biogeography Branch (CCMA-BB) to conduct biogeographic assessments of marine resources within and adjacent 

to the marine waters of NOAA’s National Marine Sanctuaries (Kendall and Monaco, 2003). 

Biogeography is the study of spatial and temporal distributions of organisms, their associated habitats, and 

the historical and biological factors that influence species’ distributions. Biogeography provides a framework 

to integrate species distributions and life history data with information on habitats of a region to characterize 

and assess living marine resources within a marine protected area. The biogeographic data are integrated in 

a Geographical Information System (GIS) to enable visualization of species’ spatial and temporal patterns and 

to predict changes in abundance that may result from a variety of natural and anthropogenic perturbations or 

management strategies (Monaco et al., 2005; Battista and Monaco, 2004). The complexity of products from 

biogeographic analysis range from simple species distribution maps of a particular habitat, to more complex 

products that combine single data layers to create maps of biodiversity or habitat complexity (NOAA, 2003b; 

Pittman et al., 2007). The biogeographic assessment approach was developed by the CCMA-BB in consultation with the ONMS in 2003 (Kendall and Monaco, 2003; Monaco et al., 2005; Figure 1.1). 

Figure 1.1. Generalized biogeographic assessment process developed by CCMA-BB. Source: Kendall and Monaco,

2003. 

1. NOAA/NOS/NCCOS/CCMA Biogeography Branch

2. The Oceanic Institute 

3. NOAA/NOS/ONMS/Papahanaumokuakea Marine National Monument 

1 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

2 

Typically a biogeographic assessment is comprised of the three primary activities: 1) compile individual biogeographic data layers, 2) perform integrated biogeographic analyses, and 3) develop products to aid in management (Figure 1.1). A key tool used to develop and implement the assessment is the use of GIS technology 

which aids in data compilation, spatial analyses, and visualization of results to support place-based management needs (Battista and Monaco, 2004). The assessment process shown in Figure 1.1 is based on geospatial 

and temporal analyses of existing physical and biological data and has resulted in many spatially-oriented 

products that help managers understand how ecosystems function. Often biogeographic analyses focus on 

determining the strength of coupling between habitats and species and defining discrete areas of biological 

significance (NOAA, 2003; NOAA, 2005; Monaco et al., 2005). 

Defining biogeographic patterns of living marine resources found throughout the Northwestern Hawaiian Islands (NWHI) was identified as a priority activity at a May 2003 workshop designed to defi ne scientifi c and 

management information needs for the NWHI. NOAA’s Biogeography Branch and the Papahanaumokuakea 

Marine National Monument (PMNM) under the direction of the ONMS designed and implemented this biogeographic assessment to directly support the research and management needs of the Monument, such as, 

minimizing impacts of permitted research activities on NWHI marine resources. Successful implementation of 

this assessment required cooperation and participation with many federal, state, academic and private sector partners. Without participation of key partners, such as NOAA’s Pacific Islands Fisheries Science Center, 

Coral Reef Ecosystem Division, the University of Hawaii, the University of Miami, the State of Hawaii’s Division 

of Aquatic Resources, and the U.S. Fish and Wildlife Service, the biogeographic assessment would have not 

been completed. 

THE NORTHWESTERN HAWAIIAN ISLANDS MARINE BIOGEOGRAPHIC ASSESSMENT 

In an effort to provide further protection of the NWHI, the Monument was created by Presidential proclamation 

on June 15, 2006. The Co-Trustees for the Monument are NOAA, the Department of the Interior and the state 

of Hawaii. This biogeographic assessment was designed to support the Monument’s scientific and management needs based on historical, recent and planned research and monitoring studies within the Monument 

(Table 1.1). The assessment has resulted in a suite of spatially-articulated products for use by the Monument 

Table 1.1. The monitoring programs that are currently collecting data in the NWHI. 

MONITORING PROGRAM OBJECTIVES YEAR EST. FUNDING AGENCIES 

Fishery monitoring and economics Fisheries catch and effort statistics 1948 NOAA PIFSC, DAR program 

Marine turtle research program Monitor selected sea turtle breeding NOAA, 1973 USFWS, PIFSC sites USFWS 

Seabird monitoring Monitoring selected nesting seabird 1978 USFWS USFWS, PIFSC species 

Fishery independent lobster Monitor lobster using fisheries-inde­ 1983 NOAA PISSC monitoring pendent sampling 

Marine mammal research program Monitor and assess subpopulations 1985 NOAA PIFSC, USFWS 

Marine debris program Rates of marine debris accumulation CRED, UH, USFWS, 1996 NOAA DAR, USGS 

Reef assessment and monitoring Monitor and assess reef communities CRED, USFWS, NMSP, 

program through integrated ecosystem science 2000 CRCP DAR, numerous collaborators 

Oceanography & water quality Physical and chemical oceanographic

program conditions and processes influencing 2000 NOAA PIFSC-CRED, UH 

reef health. 

Coral monitoring Monitoring corals at permanent sites HCRI, 2000 USFWS, PIFSC-CRED USFWS 

Connectivity and ecosystem health Examine connectivity, ecosystem 2005 NMSP HIMB health, and genetic structure 

Abbreviatons: CRCP – NOAA’s Coral Reef Conservation Program; CRED - Coral Reef Ecosystem Division; DAR - Hawaii 

Division of Aquatic Resources, Department of Land and Natural Resources; HCRI - Hawaii Coral Reef Initiative; HIMB - Hawaii 

Institute of Marine Biology; NMSP - National Marine Sanctuary Program; NOS - National Ocean Service; PIFSC - Pacifi c Islands 

Fisheries Science Center; UH - University of Hawaii; USGS – U.S. Geological Survey 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

and its partners to support ecosystem-based management and the long-term, comprehensive protection and 

conservation of the marine resources of the NWHI. Results of this assessment will also support the adaptive 

management process, identify gaps in information and direct research priorities. 

Project Objectives 

The biogeographic assessment of the NWHI contributes greatly toward ecosystem-based management of the 

marine resources of the NWHI. The study is broad in scope and includes characterization of the physical and 

biological environments (e.g., oceanography, habitats) that structure the spatial and temporal distribution of 

living marine resources within and adjacent to the Monument boundaries. The objectives of the study were: 

1. Identify and synthesize relevant biological, physical and socioeconomic data sets for the study area. 

Organize the data in a common spatial framework within a GIS. 

2. Conduct a marine biogeographic analysis of available data to identify important ecological linkages and 

biologically significant regions and time periods, based on species distributions, abundance, associated 

habitats and their ecological function. 

The objectives were addressed using the biogeographic assessment process (Figure 1.1) and resulted in a 

synthesis of multiple data sets that range across the NWHI to enable characterization of the biological and 

physical environment that structures the biogeographic patterns in space and time of living marine resources 

found within the Monument. The data, analyses and supporting information are linked using statistical and GIS 

tools to visualize the location of significant biological areas or “hot spots.” There were many alternative approaches to analyze and organize the biological, physical and habitat data compiled for this assessment. However, only a limited number of analytical options were selected based on reviewer’s comments on the project 

work plan and technical review meetings. These key analyses are presented in this document. A critical step in 

assessment process was the extensive effort to have data, analytical approaches and results peer reviewed. 

Initial results from the suite of analyses were presented to experts on NWHI marine ecosystem, as well as to 

the originators of the data sources in an attempt to improve the analyses. The role of expert review and input 

has been considerable, and the contributions made by experts have significantly enhanced the study results. 

The use of the GIS enabled species-specific data, such as distribution and abundance data or community 

metrics (e.g., species richness), to be directly linked to specific areas or habitats they correspond with across 

the study area. The GIS also facilitated integration of multiple data types and sources into a common spatial 

and temporal framework (Gill et al., 2001). 

The chapters that follow focus on the spatial and temporal distribution data and analyses from the assessment. 

The report is organized by introducing the geology, habitats and oceanographic characteristics of the NWHI 

and then followed by the biogeography of living marine resource found within and adjacent to the Monument 

(Miller et al., 2003; Maragos et al., 2004). The Connectivity and Integrated Ecosystem Studies chapter addresses combinations of the individual biogeographic data layers to characterize the Monument based on the 

integration of physical and biological data, including ecological and genetic connectivity that define the PMNM 

ecosystem. Finally, the Management Concerns and Responsibilities chapter focuses on the management of 

the Monument including the management structure, protected species occurring within the Monument, the 

management of human activities and the greatest potential threats to the region. Below are brief summaries 

that characterize the PMNM ecosystem and are discussed in greater detail in individual sections. 

Region of Interest 

The remoteness and protective status of the NWHI has minimized reef degradation suffered by many other 

coral reefs around the world (Friedlander et al., 2005, 2008; Grigg et al., 2008). The NWHI consist of small islands, atolls, submerged banks, and reefs, that stretch for more than 2,000 km northwest of the high windward 

Main Hawaiian Islands (MHI; Figure 1.2). The majority of the islets and shoals remain uninhabited, although 

Midway, Kure, Laysan Island and French Frigate Shoals have all been occupied for extended periods over 

3 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

4 

Figure 1.2. The Northwestern Hawaiian Islands, which extend across the north central Pacific, represent a vast, remote

coral ecosystem that has been subjected to relatively minimal anthropogenic impacts. Map: K. Buja. 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

the last century by various government agencies. The inaccessibility, limited fishing and lack of other human 

activities in the NWHI have resulted in minimal anthropogenic impacts (Friedlander et al., 2005, 2008), therefore providing a unique opportunity to assess how a “natural” coral reef ecosystem functions in the absence of 

major localized human intervention and contrast these with anthropogenic influences experienced in the MHI 

and other comparable ecosystems (Friedlander and DeMartini, 2002; Grigg et al., 2008). 

One of the most striking and unique components of the NWHI ecosystem is the abundance and dominance of 

large apex predators such as sharks and jacks (Figure 1.3; Hobson, 1984; Parrish et al., 1985; Friedlander and 

DeMartini, 2002), which exert a strong top-down control on the ecosystem (DeMartini et al., 2005; DeMartini 

and Friedlander, 2006) and have been depleted in most other locations around the world (Meyer and Worm, 

2003; 2005). The NWHI flora and fauna include a large percentage of species that are endemic to the Hawaiian 

Islands, which are recognized for having some of the highest marine endemism in the world (Kay and Palumbi, 

1987; Jokiel, 1987; Randall, 1998; Randall, 2007). Some of these endemics are dominant components of the 

community, resulting in a unique ecosystem that has extremely high conservation value and has identified Hawaii as an important global biodiversity hot spot (DeMartini and Friedlander, 2004; Maragos et al., 2004). The 

few alien species known from the NWHI are restricted to the anthropogenic impacted habitats of Midway Atoll 

and French Frigate Shoals (Friedlander et al., 2005, 2008; Godwin et al., 2006). Disease levels in corals in the 

NWHI are much lower than those reported from other locations in the Indo-Pacific (Aeby, 2006). 

The NWHI represent important habitat for a number of threatened and endangered species. 

Figure 1.3. Apex predators are a conspicuous and important component of the PMNM ecosystem. Galapagos sharks 

(Carcharhinus galapagensis; left) sharks at Maro Reef and giant trevally (Caranx ignobilis; right), known as ulua in Hawaii,

from French Frigate Shoals. Photos: J. Maragos. 

The Hawaiian monk seal is one of the most critically endangered marine mammals in the U.S. (approximately 

1,200 individuals) and depends almost entirely on the islands of the NWHI for breeding and the surrounding 

reefs for sustenance (Antonelis et al., 2006). Over 90% of all sub-adult and adult Hawaiian green sea turtles 

found throughout Hawaii inhabit the NWHI (Balazs and Chaloupka, 2006). Additionally, seabird colonies in 

the NWHI constitute one of the largest and most important assemblages of seabirds in the world (USFWS, 

2005). 

On June 15, 2006, President George W. Bush designed the NWHI as a Marine National Monument, the largest 

no-take marine conservation areas on earth, through the signing of Proclamation 8031. In March 2007, First 

Lady Laura Bush renamed the Monument the Papahanaumokuakea Marine National Monument on behalf of 

the President. The Monument encompasses nearly 225,300 km2

 of ocean and includes all the islands, atolls, 

shoals and banks from Nihoa Island to Kure Atoll (Figure 1.4). The unique predator-dominated trophic structure, the dominance by large numbers of endemic species, and the occurrence of a number of threatened and 

endangered species makes the NWHI an ecosystem of global significance. 

5 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 1.4. Papahanaumokuakea Marine National Monument boundaries. Map: PMNM. 

THE REGION’S UNIQUE NATURAL ENVIRONMENT 

The NWHI are influenced by a dynamic environment that includes large annual water temperature fluctuations, 

seasonally high wave energy, and strong inter-annual and inter-decadal variations in ocean productivity (Grigg, 

1983; Polovina et al., 2001). As a result of these influences and the general absence of human interference, 

natural stressors play an important role in the structure of the NWHI ecosystem (Friedlander et al., 2005). 

Large swell events generated every winter commonly produce waves up to 10-12 m in height, which limits the 

growth and abundance of coral communities, and leads to species and growth forms that are adapted to these 

dynamic high wave energy environments (Grigg et al., 2008). 

Compared with most reef ecosystems around the globe, the large annual fluctuation of sea surface temperatures (SSTs; >10 ̊C) found at the northernmost atolls of the NWHI is extremely high. Cooler water temperatures 

to the north restrict the growth and distribution of a number of coral species (Grigg, 1983), and the biogeographic distribution of many fish species in the NWHI is influenced by differences in water temperatures along 

the archipelago (DeMartini and Friedlander, 2004; Mundy, 2005). 

Large-Scale Biogeographic Regions 

The NWHI is set in a dynamic oceanographic and meteorological regime in the northern/central subtropical 

region of the Pacific Ocean (Figure 1.5). The NWHI archipelago extends such a great distance that the two 

opposite ends of the chain often experience somewhat different oceanographic and meteorological conditions 

(Table 1.2). The NWHI are not usually impacted by tropical storms but do experience large boreal winter wave 

events that assist in shaping the ecosystem. The boundary between the nutrient-poor, or oligotrophic, surface 

waters of North Pacific Subtropical Gyre and the nutrient-rich, or eutrophic, surface waters of the North Pacific 

Subpolar Gyre is frequently in the NWHI region (Leonard et al., 2001). This front shifts 15° (between 30o and 

45oN) seasonally (Polovina et al., 2001), reaching far enough south in the winter to encompass the northern 

most three atolls (Kure, Midway, and Pearl and Hermes). The southern extension of this front into the NWHI region, migrating on interannual and decadal time scales, brings colder and nutrient rich waters that are likely important to the productivity and ecology of these coral reef ecosystems. The location of this front also influences 

6 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

marine debris concentrations (Kubota, 

1994), which has been shown to most 

severely impact the northern atolls 

(Boland et al., 2004; Donohue et al., 

2001). 

Geology and Evolutionary History 

The Hawaiian Archipelago originated 

over a relatively stationary melting 

anomaly or hot spot in earth’s mantle 

located below the floor of the Pacific 

Plate, which is drifting over the hot spot 

to the northwest at a rate of about 8 cm/ 

yr (Figure 1.6; Grigg et al., 2008; Rooney 

et al., 2008). Because the plate is slowly 

cooling as it moves away from the hot 

spot, the overriding islands and other 

volcanic features are slowly subsiding. 

Beginning at Nihoa and Mokumanamana Island (approximately seven and 

10 million years old, respectively) and 

extending to Midway and Kure Atolls 

(approximately 28 million years old), the 

NWHI represent the older portion of the 

emergent Hawaiian Archipelago (Grigg, 

1988; Juvik and Juvik, 1998; Rooney et 

al., 2008). 

The Hawaiian Archipelago is 3,900 km 

from the west coast of the U.S. mainland, 

3,800 km from Japan, and over 1,000 km 

from the nearest island archipelago (the 

Line Islands). This geographic isolation 

of the entire Hawaiian Island chain has 

resulted in a large number of species 

that are found nowhere else on earth, 

and the proportion of these endemic 

species (>25% for most taxa) to other 

native species is some of the highest recorded for any tropical marine ecosystem to date. Some of these endemics 

are dominant components of the coral 

reef community, resulting in a unique 

ecosystem that has extremely high conservation value (DeMartini and Friedlander, 2004; Maragos et al., 2004). 

Figure 1.5. Topographic map showing location in Pacific Ocean of the 

Northwestern Hawaiian Islands (NWHI) and the major ocean currents in the

region (North Equatorial Current (NEC, South Equatorial Current (SEC),

North Equatorial Counter Current (NECC), South Equatorial Counter Current (SECC), Equatorial Under Current (EUC). Source: CRED. 

Table 1.2. Coordinates and Hawaiian names of the 10 islands presented 

from north to south. 

ISLAND HAWAIIAN NAME LATITUDE LONGITUDE 

Kanemilohai, Kure Atoll 28° 26’N 178° 19’W Mokupapapa 

Midway Atoll Pihemanu 28° 14’N 177° 22’W 

Pearl and Hermes Atoll Holoikauaua 27° 51’N 175° 51’W 

Lisianski Island and Papaapoho 26° 3’N 173° 58’W Neva Shoals 

Laysan Island Kauo 25° 47’N 171° 44’W 

Maro Reef Nalukakala, Koanakoa 25° 27’N 170° 37’W 

Gardner Pinnacles Puhahonu 24° 52’N 168° 1’W 

French Frigate Shoals Mokupapapa, Kanemilohai 23° 46’N 166° 12’W 

Mokumanamana Island Mokumanamana 23° 27’N 164° 31’W 

Nihoa Island Nihoa 23° 5’N 161° 51’W 

Figure 1.6. Lava flowing into the ocean off the southeast coast of the island

of Hawaii. Photo: Hawaii Volcano Naitonal Park. 

7 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

MAJOR TAXA OF MARINE RESOURCES 

Benthic Communities 

The composition and distribution of benthic communities in the NWHI reflect the interaction of numerous influences, including isolation, latitude, exposure, and the successional age of the island they inhabit. Mosaics of 

habitats range from coral-dominated areas to vast expanses of unconsolidated sediments such as sand and 

mud inhabited by a few epi-benthic fauna. 

Despite their high latitude location, slightly more species of coral have been reported from the NWHI (52 species) compared with the MHI (48 species; Maragos et al., 2004), although a number of potentially new species 

have recently been discovered (Friedlander et al., 2008). Kure is the world’s most northern atoll (28° 26’N) and 

is referred to as the Darwin Point, where coral growth and subsidence /erosion balance one another (Grigg, 

1982). Beyond this point lies a chain of seamounts that get progressively deeper and older as they move away 

from a stationary melting point or hot spot in the Pacific plate located southeast of the big island of Hawaii 

(Grigg, 1988). 

The coral assemblage in the NWHI contains a large number of endemics (approximately 30%), including at least seven species of table corals (acroporids), 

which are the dominant reef-building 

coral in the Indo-Pacific, but are absent 

from the MHI (Figure 1.7, Maragos et al. 

2004). Coral disease is currently low in 

the NWHI; but increases in the frequency and intensity of bleaching events due 

to global warming could stress corals 

and make them more susceptible to disease. 

Unlike the MHI where alien and invasive 

algae have overgrown many coral reefs, 

the shallow reefs in the NWHI appear 

to be free of invasive algae, and high 

natural herbivory (grazing) results in a 

pristine algal assemblage. Algal diversity appears similar across the NWHI chain even though brown algae 

tend to be more abundant at Midway and Kure Atolls than at most other islands (Vroom and Page, 2006). The 

cooler SSTs found at Kure and Midway Atolls during winter months may favor a higher abundance of brown 

algal species. Lower abundance of green algae at Midway may result from higher herbivorous fi sh densities 

at this atoll system, suggesting possible top-down control of the benthic habitat (DeMartini and Friedlander, 

2004, 2006). 

The NWHI are documented to contain the highest percent cover of algal species when compared to other 

geographic locations throughout the U.S. tropical Pacific, and the lowest percent cover of living coral (Vroom 

et al., 2006). This is likely due to the subtropical location of the NWHI and cool SSTs that bathe biological 

communities during winter months. Despite relatively high algal populations, the NWHI remain a healthy and 

thriving marine ecosystem. 

Fishes 

A total of 457 reef and shore fishes have been reported from the MHI while 258 are documented from Midway 

Atoll in the NWHI (Randall et al., 1993). Despite these differences, the total number of species observed on 

quantitative transects in the NWHI (210) and was similar to the 215 species reported in a recent comprehensive quantitative study around the MHI (Friedlander et al., 2005). The lowest overall fish species richness in 

Figure 1.7. Table coral (Acropora cytherea) at French Frigate Shoals. Photo: J. Watt. 

8 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

the NWHI occurs at the small basalt islands (Mokumanamana, Gardner, Nihoa). It is highest at French Frigate Shoals and Pearl and Hermes Atoll. Greater species richness at French Frigate Shoals may be related to 

higher coral richness and greater habitat diversity (Maragos et al., 2004) while large area, habitat diversity and 

the presence of subtropical and temperate species that occur at greater depths influence greater richness at 

Pearl and Hermes. 

Reef fish trophic structure in the NWHI is strongly dominated by carnivores (Hobson, 1984; DeMartini and 

Friedlander, 2006). Fish biomass in the NWHI is nearly three times greater than in the MHI with most of the 

difference resulting from large apex predators (primarily sharks and jacks; Friedlander and DeMartini, 2002). 

Today, these top carnivores, analogous to lions and wolves on land, are seldom encountered by divers in the 

inhabited Hawaiian Islands. A number of species such as the endemic spectacled parrotfi sh (Chlorurus perspicillatus), the endemic Hawaiian hogfi sh (Bodianus bilunulatus), and bigeye emperor (Monotaxis grandoculis) are quite abundant and obtain large size in the NWHI. These species are heavily exploited for commercial, 

subsistence and recreational use in the MHI, and their reduced number and sizes in the MHI is likely the result 

of years of chronic overfishing (Friedlander and DeMartini, 2002). 

Seabirds 

Seabird colonies in the NWHI constitute 

one of the largest and most important 

assemblages of seabirds in the world, 

with approximately 14 million birds (5.5 

million breeding annually) representing 

22 species (Friedlander et al., 2005; 

USFWS, 2005). More than 95% of the 

world’s Laysan albatross (Phoebastria immutabilis; Figure 1.8) and Blackfooted albatross (P. nigripes) nest in the 

NWHI (USFWS, 2005). For several other species such as Bonin Petrel (Pterodroma hypoleuca), Christmas Shearwater (Puffinus nativitatis), Tristram’s 

Storm-petrel (Oceanoframa tristrami) 

and Grey-backed Tern (Sterna lunata), 

the NWHI supports colonies of global 

significance. The last complete inventory of NWHI breeding populations was 

done between 1979 and 1984 (Fefer et 

al., 1984). Population trends since then have been derived from more intensive monitoring at three islands 

and are stable or increasing for most species at these locations but there is concern for a few, especially the 

albatross due to ingestion of plastics, loss of forage base and other large-scale issues (USFWS, 2005). 

Protected Species

Hawaiian Monk Seal 

The Hawaiian monk seal (Monachus schauinslandi) is listed as Endangered under the Endangered Species 

Act (ESA) and Depleted under the Marine Mammal Protection Act. It is the only endangered pinniped occurring 

entirely within U.S. waters. Monk seals occur throughout the Hawaiian Archipelago, and although most are 

found in the NWHI, a small but increasing number pup in the MHI. They commonly occur on isolated beaches 

for resting, molting, birthing and nursing offspring, spending nearly two-thirds of their time in marine habitats 

(Antonelis et al., 2006). A recent monk seal recovery report estimates that there are only 1,200 Hawaiian monk 

seals still alive (Figure 1.9) and if the declining population trend continues there will be fewer than 1,000 within 

the next three or four years, a decrease of more than 60% since the 1950s. When compared historically, the 

monk seal beach count abundance index reached record lows in 2005. 

Figure 1.8. Laysan Albatrosses at Midway Atoll NWR. Photo: A. Friedlander. 

9 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Hawaiian Green Sea Turtle 

The green sea turtle (Chelonia mydas) 

is the most abundant large marine herbivore globally (Bjorndal, 1997) and has 

a circumtropical distribution with distinct 

regional population structures (Figure 

1.10; Bowen et al., 1992). Worldwide, 

the green turtle has been subject to a 

long history of human exploitation with 

some stocks now extinct and others in 

decline. Green sea turtles in U.S. waters 

have been protected under the federal 

ESA since 1978. The Hawaiian green 

turtle stock, or honu, comprises a single 

closed genetic stock that is endemic to 

the Hawaiian Archipelago (Bowen et 

al., 1992) with numerous distinct foraging grounds within the 2,200 km span 

of the Hawaiian Archipelago From the 

mid-1800s until about 1974, the Hawaiian stock was subject to human exploitation such as turtle harvesting at foraging grounds, harvesting of nesters and 

eggs, and nesting habitat destruction. 

The primary rookery for the Hawaiian 

green sea turtle is located on French 

Frigate Shoals which accounts for more 

than 90% of all nesting within the Hawaiian Archipelago. The main rookery island at French Frigate Shoals 

is East Island where at least 50% of all French Frigate Shoals nesting occurs. Nesting females exhibit strong 

island fidelity, and the Hawaiian green sea turtle stock has been continuously monitored for several decades. 

Annual surveys of the number of female green turtles coming ashore to nest each night have been conducted 

at East Island since 1973 (Balazs, 1980). 

The long-term trends based on a population model for the East Island nester abundance illustrates a dramatic 

increase in abundance over the past 30-years, and substantial fluctuations in the number of annual nesters 

has been observed (Balazs and Chaloupka, 2006). Such fluctuations are characteristic of green turtle nesting 

populations and reflect a variable proportion of females in the population that breed each year in response to 

ocean-climate variability. The Hawaiian green sea turtle stock is showing signs of recovering after more than 

25 years of protecting their nesting and foraging habitats in the Hawaiian Archipelago (Chaloupka and Balazs, 

2007). 

HISTORY OF USE AND MANAGEMENT 

The designation of the Monument is the most recent increase in protections and management of the NWHI. 

The NWHI has a long history of human use and increasing efforts for conservation management (Figure 1.11). 

Native Hawaiians traversed and seasonally used the NWHI for hundreds of years and continue today to maintain their strong cultural ties to the land and sea of the NWHI. Post-Western-contact, the NWHI continued to be 

explored and the harvest of natural resources including guano mining, egg harvesting, fishing and other natural resource extraction occurred. The U.S. Military maintained active military bases during much of the 1900s. 

In 1909 the first natural resource protection was put in place with the designation of the Hawaiian Islands Bird 

Reservation. Since that time, additional reserves and refuges have been established to protect this unique 

ecosystem. The most recent protections were implemented with the designation of the Papahanaumokuakea 

Marine National Monument June 15, 2006. 

Figure 1.9. Hawaiian monk seal and endemic Hawaiian green sea turtle at

NWHI. Photo: National Marine Fisheries Service. 

Figure 1.10. Endemic Hawaiian green sea turtle at Midway Atoll. Photo: J. 

Watt. 

10 
Introduction

 

Archeological remains show evidence of places of 

worship and home sites on Mokumanamana and 1000YB Nihoa for at least a 500-700 hundred year period 

(Emory, Cleghorn 1988, Irwin 1992). 

Commercial harvest of whales, seals, turtles, sharks, 

see cucumbers, and pearl oysters by European 1700s
 

explorers
 

Seabirds feathers and eggs taken by Japanese and 1800s under permit from the Kingdom of Hawaii 

1822 Nihoa claimed under the Kamehameha Monarchy 

Laysan and Lisianski claimed by the Kingdom of 1857 Hawaii
 

U.S. takes formal possession of Midway Atoll. 1869
 

1886 Kure Atoll annexed by King Kalakaua.
 

1903 Transpacific cable station in operation at Midway. 

President Theodore Roosevelt signs Executive Order 

to include NWHI in National Wildlife Refuge System. 1909
 

Tanager Expedition – Collected biological samples 

and documented changes at Laysan Islands from 1923 guano mining and resource harvest in the 19th and 

early 20th century. 

1930s Pan American Clippers fly from Honolulu to Midway 

U.S. Navy begins construction of Pacific Naval Air 1939 Station 

French Frigate Shoals becomes a U.S. Naval air 1940s facility 

Battle of Midway – 100-200 mi north of Midway. This 

decisive victory was the turning point for the war in 1942
 

the Pacific.
 

Cooperative Quadripartite Program. NWHI fishery 

Mid 1970s – investigations involving National Marine Fisheries 

early 1980s Service, U.S. Fish and Wildlife Service, Hawaii 

Division of Aquatic Resources, and the University of 

Hawaii. 

First NWHI Rapid Assessment and Monitoring 

Program (RAMP) cruise. Multi-disciplinary, multi- President Clinton signs Executive Order creating the 2000 NWHI Coral Reef Ecosystem Reserve. 

chemical, and geological characteristics of the NWHI. 

agency investigation of biological, physical, 

President George W. Bush issues Presidential 

Proclamation establishing Northwestern Hawaiian 2006 

Islands Marine National Monument 

Figure 1.11. Time line of the history of the NWHI use and management. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

11 
Introduction

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

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15 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

17Oceanographic and Physical Setting

Oceanographic and Physical Setting

Arthur Desch1, Timothy Wynne1, Russell Brainard2, Alan Friedlander3,4 and John Christensen1

INTRODUCTION

The Northwestern Hawaiian Islands 

(NWHI) are set in a dynamic oceanographic and meteorological regime in 

the northern/central subtropical region 

of the Pacific Ocean (Figure 2.1). The 

boundary between the nutrient-poor surface waters of North Pacific Subtropical 

Gyre and the nutrient-rich surface waters of the North Pacific Subpolar Gyre 

frequently influence the NWHI region 

(Kazmin and Rienecker, 1996; Leonard 

et al., 2001; Polovina et al., 2001). This 

front shifts seasonally (Polovina et al., 

2001) and migrates on interannual and 

decadal time scales, bringing colder and 

nutrient rich waters that are likely important to the productivity and ecology of 

the region (Polovina and Haight, 1999; 

Nakamura and Kazmin, 2003; Polovina, 

2005). Longer-term changes, particularly those related to climate, are of concern since the reef ecosystems of the NWHI may not have encountered 

such conditions for hundreds, thousands or even millions of years (Rooney et al., 2008). 

The health, functioning and biogeography of ecosystems of the NWHI are primarily controlled by the oceanographic processes and conditions, both physical and chemical, to which they are exposed. The Monument’s 

diverse biological ecosystems, including fishes, corals and other invertebrates, algae, turtles, seabirds and 

marine mammals, is significantly influenced by ocean currents, waves, nutrients, temperature, and other measures of water quality and oceanographic conditions. The most important factors controlling the distribution 

and abundance of coral reefs in the NWHI are depth and shelter from large open ocean winter swell (Grigg. 

1983).

This chapter provides a comprehensive analysis of ocean currents, waves, temperature, winds and productivity 

using satellite remote sensing data to offer a quantitative assessment of regional ocean climate. The objective 

is to capture spatial and temporal patterns in each of these parameters and to set context for the biogeographic 

assessment that follows. The Monument sits in a region of the Pacific Ocean that is dominated by large-scale 

circulation patterns that fluctuate over periods of years and decades. With that perspective, these data sets 

have been collected and analyzed over a spatial scale that includes much of the North Pacific Ocean. Large 

scale events and processes are the focus here. To illustrate this concept, Figure 2.2 provides a view of global 

sea surface temperature (SST), chlorophyll (ocean color), wind and sea surface height or SSH (proxy for currents). Each of these examples represents the average condition, worldwide, for the month of March. This view 

is provided as a reminder that while the NWHI cover a vast region, variability in oceanographic conditions as 

resolved by remote sensing platforms is most evident at basin-wide scales. That is, analysis of remote sensing data within the NWHI is not as variable as the Pacific basin as a whole. A short summary of regional cli1. NOAA/NOS/NCCOS/CCMA Coastal Oceanographic Assessment Status and Trends Branch

2. NOAA/NMFS/Pacific Islands Fisheries Science Center, Coral Reef Ecosystem Division

3. NOAA/NOS/NCCOS/CCMA Biogeography Branch

4. The Oceanic Institute

Figure 2.1. Hawaiian Archipelago Including the NWHI (Nihoa Island to Kure 

Atoll) and Main Hawaiian IslandsI (Hawaii to Kauai). Inset shows the Hawaiian Archipelago in the Pacific Ocean. Source: PMNM, 2008.
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

mate and oceanography is presented 

in advance of the quantitative analysis 

to provide points of reference for the 

results presented. 

REGIONAL SUMMARY 

Climate 

The climate of the entire Hawaiian Archipelago features mild temperatures 

year-round, moderate humidity, persistent northeasterly trade winds and 

infrequent severe storms. Hawaii’s 

climate is notable for its low day-today and month-to-month variability 

(Giambelluca and Schroeder, 1998). 

The climate is influenced by the marine tropical or marine Pacific air 

masses depending upon the season. 

During the summer, the Pacific High 

Pressure System dominates, with the 

ridge line extending across the Pacific north of Kure and Midway. This 

places the region under the influence 

of easterly winds, with marine tropical and trade winds prevailing. During 

the winter, especially from November 

through January, the Aleutian Low 

moves southward over the North Pacific, displacing the Pacific High (Grigg 

et al., 2008). The Kure-Midway region 

is then affected by either marine Pacific or marine tropical air, depending 

upon the intensity of the Aleutian Low 

or the Pacific High Pressure System 

(Amerson et al., 1974). The surrounding ocean has a dominant effect on 

the weather of the entire archipelago. 

Air temperature at the northern end of 

the archipelago varies between 11 and 

33°C. Air temperature measurements 

made at six sites on Nihoa Island (23o 

N latitude) from March 2006 to March 

2007 ranged between 16 and 34°C. 

Annual rainfall over the last 26 years 

has been 73.28 cm on average, ranging between 40.61 and 104.24 cm/ 

year (PMNM, 2008). 

ABCD

Figure 2.2. (A) Global climatological SST (oC), (B) chlorophyll mg/m

3

, (C)

wind m/sec (D) and sea surface height anomaly cm estimates for the month

of March. The NWHI study area is shown as a black box. 

18 

El Niño – Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) 

ENSO is an interannual global climate phenomenon that results from the large-scale coupling of atmospheric 

and oceanic processes, which creates significant temperature fluctuations in the tropical surface waters of the 

Pacific and other oceans. The two distinct ENSO signatures in the Pacific Ocean are known as El Niño and La 

Niña. During El Niño events, the Aleutian Low pressure system tends to be more intense and extend further to 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

the south (closer to the NWHI), thereby 

producing stronger winds, larger waves 

and cooler water temperatures in the 

NWHI (Bromirski et al., 2005). During 

La Niña, SSTs in the eastern tropical 

Pacific are below average, and temperatures in the western tropical Pacific are 

above average (Figure 2.3). Leonard 

et al. (2001) and Rooney et al. (2008) 

have suggested that positive ENSO 

signatures (warming) correspond with 

southern extensions of the North Pacific subtropical front. A strong band of 

cool water (blue in false color range) 

appears along the Equator, particularly 

strong near South America. Warm conditions (orange in false color range) appear north and south of this strong blue 

band (Figure 2.3). The NWHI be seen 

straddling both warm and cold portions 

of the basin-wide temperature anomaly, 

highlighting complex regional thermal structure. Because biological communities are significantly influenced 

by spatially and temporally-varying ocean currents, temperature and nutrients (Polovina et al., 1995; Seki et 

al., 2002; Polovina et al., 2004), regional biogeography is equally complex and dynamic. 

The PDO is a long-lived El Niño-like pattern of Pacific climate variability. While the two climate oscillations have 

similar spatial footprints, they have very different behavior in time. Two main characteristics distinguish PDO 

from ENSO are: 1) 20th century PDO events persisted for 20-to-30 years, while typical ENSO events persisted 

for 6 to 18 months; and 2) the climatic effects of PDO are most visible in the North Pacific, while secondary 

signatures exist in the tropics. The opposite is generally true for ENSO. Several independent studies provide 

evidence that two full PDO cycles have occurred over the past century, where cool regimes prevailed from 

1890-1924 and again from 1947-1976, and warm regimes dominated from 1925-1946 and from 1977 through 

the mid-1990s. Additional research suggests that 20th century PDO fluctuations were most energetic in two 

general periodicities, one from 15-to-25 years, and the other from 50-to-70 years (http://jisao.washington.edu/ 

pdo/). 

Ocean Temperature 

SST is an important physical factor influencing coral reefs and other marine ecosystems of the Monument. 

Maximum monthly climatological mean SST measured over the last 20 years at Kure is 27 oC in August and 

September (NOAA Pathfinder SST time series; Hoeke et al., 2006), with monthly minimums in February at 19 

oC. The large seasonal temperature fluctuations at the northern end of the archipelago result in the coldest – 

and sometimes the warmest – SSTs in the entire Hawaiian chain (Brainard et al., 2004). At the southern end 

of the Monument, the annual variation in SST is much less, with French Frigate Shoals only varying between 

23.3 and 27.5o C. 

Winter temperatures tend to be 3-7°C cooler at the northerly atolls than at the southerly islands and banks as 

the subtropical front migrates southward. These cooler winter temperatures are thought to reduce coral growth 

rates (Grigg 1983, Grigg et al. 2008). In addition to the strong annual cycle, SST observations show significant 

interannual and decadal variability (Figure 2.4). The highest summer maximum SSTs at the northern atolls occurred during the summers of 1987, 1991 and 2002, possibly suggesting a teleconnection with ENSO events. 

Winter minimum temperatures at the northern atolls appear to oscillate over a longer time period, as indicated 

by a significant warming of winter SSTs beginning in 1999 and lasting for several years (Brainard et al., 2004). 

During the period between July and September 2002, ocean temperatures along the Hawaiian Archipelago 

were warmer than average. 

Figure 2.3. Diagram SST anomalies in November 2007 showing La Niña

conditions. Blue tones indicate cooler than average surface temperatures,

while orange tones indicate warmer than average. The Hawaiian Islands,

including the NWHI are in the black box. 

SST Anomaly

 cooler

 warmer 

19 
Oceanographic and Physical Setting

Necker

Marro

SMA

Mokumanamana

Maro

Jan-85 Jan-86 Jan-87 Jan-88 Jan-89 Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

16 

18 

20 

22 

24 

26 

28 

30 

Nihoa French Frigate Shoals Gardner Pinnacles Laysan Lisianski Pearl and Hermes 

Kure 

Special Management Area (Midway) 

Figure 2.4. Pathfinder SST (oC ) time-series for islands, atolls and shoals throughout the Monument (1985-2006). 

While coral bleaching can be caused by a wide range of environmental variables acting alone or in combination (Jokiel and Brown, 2004), the predominant cause of increasing incidences of coral bleaching globally is 

believed to be persistent warmer than average water temperatures (Jokiel and Coles, 1990; Kenyon et al., 

2006a,b), and indeed a significant bleaching event was documented during the summer of 2002 (Friedlander 

et al., 2005; Hoeke et al., 2006, Kenyon et al., 2006a,b). 

Ocean Currents 

Ocean currents transport and distribute larvae among and between different atolls, islands and submerged 

banks of the NWHI, and also provide the mechanism by which species are distributed to and from the main 

eight Hawaiian Islands, as well as other regions (Polovina et al., 1995). The relatively low species diversity and 

high endemism of the NWHI are the result of the relative oceanographic isolation of the Hawaiian Archipelago 

(Grigg et al., 2008; Demartini and Friedlander, 2004; Friedlander et al., 2008). 

Ocean currents are measured and monitored in the NWHI in many different ways. Since 1990, ocean current profiles along the Hawaiian Archipelago have been measured using Acoustic Doppler Current Profilers 

(ADCP) aboard the NOAA ships Townsend Cromwell (1990 to 2002) and Oscar Elton Sette (2003 to present) 

during routine transects along the archipelago to support a number of scientific cruises for NOAA’s Pacific Islands Fisheries Science Center (PIFSC). 

Based on 10 years of ADCP data (1990-2000), Firing et al. (2004a) demonstrated that upper ocean currents 

in the NWHI are highly variable in both speed and direction. Averaged over time, the resultant mean flow of 

the surface waters tend to flow predominantly from east to west in response to the prevailing northeast trade 

winds. The lack of coral reef ecosystems and low biodiversity to the east, or upstream, of the Hawaiian Archipelago explains the low species richness and high endemism (PMNM, 2008). Surface Velocity Program 

current drifters and autonomous profiling explorer drifters have also been deployed in the NWHI by PIFSC 

annually since 2001. These drifters provide indications of the Lagrangian (or water-following) flow, thereby 

representing potential larval pathways (Firing et al., 2004a). 

20 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Ocean Waves 

Common throughout the region and perhaps more significant as a natural process affecting the geology and 

ecology of the Monument, are the extra-tropical storms and significant wave events that regularly move across 

the North Pacific in the boreal winter (Friedlander et al., 2008, Grigg et al., 2008). Among each of the islands, 

atolls and submerged banks of the NWHI, the distributions of species of corals and algae, and their associated 

fish and invertebrate assemblages are often determined not only by the ocean currents, but also by the exposure to ocean waves. Many species of corals and algae can only survive in sheltered or quiescent habitats. 

Other species; however, can survive or even thrive in the high wave-energy habitats on the northwestern facing reefs that are exposed to tremendous waves caused by winter storms across the North Pacific. 

These large wave events, greater than 10 m, influence the growth forms and distribution of coral reef organisms (Dollar, 1982; Dollar and Grigg, 2004; Grigg et al., 2008) and affect the reproductive performance 

of winter-breeding seabirds nesting on 

low islets in the Monument. Most large 

wave events, 5 to 10 m, approach the 

NWHI from the west, northwest, north 

and northeast, with the highest energy 

generally occurring from the northwest 

sector. The southern sides of most of 

the islands and atolls of the NWHI are 

exposed to fewer and weaker wave 

events. Annually, mean wave energy 

and wave power (energy transferred 

across a given area per unit time) are 

highest (approximately 1.3 W/m) between November and March and lowest 

(approximately 0.3 W/m) between May 

and September (Figure 2.5). Extreme 

wave events, 10 m or higher, affect shallow water coral reef communities with at 

least an order of magnitude more energy than the typical winter waves (Grigg 

et al., 2008). 

Significant wave events vary over interannual and decadal time scales. This temporal variability of wave power 

allows expansions and retractions of the spatial and vertical ranges of the same species during relatively quiescent and turbulent years, respectively (Rooney et al., 2008). Over the past 20 years, wave measurements at 

NOAA buoy 51001 (near Nihoa Island in the NWHI) show a pattern of numerous extreme wave events during 

the periods 1985-1989 and 1998-2002 and low numbers of extreme wave events in the early 1980s and the period 1990-1996. This apparent decadal variability of wave power is possibly related to the PDO (Mantua et al., 

1997). Studies have shown decadal oscillations of various components of NWHI ecosystems (lobsters, monk 

seals, seabirds, etc.) relate to larger scale climate shifts across the North Pacific (Polovina et al., 1995). 

Primary Productivity / Ocean Color 

Productivity in the NWHI is influenced by local and regional factors, and upwelling may occur in response to 

localized wind and bathymetric features (Friedlander et al., 2005). The Monument is located at the northern 

edge of the oligotrophic tropical Pacific, in the North Pacific central gyre ecosystem (Figure 2.6). Regional factors are largely influenced by the position of the subtropical front and associated high chlorophyll content of 

waters north of the front (PMNM, 2008). High chlorophyll waters intersect the northern portions of the NWHI 

during southward winter migrations of the subtropical front. The influx of nutrients to the NWHI from these migrations is considered a significant factor influencing different trophic levels in the NWHI (Polovina et al., 1995). 

It is near the 18°C isotherm, a major ecological transition zone in the northern Pacific. This boundary, also 

known as the “chlorophyll front”, varies in position both seasonally and annually, occasionally transgressing the 

Figure 2.5. Diagram of Climatological values of wave power (W/m) derived

from NOAA buoy # 51001 located near Nihoa Island from 1981 to 2003. 

Blue circles represent monthly means; blue lines represent wave power

maxima. Source: NOAA NDBC. 

21 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monument boundary and surrounding 

the northern atolls of Kure and Midway 

(PMNM, 2008). 

Movement of this front influences overall 

ocean productivity, and resultant recruitment of certain faunal elements such as 

Hawaiian monk seals and Laysan and 

Black-footed Albatrosses (Polovina et 

al., 1994). The northernmost atolls also 

are occasionally affected by an episodic 

eastward extension of the Western Pacific warm pool, which can lead to higher summer ocean temperatures at Kure 

than are found in the more “tropical” 

waters of the MHI further south (Hoeke 

et al., 2006). This interplay of oceanography and climate is still not completely 

understood, but is a dynamic not seen 

in most other tropical atoll ecosystems. 

As a result, it provides a useful natural 

laboratory for understanding phenomena such as periodic coral bleaching and the effects of El Niño and La Niña ocean circulation patterns (see 

ocean temperature). 

Satellite observations of ocean color from the National Aeronautics and Space Administration’s (NASA) Seaviewing Wide Field-of-view Sensor (SeaWiFS) reveal a significant chlorophyll front associated with the subtropical front, with high chlorophyll north of the front and low oligotrophic waters south of the front. These 

observations reveal significant seasonal and interannual migrations of the front northward during the summer 

months and southward during the winter months (Seki et al., 2002). The southward migration of the subtropical front generally brings these high chlorophyll waters to intersect the northern portions of the NWHI. During 

some years, these winter migrations of the subtropical front extend southward to include the northern end of 

the NWHI. Additional evidence suggests decadal scale movements in the southward extent of the subtropical front. During periods when high chlorophyll waters intersect the NWHI, overall productivity of the affected 

reef ecosystems is expected to be elevated. Changes across many trophic levels of the NWHI ecosystem are 

believed to be associated with these migrations (Polovina et al., 1995). 

OCEAN REMOTE SENSING ANALYSIS: DATA AND METHODS 

This oceanographic assessment is based largely on data acquired from satellite and in situ sensors to characterize conditions for each of the management areas within the Monument, as well as the larger ecological 

region. For this report, the study area is defined as: north bounding coordinate – 45oN; south bound – 15oN; 

east bound – 145oW; and west bound – 175oE. Spatial patterns in the temperature, temperature fronts and 

chlorophyll were identified, as well as the variability in those patterns. Time series information was also extracted from the datasets to investigate trends at a variety of time-scales. 

The Monument includes 10 special management zones and eco-regions. These management regions are 

centered on relatively untouched islands, reefs and atolls that are home to thousands of species, some that 

are found nowhere else on earth. The oldest (approximately 28 million years old) and most northern are Kure 

Atoll, Midway Island and Pearl and Hermes Atoll. These three ecosystems are subject to similar oceanographic 

influences and will be analyzed together as the northern grouping. The adjacent, and next most southeasterly 

grouping – Lisianski Island, Laysan Island, Maro Reef and Gardner Pinnacles – lie along the same latitudiFigure 2.6. Diagram of Central Pacific Gyre. The North Pacific, California,

North Equatorial, and Kuroshio currents along with atmospheric winds generate the North Pacific Subtropical Gyre. The subtropical Convergence

Zone, an area where marine debris is known to accumulate, shifts seasonally between 23oN and 37oN latitude. 

22 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

nal zone and exhibit similar temperature 

and chlorophyll climatological profiles, 

as well as being subjected to similar 

current regimes. These will be analyzed 

together as the central group. The most 

southern and youngest (7-12 million 

years old) of the atolls are French Frigate Shoals, Mokumanamana Island, 

and Nihoa Island (Figure 2.7). These 

three experience milder SSTs, smaller 

temperature ranges through the year 

and are less impacted by winter storm 

waves. 

The study area encompasses a region 

much larger than the Monument boundaries so as to allow ecosystem-scale information to be included in management 

decisions. Much of the oceanographic 

variety in the region of the Monument 

happens well away from the atolls themselves. The northern group of atolls is 

the only which experiences extreme 

events and changes on a fairly regular 

basis. Even though the Monument itself 

is relatively calm compared to the ocean environment around it, the more extreme events of the central pacific 

influence the migration of fauna in and around the Monument atolls, and thus must be considered. 

Data Assembly and Processing 

The majority of remote sensing data products were obtained as monthly composites (mean), and subsequently 

processed into seasonal and interannual monthly means and medians. Seasonal means were calculated using the following constraints: winter (January, February, March); spring (April, May, June); summer (July, August, September); and fall (October, November, December). Production of a consistent time series of imagery 

in this manner allowed extraction of data from each source within regions of interest, and for regional averages 

within the bounds of the entire Monument. These time series were extracted for 10 locations in the study region (Figure 2.7, orange polygons), as well as the three regional groupings and the Monument as a whole for 

preliminary analyses of episodic, seasonal and interannual patterns. Interannual monthly means were then 

derived from the extracted time series. These data composites over the entire Monument, or for specific locations, were created to summarize trends and to highlight episodic and seasonal events useful for interpreting 

biogeographic patterns discussed later in this report. Time series images consist of all monthly mean or median data for each month over time. For example, the month of January has an image of mean chlorophyll for 

each of the years 1998 to 2007. These 10 monthly images are then averaged to obtain an interannual mean 

of chlorophyll. Monthly and seasonal anomaly images were produced to illustrate the differences between the 

long-term interannual mean and the monthly image. 

Chlorophyll 

Chlorophyll products were derived from data obtained from SeaWiFS. SeaWiFS data for research and educational applications have been available through the NASA since its launch in September of 1997 through 

December 2007. The sensor provides reliable daily observations for the United States at a nominal spatial 

resolution of 1.1 km for spectral bands encompassing the visible and near-infrared spectrum. The 4 km Global 

Area Coverage (GAC) product was used because data quality and density of the 1.1 km data was insufficient 

in the NWHI region (Figure 2.8). 

Figure 2.7. Locator map of the study area. Cross-hatched regions represent the northern, central, and southern analysis areas. 

23 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

The entire SeaWiFS GAC dataset was 

processed with SeaDAS version 5, applying the improved algorithms and 

obtaining georeferenced chlorophyll-a 

data at 4-km spatial resolution for the 

central Pacific region. Products were 

created for the central Pacific region 

specifically to include the boundaries 

of the Monument and also encompass 

the surrounding environment to allow 

management and scientific inquiry to include the greater ecosystem contextual 

processes. Estimations of chlorophyll-a 

in units of μg/L were derived using the 

standard OC4v4 equation that NASA 

used for global products from SeaWiFS. 

NOAA’s Center for Coastal Monitoring 

and Assessment (CCMA) has developed algorithms, implemented by NASA 

for standard processing, to improve the 

generation of ocean color data and estimation of chlorophyll from SeaWiFS 

(Stumpf et al., 2003). 

Chlorophyll-a is the dominant pigment in 

marine photosynthetic organisms, and 

is referred to simply as chlorophyll within this report. Time series image sets of chlorophyll were created for the 

specified regions in Geotiff format. These time series images are useful for determining trends in algal bloom 

activity and ocean productivity. Final products were projected using the Albers Conical Equal Area (ACEA) 

projection with the World Geodetic System 1984 (WGS-84) datum. The imagery time series generated from 

the SeaWiFS data are monthly medians. Seasonal means were created from the appropriate monthly median 

files resulting in a seasonal image (seasons previously defined), and interannual monthly and seasonal files 

were generated using all monthly images for a particular month (or season) in the time series as input. 

Sea Surface Temperature and Frontal Boundaries 

SST data were developed from the NASA Pathfinder Version 5.0 dataset. This dataset derives a climatological 

grade SST product from Advanced Very High Resolution Radiometer (AVHRR) imagery, which was generated 

from several NOAA Polar-orbiting Environmental Satellites between 1985 and the present. The Pathfinder 

dataset was calibrated for inter-comparison of the temperature data across the entire period, facilitating climate and other studies (NASA, 2004; NASA, 2005). Ocean fronts data, regions that delineate the boundary 

between different water masses, were obtained from the Geostationary Operational Environmental Satellite 

(GOES). 

Fronts were generated from GOES 2000-2006 hourly images (averaged to months) sampled to 4 km (Figure 

2.9). Fronts were identified in each image using an algorithm developed by Canny (1986). Front occurrences 

were tallied at each pixel location for a month, season or year as needed. Climatological means were also created. Data products were mapped and subset to the study area. Geotiffs were created using the ACEA projection with the WGS-84 datum (Figure 2.9). 

Spatial resolution of the Pathfinder data varies slightly with latitude, with a horizontal resolution of approximately 4 km at 35 degrees of latitude. Pathfinder is distributed along a 0.04 degree grid in Cartesian coordinates. 

The original global 4 km data were subset to the study area bounds. Geotiffs were created of the monthly mean 

time series (1985-2006) using the ACEA projection with the WGS-84 datum. SST image datasets were created 

from monthly means for the region; units are degrees Celsius (oC). 

Figure 2.8. Example Global Area Coverage (GAC) chlorophyll distribution 

throughout the study region (April 2004). Warm tones represent high chlorophyll, while cool tones represent lower estimated chlorophyll concentrations (Units are μg/L). 

24 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Ocean Currents 

The calculation of SSH is based on a 

reference ellipsoid. This reference ellipsoid is a raw approximation of Earth’s 

surface, a sphere flattened at the poles. 

This position is determined relative to 

an arbitrary reference surface, an ellipsoid. The satellite altitude above the 

reference ellipsoid (distance S) is available to within 3 cm. The SSH, is the 

range at a given instance from the sea 

surface to a reference ellipsoid. Since 

the sea depth is not known accurately 

everywhere, this reference provides accurate, homogeneous measurements. 

The sea level is simply the difference 

between the satellite height and the altimetric range. 

Merged sea surface height anomaly 

(SSHA) data from altimetry were obtained from Archiving, Validation and Interpretation of Satellite Data in Oceanography (AVISO) delayed time products of SSH generated from merged 

Topex/Poseidon (T/P), Jason-1/2, ERS-1/2 and ENVISAT missions. Merged SSHA data from altimetry were 

obtained from AVISO delayed time products of SSH generated from merged Topex/Poseidon (T/P), Jason1/2, ERS-1/2 and ENVISAT missions. Weekly (seven-day) and monthly averaged data were used. Monthly 

estimates of vertical SSH from mean sea level were obtained following a simple bin averaging technique. A 

calendar of monthly averaged SSHA data to dissect climatological patterns of space-time variability for the 

region of interest is shown. 

Post processing involved conversion from Network Common Data Format (NetCDF) format to raw binary 

image format, binning of weekly SSHA data, georeferencing and tiff generation of by-products. The binning 

procedure followed a simple arithmetic averaging technique to compute a monthly estimate of vertical SSH 

from mean sea level. Map projection is a 1/4° geographic (lat/long) projection grid, where number of values for 

X (found in file) = 1,080 and number of values for Y (found in file) = 720. Final georeferenced products were 

converted to 32 bit Geotiffs (v6). 8 bit Geotiffs were also created for reference. The time period for SSHA data 

analyzed here range from October 1992 to present. 

Winds 

NOAA’s National Centers for Environmental Prediction (NCEP) generates global wind data termed “reanalysis 

winds” which are processed using a state of the art analysis system, and are used primarily for long-term climate studies. The data were produced at a 2.5 degree spatial resolution. NCEP uses all available atmospheric 

data to model winds every six hours, and is available from January 1, 1948 through the present. Reanalysis 

winds are distributed in NetCDF, and have a time component, latitude, longitude, zonal component (u) and a 

meridional component (v). 

From the u and v wind components, direction (in degrees) and magnitude (in speed; m/s) can easily be derived. The data are available for 17 different pressure levels. To estimate the winds closest to the atmosphereocean interface we chose the highest pressure level (1,000 millibars). Using the six hour observations, NCEP 

calculates daily, monthly, and annual average and standard deviation reanalysis wind products. NOAA’s CCMA 

has created direction and speed images created as 32-bit Geotiffs in geophysical units primarily for qualitative 

assessment purposes and an 8-bit scaled Geotiff version primarily designed for quantitative assessments. 

Monthly, seasonal and annual means for the study region have been created in this fashion. 

Figure 2.9. Example average sea surface frontal boundaries for the region

(April, 2005). Dense clustering of boundaries, and lighter tones indicate

elevated frontal boundary detection. Note higher frontal activity in the northern and western reaches of the Monument. 

25 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

The monthly data from NASA’s Quick Scatterometer (QuikSCAT) was obtained and processed form from the 

French Institute for Exploring the Sea (IFREMER). Scatterometers, such as QuikSCAT, measure the roughness of the surface of the ocean, which in turn may be used as a proxy to estimate wind speed and direction. 

Scatterometer data are not available near or adjacent to land. The QuikSCAT NetCDF data files were generated from monthly data composites that covered the period ranging from August 1999 though February 2007. 

Seasonal and yearly climatological files were generated through the combination of monthly data composites 

that covered the period January 2000 though December 2006. The data were spatially subset to the study 

area at a spatial resolution of 0.5 degrees per pixel. Each file contained the following parameters: wind stress 

curl (Pa/m), wind speed divergence (m/s), wind speed (m/s), zonal wind speed (m/s), meridional wind speed 

(m/s), wind stress (Pa), meridional wind stress (Pa) and zonal wind stress (Pa; IFREMER, 2002). The resulting data files for each parameter were converted to 8-bit and 32-bit Geotiff format, in the same manner as the 

reanalysis wind products. 

OCEAN REMOTE SENSING ANALYSIS: RESULTS 

Sea Surface Temperature 

Latitude is a primary driver in oceanographic conditions of the Monument and SST is highly correlated with 

latitude. This is evident in the stratification of SST within the Monument moving from north to south. SST analysis suggests that the 10 management regions can be segregated into three latitudinal subgroups. Mean SST 

highs in August and September are similar for all of the regions, around 27oC, but lows in February and March 

are varied and highlight the latitudinal differences (Figure 2.10). 

The northern atoll group (Kure, Pearl and Hermes and Midway) has a wide range of temperatures throughout 

the year, typically from around 20oC in February to 27oC during the summer; however, temperatures have 

reached as low as 16oC and as high as 29oC. This range is one of the widest temperature ranges for any coral 

reef system on the planet (Friedlander et al., 2005). In addition, the northern islands are unexpectedly warmer 

in the summer than the most southern atolls of Nihoa, Mokumanamana and French Frigate Shoals. This northsouth temperature stratification results in a latitudinal partitioning of flora and fauna causing endemic species 

and species composition changes within the Monument (Polovina et al., 1995; Friedlander et al., 2005). 

Average monthly SST images clearly show the seasonal variation and north-south temperature gradient in the 

NWHI (Figure 2.11). The southern region experiences warmer temperatures compared to those in the north, 

but less variability throughout the year, while the northern atolls have much more variability within and between 

years (Figures 2.4 and 2.11). The southernmost island grouping (French Frigate Shoal, Mokumanamana Island, and Nihoa island) experience an environment with a restricted range in temperature when compared to 

islands to the north and west; approximately 23oC in the winter to 27oC in the summer. Summer SSTs for this 

group are generally lower than or the same as the northern atoll group. This is possibly due to weaker winds in 

the north, caused by proximity to the North Pacific high pressure ridge, resulting in less mixing with subsurface 

waters (Hoeke et al., 2006). 

Pattern and periodicity in SSTs within the Monument are remarkably stable from 1985-2006 (Figure 2.12). 

Anomalies are rarely more than a degree from the long-term mean and typically occur during the winter months 

(Figure 2.12). Wintertime negative temperature anomalies occurred in June 1987, May 1992, December 1996, 

February 1997 and June 1997, while positive anomalies occurred during the early spring in 1999, 2000 and 

2001 (Figure 2.12). These observed anomalous variations in SST are likely associated with the interactions 

and state of the PDO and ENSO and trend strongly towards the phase of the PDO, either warm or cold. There 

is less observed variability during the summer months; however, prolonged positive anomalies of 1oC during 

the warmest months are likely indicators of coral bleaching (Kenyon et al., 2006a; Kenyon and Brainard, 2006). 

Similar time-series analysis has been performed for data extracts from each of the 10 islands, atolls and special management areas. Results are provided in Appendix I. 

26 
Oceanographic and Physical Setting

Mokumanamana

Maro

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands Figure 2.10. Long-term average monthly SST derived from NASA Pathfinder AVHRR. SST imagery for climatological monthly mean in Monument region. Time series ranges from 1985-2006. 

27 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

28 

Figure 2.11. Monthly mean climatological SST, 1985-2006. Color bar is in degrees Celsius. Warm waters encompass the 

entire island chain in summer months but cooler waters intrude on the northern end of the Monument from November 

through May. 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

-2 

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Date 

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 (deg C) 

mean sst grand mean sst 

A

Figure 2.12. Panel A shows SST derived from NASA Pathfinder AVHRR imagery. Data from the entire Monument have 

been averaged to highlight temporal patterns from 1985 through 2006. Grand mean indicates the “climatological” average. Panel B shows temperature anomalies for the same period of record. Green bar indicates the range of one standard

deviation of the anomaly time series. Peaks that fall above or below this range can be considered departures from “expected” anomalies. 

NOAA led Pacific Reef Assessment and Monitoring Program expeditions to the NWHI documented the first 

recorded major bleaching events in the region. The NWHI were impacted by mass coral bleaching during 

late summer 2002 and again in 2004 principally due to a distinct region of higher than normal temperatures 

pervasive in the northern reaches of the Monument (Figure 2.13; Abey et al., 2003; Kenyon et al., 2006). No 

records of mass coral bleaching in the NWHI existed before this time. It was previously thought that the NWHI 

were less susceptible to bleaching due to the high latitude location whereas coral bleaching was documented 

in the MHI back in 1996 (Jokiel and Brown, 2004). During both events, bleaching was most severe at the three 

northern-most atolls (Pearl and Hermes, Midway and Kure), with lesser incidences of bleaching at Lisianski 

Island and farther south in the NWHI. SST data derived from both remotely sensed satellite observations as 

well as in situ buoys from the NOAA’s Coral Reef Early Warning System suggest that protracted, elevated SST 

was a likely explanation for the bleaching response. This period of elevated SST coincided with a prolonged 

period of light wind speed, suggesting increased stratification due to decreased wave mixing of the upper 

ocean (Hoeke et al., 2006). 

The time series analysis of SSTs data also suggests that two bleaching events may have occurred undetected 

in the summers of 1987 and 1991 (Figure 2.14). On these occasions, the northern atolls experienced temperature anomalies of 1oC or greater during the highest mean temperature months of August and September. 

Similar or larger positive anomalies have occurred in other regions and times but likely did not lead to coral 

bleaching because these events did not occur during peak temperature months. 

29 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands A B

+3 oC 

-3 oC 

Figure 2.13. SST Anomaly images for August 2002 (A) and September 2004 (B). These periods of anomalously high 

SSTs in the northern atolls have been associated with coral bleaching. Source: NOAA GOES Imager. 

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Kure Pearl and Hermes Midway 

AB

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30 

Figure 2.14. SST Anomaly images for September 1987 (A) and September 1991 (B). Distinct SST peaks in the northern 

atolls can be seen in the time series data (C). 
Oceanographic and Physical Setting

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 2.15. Average monthly sea surface frontal boundaries for the region. Dense clustering of boundaries, and lighter 

tones indicate elevated frontal boundary detection. Note higher frontal activity in the northern and western reaches of the

Monument. Color strip denotes calculated frontal probability. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Sea Surface Temperature Fronts 

Bottom topography, ocean current confluence, variable wind stress and heat-water exchange across the sea 

surface produces patterns of vertical circulation, fronts or eddy-like motions that can affect biological distributions (Kazmin and Rienecker, 1996; Polovina, et al., 2001; Nakamura and Kazmin, 2003). Fronts are created 

by a variety of physical processes and have a wide range of biological consequences. A frontal system denotes 

areas of water mass convergence and usually produces zones of downwelling and upwelling flow. These vertical displacements have considerable ecological effects because environmental gradients, such as light, pressure, temperature, salinity, oxygen, nutrients, etc., are steepest in the vertical axis of the water column. 

Vertical motion in fronts is often highly localized and can be easily identified with remote sensing techniques 

(Ullman and Cornillon, 1999). Areas with frontal activity tend to be areas of high biological activity (Polovina et 

al., 2001; Nakamura and Kazmin, 2003). The vigorous mixing of the water column at water mass confluence 

stimulates phytoplankton photosynthesis and sustains concentrations along the frontal zone (Savidge, 1976; 

Savidge and Foster, 1978). In response, zooplankton tend to concentrate along the fronts and are preyed upon 

by higher trophic groups. Marine birds, marine mammals and fish often aggregate at frontal areas as well. 

Tracking and catch studies have shown that key apex predators, swordfish, albacore tuna and loggerhead 

turtles, use these fronts for forage habitat on long distance migrations through the North Pacific (Bigelow et 

al., 1999; Laurs et al., 1984; Polovina, et al., 2001). Additionally, it has been shown that biological diversity is 

positively correlated with thermal fronts (Kazmin and Rienecker, 1996) 

SST fronts are an important marine ecological feature for the overall eco-region of the Monument and the 

dynamic environment created by the fronts support many species that reside near or in the Monument. Large, 

persistent front generating regions are important for species transiting through the Monument during migration. However, front concentration within the Monument is relatively low, reaching highest levels in spring and 

primarily in the northern end of the Monument where the subarctic and subtropical gyres interact. Consistent 

with SST observations, SST frontal data indicate a seasonal patterned and latitudinal division within the Monument. Figure 2.15 illustrates the north-south movement of frontal concentration throughout the year. The northern region of the Monument experiences an active frontal season from December through April, usually with 

a peak in March. Even during the peak frontal probability period the southern region experiences few fronts. 

In mid-summer the frontal activity zone retreats far enough north that even the most northern atolls may not 

experience any significant fronts. 

These pelagic habitats are poorly understood and warrant additional studies to improve the knowledge base 

for ecosystem management. It is possible with remotely sensed data to track these frontal zones over large, 

difficult to access regions through time. The interaction of these productive zones with the biota of the Monument may hold clues to long term sustainability of the Monument reef systems. 

31 
Oceanographic and Physical Setting

Necker

Marro

Mokumanamana

Maro

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

32 

Chlorophyll 

Chlorophyll concentrations are relatively low throughout the Monument, exhibiting oligotrophic characteristics 

common in open ocean environments. Even at these low levels, seasonal and latitudinal patterns are evident 

in both the chlorophyll images and the time series charts. The images shown in Figure 2.16 illustrates the temporal distribution of chlorophyll. This distribution is determined by the location of the convergence zones of the 

subarctic and subtropical gyres. A major area of productivity associated with this convergence area, referred 

to as the transition zone chlorophyll front (TZCF), contributes significantly to the variable productivity of the 

Monument region. 

Figure 2.16. Average monthly chlorophyll concentration (mg/m

3

) values for the study region. 

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Kure 

The TZCF is a high productivity zone in the open ocean used by many species as an important feeding and migration zone. The TZCF has been identified as a chlorophyll concentration of approximately 0.2 μg/L or greater 

as measured from satellite (Polovina, 2005). The TZCF only rarely transits far enough south during its winter 

southerly shift to interact directly with the northern regions of the Monument. Even in these instances chlorophyll concentrations within the Monument generally do not reach as high as 0.2 μg/L. However, both permanent and seasonal residents of the Monument do make use of this productive zone and more southern tracks 

of the TZCF have been correlated with higher fish catches in the Hawaiian Islands (Polovina et al., 2001). 

Coral reefs are also impacted by these occasional pulses of higher chlorophyll through population increases of 

the coral eating sea star, Acanthaster planci commonly known as the crown-of-thorns sea star (Hoeke et al., 

2006). These periodic increases in productivity within the Monument likely have meaningful consequences to 

management of the atolls and reefs of the Monument. 

Mean chlorophyll concentrations have cyclical temporal variability. Higher chlorophyll concentrations move 

south into the Monument boundaries during the winter months and retreat far north in the summer. The northern region experiences the largest variability in mean concentration from high season to low season ranging 

from highs of nearly 0.18 μg/L to lows below 0.06 μg/L. The central and southern regions exhibit a more constant environment with chlorophyll concentrations ranging between 0.07 and 0.11 μg/L. In addition to seasonal 

changes, the northern regions also exhibit high interannual variability in chlorophyll concentrations. The northern atolls experienced very low concentrations of chlorophyll in 1999, 2000 and 2001, but also relatively high 

concentration years in 1998, 2003, 2004 and 2005 (Figure 2.17). Note that even the highest mean monthly 
Oceanographic and Physical Setting



A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

chlorophyll concentration is below the threshold of 0.2 μg/L used to identify the biologically active TZCF. Timeseries analysis has been performed for chlorophyll data extracts from each of the analysis regions, and results 

are provided in Appendix II. 

While these values are low relative to coastal continental chlorophyll concentrations, these chlorophyll blooms 

offer sustenance to support a diverse community around the atolls of the Monument. The southern atoll group 

exhibits little variance through time and can be characterized as having generally low chlorophyll concentrations, usually between 0.06 and 0.09 μg/L. The central region exhibits slightly higher variability and a broader 

range in chlorophyll concentrations when compared to the south, likely owing to its position as a transition zone 

between the subarctic north and the subtropical south. 

Trends in chlorophyll concentration anomalies can be correlated with the PDO and ENSO via the multivariate 

ENSO index (MEI). Chlorophyll concentrates in the more northern atolls are positively correlated with the PDO 

index (ρ=+ 0.404) where as the southern atolls are negatively correlated (ρ=-0.02). The rank correlation compares the relative size and direction of the indicators. For example, in the northern regions from 1998-2002, 

relatively strong cool phase PDO index values (negative) are positively correlated with periods of relatively low 

chlorophyll concentration anomalies (Figure 2.18). This correlation is expected as a cool phase PDO is typically indicated by higher SSTs in the north central Pacific (Mantua et al., 1997), and warmer SSTs are associated 

with lower levels of chlorophyll production. An inverse relationship between chlorophyll concentrations and the 

PDO index in the southern atolls is explained by the typically cooler tropical waters in the eastern Pacific during 

cool phase PDO and the association of higher chlorophyll counts and cooler waters. Additionally, PDO effects 

are primarily seen in the more northern latitudes (Mantua et al., 1997), so an increasing strong relationship with 

increasing latitude is not entirely surprising. 

Figure 2.17. Time-series for chlorophyll (top) and chlorophyll (mg/m

3

) anomaly (bottom) in each analysis region of the

Papahanaumokuakea Marine National Monument (1997-2006). Source: SeaWiFS. 

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O

e

J

O

e

e

FF

Jun

O

F

Jun

O

F

Jun

O

F

Jun

PDO chl anom Poly. (chl anom) Poly. (PDO) Date 

140
 

120
 

100
 

80
 

60
 

40
 

20
 

0
 

7

8

8

8

9

9

9

0

0

0

1

1

1

2

2

2

3

3

3

4

4

4

5

5

5

6

6

6

7

-9

99

9

99

9

00

0

00

0

00

7 

0

00

0

0

0

0

00

0

0

0

0

00

ct

bunctbunctbunctbunctbunctbunctbunctbunctb-

-

e

ctb-

-

O

e

e

e

e

e

e

e

e

e

F

J

O

F

J

O

F

J

O

F

J

O

F

J

O

F

J

O

F

J

O

F

J

O

F

Jun

O

F

Jun

Date PDO chl anom Poly. (chl anom) Poly. (PDO) 

Figure 2.18. Plots of rank-ordered chlorophyll anomaly and PDO Index 1997-2007 values for the northern (top), central

(middle) and southern (bottom) regions of the Monument. Lines represent non-linear trends through the time-series to

highlight the degree and nature of correspondence. Poly is a 3rd order polynomial fit through each time-series (trend). 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

34 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Six El Niño events occurred during the time series analyzed here, including: 1987, late 1991- early 1992, late 

1997-early 1998, late 2002-early 2003, late 2004-early 2005 and late 2006 (National Weather Service, 2007). 

The 1997-1998 was possibly the most intense in the 20th century; however, the northern region of the NWHI 

were more strongly influenced by the weaker events of 2003, 2004 and 2005. This is possibly due to interactions between PDO and ENSO. The El Niño events are evident in the SST time series throughout the Monument but are particularly apparent in the chlorophyll time series of the northern atolls. The 1997-1998, 2003, 

2004 and 2005 El Niños led to much higher chlorophyll concentrations than normal in the northern half of the 

Monument. During El Niño events, the Aleutian Low pressure system is more intense and extends south into 

the Monument region, resulting in stronger winds, more mixing and cooler SSTs (Bromirski et al., 2005). La 

Niña phases of ENSO show opposite characteristics in the Monument region leading to warmer waters and 

lower chlorophyll concentrations. La Niña events occurred in 1988, early 1989, and late 1998-2000. The La 

Nina events produced slight decreases in chlorophyll, but not of the magnitude of increase seen in the El Niño 

years. 

Wind 

Winds of the NWHI are generally dominated by the Trades, a persistent system that blows from the northeast 

to the southwest. These winds move from the Americas to Asia between the equator and 30oN, and are remarkably consistent throughout the year. Meridional variability is relatively weak and is dominated by Coriolis 

Forces which set up the North Pacific Gyre. Meridional winds are defined as the directional component along 

the local meridian, and are positive if from the south, and negative if from the north. Likewise, the zonal wind 

component is positive if it blows from the west and negative if from the east (i.e., Westerlies). An analysis of 

wind data (1985-present) revealed strong NWHI zonal variability in the NWHI, and three distinct components 

in the region. 

The southerly portion of all monthly wind climatologies – from 15oN to approximately 30oN – is dominated by 

the trade winds which are associated with warmer air and the Pacific High Pressure System (Figure 2.19). 

North of the trade wind zone is a transitional area extending from approximately 30oN to 40oN of weak variable 

winds known as the North Pacific Doldrums, which ancient mariners referred to as the “Horse Latitudes”. In the 

northern portion of the study area (above 40°N), winds prevail out of the west southwest, which is associated 

with cooler air and dominated by the Aleutian Low pressure system. The location of the three respective areas 

migrates north and south seasonally, and is a major forcing function of regional oceanographic conditions. In 

addition to the analysis of monthly winds described above, average annual winds were calculated and analyzed for the study area. Most years exhibited only modest changes in interannual variability. The one notable 

exception was the intense El Niño event of 1997. Figure 2.20 shows the annual mean wind vectors from 1996, 

1997 and 1998, sequentially. The Trade Winds in the annual mean of 1997 a near full directional reversal. In 

1996 and 1998 the Trade Winds were out of the east northeast, as expected. In 1997; however, the winds were 

strongly blowing out of the south southwest. Also notable is that the general circular pattern of the winds, which 

typically form a gyre in the North Pacific, were absent. Throughout the analyzed region winds were out of the 

southwest which is a drastic difference from all other calendar years analyzed (1985-2007). 1997 also showed 

remarkable zonal variability along 30oN. West of -170o the magnitude of the winds were much less than they 

were to the east. 

Circulation around the high pressure is clockwise in the northern hemisphere and counterclockwise in the 

southern hemisphere. The high pressure in the center is due to the westerly winds on the northern side of the 

gyre and easterly trade winds on the southern side of the gyre. These cause frictional surface currents towards 

the latitude at the center of the gyre. The buildup of water in the center of the gyre creates equatorward flow in 

the upper 1,000 to 2,000 m of the ocean, through rather complex dynamics. This equatorward flow is returned 

poleward in an intensified western boundary current. The North Pacific Gyre comprises most of the northern 

Pacific Ocean, and occupies an area of approximately 34 million km2. The Gyre has a clockwise circular pattern and comprises four prevailing ocean currents: the North Pacific Current to the north, the California Current 

to the east, the North Equatorial Current to the south, and the Kuroshio Current to the west. 

35 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

36 

Jan Feb Mar 

Apr May Jun 

Jul Aug Sep 

Oct Nov Dec 

Figure 2.19. Long-term averaged monthly climatological wind data from 1948 through 2007 from the NCEP Reanalysis 

winds. Wind field data are superimposed on a false-color image of average monthly SSTs (warm tones=warm water, cool 

tones=cool water). Arrow size denotes relative wind strength. Source: AVHRR climatology. 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

1996 1997 1998 

Figure 2.20. Three examples of annual means (1996, 1997 and 1998) from the NCEP Reanalysis winds. The El Niño 

event from 1997 shows relatively drastic variability from the preceding and subsequent years. Arrow size denotes relative 

wind strength. 

Sea Surface Height and Currents 

The height of the sea surface is determined by the mass of water at a given location and by the water’s density 

(a function of temperature, salinity and pressure). Space based altimeters such as the Jason and Topex/Poseidon missions measures changes in SSH due to both of these factors - redistribution of mass and changes 

in density. On seasonal to interannual time-scales, density changes are the largest contributor to sea level 

variability. In the tropics they are the dominant one (Gilson et al., 1998). 

Ocean currents can increase SSH by up to a meter higher over the surrounding area. Currents can therefore 

be mapped by measuring height variations. A view of the global ocean circulation shows currents circulating 

around elevations and depressions in SSH. Currents flows around positive SSH in a clockwise direction in the 

Northern Hemisphere, and in a counterclockwise direction around negative SSH (the opposite occurs in the 

Southern Hemisphere). Figure 2.21 shows an example AVISO derived SSHA image for the study region during 

December 2005. Warm tones indicate regions of surface height elevation, while cool tones highlight surface 

depressions. Current vectors derived from SSHA are superimposed on the image to show modeled surface 

currents (geostrophic flow). As described, note the counterclockwise rotation around the blue tones. 

Numerous studies have summarized the positive association between SSH maximums and SST maximum in 

open ocean environments (Jones et al., 1998; Wilson and Coles, 2005; Fu 2004). Given the setting of the Monument in the middle of the Pacific Ocean, it is therefore not surprising that SSHA patterns correlate with SST 

seasonal patterns. The difference between the measurements is that SSH are more a measure of the heat 

(energy) that is stored in the ocean below while SST is a surface measurement that tells us about interactions 

with the atmosphere on a more immediate time scale (JPL). The ocean energy below the surface reflected in 

the SSHA influences surface events over much longer periods and areas. 

Localized and episodic SSHA events can be attributed more readily to wind events (Di Lorenzo et al. 2008; 

http://www.ig.utexas.edu/research/projects/od_sst/) but larger regional SSHA patterns are clearly tied to SST. 

The direct influence of SSHA on the atolls of the Monument can be found in generation of winds and a current 

related to transient local eddies and fronts (Seki et al., 2002). Mesoscale SSHAs can be used to identify areas 

of convergence that can indicate upwelling and productive ocean zones concentrating and attracting species 

throughout the food web (Seki et al., 2002). These mesoscale features are embedded in larger scale frontal 

zones that scan large quadrants of the Pacific Ocean and change over periods of months and years. The PDO 

is a long period ocean feature reflected in SSHA. The PDO waxes and wanes between cool and warm phases 

approximately every five to 20 years. In the cool phase, higher than normal SSH caused by warm water form a 

horseshoe pattern that connects the north, west and southern Pacific, with cool water in the middle (JPL). The 

NWHI lie along the typical boundary between cool and warm waters during a cool phase PDO. 

37 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

SSHAs in the Monument do have a seasonal signal with higher anomalies occurring in late summer and lows 

in the spring (Figure 2.22). The regional differences observed in the other oceanographic factors are not as 

pronounced with SSHA. The northern regions do experience a less pronounced swing in anomalies from high 

season to low season. 

Figure 2.21. Example sea surface height anomaly image and associated surface currents in the study region (December

2005). Red tones indicate “peaks”, while blue tones indicate “valleys”, and arrows indicate direction of flow. Muted polygons delineate Monument “Special Protection Areas”. 

Figure 2.22. Average monthly sea surface height anomaly (cm) for each region in the Monument.
 

38 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

EXISTING DATA GAPS 

Overall there is a need for basic information on spatial and temporal patterns of water movement, quality and 

characteristics within the NWHI at a range of scales. Moving forward it is important for resource managers to 

have a unified hydrodynamic model to describe connectivity, identify seasonal areas of oceanographic productivity, detect change in the pattern and scales of movement, dispersal and recruitment of living resources 

at various life stages, identify and document variability in larval and nutrients sources, understand debris dispersal and establish management units within the NWHI. Specific opportunities include research to improve 

the understanding of: 

• carbon, nitrogen and phosphorus in the ecosystem and the transfer to higher trophic levels; 

• community changes that will result from alterations to reef structure by major ocean/atmosphere events; 

• discerning anthropogenic impacts from natural variability of the physical ocean environment; 

• PDO/ENSO events and effects; 

• geomorphological and sedimentalogical processes affecting reefs and terrestrial areas; 

• dispersion patterns of key pollutants; and 

• physical and biological effects of extreme events on the ecosystem. 

CONCLUSIONS 

The Monument is a unique open ocean ecological observatory, relatively free from the activities of humans 

and so large it encompass multiple overlapping and interacting marine ecosystems. The Monument’s position 

near the shifting boundary of the oligotrophic North Pacific Central Gyre and the productive waters of the North 

Pacific Subpolar Gyre makes it an ecosystem that is influenced directly by climate systems that vary greatly in 

time, over years and decades, and space, over hundreds of kilometers. The atolls and islands are subject to 

typical yearly seasonal patterns as well as the larger climactic cycles of the PDO and the ENSO. 

The ecosystems of the Monument are linked by these circulation patterns but are also stratified by their distance from the frontal zone where the gyres meet. There are three latitudinal groups within the Monument 

bounds. The northern group, Kure, Midway and Pearl and Hermes; the central group, Lisianski, Laysan, Maro 

Reef and Gardener Pinnacles; and the southern group, French Frigate Shoals, Mokumanamana and Nihoa. 

These groups exhibit similarities in all the factors that were examined. The environmental factors examined in 

this report are all directly impacted by the changes in the basin wide circulation system. These linkages happen 

over monthly, seasonal, annual and longer term climactic time intervals. Examination of chlorophyll-a, SST, 

SST fronts, and SSHA over climatological and monthly periods make it clear that these factors are linked. 

In addition, these factors correlate with patterns and changes in climactic scale events such as the PDO and 

ENSO. These large-scale oceanographic forcing mechanisms change the characteristics of water temperature 

and productivity across the Pacific, and have a significant effect on the habitat range and movements of pelagic species in the NWHI. Tuna are often concentrated near islands and seamounts that create oceanographic 

divergence and convergence zones, which in turn tend to concentrate forage species (PMNM, 2008). Swordfish and numerous other pelagic species tend to concentrate along food-rich temperature fronts between cold 

upwelled water and warmer oceanic water masses (Polovina et al., 2001). These frontal zones also have been 

determined to function as migratory pathways for loggerhead sea turtles (Polovina et al., 2001, 2004). 

Hundreds of thousands of seabirds breed in the Monument and are primarily pelagic feeders. The fish and 

squid they consume are generally associated with schools of larger predatory fish described above. While both 

the predatory fish and the birds are capable of foraging throughout their pelagic ranges (which encompass 

the entire Monument and tropical Pacific Ocean), the birds are most successful at feeding their young when 

they can find schools of predatory fish within easy commuting range of the breeding colonies (Ashmole, 1963; 

Feare, 1976; Flint, 1991). 

39 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Recent analyses of SeaWiFS remotely-sensed ocean color data shows an expansion of low productivity ocean 

water worldwide (Polovina et al., 2008). This expansion of low chlorophyll water has reached the Hawaiian 

Archipelago and has implications for the productivity of the entire ecosystem. These oligotrophic areas are 

expected to continue to expand with future global warming forcing (Polovina et al., 2008). 

While there is well documented small-scale (i.e., local) variation in population structures (Ashmole and Ashmole, 1967; Boehlert, 1993; Johannes, 1981), the large-scale patterns in oceanography described in this 

chapter provide a dominant force in modulating these populations. Finer-scale, stochastic processes also operate within this climate driven construct. It is important to note that these processes cannot easily be resolved 

using remote sensing technologies (e.g., wind wakes, wake eddies, etc.), yet are what likely produce pelagic 

“habitat” conditions that attract individuals and sub-populations to a given region, island, atoll or pinnacle. The 

following chapters featured in this document will provide a more detailed view of the abundance, distribution 

and temporal “behavior” of biological populations inhabiting the NWHI. 

40 
Monthly Mean Sea Surface Temperature for Kure Atoll 1985-2006 

29.0 

28.0 

27.0 

26.0 

Jan-01Jul-01Jan-02Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Date mean sst grand mean sst 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

19.0 

18.0 

17.0 

16.0 

15.0 

SST (deg C) 

Anomaly Date 

Jul-01Jan-02Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Kure Atoll 1985-2006 

3.5
 

3
 

2.5
 

2
 

1.5
 

1
 

0.5 

0 

-0.5 

-1 

-1.5 

-2 

-2.5 

-3 

-3.5 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01

SST (deg C) 

Seasonal Mean Sea Surface Temperature for Kure Atoll 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

19.0 

18.0 

Date mean sst grand mean sst 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001Sum 2001Win 2002Sum 2002
Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

APPENDIX I. SEA SURFACE TEMPERATURE (AND RELATED) TIME SERIES PLOTS 

41 
Monthly Mean Sea Surface Temperature for Special Management Area 1985-2006 

29.0 

28.0 

27.0 

26.0 

Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02Jul-02Jan-03Jul-03Jan-04Jul-04Jan-05Jul-05Jan-06Jul-06 

Date 

mean sst grand mean sst Jan-86 Jul-86 Jan-87 Jul-87

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

19.0 

18.0 

17.0 

16.0 

Jan-85Jul-85

SST (deg C) 

Jan-04Jul-04Jan-05Jul-05Jan-06Jul-06

Monthly Mean Sea Surface Temperature Anomalies, Special Management Area 1985-2006 

3.5
 

3
 

2.5
 

2
 

1.5
 

1
 

0.5 

0 

-0.5 

-1 

-1.5 

-2 

-2.5 

-3 

-3.5 

-4 

-4.5 

Jul-87Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02Jul-02Jan-03Jul-03

Anomaly Anomal Date

Jan-85Jul-85Jan-86Jul-86Jan-87Jan-88

SST (deg C) 

Date mean sst grand mean sst Win1988 Sum 1988 Win 1989 Sum 1989 Win 1990 Sum 1990 Win 1991 Sum 1991 Win 1992 Sum 1992 Win 1993 Sum 1993 Win 1994 Sum 1994 Win 1995 Sum 1995 Win 1996

Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001Sum 2001Win 2002Sum 2002Win 2003Sum 2003Win 2004Sum 2004Win 2005Sum 2005Win 2006Sum 2006

Seasonal Mean Sea Surface Temperature for Special Management Area 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

19.0 

18.0 

Win 1986Sum 1986Win 1987Sum 1987

SST (deg C) 

Win1985Sum 1985

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

42 
Monthly Mean Sea Surface Temperature for Pearl and Hermes 1985-2006 

29.0 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

19.0 

18.0 

Jul-02Jan-03Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Date 

mean sst grand mean sst 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02

SST (deg C) 

Jan-03Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Pearl and Hermes 1985-2006 

3.5
 

3
 

2.5
 

2
 

1.5
 

1
 

0.5 

0 

-0.5 

-1 

-1.5 

-2 

-2.5 

-3 

-3.5 

Jul-00Jan-01Jul-01Jan-02Jul-02

Date Anomaly Anomal 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00

SST (deg C) 

mean sst grand mean sst 

Date 

Sum 2002Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


Seasonal Mean Sea Surface Temperature for Pearl and Hermes 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

19.0 

18.0 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001Sum 2001Win 2002

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

43 
Jul-02

Jan-03Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Date 

mean sst grand mean sst 

Monthly Mean Sea Surface Temperature for Lisianski Island 1985-2006 

29.0 

28.0 

27.0 

Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

Jan-85Jul-85

SST (deg C) 

Jan-03Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Lisianski Island 1985-2006 

2.5
 

2
 

1.5
 

1
 

0.5 

0 

-0.5 

-1 

-1.5 

-2 

-2.5 

Jul-01Jan-02Jul-02

Date Anomaly Anomal 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01

SST (deg C) 

Win 2002Sum 2002Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


Date mean sst grand mean sst 

Sum 2001

Seasonal Mean Sea Surface Temperature for Lisianski 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

44 
Monthly Mean Sea Surface Temperature for Laysan Island 1985-2006 

Jan-02Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Date 

mean sst grand mean sst 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01

29.0 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

SST (deg C) 

Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Laysan Island 1985-2006 

2.5
 

2
 

1.5
 

1
 

0.5 

0 

-0.5 

-1 

-1.5 

-2 

-2.5 

Jan-00Jul-00Jan-01Jul-01Jan-02Jul-02

Date Anomaly Anomal 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99

SST (deg C) 

Date 

mean sst grand mean sst 

Sum 2001Win 2002Sum 2002
Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


Seasonal Mean Sea Surface Temperature for Laysan Island 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

45 
Jan-02

Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Marro Reef 1985-2006 Maro

2.5
 

2
 

1.5
 

1
 

0.5 

0 

-0.5 

-1 

-1.5 

-2 

-2.5 

Date Anomaly 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01

SST (deg C) 

Sum 2001Win 2002Sum 2002
Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


Seasonal Mean Sea Surface Temperature for Marro Reef 1985-2006 Maro

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Date 

mean sst grand mean sst 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001

SST (deg C) 

Jan-02Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


mean sst grand mean sst Date 

Monthly Mean Sea Surface Temperature for Marro Reef 1985-2006 Maro

29.0 

28.0 

27.0 

Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

20.0 

Jan-85Jul-85

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

46 
Monthly Mean Sea Surface Temperature for Gardner Pinnacles 1985-2006 Jan-02

Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Date 

mean sst grand mean sst 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01

29.0 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

SST (deg C) 

Jul-02Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Gardner Pinnacles 1985-2006 

1.5 

1 

0.5 

0 

-0.5 

-1 

-1.5 

Jan-02

Date

Anomaly 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01

SST (deg C) 

Date mean sst grand mean sst 

Sum 2002
Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


Seasonal Mean Sea Surface Temperature for Gardner Pinnacles 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001Sum 2001Win 2002

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

47 
Jul-02

Jan-03Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Date mean sst grand mean sst 

Mean Sea Surface Temperature for French Frigate Shoals NMS 1985-2006 

29.0 

28.0 

27.0 

Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Jan-85Jul-85

SST (deg C) 

Jan-03Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Mean Sea Surface Temperature Anomalies, French Frigate Shoals 1985-2006 

1.5 

1 

0.5 

0 

-0.5 

-1 

-1.5 

Jul-01Jan-02Jul-02

Anomaly Date

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01

SST (deg C) 

Win 2002Sum 2002Win 2003
Sum 2003
Win 2004
Sum 2004
Win 2005
Sum 2005
Win 2006
Sum 2006


Date mean sst grand mean sst 

Sum 2001

Seasonal Mean Sea Surface Temperature for French Frigate Shoals 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

48 
Monthly Mean Sea Surface Temperature for Mokumanamana Island 1985-2006 

Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02Jul-02Jan-03Jul-03Jan-04Jul-04Jan-05Jul-05Jan-06Jul-06 

mean sst grand mean sst Date 

29.0 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Jan-85Jul-85Jan-86

SST (deg C) 

Jan-04Jul-04Jan-05Jul-05Jan-06Jul-06 

Monthly Mean Sea Surface Temperature Anomalies, Mokumanamana Island 1985-2006 

1.5 

1 

0.5 

0 

-0.5 

-1 

-1.5 

Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jan-00Jul-00Jan-01Jul-01Jan-02Jul-02Jan-03Jul-03

Date Anomaly 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89

SST (deg C) 

Date mean sst grand mean sst 

Win 2003Sum 2003Win 2004Sum 2004Win 2005Sum 2005Win 2006Sum 2006 

Seasonal Mean Sea Surface Temperature for Mokumanamana Island 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999Win 2000Sum 2000Win 2001Sum 2001Win 2002Sum 2002

SST (deg C) 

Win1985Sum 1985Win 1986

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

49 
Jan-01

Jul-01Jan-02Jul-02
Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature for Nihoa 1985-2006 

29.0 

28.0 

27.0 

Jan-00

Date 

mean sst grand mean sst 

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99Jul-00

SST (deg C)

26.0 

25.0 

24.0 

23.0 

22.0 

21.0 

Jan-01Jul-01Jan-02Jul-02
Jan-03
Jul-03
Jan-04
Jul-04
Jan-05
Jul-05
Jan-06
Jul-06


Monthly Mean Sea Surface Temperature Anomalies, Nihoa 1985-2006 

1.5 

1 

0.5 

0 

-0.5 

-1 

-1.5 

Jan-00Jul-00

Anomaly Date

Jan-85Jul-85Jan-86Jul-86Jan-87Jul-87Jan-88Jul-88Jan-89Jul-89Jan-90Jul-90Jan-91Jul-91Jan-92Jul-92Jan-93Jul-93Jan-94Jul-94Jan-95Jul-95Jan-96Jul-96Jan-97Jul-97Jan-98Jul-98Jan-99Jul-99

SST (deg C) 

Win 2001Sum 2001Win 2002Sum 2002Win 2003Sum 2003Win 2004Sum 2004Win 2005Sum 2005Win 2006Sum 2006

Date mean sst grand mean sst 

Win 2000Sum 2000

Seasonal Mean Sea Surface Temperature for Nihoa 1985-2006 

28.0 

27.0 

26.0 

25.0 

24.0 

23.0 

22.0 

Win1985Sum 1985Win 1986Sum 1986Win 1987Sum 1987Win1988Sum 1988Win 1989Sum 1989Win 1990Sum 1990Win 1991Sum 1991Win 1992Sum 1992Win 1993Sum 1993Win 1994Sum 1994Win 1995Sum 1995Win 1996Sum 1996Win 1997Sum 1997Win 1998Sum 1998Win 1999Sum 1999

SST (deg C) 

Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

50 
Oceanographic and Physical Setting

Mean Seasonal Chlorophyl for Kure 1997-2007

Date 

mean seasonal chl grand mean seasonal chl 

0.05 

0.07 

0.09 

0.11 

0.13 

0.15 

0.17 

0.19 

0.21 

0.23 

0.25 

Mean Seasonal Chlorophyll for Kure 1997-2007 

Fall 1997Spr 1998Fall 1998Spr 1999Fall 1999Spr 2000Fall 2000Spr 2001Fall 2001Spr 2002Fall 2002Spr 2003Fall 2003Spr 2004Fall 2004Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

Chl (ug/L) 

Monthly Median Chlorophyll for Kure 1997-2007 

0.25 

0.30 

Apr-05
Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date median chl grand mean chl 

Oct-97Jan-98Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05

0.20 

0.15 

0.10 

0.05 

Chl (ug/L)

51 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

APPENDIX II. CHLOROPHYLL (AND RELATED) TIME SERIES PLOTS 

Monthly Median Chlorophyll Anomaly, Kure 1997-2007 

-0.10 

-0.05 

0.00 

0.05 

0.10 

0.15 

Apr-05
Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

median monthly chl anomaly Date

Oct-97

Jan-98Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05

Chl (ug/L) 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Special Management Area 1997-2007 

0.19 

0.21 

0.23 

Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

median chl grand mean chl Date

Oct-97Jan-98

Apr-98Jul-98

Oct-98Jan-99

Apr-99Jul-99

Oct-99Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Oct-04Jan-05

Apr-05Jul-05

Oct-05Jan-06

0.17 

0.15 

0.13 

0.11 

0.09 

0.07 

0.05 

Chl (ug/L)

Mean Seasonal Chlorophyl for Special Management Area 1997-2007

Date 

mean seasonal chl grand mean seasonal chl 

0.05 

0.07 

0.09 

0.11 

0.13 

0.15 

0.17 

0.19 

Mean Seasonal Chlorophyll for Special Management Area 1997-2007 

Fall 1997

Spr 1998

Fall 1998

Spr 1999

Fall 1999

Spr 2000

Fall 2000

Spr 2001

Fall 2001

Spr 2002

Fall 2002

Spr 2003

Fall 2003

Spr 2004

Fall 2004

Spr 2005

Fall 2005

Spr 2006Fall 2006Spr 2007

Chl (ug/L) 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monthly Median Chlorophyll Anomaly, Special Management Area 1997-2007 

-0.08 

-0.06 

-0.04 

-0.02 

0.00 

0.02 

0.04 

0.06 

0.08 

0.10 

Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

median monthly chl anomaly Date

Oct-97

Jan-98

Apr-98Jul-98

Oct-98Jan-99

Apr-99Jul-99

Oct-99Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Oct-04Jan-05

Apr-05Jul-05

Oct-05Jan-06

Chl (ug/L) 

52 
Oceanographic and Physical Setting

Mean Seasonal Chlorophyl for Pearl and Hermes 1997-2007

Date 

mean seasonal chl grand mean seasonal chl 

Fall 2005Spr 2006Fall 2006Spr 2007

0.05 

0.07 

0.09 

0.11 

0.13 

0.15 

0.17 

0.19 

Mean Seasonal Chlorophyll for Pearl and Hermes 1997-2007 

Fall 1997

Spr 1998

Fall 1998

Spr 1999

Fall 1999

Spr 2000

Fall 2000

Spr 2001

Fall 2001

Spr 2002

Fall 2002

Spr 2003

Fall 2003

Spr 2004

Fall 2004

Spr 2005

Chl (ug/L) 

Monthly Median Chlorophyll for Pearl and Hermes 1997-2007 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

Apr-05Jul-05

Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date median chl grand mean chl 

Oct-97Jan-98

Apr-98

Jul-98

Oct-98Jan-99

Apr-99Jul-99Oct-99

Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Oct-04Jan-05

Chl (ug/L) 

53 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands Jul-05 Oct-05
 Jan-06
 Apr-06
 Jul-06
 Oct-06
 Jan-07
 Apr-07
 Jul-07
 

Monthly Median Chlorophyll Anomaly, Pearl and Hermes 1997-2007 

-0.08 

-0.06 

-0.04 

-0.02 

0.00 

0.02 

0.04 

0.06 

0.08 

0.10 

0.12 

Apr-05

Date 

median monthly chl anomaly 

Oct-97

Jan-98

Apr-98Jul-98

Oct-98Jan-99

Apr-99Jul-99

Oct-99Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Oct-04Jan-05

Chl (ug/L) 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Lisianski Island 1997-2007 

0.16 

0.18 

Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

median chl grand mean chl Date

Oct-97Jan-98Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05

0.14 

0.12 

0.10 

0.08 

0.06 

Chl (ug/L) 

Mean Seasonal Chlorophyl for Lisianski 1997-2007

Date 

median seasonal chl grand mean seasonal chl 

0.08 

0.09 

0.10 

0.11 

0.12 

0.13 

0.14 

Mean Seasonal Chlorophyll for Lisianski 1997-2007 

Fall 1997Spr 1998Fall 1998Spr 1999Fall 1999Spr 2000Fall 2000Spr 2001Fall 2001Spr 2002Fall 2002Spr 2003Fall 2003Spr 2004Fall 2004Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

Chl (ug/L) 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monthly Median Chlorophyll Anomaly, Lisianski Island 1997-2007 

-0.04 

-0.03 

-0.02 

-0.01 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date

median monthly chl anomaly 

Oct-97Jan-98

Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03
Apr-03
Jul-03
Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05

Chl (ug/L) 

54 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Laysan Island 1997-2007 

0.06 

0.08 

0.10 

0.12 

0.14 

0.16 

0.18 

Date median chl grand mean chl 

Oct-97Jan-98Apr-98

Jul-98Oct-98

Jan-99

Apr-99Jul-99Oct-99

Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Oct-04Jan-05

Apr-05Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Chl (ug/L)

Mean Seasonal Chlorophyl for Laysan 1997-2007

Date 

median seasonal chl grand mean seasonal chl 

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

0.13 

Mean Seasonal Chlorophyll for Laysan 1997-2007 

Fall 1997

Spr 1998

Fall 1998

Spr 1999

Fall 1999

Spr 2000

Fall 2000

Spr 2001

Fall 2001

Spr 2002

Fall 2002

Spr 2003

Fall 2003

Spr 2004Fall 2004

Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

Chl (ug/L) 

55 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monthly Median Chlorophyll Anomaly, Laysan Island 1997-2007 

-0.04 

-0.03 

-0.02 

-0.01 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date 

median monthly chl anomaly 

Oct-97Jan-98

Apr-98Jul-98Oct-98

Jan-99

Apr-99Jul-99

Oct-99Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04Oct-04

Jan-05Apr-05

Chl (ug/L) 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Marro Reef 1997-2007 

0.12 

0.13 

0.14 

Maro

Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date median chl grand mean chl 

Oct-97Jan-98Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05

Chl (ug/L) 

0.11 

0.10 

0.09 

0.08 

0.07 

0.06 

Mean Seasonal Chlorophyl for Marro 1997-2007 Maro

Date 

median seasonal chl grand mean seasonal chl 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

0.13 

Mean Seasonal Chlorophyll for Maro Reef 1997-2007 

Fall 1997Spr 1998Fall 1998Spr 1999Fall 1999Spr 2000Fall 2000Spr 2001Fall 2001Spr 2002Fall 2002Spr 2003Fall 2003Spr 2004Fall 2004Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

Chl (ug/L) 

Monthly Median Chlorophyll Anomaly, Marro Reef 1997-2007 

-0.04 

-0.03 

-0.02 

-0.01 

0.00 

0.01 

0.02 

0.03 

0.04 

Maro

Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07


Date median monthly chl anomaly 

Oct-97Jan-98Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05

Chl (ug/L) 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

56 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Gardner Pinnacles 1997-2007 

0.16 

0.14 

0.12 

0.10 

0.08 

0.06 

0.04 

OcJApr-98

J

OcJ

J

an-99

Apr-99JOc

J

Apr-00J

an-98

Oc

Apr-01J

OcJ

Apr-02J

an-00

J

J

an-01

Oc

Apr-03

OcJ

J

J

u

OcJ

u

u

OcJJJ

u

u

OcJ

u

u

u

uu

t-97

l-98

t-98

l-99

t-99

l-00

t-00

l-01

t-01

an-02

l-02

t-02

an-03

l-03

t-03

an-04

Apr-04

l-04

t-04

an-05

Apr-05

l-05

t-05


an-06


Apr-06


l-06


t-06


an-07


Apr-07


l-07
 

Date median chl grand mean chl 

Chl (ug/L) 

Mean Seasonal Chlorophyl for Gardner Pinnacles 1997-2007

Date 

median seasonal chl grand mean seasonal chl 

Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

0.06 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

Mean Seasonal Chlorophyll for Gardner Pinnacles 1997-2007 

Fall 1997

Spr 1998

Fall 1998

Spr 1999

Fall 1999

Spr 2000

Fall 2000

Spr 2001

Fall 2001

Spr 2002

Fall 2002

Spr 2003

Fall 2003

Spr 2004

Fall 2004

Chl (ug/L) 

57 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monthly Median Chlorophyll Anomaly, Gardner Pinnacles 1997-2007 

-0.03 

-0.02 

-0.01 

0.00 

0.01 

0.02 

0.03 

0.04 

Oct-04Jan-05Apr-05

Jul-05

Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date 

median monthly chl anomaly 

Oct-97Jan-98

Apr-98Jul-98

Oct-98Jan-99

Apr-99Jul-99

Oct-99Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03

Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Chl (ug/L) 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for French Frigare Shoals 1997-2007

0.14 

0.16 

Monthly Median Chlorophyll for French Frigate Shoals 1997-2007 

Date median chl grand mean chl 

Oct-97Jan-98Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05Jul-05Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

0.12 

0.10 

0.08 

0.06 

0.04 

Chl (ug/L)

Mean Seasonal Chlorophyl for French Frigate Shoals 1997-2007

Date 

median seasonal chl grand mean seasonal chl 

Spr 2004Fall 2004Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

0.06 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

Mean Seasonal Chlorophyll for French Frigate Shoals 1997-2007 

Fall 1997

Spr 1998Fall 1998Spr 1999Fall 1999Spr 2000Fall 2000Spr 2001Fall 2001Spr 2002Fall 2002Spr 2003Fall 2003

Chl (ug/L) 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monthly Median Chlorophyll Anomaly, French Frigate Shoals 1997-2007 

-0.04 

-0.02 

0.00 

0.02 

0.04 

0.06 

0.08 

Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05Jul-05Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date 

median monthly chl anomaly 

Oct-97Jan-98

Apr-98Jul-98Oct-98Jan-99Apr-99Jul-99Oct-99Jan-00Apr-00Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02

Chl (ug/L)

58 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Necker Island 1997-2007 Mokumanamana 1997-2007 

Date median chl grand mean chl Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Oct-99 Jan-00 Apr-00 Jul-00 Oct-00 Jan-01 Apr-01 Jul-01 Oct-01 Jan-02 Apr-02 Jul-02 Oct-02

Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05Jul-05Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

0.18 

0.16 

0.14 

0.12 

0.10 

0.08 

0.06 

Oct-97Jan-98Apr-98

Chl (ug/L) 

Monthly Median Chlorophyll Anomaly, Necker Island Mokumanamana 1997-2007 1997-2007

Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date 

median monthly chl anomaly Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Oct-99 Jan-00 Apr-00

Jul-00Oct-00Jan-01Apr-01Jul-01Oct-01Jan-02Apr-02Jul-02Oct-02Jan-03Apr-03Jul-03Oct-03Jan-04Apr-04Jul-04Oct-04Jan-05Apr-05Jul-05

0.08 

0.06 

0.04 

0.02 

0.00 

-0.02 

-0.04 

Oct-97Jan-98

Chl (ug/L) 

Date 

median seasonal chl grand mean seasonal chl 

Mean Seasonal Chlorophyl for Necker Island 1997-2007 

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

0.13 

0.14 

Fall 1997Spr 1998Fall 1998Spr 1999Fall 1999Spr 2000Fall 2000Spr 2001Fall 2001Spr 2002Fall 2002Spr 2003Fall 2003Spr 2004Fall 2004Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

Chl (ug/L) 

59 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 
Oceanographic and Physical Setting

Monthly Median Chlorophyll for Nihoa 1997-2007 

0.14 

0.16 

median chl grand mean chl Date

Oct-97Jan-98Apr-98Jul-98Oct-98

Jan-99

Apr-99Jul-99Oct-99

Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03Apr-03Jul-03

Oct-03Jan-04

Apr-04Jul-04

Oct-04
Jan-05
Apr-05
Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

0.12 

0.10 

0.08 

0.06 

0.04 

Chl (ug/L) 

Mean Seasonal Chlorophyl for Nihoa 1997-2007

Date 

median seasonal chl grand mean seasonal chl Spr 1999 Fall 1999 Spr 2000 Fall 2000 Spr 2001 Fall 2001 Spr 2002

Fall 2002

Spr 2003Fall 2003

Spr 2004

Fall 2004Spr 2005Fall 2005Spr 2006Fall 2006Spr 2007

0.05 

0.06 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

0.13 

0.14 

Mean Seasonal Chlorophyll for Nihoa 1997-2007 

Fall 1997

Spr 1998

Fall 1998

Chl (ug/L) 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Monthly Median Chlorophyll Anomaly, Nihoa 1997-2007 

-0.03 

-0.02 

-0.01 

0.00 

0.01 

0.02 

0.03 

0.04 

0.05 

0.06 

Oct-98Jan-99

Apr-99Jul-99Oct-99

Jan-00

Apr-00Jul-00

Oct-00Jan-01

Apr-01Jul-01

Oct-01Jan-02

Apr-02Jul-02

Oct-02Jan-03
Apr-03
Jul-03


Oct-03Jan-04

Apr-04Jul-04

Oct-04
Jan-05
Apr-05
Jul-05
Oct-05
Jan-06
Apr-06
Jul-06
Oct-06
Jan-07
Apr-07
Jul-07
 

Date median monthly chl anomaly 

Oct-97Jan-98

Apr-98Jul-98

Chl (ug/L) 

60 
Oceanographic and Physical Setting

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

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63 

Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Geology and Benthic Habitats 

Jonathan Weiss1,2, Joyce Miller1,3, Emily Hirsch1,4, John Rooney1, Lisa Wedding5,6 and Alan Friedlander6,7 

INTRODUCTION AND ORIGIN 

The Northwestern Hawaiian Islands 

(NWHI) are in the middle section of the 

6,126 km long Hawaiian–Emperor seamount chain, considered to be the longest mountain chain in the world (Grigg, 

1983; Figure 3.1). Over many millions 

of years, a relatively stationary plume of 

hot mantle, or hot spot, located below 

the floor of the Pacific Plate (Grigg 1982, 

1997; Rooney et al., 2008) has and continues to erupt at the seafl oor creating 

a chain of volcanoes that comprise the 

islands, banks, atolls and seamounts 

of the Hawaiian Archipelago (Figure 

3.2). Each begins as a small submarine volcano and over time can grow to 

reach well above sea level. Eventually 

the volcanoes cool and subside as they 

slowly move away from the hot spot in a 

northwestward direction at about 8 cm/ 

yr (Clague and Dalrymple, 1987). 

The tops and edges of the volcanoes, 

if they are at or near sea level, support 

large and diverse coral reef communities. As the volcanic edifi ce subsides, 

an atoll can form as reef builders keep 

the top of the volcano near sea level by 

growing vertically and creating a thick 

carbonate cap. The Darwin Point marks 

the threshold where vertical growth, or 

net accretion, of reef building organisms 

is zero or negative and the atoll drowns 

and becomes a guyot (Figure 3.3; Grigg 

et al., 2008). This point, named after 

Charles Darwin, who first proposed an 

evolutionary model for atoll formation in 1836, marks a significant milestone in the life of a Hawaiian volcano. 

Currently Kure Atoll lies very near its Darwin Point. It is the oldest Hawaiian island still above sea level although 

it consists of only 1 km2

 of emergent land and 66 km2 of lagoon (Juvik and Juvik, 1998). Dozens of seamounts 

and guyots extend from north of Kure to the Aleutian Trench and mark the ancient remnants of volcanoes similar to those that comprise the Hawaiian Archipelago (Davies et al., 1972). 

Figure 3.1. Oblique southern perspective of the bathymetry of the Pacific 

plate between Hawaii and the Aleutian Islands constructed to show the Hawaiian-Emperor Seamount chain and the progressive subsidence of each

volcano over time. Sources: Neall and Trewick 2008; image prepared by 

Jon Procter. 

Figure 3.2. The island of Hawaii currently sits over the hot spot that has

formed the Hawaiian Archipelago over tens of millions of years. Photo: Hawaii Volcano National Park. 

1. NOAA/NMFS/Pacific Islands Fishery Science Center, Coral Reef Ecosystem Division

2. University of Hawaii Department of Geology and Geophysics

3. Joint Institute for Marine and Atmospheric Research

4. Aquatic Farms Ltd.

5. University of Hawaii at Manoa

6. NOAA/NOS/NCCOS/CCMA Biogeography Branch

7. The Oceanic Institute 

65 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

General Description of the Archipelago 

The youngest and largest of the emergent Hawaiian Islands is the island of 

Hawaii, which is composed of fi ve volcanoes including the currently active 

Kilauea Volcano and Mauna Loa and 

Mauna Kea, which are the two massive 

shield volcanoes that form the bulk of 

the island (Figure 3.4). They both extend 

from the seafloor at >5,000 m below sea 

level to >4,000 m above sea level and 

Mauna Kea is the single largest mountain on Earth. Loihi is the youngest 

submarine volcano in the archipelago 

and is located 30 km southeast of Hawaii Island. Northwest of Hawaii Island 

the islands of Maui, Lanai, Kahoolawe 

and Molokai, make up the island cluster known as “Maui Nui”. The highest 

point in Maui Nui is Haleakala volcano 

on Maui at 3,055 m. Further northwest 

is Oahu, the most densely populated island in the chain. Kauai, the Garden Isle, is approximately 5.1 million years old and is deeply eroded with lush 

vegetation and steep cliffs (Juvik and Juvik, 1998). Niihau and Lehua, which lie 27.7 km southwest of Kauai, 

are far drier than their larger and higher elevation neighbor, Kauai. Lehua is a private island inhabited by an 

isolated population of native Hawaiians and access to the island is strictly controlled. Kaula Rock, an uninhabFigure 3.3. Reef accretion across the Hawaiian Archipelago. Note that the 

net accretion rate diminishes to zero just beyond Kure Atoll, thereby defining a threshold for atoll formation known as the Darwin Point beyond which

atolls drown. Source: Grigg, 1997; image: S. Hile. 

66 

Figure 3.4. Islands, banks and atolls of the Hawaiian Archipelago. 
Geology and Benthic Habitats

Table 3.1. Area mapped by aggregated habitat cover type and geographic 

scale (km2) based upon IKONOS satellite imagery. Source: NOAA, 2003. 

AREA AREA (km2

) ISLAND LAND AREA (km2

) (km2) <10 <100 FM FM 

Kaula 0.6 0 70.5 

Bank E of Nihoa Submerged 0 146.9 

Nihoa 0.7 5.6 570.8 

Bank SW of Nihoa Submerged 0 336.2 

Bank NW of Nihoa Submerged 0 63.8 

Twin Banks Submerged 2.3 72 

Mokumanamana 0.2 9.1 1,557.2 

French Frigate Shoals 0.2 469.4 943.4 

Southeast Brooks Bank 1 Submerged 0 29.4 

Southeast Brooks Bank 2 Submerged 0 142.3 

Southeast Brooks Bank 3 Submerged 0 158.5 

Southeast Brooks Bank 4 Submerged 0 3.4 

Brooks Bank NW of St. Submerged 0 67.8 

Rogatien 

St Rogatien Bank Submerged 0 383.1 

Gardner Pinnacles 0.02 0.7 2,446.6 

Raita Bank Submerged 16 571.1 

Maro Reef Awash 217.5 1,935.3 

Laysan Island 4.1 26.4 584.5 

Northhampton Seamounts (4) Submerged 0 404.3 

Pioneer Bank Submerged 0 434.6 

Lisianski Island/Neva Shoal 1.5 215.6 1,246.6 

Bank NW of Lisianski Submerged 0 106.7 

Bank SSE of Pearl and Submerged 0 5.5 

Hermes 

Bank ESE of Pearl and Submerged 0 4.8 

Hermes 

Pearl and Hermes Atoll 0.3 374.5 816.6 

Salmon Bank Submerged 0 163.2 

Gambia Shoal Submerged 0 0.5 

Ladd Seamount Submerged 54.2 144.1 

Midway Atoll 64 85.4 344.1 

Nero Seamount Submerged 25 71.8 

Kure Atoll 1.0 90.2 

Bank W of Kure Submerged NA NA 

TOTAL AREA 1,591.9 13,805.6 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

ited island southwest of Niihau, marks

the transition between the main or windward islands and the northwestern or

leeward islands. The two thousand km

of ocean between Kaula Rock and Kure 

Atoll separates the 10 islands and atolls 

in the NWHI and a few small emergent

pieces of land with a total area of just

over 15 km2 (Juvik and Juvik, 1998).

Northwest of Mokumanamana and Nihoa, are remnant basaltic pinnacles including La Perouse Pinnacle at French

Frigate Shoals and the Gardner Pinnacles. The maximum elevation of the

islands northwest of Gardner Pinnacles 

does not exceed 12 m and on some

atolls or islands only reaches 3 m. 

Table 3.1 shows the land areas of all

emergent islands in the NWHI, as well

as the submerged marine area encompassed by the 10-fathom (18.29 m) and

100-fathom (182.9 m) isobaths. Within

10 fathoms total shallow water habitats

constitute 1,595 km2, including the area

within lagoons. The area of shallow water habitats within the 100 fathom isobath 

is 13,771 km2. However, these numbers 

are representative of a two dimensional

surface and do not truly convey the surface area of the benthos, which, due to

the 3-D topographic complexity of the

seafloor, is actually substantially greater. 

Accurate bathymetric data for the NWHI 

are being collected and synthesized by

the NOAA Coral Reef Ecosystem Division, the Hawaii Mapping Research

Group, Joint Institute for Marine and Atmospheric Research (JIMAR), and the

Hawaii Undersea Research Laboratory,

at the University of Hawaii’s School of

Ocean and Earth Science and Technology. 

Pre-Holocene Reef History 

The Hawaiian–Emperor chain includes at least 129 massive shield volcanoes that formed over the past 85 million years, with volcano ages generally decreasing in age towards the southeast (Jackson et al., 1975; Clague, 

1996). The overall age progression of the islands has been confirmed by several studies using radiometric 

isotopes to date volcanic rocks from islands and seamounts along the chain (Table 3.2; Clague and Dalrymple, 

1987; Garcia et al., 1987) although suitable samples for dating many of the NWHI are difficult to obtain. It has 

been proposed that the frequency of volcano formation has increased over time based on the decrease in 

volcano spacing over time. It has also been proposed that the islands at the younger end of the chain are also 

significantly higher than those formed earlier (Clague, 1996). 

67 
Geology and Benthic Habitats

Table 3.2. Characteristics of the islands, atolls, and some submerged banks in the NWHI , listed in order from the northwest down to the southeast. Note that most of the subaerially exposed islands, sea stacks, and atolls are surrounded by

extensive shallow banks. Island ages are from Clague (1996), with values in brackets from K-Ar dated basalt samples,

and other ages estimated from geophysical calculations. Lagoon water volumes are from Hoeke et al., 2006. 

REEF BACK- LAGOON EMER- REEF/ SUMMIT ISLAND, ATOLL OR TYPE OF HABITAT LONGITUDE LATITUDE AGE (MA) GENT LAGOON DEPTH BANK FEATURE <100 m LAND VOLUME (m) (km2

) (km2

) (103 m3) 

Kure Atoll Closed atoll 178° 19.55’ 28° 25.28’ 29.8 0.86 167 141,000 -

Nero Seamount Bank 177° 57.07’ 27° 58.88’ 29.1 0.00 17 - 68 

Midway Atoll Closed atoll 177°22.01’ 28° 14.28’ [27.7], 28.7 1.42 223 213,000 -

Pearl and Hermes Atoll Closed atoll 175° 51.09’ 27° 51.37’ [20.6], 26.8 0.36 1,166 2,930,000 -

Lisiankski Island Neva Open atoll 173° 58.12’ 26° 4.2’ 23.4 1.46 979 242,000 - Shoal 

Pioneer Bank Bank 173° 25.58’ 26° 0.71’ 22.8 0.00 390 - 26 

North Hampton Bank 172° 14.08’ 25° 26.84’ [26.6], 21.4 0.00 430 - 5 Seamounts 

Carbonate Laysan Island 171° 44.14’ 25° 46.13’ [19.9], 20.7 4.11 57 3,600 - island 

Maro Reef Open atoll 170° 38.34’ 25° 30.2’ 19.7 0.00 1,508 611,000 -

Raita Bank Bank 169° 30.04’ 25° 31.72’ 17.9 0.00 650 - 16 

Basalt sea Gardner Pinnacles 167° 59.82’ 25° 0.04’ [12.3], 15.8 0.02 1,904 - - stacks 

St. Rogoties Banks Banks 164° 7.26’ 24° 20.0’ 14.7 0.00 500 - 22 

Brocks Banks Banks 166° 49.31’ 24° 7.03’ [13.0], 13.6 0.00 320 - 20 

French Frigate Shoals Open atoll 166° 10.75’ 23° 45.99’ 12.3 0.23 733 1,910,000 -

Bank 66 Bank 165° 49.37’ 23° 51.86’ 11.9 0.00 0 - 120 

Mokumanamana Basalt island 164° 41.90’ 23° 34.64’ [10.3], 10.6 0.21 1,538 64.2 -

Twin Banks Bank 163° 3.78’ 23° 13.08’ 8.7, 8.3 0.00 9.5 - 53 

Nihoa Island Basalt island 161° 55.25’ 23° 3.73’ [7.2], 7.3 0.82 246 - -

Figure 3.5. Latitudinal variations in coral colony growth rates and reef accretion across the Hawaiian Archipelago. Source: Grigg, 1982. 

14 

/yr)m

12 

te (m10 

a

8 

 Rthw

6 

roral G

4 

o

2 

C

0 

Kure FFS Oahu Hawaii 

1.65 

) 

1.60 

3 mm1.55 g/

1.50 

m (yti 1.45 ns

1.40 

De

1.35 

1.30 

Kure FFS Oahu Hawaii 

/yr) 16 2 /m

14 

3 O

12 

Ca C10 (kg

8 

ccretion

6 

4 

eef A

2 

0 

R

Kure FFS Oahu Hawaii

12 

/yr) 

10 

m (m

8 

ccretion

6 

ral A

4 

o

2 

C

0 

Kure FFS Oahu Hawaii 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

68 

Holocene Reef Development 

Using values of island-specific coral community measures from Grigg

(1982), vertical rates of reef accretion

can also be estimated and are shown

for four islands in Figure 3.5. As the figure suggests, Grigg (1982) found that

growth rates show a strong latitudinal

dependence, with corals in cooler more 

northerly islands growing more slowly.

He also noted that, based on the work of 

Gross et al. (1969), at least at the more 

northerly atolls the carbonate contribution from coralline algae is likely to be 

significantly more than that from corals. 
Geology and Benthic Habitats

Table 3.3. Area in the NWHI mapped by aggregated habitat cover type 

based upon IKONOS satellite imagery. Source: NOAA 2003. 

AGGREGATED HABITAT COVER TYPE AREA PERCENT 

MAPPED TOTAL 

Hardbottom with >10% live coral 108.8 4.61 

Hardbottom with >10% crustose coralline algae 7.3 0.31 

Hardbottom (uncolonized) 101.4 4.30 

Hardbottom with >10% macroalgae 105.2 4.46 

Hardbottom with indeterminate cover 822.8 34.85 

Unconsolidated with 10% or less macroalgae or 1,149.6 48.70 

seagrass 

Unconsolidated with >10% macroalgae or 65.8 2.79 

seagrass 

Total Habitat Area Classified 2,360.8 100.00 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

BENTHIC HABITAT MAPPING 

Potential Reef Area 

Geographic information system-based

analyses were used to derive comprehensive, consistent estimates of the

potential area of broadly defi ned, shallow-water, tropical and subtropical coral 

ecosystems within the territorial sea and 

exclusive economic zone of the United

States (Rohmann et al., 2005). Nautical 

charts, published by NOAA’s Offi ce of 

the Coast Survey, provide a consistent

source of 10-fathom (ca.18 m) and 100­

fathom (ca. 183 m) depth curve information. The 10-fathom or 100-fathom

depth curves are used as surrogates for 

the potential distribution and extent of

shallow-water coral ecosystems in tropical and subtropical U.S. waters (Figure 3.6). The NWHI constitute between 

4.3% and 12.6% of the total U.S. potential coral reef ecosystem area within 10 

fathoms, depending on inclusion versus 

exclusion of the west Florida shelf area 

(Rohmann et al., 2005). The NWHI constitute 9.6% of the total U.S. potential

coral reef ecosystem area within 100

fathoms, with the inclusion of the west

Florida shelf area (Rohmann et al.,

2005). 

NOAA Mapping Programs 

In support of the U.S. Coral Reef Task 

Force’s mission to “Produce comprehensive digital maps of all shallow (<30 

m) coral reef ecosystems in the United 

States and characterize priority moderate-depth reef systems by 2009,”

NOAA has developed a comprehensive 

mapping program in the Pacifi c Region 

using IKONOS satellite imagery in

shallow water (<30 m) and multibeam 

sonar technology in depths as deep 

as 3,000 m (Table 3.3). In intermediate 

depths (10-30 m) IKONOS and multibeam mapping techniques can provide 

complementary or overlapping coverage. In addition, IKONOS images can 

be used to create “estimated depths” 

to fill bathymetric gaps in very shallow 

water (<15 m) where multibeam vessels cannot safely survey (Stumpf and 

Holderied, 2003). 

Figure 3.6. Potential reef area from the shoreline to 10-fathoms (top) and

100-fathoms (bottom) based on NOAA nautical charts. Source: Rohmann 

et al., 2005. 

69 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

70Geology and Benthic Habitats

Shallow Water IKONOS Satellite Mapping

NOAA’s Biogeography Branch has

sponsored a shallow water (0-30 m)

benthic habitat mapping program using IKONOS satellite imagery, which in

2003 produced the Atlas of the ShallowWater Benthic Habitats of the Northwestern Hawaiian Islands (available at

http://ccma.nos.noaa.gov/ecosystems/

coralreef/nwhi/welcome.html). IKONOS

high-resolution satellite imagery was

used to derive benthic habitat maps,

estimated depth, and the color images.

The detailed benthic habitat classification scheme was designed to categorize

benthic habitat by substrate category

(e.g., unconsolidated and hardbottom),

structure (e.g., linear reef or pavement)

and cover (e.g., coral or macroalgae;

Figure 3.7, Table 3.4; http://biogeo.nos.

noaa.gov). Of the area mapped, 49%

was unconsolidated sediment while

35% was indeterminate.

Moderate-Depth Multibeam Mapping

NOAA’s Coral Reef Ecosystem Division (CRED) initiated a moderate-depth multibeam mapping program 

which was conceived in 2001, implemented between 2002 and 2005, and has produced over 45,000 km2

 of 

bathymetric data in the NWHI since 2002 (Table 3.5; Miller et al., 2003). This mapping program is designed to 

extend and be complementary to the shallow-water IKONOS mapping program discussed above.

In 2002 multibeam surveys to define 25, 50, and 100-fm isobaths in the NWHI were conducted by NOAA 

and University of Hawaii (UH) personnel aboard UH’s R/V Kilo Moana, using Kongsberg/Simrad EM1002 

Table 3.4. Area mapped by aggregated habitat cover type and geographic scale (km2) based upon IKONOS satellite 

imagery. Source: NOAA, 2003.

TOTAL KURe 

ATOLL

MIDwAy 

ATOLL

PeARL & 

heRMes 

ATOLL

LIsIAnsKI 

IsLAnD

LAysAn 

IsLAnD

MARO 

Reef

fRench 

fRIgATe 

shOALs

MOKUMAnAMAnAnIhOA 

IsLAnD

Hardbottom with >10% 

live coral 1.8 1.4 20.3 16.4 5.8 14.8 48.3 0 0.1

Hardbottom with >10% 

crustose coralline algae 0.7 0.1 0 0 0.5 1.3 4.7 0 0

Hardbottom 

(uncolonized) 11.6 14.9 13.7 0.9 2.9 6.8 49.9 0 0.7

Hardbottom with >10% 

macroalgae 5.8 22.4 62.2 6.1 0.1 0.4 3.7 0 4.5

Hardbottom with indeterminate cover 8.4 6.7 49.3 183.5 81.7 180.1 46.1 208.1 58.9

Unconsolidated with 

10% or less macroalgae 

or seagrass

38.8 49.9 226.2 231.8 36.2 295.7 241.5 19.5 10

Unconsolidated with 

>10% macroalgae or 

seagrass

2.7 0.2 19.9 0 0 19.6 23.4 0 0

Total Habitat Area 

Classified 69.8 95.5 391.6 438.7 127.2 518.7 417.6 227.6 74.1

5%

0%

4%

4%

35%

49%

3%

Hardbottom with >10% live 

coral

Hardbottom with >10% 

crustose coralline algae

Hardbottom (uncolonized)

Hardbottom with >10% 

macroalgae

Hardbottom with indeterminat

cover

Unconsolidated with 10% or 

less macroalgae or seagrass

Unconsolidated with >10% or

less macroalgae or seagrass

Figure 3.7. Area in the NWHI mapped by aggregated habitat cover type 

based upon IKONOS satellite imagery. Source: NOAA, 2003.
Geology and Benthic Habitats

Table 3.5. NWHI multibeam mapping statistics and estimates. 

MAPPING COMPLETED ESTIMATE TO 

2002-2008 COMPLETE 

km2 Days Days Remaining 

Deep (100-5,000 m) 41,664 28 67 

Mid-Depth (10-100 m) 3,854 134 275 

Totals 45,518 162 342 

Lisianski to Maro Kure to Lisianski 

Gardner to 

Mokumanamana 

Nihoa and 

southward 

Figure 3.8. Multibeam maps of all data collected in the NWHI through 2006. Maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

the banks and atolls that are shown in 

Figure 3.8. Moderate depth multibeam 

sonar surveys were conducted in the

NWHI between 2003 through 2008 by

personnel from CRED, NOAA’s Office 

of National Marine Sanctuaries, and

other partners using mapping systems 

aboard the NOAA Ship Hiialakai and 

the survey launch R/V Acoustic Habitat Investigator (AHI). The Hiialakai is equipped with two Kongsberg/ 

Simrad multibeam sonars: a 30-kHz EM300 with mapping capability from approximately 100-3000+ m and a 

300-kHz EM3002D with mapping capability from about 5-150 m. The R/V AHI has a 240-kHz Reson 8101ER 

with mapping capability from about 5-300 m. Both vessels have Applanix POS/MV motion sensors, which provide navigation and highly accurate readings of the vessel motion in all axes. Optical validation data have also 

been collected since 2001 using towed and drop camera systems aboard the Hiialakai, AHI and the NOAA 

Ship Oscar Elton Sette. 

Bathymetric data from these 2003-2008 Hiialakai and AHI surveys add to previously published data (Miller et 

al., 2003) from the 2002 R/V Kilo Moana surveys as well as estimated depths from IKONOS imagery Figure 

3.8 and Table 3.5 show current bathymetric coverage in NWHI. 

71 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Bathymetric grids at various resolutions are updated annually and published on the web at the Pacifi c Islands 

Benthic Habitat Mapping Center (PIBHMC; www.soest.hawaii.edu/pibhmc). As shown in Figure 3.8, some bathymetric data have been collected and processed at all of the islands and banks in the NWHI in water depths 

ranging from 3 to 3,000 m with almost complete coverage at Kure, Midway, Pearl and Hermes, Brooks Banks 

and French Frigate Shoals, and partial coverage at other locations. The bank on the southwest side of French 

Frigate Shoals was the first area to be mapped in early 2005 and 95% completed in 2008, and this data set is 

used later in this chapter to illustrate the various benthic habitat mapping products, their potential uses, and 

interpretation. Similar products for other banks are regularly added to the PIBHMC web site as mapping, data 

processing, product and metadata generation, and interpretation are completed. 

The geomorphological data layers of substrate, slope, rugosity, and bathymetric position index (BPI) produced 

at the PIBHMC are derived from multibeam bathymetry. Derivative data products (e.g., slope, rugosity and 

BPI) add geomorphological information about characteristics (e.g., roughness) that may assist in determining 

benthic habitat utilization. An explanation of each derivative type is given here. At this time a complete set of 

derivate products has been developed only for French Frigate Shoals. 

Rugosity: Cell values reflect the surface area to planimeteric area ratio (surface area) / (planimetric area) 

for the area contained within that cell’s boundaries. This measure provides an index of topographic roughness and convolutedness (Jenness, 2003). Distributions of fish and other mobile organisms are often found 

to positively correlate with increased complexity of the seafloor. Investigations are underway for the development of the most appropriate spatial metrics for quantifying benthic complexity for the purposes of 

relating these metrics to fish distributions in Pacific coral reef ecosystems. Results of the Jenness (2003) 

method are provided as a standardized and well-documented interim product. 

Slope: Cell values reflect the maximum rate of change (in degrees) in elevation between neighboring 

cells. 

Substrate: This is a preliminary product that is still under development. Cell values refl ect whether the 

seafloor is hard bottom or soft bottom based on an unsupervised classification run in Environment for Visualizing Images (ENVI) software. The classifications (hard bottom versus soft bottom) are based on backscatter, bathymetry, acoustic derivatives and optical data. 

Bathymetric Position Index: BPI is a second order derivative of bathymetry. The derivation evaluates 

elevation differences between a focal point and the mean elevation of the surrounding cells within a user 

defined annulus or circle. A negative value represents a cell that is lower than its neighboring cells (depressions) and a positive value represents a cell that is higher than its neighboring cells (crests). Larger numbers represent more prominent features on the seafloor, which differ greatly from surrounding areas. Flat 

areas or areas with a constant slope produce near-zero values. (Lundblad et al., 2006). 

72 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Summary of Multibeam Data 

Based on available multibeam data, summary 

statistics (slope, aspect ratio and rugosity) were 

developed for five depth bins based on natural breaks (9-226 m, 226-588 m, 588-1,045 m, 

1,045-1,649 m and 1,649-3,071 m). Slope values 

overall are lowest in the shallow (<226 m) depth 

bin (Figure 3.9). Islands further upchain such as 

Kure, Midway, Pearl and Hermes and Lisianski 

have higher slope values, on average, compared 

with locations further southeast along the chain. 

Aspect ratio (Δ Z/ΔX) does not vary greatly by 

depth bin or among reefs. Rugosity increases 

slightly with depth and the highest rugosity was 

found at Pearl and Hermes Atoll. 

Island Profiles 

The following sections summarize the geologic 

and benthic habitat information available for each 

emergent island in the NWHI, as of January 2009. 

The data include results from both IKONOS satellite imagery and multibeam data analyses. 

73 

Figures 3.9. A) Average slope by depth bin from multibeam sonar data collected at select islands within the NWHI; B) Average 

aspect ratio by depth bin from multibeam sonar data collected at

select islands within the NWHI; and C) Average rugosity by depth 

bin from multibeam sonar data collected at select islands within 

the NWHI. 

<226 

<588 

<1046 

<1649 

<30071 

NIH

MMM 

FFS

MAR

LIS

PHR

MID

KUR 

0 

5 

10 

15 

20 

25 

30 

NIH 

MMM 

FFS 

MAR 

LIS 

PHR 

MID 

KUR 

<226

<588

<1046

<1649 

<30071 

NIH

MMM 

FFS

MAR

LIS

PHR

MID

KUR 

0 

50 

100 

150 

200 

250 

NIH 

MMM 

FFS 

MAR 

LIS 

PHR 

MID 

KUR 

<226 

<588 

<1046 

<1649 

<30071 

NIH

MMM 

FFS

MAR

LIS

PHR

MID

KUR 

0.00 

0.20 

0.40 

0.60 

0.80 

1.00 

1.20 

1.40 

NIH 

MMM 

FFS 

MAR 

LIS 

PHR 

MID 

KUR 

A 

B 

C Average Slope Average Aspect Ratio Average Rugosity 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

74 

Nihoa Island 

Nihoa Island is located approximately

249.4 km northwest of Kauai, the closest to the Main Hawaiian Islands (MHI).

Measuring roughly 0.68 km2

, this island

is the largest emergent volcanic island

within the Monument and the tallest,

reaching an elevation of 275.2 m at

Miller Peak. It is also the geologically

youngest island within the Monument,

with an age calculated at 7.3 million

years (Clague, 1996). Nihoa is a deeply

eroded remnant of a once large volcano, 

and the large basaltic shelf of which it is 

a part stretches 28.9 km in a northeastsouthwest direction and ranges between 

34.1 and 66.1 m deep (NOAA, 2003).

The island’s two prominent peaks and

steep sea cliffs are clearly visible from a

distance, rising like a fortress above the

sea. The island’s northern face is comFigure 3.11. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left), 

and habitat zones for Nihoa Island (bottom right). Maps: L. Wedding. 

Figure 3.10. Benthic habitats around Nihoa based on IKONOS satellite

data. Source: NOAA, 2003. 

Hardbottom with >10% live coral 

Hardbottom with >10% crustose 

coralline algae 

Hardbottom (uncolonized) 

Hardbottom with >10% 

macroalgae 

Hardbottom with indeterminate 

cover 

Unconsolidated with 10% or less 

macroalgae or seagrass 

Unconsolidated with >10% 

macroalgae or seagrass 

1% 

13% 6%

80% 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

posed of a sheer cliff made up of successive layers of basaltic lava, within which numerous volcanic dikes are 

visible. The island’s surrounding submerged reef habitat totals approximately 574.6 km2 and is a combination 

of uncolonized hard bottom, macroalgae, pavement with sand channels and live coral, and uncolonized volcanic rock (NOAA, 2003; Figures 3.10, 3.11). The principal shallow water bottom habitats around Nihoa consist 

of hard basalt as vertical walls, horizontal wave-cut basalt benches, elevated mounds, and large blocks and 

boulders. Nihoa supports coral communities with very limited total habitat, most of which is not protected from 

the heavy and chronic wave action that strikes this small island from all directions. These habitats have been 

shaped by and are constantly eroded by the pounding waves. 

Multibeam surveys were conducted around Nihoa Island and on West Nihoa Bank on several different cruises, 

including R/V Kilo Moana KM-02-06, Hiialakai HI-05-01 and Hiialakai HI-06-12. The first two survey patterns 

around Nihoa Island were designed to delineate the 25-, 50-, and/or 100-fm boundaries needed for the National Marine Sanctuary designation process. Slope, aspect, and rugosity all increased with depth although the 

difference was small (Table 3.6). In Tables 3.6 -3.13 minimum, maximum, range, mean and standard deviation 

for bathymetry are in meters; slope and aspect are in degrees (0-360); and rugosity is a dimensionless ratio 

of surface area to planimetric area. High rugosity typically indicates a rough and complex substrate that often 

correlates with potential coral habitat. 

Bathymetry data for all islands was merged into a single raster. This was reclassifi ed into five depth classes 

using natural breaks - a method which seeks to equalize the variation between each class - in the ArcGIS 9.2 

Spatial Analyst extension. Using these 5 classes as zones, zonal statistics were run on bathymetry, slope, 

aspect and rugosity by island, using the “zonal statistics as table” tool in Spatial Analyst. This resulted in 

Table 3.6. Summary statistics for multibeam surveys conducted around Nihoa Island and on West Nihoa Bank. 

NIHOA DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD 

DEVIATION 

Bathymetry 

9 to 226 353.68 -225.17 -25.21 199.96 -69.46 41.34 

266 to 588 248.65 -500.00 -225.17 274.82 -356.89 65.18 

Slope 

9 to 226 - 0.00 68.01 68.01 3.72 7.79 

266 to 588 - 0.00 75.99 75.99 8.96 7.66 

Aspect 

9 to 226 - 0.00 360.00 360.00 180.02 111.23 

266 to 588 - -1.00 360.00 361.00 191.13 118.97 

Rugosity 

9 to 226 - 1.00 2.86 1.86 1.01 0.06 

266 to 588 - 1.00 4.44 3.44 1.03 0.05 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a given metric within a universal depth class. 

75 

Figure 3.12. 5 m and 20 m bathymetry for Nihoa with derived depths from IKONOS imagery near island center. Maps: L. 

Wedding. 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.12 (continued). Rugosity (5 m), and slope (5 m) for Nihoa with derived depths from IKONOS imagery near island

center. Maps: L. Wedding. 

the generation of summary statistics for 

each island in terms of the NWHI as a 

whole, making it possible, for example, 

to compare the average slope of Kure 

with that of Maro within the same depth 

class. 

Cruise Hiialakai HI-06-12 surveys on 

West Nihoa Bank were conducted to 

provide continuous coverage in order 

to better delineate topography on submerged banks; the resulting maps revealed some intriguing features on the 

southern part of West Nihoa Bank (Figure 3.12). Surveys of bottom fi sh habitats (Figure 3.13) and fi sh abundance 

were also conducted during Hiialakai 

HI-06-12. Figure 3.13. Detailed hillshade of bathymetric data on the southern portion

of West Nihoa bank. 

Mokumanamana Island 

Mokumanamana Island is a hookshaped dry volcanic island that includes 

about 18 hectares of land with 9.1 km2 

of potential coral reef habitat within 10 

fathoms and a large bank that includes 

1,557 km2

 of habitat within 100 fathoms. 

Mokumanamana is a dry volcanic island 

shaped like a fishhook, and includes approximately 0.18 km2

 of land. Geologists 

believe the island, with an estimated age 

of 10.6 million years, was once the size 

of Oahu in the MHI, with a maximum 

paleo-elevation of 1,036 m (Clague, 

1996), but due to centuries of erosion 

its highest point, at Summit Hill, is now 

only 84.1 m above sea level. All shallow Figure 3.14. Percent composition of mapped benthic habitats at Mokumanamana based on NOAA benthic habitat maps. Source: NOAA, 2003. 

Hardbottom with >10% live coral 

Hardbottom with >10% crustose 

coralline algae 

Hardbottom (uncolonized) 

Hardbottom with >10% macroalgae 

Hardbottom with indeterminate 

cover 

Unconsolidated with 10% or less 

macroalgae or seagrass 

Unconsolidated with >10% 

macroalgae or seagrass 

91% 

76 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.15. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left),

and habitat zones (bottom right) for Mokumanamana. Maps: L. Wedding. 

Table 3.7. Summary statistics for multibeam surveys conducted around Mokumanamana in 2002. 

MOKUMANAMANA DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD 

DEVIATION 

Bathymetry 

9 to 226 202.99 -286.14 -1.03 285.11 -90.93 57.43 

266 to 588 362.93 -737.97 -145.73 592.23 -376.12 88.38 

588 to 1,046 77.04 -1,132.92 -394.30 738.62 -812.10 125.46 

1,046 to 1,649 53.09 -1,500.00 -953.00 547.00 -1,290.05 140.25 

Slope 

9 to 226 - 0.00 69.72 69.72 7.81 10.13 

266 to 588 - 0.00 77.49 77.49 8.38 8.40 

588 to 1,046 - 0.00 77.45 77.45 13.91 10.48 

1,046 to 1,649 - 0.00 76.94 76.94 20.04 13.80 

Aspect 

9 to 226 - -1.00 360.00 361.00 179.46 113.87 

266 to 588 - -1.00 360.00 361.00 168.49 120.76 

588 to 1,046 - -1.00 360.00 361.00 149.07 119.73 

1,046 to 1,649 - -1.00 360.00 361.00 167.43 126.94 

Rugosity 

9 to 226 - 1.00 3.33 2.33 1.03 0.09 

266 to 588 - 1.00 5.67 4.67 1.03 0.07 

588 to 1,046 - 1.00 4.51 3.51 1.07 0.13 

1,046 to 1,649 - 1.00 4.87 3.87 1.16 0.25 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a given metric within a universal depth class. 

77 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

78Geology and Benthic Habitats

marine habitats are basalt surfaces exposed to high wave action and the effects of scour (surge combined with 

sand and other sediments) is evident from the wave-cut bench in West Cove and the deeply cut sand channels 

and chasms at several locations in deeper water (Figures 3.14, 3.15). Reef growth in shallow waters, if any, is 

minimal and the punishing effects of large waves as demonstrated by the high wave cut sea cliffs above sea 

level and wave planed benches and shelves below sea level. The bank provides excellent habitat for spiny 

lobsters (Panulirus marginatus) and slipper lobsters (Scyllarides squammosus), especially in habitats of less 

than 27.4 m depth and high benthic relief (Parrish and Polovina, 1994).

Multibeam surveys around Mokumanamana were conducted in 2002 (KM0206)

and 2008 (HI0804; Table 3.7, Figure

3.16). The 2002 surveys were for 25-,

50-, and/or 100-fm boundary delineation

and the survey in 2008 was planned to

better delineate the Necker Ridge that

runs southwest from Mokumanamana,

which is under consideration as a possible extension to the U.S. Exclusive

Economic Zone. The data from the

2008 surveys have not yet been fully

processed and Figure 3.16 shows only

data collected in 2002. Slope and rugosity increase with increasing depth while

the aspect ratio is highest in the shallowest depth range (<226 m; Table 3.7).

French Frigate Shoals

French Frigate Shoals is the largest atoll 

in the chain, taking the form of an 28.9 

km long crescent. It is estimated to be 

12.3 million years old (Clague, 1996). 

The shoals consist of 0.27 km2

 of total 

emergent land surrounded by approximately 931 km2

 of coral reef habitat, with 

a combination of sand, rubble, uncolonized hard bottom, and crustose coralline algae in the windward and exposed 

lagoon areas, and patch and linear coral 

reefs in more sheltered areas (NOAA, 

2003; Figures 3.17, 3.18). Tern Island in 

the atoll is the site of a U.S. Fish and 

Wildlife Service field station, which occupies a former U.S. Coast Guard (USCG)

Long-Range Aids to Navigation (LORAN) station that closed in 1979. The 

lagoon is also unusual in that it contains 

one exposed volcanic pinnacle (La Perouse) representing the last vestiges of 

the high island from which the atoll was 

derived, as well as approximately nine low, sandy islets. The sand islets are small, shift position, and disappear 

and reappear. 

Figure 3.16. Multibeam bathymetric data around Mokumanamana Island 

collected in 2002 and 2006 derived depths from IKONOS imagery near 

island center. Map: L. Wedding.

Figure 3.17. Percent composition of mapped benthic habitats at French 

Frigate Shoals based on NOAA benthic habitat maps. Source: NOAA 

2003.

Hardbottom with >10% live coral

Hardbottom with >10% crustose

coralline algae

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover

Unconsolidated with 10% or less

macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass

6% 12%

1%

12%

1%

11%

57%

12%

12%

11%

57%

6%

1%

1%

Hardbottom with >10% live coral

Hardbottom with >10% crustose

coralline algae

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover

Unconsolidated with 10% or less

macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.18. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left),

and habitat zones (bottom right) for French Frigate Shoals. Maps: L. Wedding. 

Table 3.8. Summary statistics for multibeam surveys conducted around French Frigate Shoals (2002-2008). 

FRENCH FRIGATE SHOALS DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD 

DEVIATION 

Bathymetry 

9 to 226 681.15 -294.50 0.00 294.50 -42.15 50.69 

266 to 588 284.10 -620.51 -134.19 486.32 -400.26 100.79 

588 to 1,046 54.56 -699.90 -572.38 127.52 -638.08 33.01 

Slope 

9 to 226 - 0.00 70.49 70.49 2.40 4.33 

266 to 588 - 0.00 73.04 73.04 6.28 6.10 

588 to 1,046 - 0.00 62.14 62.14 6.84 5.45 

Aspect 

9 to 226 - -1.00 360.00 361.00 150.34 115.05 

266 to 588 - -1.00 360.00 361.00 171.14 127.29 

588 to 1,046 - -1.00 359.99 360.99 235.36 79.11 

Rugosity 

9 to 226 - 1.00 3.25 2.25 1.01 0.03 

266 to 588 - 1.00 3.74 2.74 1.01 0.03 

588 to 1,046 - 1.00 2.29 1.29 1.02 0.04 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a given metric within a universal depth class. 

79 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.19. 5 m (top left) and 20 m bathymetry (top right), rugosity (5 m)(bottom left), and slope (5 m)(bottom right) for

French Frigate Shoals. 20-m bathymetry plot includes derived depths from IKONOS imagery. Maps: L. Wedding. 

Slope increases rapidly between the shallow and intermediate depth range (266-588 m) and then increases 

slightly between 588 and 1,046 m. Aspect ratio shows a gradual increase from shallow to deep depth bins 

while rugosity did not vary with depth (Table 3.8). 

French Frigate Shoals is the first island for which a substrate type map has been produced. Using depth, backscatter, multibeam derivatives such as rugosity, slope, and variance (Figure 3.19), an unsupervised classification was performed to classify the substrate type into hard and soft bottom classes (Figure 3.20). Figures 3.21 

through 3.24 shows information used in developing hard/soft and BPI maps. These products are designed to 

aid management agencies in developing sampling protocols that focus on hard (non-sand) substrates for coral 

benthic habitat studies and benthic habitat maps. 

80 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.20. (A) Multibeam bathymetry data collected on the bank top at French Frigate Shoals. Black box corresponds

to the location of the bathymetry (B) and backscatter (C) close-ups. Stars in (B) and (C) indicate the locations, from top to

bottom (northwest to southeast), of the TOAD frame grabs shown in (D, E, and F). These data are used to create accurate 

habitat maps for moderate depth ecosystems in the NWHI using image processing techniques. 

81 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.21. Hard/soft substrate type from French Frigate Shoals as produced by an unsupervised classifi cation using 

ENVI. 

82 

Figure 3.22. Bathymetric Position Index (BPI) zones for French Frigate Shoals. Source: Lundblad et al., 2006. 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.23. Bathymetric Position Index (BPI) structures for French Frigate Shoals. Source: Lundblad et al., 2006. 

Figure 3.24. French Frigate Shoals backscatter (top) and optical data (center) used to develop hard soft maps. The bottom panel shows a profile of the terrain from concurrent bathymetric data. Red dots indicate location of three photographs.

Dark areas in the backscatter indicate high intensity and can often be correlated to areas of coral cover, hard substrate, 

and elevated bathymetry (two left photos), while lighter areas can often be correlated with sandy, softer substrate and 

depressions. 

83 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Brooks and St. Rogatien Banks 

The Brooks and St. Rogatien Banks include four submerged banks between French Frigate Shoals and Gardner Pinnacles (Figure 3.25). These four banks are guyots (flat-topped seamounts) and all have at least two 

different terraces near their summits that indicate previous sea level stands. 

A 

B C 

Figure 3.25. 3-D perspective of Brooks Banks. (A) Perspective view of the Brooks Banks looking from the northeast. The

Brooks Banks exhibit a classic flat-topped morphology created by erosion when the banks were previously at or near sealevel. Multiple terraces around the bank edges are evidence for additional sea-level stands (B,C). Submarine canyons

incise the steep bank edges and blocks of material at the base of the slopes are probably slumps or landslide deposits. 

84 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Gardner Pinnacles 

Gardner Pinnacles consists of two emergent basaltic volcanic peaks estimated to be 15.8 million years in age 

(Clague 1996), which represent the oldest high islands in the Hawaiian chain. In scale, these pinnacles are 

small, the largest reaching only 54.8 m high and having a diameter of approximately 179.8 m. Due to their 

limited size, they support only a single species of land plant (Portulaca lutea) and a few terrestrial arthropod 

species, but they are by contrast excellent habitat for seabirds (Clapp, 1972). Guano from such seabirds gives 

the peaks a “frosted” appearance, indicating their importance as roosting and breeding sites for at least 12 

subtropical species. These remnant volcanic pinnacles are surrounded by approximately 2,428 km2 of coral 

reef habitat, most of which is in waters 18.3 m or deeper (Figure 3.26). The shallow water reef area within 10 

fathoms covers less than one square kilometer (0.7 km2) but the surrounding bank out to 100 fathoms covers 2,428 km2

. The relatively flat bank is in the 30 to 40 m depth range and consists of mostly sand and algal 

bottom with occasional rock outcroppings. The Pinnacles do not offer much protection from heavy waves and 

corals are more abundant on elevated surfaces and behind rises or mounds that are protected from wave action. The lack of shallow water environments limits the number of reef building species that can survive the 

conditions at the reefs and powerful wave action reduces the growth rate of corals (Grigg 1981), coralline algae 

and other reef-building organisms. 

Multibeam data were collected in 2002 at Gardner Pinnacles on cruise KM0206 on the 25, 50 and/or 100-fm 

isobaths in order to delineate boundaries for the National Marine Sanctuaries program (Figure 3.27). 

Figure 3.26. IKONOS satellite image (top left), extent of water depth <20 m (top right), and habitat zones (bottom left) for

Gardner Pinnacles. Maps: L. Wedding. 

85 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.27. Gardner Pinnacles multibeam data collected in 2002 during KM0206. 

86 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

87Geology and Benthic Habitats

Maro Reef

Maro Reef is a largely submerged open

atoll 19.7 million years old (Clague,

1996). At very low tide, only a small

coral rubble outcrop of a former island

is believed to break above the surface;

as a result, Maro supports no terrestrial

biota. In contrast, the shallow water reef

system is extensive, covering nearly

2,023 km2, and is the largest coral reef

in the Monument. Maro’s reefs are intricate and reticulated, forming a complex

network of reef crests, patch reefs, and

lagoons. Deepwater channels with irregular bottoms cut between these shallow

reef structures, but navigation through

them is difficult and hazardous. Cover

types range from unconsolidated with

10% or less macroalgae cover to areas

with greater than 10% coral or crustose

coralline algae (NOAA, 2003; Figures 3.28, 3.29). 

Figure 3.28. Percent composition of mapped benthic habitats at Maro Reef 

based on NOAA benthic habitat maps. Source: NOAA, 2003.

4% 3% <1% 1%

0%

35%

57%

Hardbottom with >10% live

coral

Hardbottom with >10% crustose

coralline algae

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover

Unconsolidated with 10% or

less macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass

Hardbottom with >10% live

coral

Hardbottom with >10% crustose

coralline algae

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover

Unconsolidated with 10% or

less macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass

57%

35%

4% 0% 3% <1% 1%

Figure 3.29. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left), 

and habitat zones (bottom right) for Maro Reef. Maps: L. Wedding.
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

88 

Because the outermost reefs absorb the majority of the energy from the open ocean swells, the innermost reticulated reefs and aggregated patch reefs are sheltered and have the characteristics of a true lagoon. Given 

the structural complexity of this platform, its shallow reefs are poorly charted and largely unexplored. 

Multibeam surveys were conducted at 

Maro Reef in 2002 (KM0206) and 2005 

(HI0508; Figure 3.30). The 2006 “ring” 

surveys on the perimeter were planned 

to delineate the 25-, 50-, and/or 100-fm 

isobaths for boundary designation purposes. 

At Maro, slope increases greatly between the shallow (<226 m) and intermediate depths (226-588 m) and then 

declines slightly with greater depths 

(588-1,045 m). Aspect ratio declined 

slightly with depth from shallow to deep 

while rugosity was similar among all 

depths (Table 3.9). 

Figure 3.30. 20 m Multibeam bathymetric data collected at Maro Reef in

2002 and 2005 with derived depths from IKONOS imagery near island center. Map: L. Wedding. 

Table 3.9. Summary statistics for multibeam surveys conducted around Maro Reef (2002-2006). 

MARO DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD DEVIATION 

Bathymetry 9 to 226 900.29 -259.40 -1.00 258.40 -65.03 56.96 

266 to 588 277.74 -616.72 -202.22 414.50 -356.19 106.15 

588 to 1,046 133.73 -800.00 -559.44 240.56 -689.07 61.27 

Slope 9 to 226 - 0.00 62.67 62.67 2.47 4.30 

266 to 588 - 0.00 64.64 64.64 8.48 7.65 

588 to 1,046 - 0.00 55.35 55.35 7.82 5.76 

Aspect 9 to 226 - -1.00 360.00 361.00 184.40 108.58 

266 to 588 - 0.00 360.00 360.00 175.34 108.21 

588 to 1,046 - -1.00 360.00 361.00 155.68 77.84 

Rugosity 9 to 226 - 1.00 2.23 1.23 1.00 0.03 

266 to 588 - 1.00 2.43 1.43 1.02 0.04 

588 to 1,046 - 1.00 2.08 1.08 1.02 0.04 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a given metric within a universal depth class. 
Geology and Benthic Habitats

Figure 3.32. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left),

and habitat zones (bottom right) for Laysan Island. Maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Laysan 

Laysan is a formed atoll, estimated to be 

20.7 million years old (Clague, 1996),

with a maximum elevation of approximately 15 m above sea level. By land

area it is the second largest island in the 

Monument, with a land area of approximately 3.7 km2

, surrounded by close to

405 km2

 of coral reef. Most of the reef

area at Laysan lies in deeper waters,

with a small, shallow water reef area in

a bay off the southwest side of the island. It is well vegetated (except for its

sand dunes) and contains a hyper-saline lake, which is one of only fi ve natural lakes in the state of Hawaii. Laysan’s 

coral reef habitat totals approximately

26.5 km2

 within 10 fathoms and 584.5

km2

 out to 100 fathoms (Figures 3.31,

3.32). The fringing reef surrounding the

island varies from 100 to 500 m in width and is most extensive at the northwest end of the island. Inside the 

Figure 3.31. Percent composition of mapped benthic habitats at Laysan

Island based on NOAA benthic habitat maps. Source: NOAA, 2003. 

Hardbottom with >10% live 

coral 

Hardbottom with >10% 

crustose coralline algae 

Hardbottom (uncolonized) 

Hardbottom with >10% 

macroalgae 

Hardbottom with indeterminate 

cover 

Unconsolidated with 10% or 

less macroalgae or seagrass 

Unconsolidated with >10% 

macroalgae or seagrass

<1% 5% <1% 2% 

<1% 

28% 

65% 

89 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

90Geology and Benthic Habitats

reef is a narrow, shallow channel which

nearly encircles the island except for

the south and southeast sides. Deeper

reef habitats are mostly robust spurand-grooves around most of the island

and a heavily eroded northern section

with numerous caves, overhangs and

large holes on a sloping reef with small

sand channels. The base of these reefs

and the spur-and-grooves ended in

broad sand flats with numerous small

overhangs and holes. Despite lacking

much protection from the detrimental

effects of waves, Laysan supports a

surprisingly rich coral environment with

good development along its leeward

coasts. The small back reef, pass and

moat near the island’s western boat

landing also help to diversify habitats

and the number of coral species inhabiting them. 

Multibeam surveys were conducted in 2002 during KM0206 in order to delineate 25, 50 and/or 100-fm boundaries around Laysan Island (Figure 3.33). 

Lisianski-Neva Shoal

Lisianski Island (Papaapoho) is another 

raised atoll, rising to 12.1 m above sea 

level, and with approximately 1.6 km2

 of 

emergent land is the third largest island 

within the Monument. This 23.4-millionyear-old island (Clague, 1996) is over 

1.9 km across, consisting of an elevated 

rim surrounding a broad central depression, although unlike Laysan it does not 

enclose an interior saline lake. The coral 

cover on the platform around the island, 

called Neva Shoal, is extensive, totaling 

over 1,174 km2 (Figures 3.34, 3.35).

Papaapoho describes a flat area with a 

depression or hollow, which is exactly 

how the island is shaped. Its highest 

point is a 12.2 m-high sand dune, and its 

lowest point is a depression to the south 

that runs as a channel toward the ocean.

Multibeam surveys were conducted in 2002 during KM0206 (Figure 3.36) in order to delineate 25, 50 and/or 

100-fm boundaries around Lisianski Island and Neva Shoals. The slope increases dramatically between the 

shallow (<226 m) and the intermediate depth range (226-588 m) before it declines slightly in the deeper depth 

bin (588-1,045 m). Aspect ratio is highest in the deep and shallow depth ranges while the intermediate depth 

ranges (266-588 m) had the lowest aspect ratio. Rugosity increased sharply between shallow and intermediate 

depths with a slight decrease in the deepest depth bin (Table 3.10). 

Figure 3.33. 20-m multibeam data collected around Laysan Island (upper 

right) and Northampton Seamounts (lower left). Derived depths from IKONOS imagery are shown around Laysan Island. Map: L. Wedding.

Figure 3.34. Percent composition of mapped benthic habitats at LisianskiNeva Shoals based on NOAA benthic habitat maps. Source: NOAA, 2003.

<1% 4% <1%

1%

53% 42%

Hardbottom with >10% live

coral

Hardbottom with >10%

crustose coralline algae

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover

Unconsolidated with 10% or

less macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass

Hardbottom with >10% live

coral

Hardbottom with >10%

crustose coralline algae

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover

Unconsolidated with 10% or

less macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass

53% 42%

<1% 4% <1%

1%
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.35. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left),

and habitat zones (bottom right) for Lisianski-Neva Shoals. Maps: L. Wedding. 

Figure 3.36. 20 m multibeam data collected around Lisianski-Neva Shoal in

2002 with derived depths from IKONOS imagery near island center. Map: 

L. Wedding. 

91 
Geology and Benthic Habitats

5% 5%
 3% Hardbottom with >10% live

coral

Hardbottom with >10%

crustose coralline algae 16%

Hardbottom (uncolonized)

Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover 

13% 

Unconsolidated with 10% or

58% less macroalgae or seagrass

Unconsolidated with >10%

macroalgae or seagrass

Figure 3.37. Percent composition of mapped benthic habitats at Pearl and

Hermes Atoll based on NOAA benthic habitat maps. Source: NOAA, 2003. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands
 

Table 3.10. Summary statistics for multibeam surveys conducted around Lisianki (2002).
 

LISIANKI DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD DEVIATION 

Bathymetry 

9 to 226 367.36 -366.03 -1.00 365.03 -47.61 51.89 

266 to 588 166.36 -683.59 -159.95 523.64 -430.03 102.21 

588 to 1,046 194.73 -999.99 -511.34 488.65 -785.34 119.57 

Slope 

9 to 226 - 0.00 78.38 78.38 4.34 8.52 

266 to 588 - 0.00 81.39 81.39 21.19 12.56 

588 to 1,046 - 0.00 72.36 72.36 19.10 8.47 

Aspect 

9 to 226 - -1.00 360.00 361.00 174.50 105.29 

266 to 588 - -1.00 360.00 361.00 149.92 103.05 

588 to 1,046 - -1.00 360.00 361.00 177.09 105.33 

Rugosity 

9 to 226 - 1.00 6.83 5.83 1.02 0.08 

266 to 588 - 1.00 6.89 5.89 1.12 0.19 

588 to 1,046 - 1.00 3.39 2.39 1.08 0.08 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a given metric within a universal depth class. 

92 

Pearl and Hermes 

The name Holoikauaua celebrates the

Hawaiian monk seals that haul out and

rest here. Pearl and Hermes Atoll is a

large atoll with several small islets, forming 0.38 km2

 of land surrounded by over 

1,214 km2 of coral reef habitat (Figures

3.37, 3.38). The atoll has an estimated

age of 26.8 million years (Clague, 1996) 

and is over 32 km across and 19.3 km

wide, with dunes rising above sea level. Unlike Lisianski and Laysan to the

southeast, Pearl and Hermes Atoll is a

true atoll, fringed with shoals, permanent 

emergent islands, and ephemeral sandy 

islets. These features provide vital dry

land for monk seals, green turtles, and

a multitude of seabirds, with 16 species

breeding here. The islets are periodically washed over when winter storms

pass through the area. 

Multibeam data were collected at Pearl and Hermes Atoll in 2005 (HI0509) to delineate the 25-, 50- and/ 

or 100-fm boundaries and in 2006 to complete as much mapping of the atoll as possible (Table 3.11; Figure 

3.39). Depths surveyed ranged from 9 m down to over 3,000 m. Slope increased by more than eight fold between the shallowest (9-226 m) and the next deepest (226-588 m) depth ranges. The slope declined slightly 

in the deepest depth bin (1,649-3,071 m). Aspect ratio increased steadily with increasing depth, while rugosity 

rose sharply between shallow (<226 m) and intermediate ranges (226-1,046 m) and then declined slightly in 

the deepest depth bin (Table 3.11). Figure 3.40 shows a guyot approximately 25 km southeast of Pearl and 

Hermes Atoll where monk seals have been reported to forage through satellite tracking. 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.38. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left),

and habitat zones (bottom right) for Pearl and Hermes Atoll. Maps: L. Wedding. 

Table 3.11. Summary statistics for multibeam surveys conducted around Pearl and Hermes (2005). 

PEARL AND HERMES DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD DEVIATION 

Bathymetry 

9 to 226 611.14 -1,818.20 0.00 1,818.20 -44.22 48.84 

266 to 588 20.70 -876.60 -10.60 866.00 -336.52 103.37 

588 to 1,046 34.20 -1,169.10 -262.60 906.50 -862.04 123.81 

1,046 to 1,649 92.48 -1,858.90 -631.80 1,227.10 -1,368.91 175.49 

1,649 to 3,071 86.96 -3,071.30 -40.70 3,030.60 -1,979.21 281.68 

Slope 

9 to 226 - 0.00 77.41 77.41 3.39 4.73 

266 to 588 - 0.00 82.89 82.89 28.25 11.14 

588 to 1,046 - 0.00 84.42 84.42 28.60 11.14 

1,046 to 1,649 - 0.00 84.72 84.72 22.32 10.32 

1,649 to 3,071 - 0.00 87.49 87.49 15.04 9.89 

Aspect 

9 to 226 - -1.00 360.00 361.00 158.44 116.76 

266 to 588 - -1.00 359.94 360.94 198.48 97.80 

588 to 1,046 - -1.00 360.00 361.00 202.81 95.63 

1,046 to 1,649 - -1.00 360.00 361.00 224.08 98.92 

1,649 to 3,071 - -1.00 360.00 361.00 225.85 98.48 

Rugosity 

9 to 226 - 1.00 14.14 13.14 1.01 0.03 

266 to 588 - 1.00 12.93 11.93 1.30 0.43 

588 to 1,046 - 1.00 18.72 17.72 1.32 0.48 

1,046 to 1,649 - 1.00 19.01 18.01 1.25 0.38 

1,649 to 3,071 - 1.00 89.27 88.27 1.16 0.46 

*NOTE: minimum = minimum value of a given metric within a universal depth class; maximum = the maximum value of a given metric within a universal depth class. 

93 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.39. 5 m and 20 m bathymetry, rugosity (5 m), and slope (5 m) for Pearl and Hermes with derived depths from 

IKONOS imagery near island center. Maps: L. Wedding. 

94 

Figure 3.40. 3-D perspective of a seamount southeast of Pearl and Hermes Atoll. V.E. = 2x. 
Geology and Benthic Habitats

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Midway Atoll 

Midway Atoll consists of three sandy islets: Sand, 4.56 km2

; Eastern, 1.36 km2; 

and Spit, 0.05 km2 for a total of 1,464 

5.9 km2

 in terrestrial area, lying within a 

large, elliptical barrier reef measuring approximately 8 km in diameter. The atoll, 

which is 28.7 million years old (Clague, 

1996), is surrounded by more than 356 

km2

 of coral reefs (Figures 3.41, 3.42). In 

1965, the U.S. Geological Survey took 

core samples and hit solid basaltic rock 

54.8 m beneath Sand Island and 377.9 

m beneath the northern reef. Numerous 

patch reefs dot the sandy-bottomed lagoon. The atoll and surrounding seas 

were also the site of a pivotal battle of 

World War II, and Midway was an active 

Navy installation during the Cold War. 

Multibeam mapping surveys at Midway were conducted in 2003 (AHI0306) to delineate 25-, 50- and 100-fm 

boundaries and in 2005 (HI0503) and 2006 (HI0609) to add to coverage around the island for benthic habitat 

Figure 3.41. Percent composition of mapped benthic habitats at Midway

Atoll based on NOAA benthic habitat maps. Source: NOAA, 2003. 

16% 

23% 

7% 

53% 

<1% 1% <1%

Hardbottom with >10% live coral 

Hardbottom with >10% crustose 

coralline algae 

Hardbottom (uncolonized) 

Hardbottom with >10% 

macroalgae 

Hardbottom with indeterminate 

cover 

Unconsolidated with 10% or less 

macroalgae or seagrass 

Unconsolidated with >10% 

macroalgae or seagrass 

95 

Figure 3.42. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth <20 m (bottom left)

and habitat zones (bottom right) for Midway Atoll. Maps: L. Wedding. 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

mapping (Figure 3.43). Slope increased by 10 fold between the shallowest and intermediate depth with a modest decline in the deepest depth bin. Aspect ratio increased moderately between shallow and intermediate 

depth but declined sharply in the 588-1,045 m depth range. Rugosity increased from shallow to intermediate 

before declining slightly in the deepest depth range (Table 3.12). 

96 

Figure 3.43. 5 m and 20 m bathymetry, rugosity (5 m), and slope (5 m) for Midway Atoll with derived depths from IKONOS 

imagery near island center. Maps: L. Wedding. 

Table 3.12. Summary statistics for multibeam surveys conducted around Midway Atoll (2003-2006). 

MIDWAY DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD DEVIATION 

Bathymetry 9 to 226 306.19 -250.60 3.00 253.60 -60.98 51.15 

266 to 588 37.32 -500.00 2.00 502.00 -349.27 77.63 

588 to 1,046 0.00 -2.00 -2.00 0.00 -2.00 0.00 

Slope 9 to 226 - 0.00 56.57 56.57 2.85 5.16 

266 to 588 - 0.00 79.34 79.34 28.83 9.04 

588 to 1,046 - 19.97 19.97 0.00 19.97 0.00 

Aspect 9 to 226 - -1.00 360.00 361.00 137.68 114.67 

266 to 588 - -1.00 360.00 361.00 170.08 95.52 

588 to 1,046 - 40.82 40.82 0.00 40.82 0.00 

Rugosity 9 to 226 - 1.00 2.29 1.29 1.01 0.04 

266 to 588 - 1.00 4.87 3.87 1.19 0.16 

588 to 1,046 - 1.11 1.11 0.00 1.11 0.00 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a 

given metric within a universal depth class. 
Geology and Benthic Habitats

4% 3% 1%

17% Hardbottom with >10% live coral

Hardbottom with >10% crustose 

coralline algae

Hardbottom (uncolonized) 

8% Hardbottom with >10%

macroalgae

Hardbottom with indeterminate

cover 

55% Unconsolidated with 10% or less 

macroalgae or seagrass

12%
 Unconsolidated with >10% 

macroalgae or seagrass

Figure 3.44. Percent composition of mapped benthic habitats at Kure Atoll 

based on NOAA benthic habitat maps. Source: NOAA, 2003. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Kure Atoll 

Kure Atoll is the most northwestern island in the Hawaiian chain and occupies a singular position at the “Darwin 

Point”: the northern extent of coral reef development, beyond which coral growth cannot keep pace with the 

rate of geological subsidence. Kure’s coral is still growing slightly faster than the island is subsiding. North of 

Kure, where growth rates are even slower, the drowned Emperor Seamounts foretell the future of Kure and all 

of the Hawaiian Archipelago. As Kure Atoll continues its slow migration atop the Pacific Plate, it too will eventually slip below the surface (Grigg, 1982). 

This 29.8 million year old atoll (Clague, 

1996) is nearly circular, with a reef 9.6 

km in diameter enclosing a lagoon with 

two islets that include over 0.81 km2

 of 

emergent land, flanked by almost 324 

km2 of coral reef habitat (Figures 3.44, 

3.45). The outer reef forms a nearly 

complete circular barrier around the lagoon, with the exception of passages 

to the southwest. Of the two enclosed 

islets, the only permanent land is found 

on crescent-shaped Green Island,

which rises to 6.1 m above sea level and 

is located near the fringing reef in the 

southeastern quadrant of the lagoon. 

The USCG established a LORAN station at Kure in 1960 (Woodward, 1972) 

and occupied it until 1993. This land use 

had far-reaching effects on all the plants 

and animals at Kure Atoll, resulting in 

elevated invasive species problems and 

contaminants left behind when the base 

closed. 

97 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.45. IKONOS satellite image (top left), benthic habitat map (top right), extent of water depth < 20 m (bottom left),

and habitat zones (bottom right) for Kure Atoll. Maps: L. Wedding. 

Multibeam data were collected around Kure Atoll in 2005 (HI0509) to delineate the 25, 50 and 100-fm boundaries and in 2006 (HI0609) to complete mapping of the atoll (Figure 3.46). Slope increased by 9 fold between 

the shallow and intermediate depth ranges (Table 3.13). Aspect ratio and rugosity also showed the same trend 

although the magnitude was not as great (Figure 3.47). Multibeam bathymetry at Kure and Midway show extensive spur and groove formations in the high resolution data. 

98 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 3.46. 5 m and 20 m bathymetry, rugosity (5 m), and slope (5 m) for Kure Atoll. Maps: L. Wedding. 

Table 3.13. Summary statistics for multibeam surveys conducted around Kure Atoll (2005-2006). 

KURE DEPTH CLASS AREA MINIMUM* MAXIMUM* RANGE MEAN STANDARD DEVIATION 

Bathymetry 

9 to 226 323.34 -225.00 1.00 226.00 -73.27 52.46 

266 to 588 30.76 -402.00 -226.00 176.00 -314.77 50.63 

Slope 

9 to 226 - 0.00 77.44 77.44 2.86 4.68 

266 to 588 - 0.00 77.82 77.82 26.69 8.43 

Aspect 

9 to 226 - -1.00 359.43 360.43 153.84 117.63 

266 to 588 - -1.00 359.79 360.79 183.77 97.63 

Rugosity 

9 to 226 - 1.00 7.63 6.63 1.01 0.03 

266 to 588 - 1.00 8.12 7.12 1.15 0.12 

*NOTE: the minimum represents the minimum value of a given metric within a universal depth class; maximum represents the maximum value of a given metric within a universal depth class. 

99 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

100 

Figure 3.47. Spur and groove formations show up clearly in the high resolution bathymetry taken around Kure Atoll. 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

EXISTING DATA GAPS
 

• A comprehensive shallow-water benthic habitat map is required to support multiple research and monitoring activities. Currently only about 50% of the shallow-water area from 0-30 m has sufficient coverage and 

quality of imagery to produce maps. 

• A complete and seamless digital terrain and bathymetric models for the Papahanaumokuakea Marine 

National Monument (PMNM) to at least 500 m is currently lacking and is necessary to better understand 

the connection of shallow and deep-water habitats. It will also help guide assessment and monitoring 

activities. 

• Need to complete high-resolution multibeam bathymetry for shallow to moderate (20 to 500 m) 

depths. 

• Need to collect shallow (<20 m) bathymetric data using Light Detection and Ranging (LIDAR) or other 

appropriate technologies. 

• Sea level curves developed from the MHI and elsewhere around the Pacific might not be appropriate 

for the NWHI. Fossil coring and other methods should be employed to better understand past sea level 

changes in the NWHI. 

• Need to determine whole reef accretion rates in different geomorphological zones. 

• Need to examine rates of terrestrial habitat loss and the factors that cause it. 

101 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

102 

REFERENCES 

Clague, D.A. 1996. The growth and subsidence of the Hawaiian-Emperor volcanic chain. Pp: 35-50. In: Keast A., S.D. 

Miller (eds.). The origin and evolution of the Pacific Island biota, New Guinea to Eastern Polynesia: patterns and pro- cesses. SPB Academic Publishing, Amsterdam, The Neatherlands. 

Clague, D.A. and G.B. Dalrymple. 1987. The Hawaiian-Emperor volcanic chain: Part I. Geologic evolution. US Geological 

Survey Professional Paper 1350, pp. 5-54. 

Clapp, R.B. 1972. The natural history of Gardner Pinnacles, northwestern Hawaiian Islands: botany. Atoll Res. Bull., 

no.163. 

Davies, T.A., P. Wilde, and D.A. Clague. 1972. Koko seamount: a major guyot at the southern end of the Emperor sea- mounts. Mar. Geol. 13: 311-321. 

Garcia, M., D. Grooms, and J. Naughton. 1987. Petrology and geochronology of volcanic rocks from seamounts along

and near the Hawaiian Ridge. Lithos 20: 323-336. 

Grigg, R. W. 1981. Coral reef development at high latitudes in Hawaii, Proceedings of the Fourth International Coral Reef 

Symposium, Manila, 1, 687-693. 

Grigg, R.W. 1982. Darwin Point: a threshold for atoll formation. Coral Reefs 1: 29-34. 

Grigg, R.W. 1983. Community structure, succession and development of coral reefs in Hawaii. Mar Ecol Prog Ser 11:1- 14. 

Grigg, R.W. 1997. Paleoceanography of coral reefs in the Hawaiian-Emperor Chain – Revisited. Coral Reefs 16, 

Suppl:S33-S38. 

Grigg, R.W., J. Polovina, A. Friedlander, and S. Rohmann. 2008. Pp: 573-594 in: Biology and paleoceanography of the 

coral reefs in the northwestern Hawaiian Islands. In: Coral reefs of the United States (B. Riegl and R. Dodge, eds.).

Springer-Vergal Publishing. 

Gross M.G., J.D. Milliman, J.I. Tracey, and H.S. Ladd. 1969. Marine geology of Kure and Midway Atolls, Hawaii: a pre- liminary report. Pac. Sci. 23:17-25. 

Hoeke, R., R. Brainard, R. Moffitt, and M. Merrifield. 2006. The role of oceanographic conditions and reef morphology in 

the 2002 coral bleaching event in the northwestern Hawaiian Islands. Atoll Res. Bull. 543:489-503. 

Jackson, E. D.; Shaw, H. R.; Bargar, K. E. Calculated geochronology and stress field orientations along the Hawaiian

chain.Earth and Planetary Science Letters, Vol. 26, p.145 

Jenness, J. 2003. Grid surface areas: surface area and ratios from elevation grids [electronic manual]. URL http://www. 

jennessent.com/arcview/arcview_extensions.htm 

Juvik, S.P. and J.O. Juvik. 1998. Atlas of Hawaii, 3rd edition. University of Hawaii Press. Honolulu. 

Lundblad, E., D.J. Wright, J. Miller, E.M. Larkin, R.B. Rinehart, S.M. Anderson, D.F. Naar, and B.T. Donahue. 2006. A

benthic terrain classification scheme for American Samoa. Marine Geodesy 29: 89-111. 

Maragos, J.E., D.C. Potts, F. Aeby, D. Gulko, J. Kenyon, D. Siciliano, and D. VanRavenswaay. 2004. 2000-2002 Rapid 

Ecological Assessment of Corals (Anthozoa) on Shallow Reefs of the Northwestern Hawaiian Islands. Part 1. Species and 

Distribution. Pacific Science 58(2): 211-230. 

Miller, J.E., R.K. Hoeke, T.B. Appelgate, P.J. Johnson, J.R. Smith, and S. Bevacqua. 2003. Atlas of the Northwestern Hawaiian Islands, Draft – February 2004, National Oceanic and Atmospheric Administration, 65 pp. 

Neall, V.E. and S.A. Trewick. 2008. The age and origin of the Pacific islands: a geological overview. Phil. Trans. R. Soc. 

B 363:3293-3308. 

NOAA (National Oceanic and Atmospheric Administration). 2003. Atlas of the Shallow-Water Benthic Habitats of the 

Northwestern Hawaiian Islands (Draft ). 160 pp. 

Parrish, F.A. and J.J. Polovina. 1994. Habitat thresholds and bottlenecks in production of the spiny lobster (Panulirus 

marginatus) in the northwestern Hawaiian Islands. Bulletin of marine science 54: 151-163. 

Rohmann, S.O., J.J. Hayes, R.C. Newhall, M.E. Monaco, and R.W. Grigg. 2005. The area of potential shallow-water tropi- cal and subtropical coral ecosystems in the United States. Coral Reefs 24:370-383. 
Geology and Benthic Habitats

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Rooney, J.J., P. Wessel, R. Hoeke, J. Weiss, J. Baker, F. Parrish, C.H. Fletcher, J. Chojnacki, M. Garcia, R. Brainard, and 

P. Vroom. 2008. Geology and Geomorphology of Coral Reefs in the Northwestern Hawaiian Islands. In: Coral reefs of the 

United States (B. Riegl and R. Dodge, eds.). Springer-Vergal Publishing. 

Stumpf, R.P. and K. Holderied. 2003. Determination of water depth with high-resolution satellite imagery over variable 

bottom types. Limnol. Oceanogr. 48: 547-556. 

Stumpf, R.P., K. Holderied, and M. Sinclair. 2003. Determination of water depth with high-resolution satellite imagery over 

variable bottom types. Limnology and Oceanography 48: 1. 

Woodward, P.W. 1972. The natural history of Kure Atoll, Northwestern Hawaiian Islands. Atoll Res. Bull. 164:1-317. 

WEBSITES 

NOAA. 2008. http://ccma.nos.noaa.gov/ecosystems/coralreef/nwhi/welcome.html 

NOAA. 2008. http://biogeo.nos.noaa.gov 

UH SOEST. 2008. http://www.soest.hawaii.edu/pibhmc/pibhmc_nwhi.htm 

NOAA. 2008. http://biogeo.nos.noaa.gov 

103 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Benthic Communities 

James Maragos1, Jean Kenyon2,3, Greta Aeby4, Peter Vroom2,3, Bernardo Vargas-Angel2,3, Russell Brainard2, 

Lisa Wedding4,5, Alan Friedlander5,6, Jacob Asher2,3, Brian Zgliczynski2 and Daria Siciliano7 

INTRODUCTION 

This chapter focuses on the shallow water benthos surrounding the 10 emergent islands, reefs and atolls 

comprising the Northwestern Hawaiian Islands (NWHI). The composition and distribution of benthic communities in the subtropical NWHI reflect the interaction of numerous influences, including geographic isolation, 

latitude, exposure and the successional age of the islands they inhabit. This mosaic of habitats extend 1,200 

nm northwest of the main Hawaiian Islands (MHI) and consist mostly of coral-dominated areas, stretches of 

hard-bottom algal-dominated meadows, and vast expanses of unconsolidated sediments such as sand and 

mud inhabited by few benthic infauna at shallower depths (<20 m). The benthic habitats at greater depths are 

relatively unknown, unexplored and are not covered here. 

CORALS 

Species Richness 

The most recent published surveys of the NWHI revealed a total of 57 species of zooxanthellate stony corals 

(Maragos et al., 2004). However 2006 surveys at greater depths and in a wider variety of habitats have yielded 

a number of new morpho-species, most of which have yet to be collected and described. Appendix I lists of all 

coral and anemone species reported at 11 islands, banks, atolls and reefs in the NWHI as of October 2006. As 

was the case during earlier compilations, 

the larger atolls with diverse habitats 

and shelter from large northwest swell 

support the greatest number of species. 

Although these numbers are similar to 

the MHI, the Hawaiian coral fauna, as 

a whole, is depauperate relative to the 

Indo-West-Pacific, where up to 700 species have been reported (Veron, 1995). 

The most plausible cause is geographic 

isolation (Grigg, 1983) associated with 

the NWHI being located at the northeastern periphery of the Indo-Pacific 

biogeographic province. 

The distribution of coral species is related to geomorphology, size and age 

of the NWHI reefs (Grigg, 1997; Figure 

4.1). There is a highly signifi cant (p< 

0.001) correlation between the number 

of coral taxa and the amount of reef 

area within 10 fathoms with French Frigate Shoals, Pearl and Hermes and Maro 

105 

Figure 4.1. Total number of coral species reported in the NWHI between 

1907 and 2006 compiled by Maragos from Dana (1846), Vaughan (1907), 

Dana (1971), Maragos et al. (2004) and unpublished records. Map: L. Wedding. 

1. U.S. Fish and Wildlife Service 

2. NOAA/NMFS/Pacific Islands Fisheries Science Center, Coral Reef Ecosystem Division

3. Joint Institute for Marine and Atmospheric Research 

4. University of Hawaii at Manoa

5. NOAA/NOS/NCCOS/CCMA Biogeography Branch

6. The Oceanic Institute 

7. University of California Santa Cruz, Institute of Marine Sciences 
Benthic Communities

100 

80

xa a T

60 

ralo Cer of

40 

bmu

20 

N

0 

Reef area < 10 fathom vs coral species richness 

Linear regression line 

95% Confidence Band 

95% Prediction Band 

0 100 200 300 400 500 

2 Reef area <10 fathoms (km )

Figure 4.2. Relationship between number of coral taxa and reef area within

10 fathoms (based on Rohman et al., 2005). Coral species richness = 24.88

+ 0.072*Reef area <10 fathoms. Source: Maragos, unpub. data. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Reef having the highest richness of coral taxa (Table 4.1, Figure 4.2). Low coral 

species richness is found at the southern end among the small basalt islands

of Nihoa, Mokumanamana and Gardner 

Pinnacles, which are openly exposed to 

severe wave events particularly during

winter months (Maragos et al., 2004 ;

Grigg et al., 2008). This area is dominated by robust species that are more tolerant of high wave action and soft corals such as Sinularia spp. and Palythoa

spp. The large middle atolls (French

Frigate Shoals and Maro) have some

of the highest coral species richness

reflecting optimal conditions in terms

of both habitat (a large open atoll) and

environmental conditions (wave shelter, 

temperature and low disturbance, as

well as the high number of Acroporidae

and Fungiidae species). Seven species

of the genus Acropora are now known

from the NWHI despite their almost complete absence in the MHI (Maragos et

al., 2004), and several additional undescribed Acropora were photographed at 

French Frigate Shoals, Neva Shoal and 

Pearl and Hermes in 2006. Compared 

to French Frigate Shoals, Pearl and

Hermes Atoll and Maro Reef, one-third 

fewer coral species are found at Mokumanamana and Nihoa islands. At the

northern end of the chain, stony coral

species decline is linked to lower winter 

water temperatures and lower average 

annual solar radiation (Grigg,1982), and 

coral development is limited by extensive sand shallows towards the eastern 

sides of the lagoons (Maragos et al.,

2004). Moreover WWII era construction 

may have extirpated some corals from

Midway’s lagoon. Kure is the world’s most northern atoll and is referred to as the Darwin Point, where coral 

growth and subsidence/erosion balance one another (Grigg,1982). However, there are at least 30 submerged 

and presumably drowning seamounts to the southeast of Kure and within the PMNM, and the “Darwin point” 

may be better characterized as a Darwin zone stretching from Nihoa to Kure. 

Examination of reefs in ordination space based on presence-absence of coral taxa reveal two major clusters 

(Figure 4.3). High concordance exists among the basalt islands of Nihoa (NIH), Mokumanamana (MMM) and 

Gardner Pinnacles (GAR). These small islands are exposed to high wave energy from all directions and have 

low coral richness and cover. The reefs from Maro (MAR) north to Kure (KUR) cluster together in ordination 

space but the three most northern atolls (Midway [MID], Pearl and Hermes [PHR], and Kure [KUR]) show the 

highest concordance. The coral assemblage at French Frigate Shoals appears unique compared with all other 

locations likely due to the high proportion of acroporid species and possible connectivity with Johnston Atoll 

830 km to the south (Grigg et al., 1981; Maragos and Jokiel, 1986). 

Table 4.1. Least squares linear regression model for reef area less than 

10 fathoms versus coral taxa richness. Source: Maragos, unpub. data.

SUMMARY OF FIT 

R2 0.79859 

R2

 Adjusted 0.773414 

Root Mean 6.390495 

Square Error 

Mean of Response 35.7 

Observations 10 

(or Sum Wgts) 

ANALYSIS OF VARIANCE 

Source DF Sum of Squares Mean Square F Ratio 

Model 1 1295.393 1295.39 31.7199 

Error 8 326.7074 40.84 Prob > F 

C. Total 9 1622.1 0.0005 

PARAMETER ESTIMATES 

Term Estimate Std Error t Ratio Prob>|t| 

Intercept 24.88415 2.7878 8.93 <.0001 

Reef area 0.072376 0.012851 5.63 0.0005 

< 10 fathoms 

106 
Benthic Communities

Stress: 0.07

MID 

KUR NIH 

LIS PHR 

LAY 

GAR 

MAR 

MMM 

FFS 

Figure 4.3. Spatial distribution of reefs in the PMNM based on presenceabsence of coral species. Results of non-metric multidimensional scaling

plot. Source: Maragos, unpub. data. 

Table 4.2. A partial list of new records and possible new coral species from the NWHI. Source: Maragos, unpub. data. 

SPECIES LOCATION YEAR OBSERVERS 

Leptoseris incrustans New record Pearl and Hermes 2006 Kenyon, PIFSC-CRED 

Montipora New species? Pearl and Hermes 2006 Vargas, PIFSC-CRED 

Acropora valida New record Laysan 2006 Kenyon, PIFSC-CRED 

Pavona maldivensis New record Maro 2006 Kenyon, PIFSC-CRED 

Diaseris distorta, Cycloseris vaughani, and Cycloseris tenuis and soft New record Lisianski (30m) 2006 Maragos, Meyer, and 

coral Sinularia sp Papastamatiou 

Acropora cytherea and A. cerealis-valida New record Pearl and Hermes 2006 Asher and Zgliczynski 

Acropora valida New record Neva Shoal 2006 Asher and Zgliczynski 

Diaseris distorta, Cycloseris tenuis, Leptastrea scabra New record French Frigate Shoals 2006 CoML 

Leptoseris papyracea?? New record French Frigate Shoals 2006 CoML 

Acropora sp.1 New species? French Frigate Shoals 2006 CoML 

Porites sp. 15 New species? French Frigate Shoals 2006 CoML 

Porites lutea New record French Frigate Shoals 2006 CoML 

Unkown species New species? French Frigate Shoals 2006 CoML 

Abbreviations: PIFSC-CRED: The Pacific Islands Fisheries Science Center Coral Reef Ecosystem Division; CoML=Census of Marine Life. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Range Extensions and Possible New

Coral Species 

Recent scientific expeditions in the

NWHI have yielded many new records

and possibly many undescribed species

of stony corals since the last compilation

by Maragos et al. (2004; Table 4.2). One

of the most exciting discoveries in 2006

was of the table coral Acropora off the

southwest spur-and-groove habitat at

Pearl and Hermes Atoll and off the shallow southeast fore reef at Neva Shoal.

Additional dives confirmed the presence of Acropora cytherea and A. cerealis-valida at Pearl and Hermes, and A.

valida at Neva Shoal, which led to other

discoveries at Neva, a second Acropora

sp.1 and three Montipora species that

are all likely new to science. 

The Census of Marine Life (CoML) cruise to French Frigate Shoals in October 2006, led to additional sightings 

of rare species including Diaseris distorta, Cycloseris tenuis, Leptoseris scabra and Acropora sp.1. Another 

rare species, resembling Leptoseris papyracea was previously known only from dredge hauls by Vaughan 

(1907) in the MHI, and was reported for the first time in the NWHI off the southeast fore reef of French Frigate 

Shoals during CoML. An unidentifi ed species, Porites sp. 15, was reported off a southwest pinnacle of French 

Frigate Shoals, and the first record of Porites lutea in the NWHI was reported off the northern reef crest. Many 

new records including several unidentified species of coral were reported during the CoML cruise. The 2006 

investigations together have yielded possibly 11 new records for the NWHI most of which are likely to reveal 

new species. Towed-diver surveys contributed directly or indirectly to several of the new records and species, 

and exploratory dives in new habitats and sites contributed the rest. The Appendix at the end of the chapter 

lists all coral and anemone species reported at 11 islands, banks, atolls and reefs in NWHI as of October 2006. 

As was the case during earlier compilations, the larger atolls with diverse habitat and shelter from large northwest swell support the greatest number of species. 

107 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

108 

The most exciting coral discovery was

of an unknown species that has not yet 

be identified to the genus and family

(Figure 4.4). This coral may be a relict that was once common in the past

and subsequently died out elsewhere

but survived in Hawaii. The other possibility is that the coral may be a type

previously restricted to deep water that

evolved and subsequently adapted itself to shallow water habitats. Randall

(2007) makes note of two fish that were 

previously characterized as relicts. Likewise it is possible for relict corals to have 

survived in Hawaii to this day. In order to confirm this, it will be necessary to collect this and other corals to 

determine their phylogenetic origin. So far coral experts have not been able to conclusively determine the family to which this coral belongs based on photographs alone. Marine life in the NWHI evolved for many millions 

of years in isolation from neighboring archipelagos and islands and it plausible that this, and perhaps other 

species, were able to survive and thrive without the threat of newer species displacing them as likely occurred 

in other archipelagos. 

French Frigate Shoals was chosen as the target for the first CoML cruise because of the potential of yielding 

new species of corals, other invertebrates and benthic algae and possibly extending the range of many other 

species. Eight more species of cnidarians have already been reported from the atoll, further cementing the 

atoll’s status as the most diverse island or atoll for corals in Hawaii. The atoll is the closest of the Hawaiian 

chain to Johnston Atoll, some 450 nm to the southwest, and Johnston may be serving as a “stepping stone” for 

the dispersal of species to Hawaii from the Line Islands and other neighboring archipelagos south of Hawaii 

(Grigg, 1981; Maragos and Jokiel, 1986; Maragos et al,. 2004). This connection would explain why French 

Frigate Shoals has so many Acropora species which flourish at Johnston and why French Frigate Shoals has 

higher numbers of coral species compared to any of the other Hawaiian Islands. 

Figure 4.4. Potential new species of Acropora sp.1 from Lisianski-Neva 

Shoals and French Frigate Shoals (left). New, potential relict species yet 

undescribed from French Frigate Shoals. The genus and family are unknown (right). Both were discovered in 2006. Photo: J. Maragos. 

Coral Endemism 

The resumption of coral surveys to the

NWHI in 2000-2006 were not focused on 

looking for new coral species because

they were not expected to be there

based on the Grigg and Dollar (1980)

estimate of only 29 total species at 80

NWHI sites. Although endemic species

and range extensions were encountered 

during the 2000-2006 surveys, most belonged to described species, although

the totals nearly doubled the number

of coral species (57) reported in the

NWHI (Maragos et al., 2004). The exploratory and CoML expeditions of 2006 

were both focused on looking for new

species. However, scientists could only

photograph and examine corals in situ

because permission was not granted to

collect corals. 

Figure 4.5. Percent endemic stony coral species at each reef in the NWHI

during 1907-2006 compiled by Maragos from Dana (1846), Vaughan 

(1907), Dana (1971), Maragos et al. (2004) and unpublished records. Map:

L. Wedding. 
Benthic Communities

Table 4.3. Number of endemic and total stony coral taxa among major reefs 

in the PMNM. Source: Maragos, unpub. data. 

ISLAND TOTAL STONY 

CORAL SPECIES 

NUMBER OF 

ENDEMIC 

PERCENT 

ENDEMIC 

Nihoa 17 4 23.5 

Mokumanamana 21 8 38.1 

French Frigate Shoals 66 27 40.9 

Gardner 29 7 24.1 

Maro 41 12 29.3 

Laysan 34 11 32.3 

Lisianski 37 15 40.5 

Pearl and Hermes 43 14 32.6 

Midway 33 8 24.2 

Kure 36 15 41.7 

Total 80 35 44 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Based on all surveys to date (Figure 

4.5; Table 4.3) , there are now approximately 80 morphologically distinct coral 

“species” in the NWHI, and about 35 are 

likely to be endemic. Perhaps an additional five species are similarly endemic, 

although other specialists (Veron, 2000) 

believe they are widespread Pacific 

species. More than 25 NWHI species 

are still undescribed or unidentifi ed, and 

once type specimens are collected and 

examined morphologically and genetically, then final determinations can be 

made on which corals are new species 

and possible endemics. Notwithstanding efforts to date, NWHI explorations 

are still inadequate, and it is likely that 

additional undescribed coral species 

will be encountered in the future. 

Table 4.4. Number of Rapid Ecological Assessments (REA) and Toweddiver Surveys (TDS) conducted by NWHI RAMP (2004 and 2006) and 

NWHI Ecosystem Reserve (2005). PHR = Pearl and Hermes. Source:

NWHI RAMP, unpubl. data. 

2004 2005 2006 

REA TDS REA TDS REA TDS 

Mokumanamana 3 0 3 0 2 4 

French Frigate Shoals 11 17 6 0 10 19 

Gardner 3 2 0 0 0 0 

Maro 9 12 7 0 9 13 

Laysan 3 5 0 0 3 6 

Lisianski 9 12 0 0 9 12 

PHR 14 21 9 0 13 26 

Midway 9 15 6 0 9 15 

Kure 9 13 6 0 9 13 

Total 70 97 37 0 64 108 

109 

Coral Cover From Quantitative 

Surveys 

Percent live coral cover was derived 

from towed-diver data and rapid ecological assessments (REAs; Kenyon et al,. 

2006a; Table 4.4; Figures 4.6 and 4.7). 

Towed-divers observe a much greater 

expanse of benthic reef habitat (approximately 2 km in length/50 minute tow) 

than can be observed by free-swimming divers conducting REA surveys 

in a comparable time period and give a 

more widespread assessment of the total coral cover for each reef. Coral REA 

surveys were conducted at 70 sites in 

2004, 37 sites in 2005 and 64 sites in 

2006 (Table 4.4). As with percent cover 

data from 2002 surveys (which were 

calculated from size frequency data of 

colony counts within transects; Friedlander et al.; 2005), line-intercept data 

from surveys in all three years indicated 

coral cover varies greatly across the 

NWHI. 

Based on towed-diver survey data, 

Lisianski (18.8%) and Maro (14.9%) 

have the highest coral cover, followed 

by French Frigate Shoals (Figure 4.6). 

Percent coral cover from the REAs is 

higher owing to the fact that they were 

conducted on hard bottom habitats only. 

However, the trends are strikingly simi- Figure 4.6. Percent live coral cover among reefs in the PMNM from toweddiver survey data, 2000-2002. Source: NWHI RAMP; map: L. Wedding 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

110Benthic Communities

lar based on average estimates from 

2004 to 2006, with the highest coral 

cover at Maro (39.0%), followed by Lisianski (37.5%) and French Frigate 

Shoals (26.0%; Figure 4.7). The lowest percent coral cover was recorded 

at Midway (1.7%), Gardner Pinnacles 

(3.5%), and Mokumanamana (4.1%). 

The lowest cover from the REA surveys 

was observed at Midway (10.1%), with 

Pearl and Hermes (12.1%) and Gardner 

Pinnacles (12.4%) also having low coral 

cover. Benthic REAs were not conducted 

at Mokumanamana from 2004 to 2006. 

Coral cover values determined from 

2002 surveys also showed the highest 

coral cover values at Maro and Lisianski 

(Friedlander et al., 2005), though their 

magnitude (>60%) was greater than the 

values derived from the line-intercept 

method in 2004-2006. 

Coral cover estimates for each reef from

towed-divers and REAs compared with

the mean coral cover for each method

showed higher relative towed-diver survey values at Lisianski and French Frigate Shoals (Figure 4.8). This is likely due

to the extensive deeper reefs that were

not surveyed on the REAs, which are restricted to 15 m depth while towed-diver

surveys operate down to 27 m. Higher

relative coral cover estimates from REA

were found at Nihoa, Midway, and Pearl

and Hermes. The latter two locations

have extensive back reef habitats that

are not well surveyed by towed-divers

due to the shallow depth.

Figure 4.8. Comparisons of coral cover between towed-diver and REA estimates. Values are percent at each reef as a proportion of mean coral cover 

for that method. Source: NWHI RAMP, unpub. data.

2.5

Mean Percent Coral Cover

2.0

1.5

1.0

0.5

0.0

NEC FFS GAR MAR LAY LIS PHR MID KUR

REAs

Tow-boards

Figure 4.7. Live coral cover among reefs in the PMNM from REA data, 

2004-2006. Source: NWHI RAMP; map: L. Wedding
Benthic Communities

Table 4.5. Relative abundance of cnidarian colonies in the NWHI based on REA surveys at 64 sites conducted by NWHI 

RAMP in 2006. All cnidarian taxa for which at least one colony was tallied in at least one location are listed. Source: 

Forsman and Maragos, unpub. data. 

SPECIES PERCENT OF CNIDARIAN FAUNA 

MMM FFS MAR LAY LISI PHR MID KUR 

Acropora cytherea 0.0% 10.7% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Acropora valida 0.0% 5.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Acropora humilis 0.0% 0.3% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Montipora capitata 2.8% 2.6% 15.1% 9.4% 17.7% 6.3% 1.1% 2.7% 

Montipora patula 2.5% 2.5% 5.2% 1.6% 6.8% 1.0% 0.1% 0.0% 

Montipora flabellata 0.0% 0.0% 0.7% 0.0% 0.0% 0.5% 13.6% 1.9% 

Montipora incrassata 0.3% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Pavona duerdeni 1.9% 2.5% 2.5% 3.8% 2.1% 0.3% 0.0% 0.0% 

Pavona varians 0.1% 0.0% 0.0% 2.1% 0.1% 0.3% 0.4% 0.2% 

Pavona maldivensis 0.0% 0.0% 0.0% 0.0% 1.1% 0.2% 0.0% 0.0% 

Cyphastrea ocellina 0.0% 7.6% 4.8% 4.5% 18.8% 1.5% 0.9% 1.5% 

Leptastrea purpurea 0.6% 1.0% 0.2% 0.2% 0.3% 7.3% 1.1% 3.6% 

Fungia scutaria 0.0% 0.0% 0.5% 0.0% 0.9% 2.4% 0.0% 0.0% 

Leptoseris incrustans 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% 0.0% 

Pocillopora damicornis 0.0% 6.9% 0.7% 0.0% 6.4% 2.6% 8.5% 13.4% 

Pocillopora eydouxi 0.0% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Pocillopora ligulata 0.7% 0.4% 1.2% 0.0% 0.6% 0.1% 0.2% 0.5% 

Pocillopora meandrina 28.9% 8.1% 6.5% 17.4% 1.1% 26.2% 11.3% 52.4% 

Porites brighami 0.6% 1.1% 0.3% 3.8% 0.6% 0.0% 0.0% 0.0% 

Porites compressa 3.8% 15.9% 39.8% 1.9% 9.7% 8.5% 6.3% 5.4% 

Porites evermanni* 2.0% 1.5% 1.3% 0.2% 11.9% 0.0% 0.1% 0.1% 

Porites lobata 55.3% 32.2% 20.1% 54.9% 20.6% 37.1% 55.9% 16.3% 

Psammocora nierstraszi 0.0% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Psammocora stellata 0.0% 0.1% 0.0% 0.2% 1.3% 3.3% 0.2% 1.1% 

Palythoa sp. 0.6% 1.3% 1.0% 0.0% 0.0% 2.3% 0.1% 0.8% 

Total cnidarians counted 689 2,408 2,443 426 1,920 2,319 1,158 1,929 

Area surveyed (m2

) 100 500 450 100 450 650 425 450 

Island/Atoll abbreviations used throughout this chapter: MMM = Mokumanamana; FFS = French Frigate Shoals; and PHR =

Pearl and Hermes Atoll; GAR = Gardner Pinnacles; MAR = Maro Reef; LAY = Laysan Island; LIS = Lisianski Island; MID = Midway 

Atoll; KUR = Kure Atoll; NIH = Nihoa Island. 

* Porites evermanni is considered to be Porites lutea by Fenner 2005, although recent molecular analyses have confi rmed that P. 

evermanni is distinct from P. lutea. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Quantitative Estimates of Coral Genera and Species Abundance Among Reefs of the NWHI 

Relative abundance of cnidarians was assessed by computing the proportion of colonies, by taxon, that occurred within belt transects (Table 4.5, Figure 4.9). Taxa comprising more than 10% of colony abundance in 

each location are highlighted in bold type. These 2006 data surveys exemplify some general patterns seen 

in all years. The relative abundance of corals varies among regions, though Porites lobata composes a majority of the fauna at numerous regions and is an important component of the fauna in all regions. Acropora, 

particularly A. cytherea, is an important component of the coral fauna at French Frigate Shoals, but less so in 

other regions where it occurs (Mokumanamana to Pearl and Hermes, inclusive). Pocillopora meandrina and 

Montipora capitata are both abundant in some regions but less common in others. Numerous taxa are represented throughout the NWHI at very low levels of abundance; although 57 species of stony corals have been 

documented in the NWHI (Maragos et al., 2004), many species occur at such low frequencies that they were 

not encountered within survey transects. Thus, relatively few coral species numerically dominate throughout 

the NWHI. When species are pooled by genus, Porites, Pocillopora and Montipora collectively emerge as the 

numerically dominant genera throughout the NWHI though their relative abundance varies by region (Figure 

4.10). 

111 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

112 

Coral Density 

Density, the number of cnidarian colonies per square meter, is another 

metric of community structure that 

reflects the degree of “packing” of 

individual colonies. Such indices are 

useful when considering processes 

that may be density-dependent, for 

example, the spreading of contagious 

diseases and fertilization by spawned 

gametes during sexual reproduction. 

Colony density should be considered 

in association with size frequency distributions in visualizing the nature of a 

population from graphed data, e.g., a 

high colony density accompanied by a 

right-skewed size frequency distribution indicates a large number of small 

colonies, while a low colony density 

accompanied by a left-skewed distribution indicates a small number of 

larger colonies. Density varies by taxon and by habitat, as demonstrated 

for Pearl and Hermes Atoll in Figure 

4.11. 

Habitat 

Coral cover varies among reef geomorphologies and reef zones (Figure 

4.12). Maro Reef has been described 

as a unique open atoll, as it lacks 

the emergent or very shallow perimeter reef around a deeper lagoon that 

characterizes a classic atoll. Instead, 

the innermost area of the reef complex, with characteristics of a protected lagoon, is separated from the 

open ocean by the surrounding mesh 

of reticulate, linear, and patch reefs. 

Average coral cover at Maro, as determined through quantitative analysis 

of benthic imagery recorded over extensive distances surveyed by towed 

divers between 2000 and 2002, was 

14.0% (Kenyon et al., 2008a). Lisianski/Neva Shoal and French Frigate Shoals are also described as open 

atolls, the former with limited perimeter reef and the latter lacking perimeter reef to the west. Average coral 

cover at Lisianski was 19.7%, the highest average reef system value determined from extensive towed-diver 

surveys throughout the NWHI (Kenyon et al., 2007b). At French Frigate Shoals, coral cover was highest on 

the back reef (18.8%) and lowest in the lagoon (7.7%; Kenyon et al., 2006b). The most northern reef systems in the NWHI (Pearl and Hermes, Midway, and Kure) are described as classic atolls, as their perimeter 

reefs more completely surround a central lagoon. Quantitative analysis of benthic video images recorded 

over extensive distances by towed divers between 2000 and 2003 indicates that, in these classic atoll geomorphologies, coral cover is highest in the lagoon at Pearl and Hermes (19.1%) and at Kure (18.6%) and on 

Figure 4.9. Relative abundance of coral species throughout the NWHI. Data

are derived from colony counts within belt transects during 2006 surveys.

Source: NWHI RAMP unpubl. data; map: L. Wedding. 

Figure 4.10. Relative abundance of coral genera throughout the NWHI.

Data are derived from colony counts within belt transects during 2006 surveys. Source: NWHI RAMP unpubl. data; map: L. Wedding. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

the back reef at Midway (6.4%; Kenyon 

et al., 2007a; 2008b). At all three locations, coral cover is lowest on the fore 

reef, ranging from 1.6% at Midway to 

9.7% at Kure. Coral cover is low (5.3%) 

on the shallow (<30 m) bank surrounding Laysan (Kenyon et al., 2007b). 

Wave exposure is a major determinant 

controlling the development of Hawaiian 

coral reefs, with moderate coral cover 

developing in areas directly exposed 

to winter wave regimes and high coral 

cover developing in sheltered embayments and areas protected from direct 

swells. In the NWHI, the greatest winter 

wave stress originates primarily from 

the northwest and secondarily from the 

northeast. At French Frigate Shoals, an 

open atoll lacking perimeter reef to the 

west, coral cover on the fore reef was 

highest in the northwest sector (approximately 26%; Kenyon et al., 2006b). At 

Pearl and Hermes Atoll, coral cover was 

highest on the fore reef in the northwest 

and north sectors (approximately 24– 

28%; Kenyon et al., 2007a). At Midway 

Atoll, coral cover on the fore reef was 

also highest on the north sector (J. Kenyon, unpubl. data). At Kure Atoll, coral 

cover on the fore reef was highest along 

the arc extending counterclockwise from 

north to west (approximately 11–16%; 

Kenyon et al., 2008b). At Laysan, coral 

cover was highest in the northwest sector 

(7.3%; Kenyon et al., 2007b). Reef-wide 

patterns of coral cover at Maro Reef and 

Lisianski vary from those at other locations in the NWHI with respect to wave 

exposure. At Maro Reef, an open atoll 

with no perimeter reef, the highest coral 

cover was along the northeast sector, 

closely followed by the southwest sector (Kenyon et al., 2008a). At Lisianski/ 

Neva Shoal, an open atoll with limited 

perimeter reef, coral cover was highest 

in the southeast and southwest sectors (approximately 25–27%; Kenyon et al., 2007b). Both Lisianski/Neva 

Shoal and Maro Reef are classified as open atolls, but their complex structure of reticulate reef with little to no 

enclosure by perimeter reef likely generates a more complicated pattern of wave exposure than that experienced by atolls more clearly delineated by a perimeter reef, and accordingly they are characterized by different 

patterns of highest coral cover. 

Figure 4.11. Colony density (n/m2) of five coral genera at Pearl and Hermes

Atoll, NWHI. Number of colonies (n) was determined from belt transect surveys conducted in 2002. Source: NWHI RAMP; map, L. Wedding. 

113 

Figure 4.12. Differences in coral cover within different reef zones in the

NWHI. Numbers represent the average coral cover: (%) + standard error. 

Coral cover calculated from size frequency data of colonies within transects.

Data based on REA surveys in 2002. Not all habitats were sampled at all 

reefs. Source: NWHI RAMP, unpublished data; map: L. Wedding. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

114 

Wave Action 

High – north and west sectors experience regular large to huge wave events, especially in winter months 

where waves can exceed more than 15 m in height. Primary benthic components on exposed reefs are energy 

tolerant species and growth forms such as crustose coralline algae, non-delicate fleshy algae and encrusting 

Porites corals. 

Medium – east sectors experience nearly constant moderate wave action due to exposure from trade wind 

generated swells. Southern exposures receive occasional large swells generated by storms of tropical origin, 

especially in summer months. 

Low – the southwesterly parts of the islands generally represent the most protected sectors of the islands, 

but this generally applies to larger islands/atolls where shelter from waves is more extensive. Areas of shelter 

are minimal for the smaller islands. Atoll lagoons are the most protected of all geomorphological zones of the 

NWHI. 

Although early work in the NWHI assumed the best developed seaward reefs would occur off southwestern coasts (Grigg, 1983), analysis of imagery from more extensive and spatially comprehensive towed-diver 

surveys indicate coral cover on the fore reef is highest along the northwest, north, or northeast sectors at 

French Frigate Shoals, Maro Reef, Laysan, Pearl and Hermes Atoll, Midway Atoll, and Kure Atoll (Kenyon et 

al., 2006b; 2007a,b; 2008a,b). Only at Lisianski/Neva Shoal is coral cover highest along the southwest sector 

(Kenyon et al., 2007b) . 

Effects of Temperature on Northwestern Hawaiian Island Corals 

The coral reefs of the NWHI are in sub-tropical latitudes and exposed to large seasonal temperature fluctuations, particularly Kure, Midway and Pearl and Hermes Atolls, at the northwestern end of the archipelago. Sea 

surface temperature (SST) at these northerly atolls can fluctuate from less than 18°C in late winter (17°C in 

1997) to highs exceeding 28°C in the late summer months (29°C in 2002). Compared with most reef ecosystems around the globe, the annual fluctuations of SST of 10°C at these northerly atolls is extremely high. The 

cooler winter temperatures are thought to reduce coral growth rates. While the summer temperatures are 

generally similar along the entire NWHI, the warmest summer temperatures tend to occur at the three northernmost atolls, presumably caused by reduced mixing due to weaker winds (situated closer to the center of 

the North Pacific high pressure ridge) and decreased circulation due to large shallow water lagoons (Brainard 

et al., 2004; Hoeke et al., 2005). Roughly two-thirds of the variability in growth rate across the archipelago can 

be explained by changes in temperature and light availability (Grigg, 1982). Growth rates for a representative 

species of coral (P. lobata) dominant throughout the chain vary from 3 mm/yr to 13 mm/yr (Grigg, 1982). 

Siciliano (2005), however, reports that, while coral growth rates generally decline as a function of increasing 

latitude in the NWHI, as originally suggested by Grigg (1982), this decrease is habitat-specific. Coral colonies 

found in protected habitats throughout the NWHI chain (i.e., back reef and lagoon habitats on the atolls; embayments sheltered from wave action at the islands lacking lagoons) grow at similar rates regardless of latitude. This is may be explained by the microclimatic conditions experienced by corals growing in the shallower 

lagoon and back reef habitats, which are not closely related to offshore SST (Jokiel and Brown, 2004). Growth 

rates in these habitats may be influenced more by light and competition for space with other corals than by the 

relatively stable, and sometimes higher ambient temperatures afforded by these protected environments from 

solar heating in shallower lagoons. Conversely, corals growing in exposed habitats throughout the NWHI (i.e., 

fore reef of atolls or the reef slope of islands lacking a lagoon) experience temperatures more akin to offshore 

SST conditions, and therefore are more likely to respond to regional SST gradients, such as decreasing SST 

with increasing latitude, resulting in the measured latitudinal decrease in growth rates in these habitats. 

The growth rates reported by Grigg (1982) may also be an under-estimate at Kure Atoll because of selective sampling. In his assessment of coral growth rate throughout the NWHI, Grigg (1982) sampled Porites 

lobata exclusively in 10 m depth from exposed southwest areas. Inspection of Porites’ growth rates in three 

habitats at Kure atoll (Table 4.6, from Siciliano, 2005) reveals that the fore reef has the lowest growth rate 
Benthic Communities

Table 4.6. Mean linear growth rates (cm/yr) of five main reef-building coral 

GENUS FORE REEF BACK REEF LAGOON 

Porites 0.45 0.74 1.01 

Pocillopora 1.69 1.72 1.69 

Montipora 0.10 0.10 0.12 

Pavona 1.63 0.76 0.63 

Leptastrea 0.20 0.22 0.24 

genera in three habitats at Kure Atoll. Source: Siciliano, 2005. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

for this genus, among all sites sampled. 

Therefore exclusive sampling from this 

area is likely to underestimate average 

growth rates per atoll. Even so, Porites’ 

growth rates from the fore reef habitat in 

Siciliano’s study (4.5 mm/yr) are higher 

than those reported by Grigg for Porites lobata (3 mm/yr), even if the data 

for Porites exclude the faster growing, 

branching forms such as P. compressa 

(largely absent from Kure’s fore reef). Encrusting and more massive growth forms of P. lobata and P. evermanni, important reef builders at Kure, were included in the more recent assessment. 

Inspection of Table 4.6 also indicates that if the Porites growth rates were adjusted to reflect those of other 

reef-building corals in the fore reef habitat using Grigg’s approach (i.e., by averaging Porites’ growth rates with 

those of other reef-building genera), the corals’ growth rate would increase to 0.8 mm/yr, rather than decrease 

as suggested by Grigg (1982), who reported an adjusted growth rate of 0.2 mm/yr for Kure Atoll. 

Monitoring Corals at Permanent Transect Sites in the Northwestern Hawaiian Islands: 2001-2006 

This section focuses on the results of 

monitoring coral communities at 27 permanently marked transects established 

at seven of the 10 NWHI from 2001-2002 

and resurveyed in September 2006, and 

account for most of the 42 permanent 

transects established in the NWHI from 

2000-2002. Changes in percent coral 

cover per transect were compared between 2001-2002 and 2006 at permanent transects (Figure 4.13). Mean coral 

cover declined by 2% from 2001-2002 

to 2006 but was not signifi cantly different between these time periods (w= 

53, p=0.51). Table 4.7 summarizes the 

results of the 2006 permanent transect 

resurveys and offers a comparisons to 

earlier surveys at the same sites. The 

changes in percent coral cover, mean 

diameter, number of coral genera and 

the density of all corals per transect are 

provided in the table. When pooling the 

data for all 27 sites, percent coral cover 

declined from 16.6 % to 14%, mean diameter declined from 22.7 to 15.5 cm, number of genera increased from 

2.9 to 4.3, and coral densities increased from 4.8 to 6.7 corals m2

 at the same set of transect sites over the four 

to five year interval. These trends are significant for all categories except percent coral cover. Changes in the 

survey techniques between the two sets of surveys can explain some of these patterns. For one, in situ census 

of corals vis-à-vis analysis of photos would likely lead to detecting greater numbers and genera for smaller corals, leading to lower mean diameter values. However, the analysis of the individual sites over the time interval 

reveals that some of these trends can only be explained by in situ observations and site-specifi c data. 

115 

Figure 4.13. Percent change in coral cover between 2001-2002 and 2006

at permanent stations in the PMNM. Source: Maragos, unpub. data; map:

L. Wedding. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 4.7. Percent coral cover, mean diameter, number of genera and frequency of all corals at each of 27 permanent 

transect sites surveyed in 2001-2002 and 2006. Bold numbers are the higher of two (earlier or later) values at each site. 

116 

SITE 

NUMBER 

FFS- 5P 

FFS 3P 

FFS 16P 

FFS 2P 

FFS 11P 

LAY 1P 

LAY 5P 

LIS 1P 

LIS 9P 

LIS 6P 

MAR 4P 

MAR 5P 

MAR 1P 

MID 7P 

MID 16P 

MID 14P 

MID 18P 

MID 19P 

MID 20P 

MID 1Pa 

MID 2P 

MID 17P 

MMM 1P 

PHR 6P 

PHR 7P 

PHR 9P 

PHR12P 

TOTALS 

HABITAT LOCALE DATE 

PERCENT 

CORAL COVER

 MEAN 

DIAMETER CM 

NUMBER 

GENERA/SITE 

DENSITY 

(#/m2

) 

2001-

2002 

2006 2001-

2002 

2006 2001-

2002 

2006 2001-

2002 

2006 

fore reef NW 7/17/2001 19.4 16.8 11.6 13.3 4 3 14.2 11.7 

lagoon basalt N cen. 7/16/2001 27.7 28.8 19.9 17.8 5 5 8.5 11.5 

Lagoon N 9/15/2001 4.8 9.5 12.3 15.1 5 4 4.6 7.8 

reef crest S 7/15/2001 27.2 33.5 26.2 20.1 7 6 5.3 9.4 

back reef N 10/30/2002 39.1 22 76.2 21.3 3 4 1.6 5.9 

channel S 9/17/2001 5.9 5.1 7.7 10.9 3 6 9.5 4.9 

reef pool SE 9/18/2002 7.7 8.7 11 14.6 3 4 5.6 4.8 

reef crest S cen. 9/30/2002 5.3 0.43 14.5 4.6 2 4 3.8 0.36 

pinnacle E 10/2/2002 19.2 24.9 22.9 16.3 2 4 5.1 9.8 

fore reef N 10/1/2002 27.9 46.8 57.4 40.6 1 3 1.8 4 

back reef NW 9/16/2002 52 34.4 36.4 20.6 3 7 6.4 11.4 

Lagoon center 9/21/2001 4.2 5.9 10.9 10.3 2 5 3.8 5.1 

fore reef SE 9/15/2002 32.4 7.9 29.6 9.3 3 7 4.6 8.2 

Lagoon E 9/23/2002 50 1.1 25 7.6 4 4 nd. 3.2* 

back reef N 12/3/2002 24.3 36 46.7 29.7 3 3 2.1 5.8 

lagoon

pinnacle 

center 9/24/2002 4.7 12.2 8 12 2 3 12.2 9.5 

back reef NE 12/4/2002 0.7 1.3 6.8 7.4 4 5 2.5 3.5 

lagoon

pinnacle 

SW 12/5/2002 5.1 0.9 14.7 13.1 2 3 2.77 1.02 

back reef NW 12/6/2002 22.3 19.2 48.7 31 3 2 1.46 2.7 

reef crest E 12/3/2002 3.3 1.04 17.6 11.7 2 4 1.73 2.46 

back reef NE 9/21/2002 13.8 13.8 22.6 21.3 4 4 2.8 2.8 

back reef E 12/4/2002 9 3.5 10.4 20 2 4 4.6 1 

basalt fore 

reef 

S 9/9/2002 6 14.6 8.4 10.6 2 4 9.1 18.4 

lagoon

pinnacle 

S 9/19/2002 2.53 1.53 11.7 7.6 2 4 1.8 4.8 

lagoon patch

reef 

center 9/27/2002 24 20.7 25.6 10.1 1 3 4.64 19.8 

Pass S 9/28/2002 1.69 0.23 14.4 9.5 2 4 1.07 0.4 

fore reef SW 9/29/2002 8.95 7.11 15.5 11.1 3 6 3.15 6.48 

27 MEANS 16.64 14 22.69 15.46 2.9 4.3 4.8 6.7 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Mokumanamana 

Permanently marked transect NEC-1P 

is located in a semi-sheltered recessed 

bay or bight off the southwest side of 

Mokumanamana and is the only permanent transect established to date. The 

site was re-surveyed on September 3, 

2006. All coral population parameters increased during the four year period between the two surveys. Mean diameter 

increased from 8.4 cm to 10.6 cm. Coral 

densities increased from 9.1 to 18.4/m2

, 

generic diversity increased from two to 

five genera, and coral cover more than 

doubled to 14.6%. All four of the smaller 

size classes for total corals increased 

substantially during the four year period 

although there were only a few corals 

represented at the higher size classes 

for each survey period (Figures 4.14 and 

4.15). Overall, all smaller size classes increased and the larger stayed the same. 

Severe exposure to waves from any direction and the large winter swell from 

the northwest may prevent development 

of large, high profile corals. The lobe 

coral (Porites lobata) followed by the 

rose/cauliflower coral (Pocillopora meandrina) continue to dominate the coral 

fauna, although the zoanthid soft coral 

(Palythoa tuberculosa) has emerged as 

a common coral on the transect in 2006, 

even though absent in 2002. The number of Porites corals doubled for the all 

four smaller size classes while Pocillopora also increased dramatically in all 

size classes. Despite the exposed and 

scoured environment at the site, corals 

have increased dramatically at NEC-1P 

over the four year period. 

French Frigate Shoals 

Eleven permanent monitoring transects for corals were established at French Frigate Shoals from 2001-2002, 

with four resurveyed in September 2006. These are: Serendipity Hollow (site FFS 11P) on the northern back 

reef; site FFS 16P at the CREWS buoy site in the northern lagoon; site FFS 3P off the north side of La Perouse 

Pinnacle in the north central lagoon; and site FFS 2P just west of Disappearing Island off the south reef crest 

of the atoll. Large northerly swell and limited time during the visit prevented safe access to and survey of the 

remaining seven sites. 

All sites showed increases in coral density (number of corals/m2

) and most showed increases in coral cover 

and generic diversity (Figures 4.16 and 4.17). The northern lagoon site (FFS-16P) showed increases in mean 

coral diameter and dramatic increases in the other coral parameters between 2001 and 2006, although the 

three smallest size classes peaked in 2002. The Serendipity Hollow (FFS 11P) site appears to have exFigure 4.14. Percent change in coral cover at Mokumanamana between

2002 and 2006. Source: Maragos, unpub. data; map: L. Wedding. 

117 

Figure 4.15. Changes in the proportion of each genus, size distribution and

cover for corals reported at Mokumanamana Island permanent sites between 2001-2002 and 2006 permanent site 1P. Source: Maragos, unpub. 

data. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

1­ 5 

6­ 10 

11­ 20 21­ 40 41­ 60 

1­ 5 

6­ 10 

11­ 20 21­ 40 41­ 60 

Coral Size Distribution (cm) 

Area - cm2 (/1,000) 

Montipora Palythoa Pocillopora Porites 

2002 2006 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

Figure 4.17. Changes in the proportion of each genus, size distribution and cover for corals reported at French Frigate 

Shoals permanent sites between 2001-2002 and 2006: a) 2P, b) 3P, c) 16P and d) 11P. Source: Maragos, unpub. data.

60

50

)00040 ,1/( 2 m

30

c - aer20

A 10

0

-5

0

0

0

0

0

0

-5

0

0

0

0

0

0

1

-1

-2

-4

-8

6

6

6

1

1

1

1

1

1

6-1

-21

1-4

-8

6

6

1

1

2

-

1

2

-

1

1

>

1

4

4

1

>

8

8

Acropora Leptastrea Montipora Pocillopora

Porites Palythoa Pavona

A

Psammocora

45

40

35

)00030 ,1/( 2

25

mc -

20

 aer15

A 10

5

0

1-5

0

0

0

0

0

-5

0

0

0

0

0

0

-1

-2

-4

-8

61

1

6

1

1-2

-

1-4

6-1

8

6

6

1

1

1-

-1

1

1

2

4

1

1

2

4

1

>

8

8

Acropora Cyphastrea Montipora Palythoa

Pavona Pocillopora Porites Psammocora

2001- 2002 2006 2001- 2002 2006

18

16

14

)0012 0,1/( 2

10

mc -

8

 aer

6 A

4

2

0

5

0

0

0

0

0

5

0

0

0

0

0

1-

-1

-2

-4

-8

6

1-

-1

4

1

-2

6

1

6

1

1-

8

6

1

1

-

1

2

4

1-

1

1

1

2

4

1-

8

8

Coral Size Distribution (cm)

Cyphastrea Leptastrea Montipora

Pavona Pocillopora Porites

2001 - 2002 2006

140

120

100

000)1,(/ 

80 2 cm60 ea rA

40

20

0

-5

0

000

0

0

-5

0

0

00

0

0

1

-1

-2-4

-8

6

6

1

-1

-2

4

8

6

6

6

111

11

6

1-1-

12

-

14

1-1

1

1

>

1

4

2

>

8

8

Coral Size Distribution (cm)

Acropora Montipora Pocillopora Porites

2001 - 2002

B

C D

2006

Coral Size Distribution (cm) Coral Size Distribution (cm)

118Benthic Communities

perienced wave damage in the recent 

past, based upon broken and overturned corals observed at the site in 

2006, but coral populations continued 

to maintain high values and post modest increases in all size classes except 

the largest two. The La Perouse site 

(FFS 3P) posted increases in generic 

richness, with the addition of Acropora, 

Montipora and Psammocora, although 

there were slight decreases in the abundance of Pocillopora and Porites. Corals at the Disappearing Island, site (FFS 

2P) showed consistent gains in the four 

smallest size classes and dramatic increases in the number of genera over 

the five year period. Moreover, six coral 

genera noticeably increased in abundance (Acropora, Pocillopora, Porites, 

Palythoa, Pavona, Psammocora) with 

Montipora showing a modest decline. Figure 4.16. Percent change in coral cover at French Frigate Shoals between 2002 and 2006. Source: Maragos unpub. data; map: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

12

10

8

6

4

2

0

)000,1/( 2 mc- aerA

Psammocora Porites Pocillopora Montipora Cyphastrea

2001 - 2002 2006

70

60

50

40

30

20

10

0

)000,1/( 2 mc- aerA

Zoanthus Porites Pocillopora Pavona Palythoa Montipora Cyphastrea

2001- 2002 2006

400

350

300

250

200

150

100

50

0

)000,1/( 2 mc- aerA

Coral Size Distribution (cm)

Porites Pocillopora Pavona Palythoa Montipora Leptastrea

A B

C Acropora

2001 - 2002 2006

Coral Size Distribution (cm) Coral Size Distribution (cm)

Figure 4.19. Changes in the proportion of each genus, size distribution and cover for corals reported at Maro Reef permanent sites between 2001-2002 and 2006: A) 15P, B) 1P and C) 4P. Source: Maragos, unpub. data.

119Benthic Communities

Maro Reef

Three permanent transect sites were 

established at Maro Reef between 

September 2001 and September 2002 

(Figures 4.18 and 4.19). Site MAR 1P is 

located on a southeast facing fore reef 

of a patch reef. Site MAR 4P is located 

at the far northwest end of Maro, on a 

south-facing leeward fore reef. MAR 

15P is near the middle of these two extremes in the central shallow protected 

lagoon 20 m north of the NOAA CREWS 

buoy. All sites were resurveyed on 7-9 

September 2006. Wave exposure varies 

considerably among the three, with the 

southeast site most exposed, the central site least exposed, and the northwest subjected to intermediate wave but 

stronger current exposure.

Coral populations showed mixed trends

over the four to five year period. The

number of genera increased from 2-3 per site in 2001-2002 and to 6-7 per site in 2006. The dominant corals 

at all three transects were the lobe coral (Porites lobata) and the rose coral (Pocillopora meandrina). Other 

common coral genera were Pavona and Montipora, the latter absent at the southeast site in 2001 (MAR 1P), 

but more abundant at all three in 2006. The encrusting brain coral (Leptastrea pruinosa) was absent at all three 

sites in 2001-2002 but emerged as a common species at the northeast site (MAR 4P).

Figure 4.18. Percent change in coral cover at Maro Reef between 2002 and 

2006. Source: Maragos, unpub. data; map: L. Wedding. 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

14

12

10

8

6

4

2

0

)000,1/( 2 mc- aerA

Cyphastrea Leptastrea Montipora Pavona Pocillopora

A

Porites

2001- 2002 2006

18

16

14

12

10

8

6

4

2

0

)000,1/( 2 mc- aerA

Coral Size Distribution (cm)

Cyphastrea Pavona Montipora Pocillopora

B

Porites

2001 - 2002 2006

Coral SizeDistribution (cm)

Figures 4.21. Changes in the proportion of each genus, size distribution, and cover for corals reported at Laysan Island 

permanent sites between 2001-2002 and 2006: A) 1P B) 5P. Source: Maragos, unpub. data. 

120Benthic Communities

Mean diameters decreased at all sites, from 10.9, 29.6 and 36.5 cm in 2001-2002 to 10.3, 9.3 and 20.6 in 2006 

at sites MAR 1P, MAR 4P and MAR 15P, respectively. However, coral densities (number of corals/m2) increased 

at all sites over the same period from 3.8, 4.7 and 6.4 to 5.1, 8.4 and 11.2 corals in 2006 at the same respective 

sites. Coral cover decreased at MAR 4P and 1P and increased at MAR 15P. At site MAR 15P the numbers of 

smaller corals generally increased, but at the southeast site (MAR-1P) and the northwest site (MAR 4P) the 

numbers for all size classes decreased. Many larger corals appeared to show signs of fragmentation to smaller 

sized corals at the two more exposed sites (MAR-1P, MAR-4P) that could explain the observed shifts in size. 

Laysan Island

Two permanent transect sites were established at Laysan Island in September 2002 and resurveyed in September 

2006. Site LAY-1P is located along the 

north side of the sand channel in the 

southwest embayment (Figures 4.20 

and 4.21). Site LAY-5P is located on 

the shallow southwest reef crest, just 

south of the embayment and west of the 

NOAA monitoring buoy. Both transects 

are sheltered from heavy winter swells 

from the northwest Pacific that strike the 

NWHI during the winter months.

Coral population parameters showed 

mixed trends over the four-year period. 

Generic richness increased from three 

to four genera at sites LAY-1P and LAY5P from 2002-2006. Mean diameters 

also increased at both sites, from 7.7 

cm to 10.9 cm at LAY-1P and from 11 

cm to 14.7 cm at LAY-5. However, coral 

densities dropped at both sites, dramatically at LAY-1P from 9.5 to 4.9, and less so at LAY-5P from 5.6 to 4.8 

over the four- ear period. About 10% of the corals, mostly Porites lobata, at LAY-1P appeared sick or dying, 

and overall coral health at this site appears less than reported there in 2002, including a 50% decrease in coral 

cover. There were few sick or dying corals at the reef crest site LAY-5P although coral cover declined slightly.

Figure 4.20. Percent change in coral cover at Laysan Island between 2002 

and 2006. Source: Maragos, unpub. data; map: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

121Benthic Communities

Laysan’s smaller oval shape renders it 

vulnerable to severe exposure to waves 

from the west to northeast, and the large 

winter swell from the northwest may 

prevent development of large, high profile corals at shallow depths. Although 

not measured during the 2006 surveys, 

benthic algal cover appeared especially 

high at the west channel site LAY-1P, 

and algae is prolific at other sites (J. 

Maragos, per. obs.). Aside from its small 

size, Laysan Island supports over a million breeding seabirds and significant 

monk seal and sea turtle populations. 

Together with seepage from its high 

nutrient-laden hypersaline lake, Laysan 

Island may be subsidizing substantial 

localized productivity from local nutrients which in turn may favor the growth 

of algae over corals in most shallow reef 

habitats. 

Lisianski Island

Three permanent 50 m long transects 

were established in shallow water near 

Lisianski Island in September-October 

2002 and all three were resurveyed 

in September 2006 (Figures 4.22 and 

4.23). Site LIS 1P was established 

on the shallow southwest fore reef at 

depths of 1.2 to 4.6 m. Site LIS 6P was 

established near the opposite, east side 

of the island at similar depths along the 

fore reef-reef crest margin. The third site 

LIS 9P was established off the northern 

fore reef slope of the island at depths of 

7.3-14.9 m. Water visibility, wave action 

and currents are notably stronger at the 

latter two sites (LIS 6P and 9P) located 

windward of the island. Site LIS 1P is 

down-drift of the island and in the direct 

path of current and water flow from the 

island.

In 2002 coral coverage was estimated 

at 5.3%, coral density at 3.8 corals/

m2

, and mean diameter at 14.5 cm at 

the southwest site LIS-1P. Corals there 

were primarily plates of Montipora corals intermixed with green algal growths 

of Neomeris and Microdictyon. On the 

opposite, eastern site, LIS-6P, large 

plates of the same coral Montipora cf. 

Figure 4.22. Percent change in coral cover at Lisianaski-Neva Shoals between 2002 and 2006. Source: Maragos, unpub. data; map: L. Wedding.

120

000)100 1,

80

(/ 2

60

cm- 40 ea rA20

0

1-5

6-10

-20

-40-801-5

0

-20

-40

11

-160

6-1

-80

11

2141

-160 81

>160

2141

81

Coral Size Distribution (cm)

Cyphastrea Montipora Pocillopora

2002 2006

10

9

000)

8

1,

7

(/ 2

6

5

cm4

3

ea r

2

A

1

0

1-5

6-10

-20

-40

-80

-160

1-5

6-10

-20

11

21

41

81

11

Montipora Pocillopora Porites

2002 2006

70

60

000)

50

1,(/ 2

40

cm30 ea r

20

A

10

0

1-5

6-10

-20

-40

-80

-160

1-5

0

-20

-40

-80

11

21

41

6-1

11

21

41

-160

81

81

Cyphastrea Montipora Pocillopora

A

Porites

B

2002 2006

C

Figure 4.23. Changes in the proportion of each genus, size distribution, and 

cover for corals reported at Lisianski-Neva Shoals between 2002 and 2006: 

A) 1P, B) 9P and C) 6P. Source: Maragos, unpub. data. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

122 

turgescens dominated the bottom, averaging 27.9% coral cover, 1.8 corals/m2, and with an average diameter 

of 57 cm in 2002. The north, offshore site consisted of hard bottom covered with encrusting Montipora corals 

at shallow (6-7.6 m) depths and transitioned to larger, widely spaced colonies of Porites lobe corals and Pocillopora rose corals over a rubble sand bottom at depths of 9.1-15.2 m. Coral coverage was 19.2% with a mean 

diameter of 23 cm and frequency 5.06 corals/m2

 in 2002. 

Four years later, resurveys yielded a near total collapse of corals at site LIS-1P. Coral cover was estimated at 

0.43%, mean diameter at 4.56 cm, and coral density at 0.36 corals/m2

, translating to only 17 corals in the three 

smallest size classes for the entire transect. In great contrast, the two windward sites fared much better over 

the four years with coral cover higher at both in 2006. Mean diameter at site LIS-6P was less but still substantial at 40.6 cm. Likewise site LIS-9P showed smaller mean diameter for corals at 16.3 cm, but coral frequencies 

nearly doubled at both windward sites, with 2006 values at 4.00 and 9.84 corals/m2 respectively. The small 

brain coral Cyphastrea appeared at all three sites for the first time in 2006, and Pocillopora increased in size 

and numbers at all three sites. The plate coral Montipora nearly disappeared by 2006 at site LIS-1P with only 

10 small colonies remaining from 184 mostly larger colonies in 2002. At the other two sites Montipora plate 

coral increased dramatically for smaller to middle sized corals. The lobe coral Porites also declined at the 

southwest site LIS-1P, but increased modestly at the northern site LIS-9P. Figure 24 illustrates the changes in 

size distribution for all corals over the four year period at the three sites. 

The collapse of the coral community at southwest site LIS-1P may have been caused by a coral bleaching 

event followed by the overgrowth of algae, the latter perhaps stimulated by plentiful nutrients leaching from 

the island and derived by extensive guano production generated by the large resident seabird populations at 

Lisianski. Ambient water temperature was higher at the site during the 2006 survey and may have a longer 

residence time in shallow depths where solar heating would be higher. Also, the waters to the southwest were 

noticeably greener due to higher phytoplankton productivity. In contrast, water clarity was better, water motion 

stronger and temperatures cooler at the two windward sites that showed increased coral development. 

Pearl and Hermes Atoll 

Eight permanent coral transects were 

established at Pearl and Hermes prior to 

the September 2006 visit. Four of these 

were established at the site of the 2000 

grounding of the fi shing vessel Swordman I. The 2006 REA team did survey 

one or more of the back reef sites but 

these data are currently not available. 

The remaining four permanent transects 

established in 2002 consist of site PHR 

6P, a shallow south lagoon pinnacle 

slope; PHR 7P, a central lagoon patch 

reef in the finger coral gardens; PHR 

9P on the floor of the main south pass 

of the atoll; and PHR-12P off the southwest fore reef of the atoll (Figures 4.24 

and 4.25). 

Coral populations showed smaller mean 

diameters (7.6 to 11.1 cm) in 2006 compared to their corresponding 2002 values 

(11.7 to 25.7 cm) at all sites. However, 

all sites showed higher generic diversity levels in 2006 (three to six genera/transect) compared to corresponding 2002 values (one to three genera). The 2006 coral populations also showed larger densities at all sites 

except PHR-9P, varying from 0.4 to19.8 corals/m2

, compared to 2002 levels (1.07 to 4.64 corals/m2). The 

Figure 4.24. Percent change in coral cover at Pearl and Hermes Atoll between 2002 and 2006. Source: Maragos, unpub. data; map: L. Wedding. 
A 

Benthic Communities

6 

1-5 

0 

0 

0 

0 

0 

0 

0 

5 

5 

10 

-1

1-2

1-4

20 40 

1-8

10 

20 40 

1-5 

-1

1-

1-2

1-4

6

6-

1

4

2

21-

1-

6

2

1

11-

6-

11-21-

5 1-

10 

20 40 80

160 

>160 

5 

10 

5

1-

10 

20 40 80 

51-

20 40 80 

160

>160 

1-

10 

20 

40 80

6-

11-21-41-

6-

11-21-41-

6-

11-21-41-

81-

81-

6-

160

11-

21-41-

81-

>160 

Leptastrea Pocillopora Porites Psammocora B Leptastrea Pocillopora Porites Psammocora

7 8 

2002 2006

1 

0 

7 2002 2006 

000) 5 

/1,000) 6 

1,

5 

 (/

4 

 (

2 ea - cm

2 cm4 

3 

rea - 3 

rA2 A

2 

1 

0 

9 

8 

1 

0 

C Leptastrea Montipora Pavona Pocillopora Cyphastrea Pocillopora Porites D 60 

50 

2002 2006 

10 

0 

7 2002 2006

1,000) 6 

/1,000) 40 

/

 (

 (

2

2

5 

 cm

m

30 

4 

 - c

ea -

ae

r

3 20 

A

Ar

2 

Coral Size Distribution (cm) Coral Size Distribution (cm) 

Figure 4.25. Changes in the proportion of each genus, size distribution, and cover for corals reported at Pearl and Hermes

permanent sites 6P, 9P, 12P and 7P from 2002 and 2006. Source: Maragos, unpub. data. 

123 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

small brain coral (Cyphastrea ocellina) was reported on three transects for the first time in 2006, and Palythoa, 

Pavona and Psammocora were all reported for the first time on one transect each. 

The three smallest size classes dominated the coral numbers at all 2006 sites except the south pass site 

(PHR-9P). Coral populations in the pass were much diminished from their 2002 levels at all size classes. 

During both the 2002 and 2006 surveys, currents ranged from 2 to 3 knots in the pass, with considerable suspended sediments. Scour and periodic wave action may be controlling coral development in the south pass. 

At the fingercoral garden site (PHR-7P), corals in the three smallest size classes were an order of magnitude 

more abundant in 2006 compared to 2002 levels for Porites compressa, although there was no substantial difference in the larger four size classes. In general, all corals combined were more numerous at the larger size 

classes at all four sites in 2002, Figure 4.25 compares size distributions for all corals in 2002 and 2006 at the 

four permanent coral transect sites. 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

124Benthic Communities

Figure 4.27. Changes in the proportion of each genus, size distribution, and cover for corals reported at 7 permanent sites 

at Midway: A) MID 1Pa, B) 2P, C) 14P, D) 17P, E) 18P, F) 19P and G) 20P. Source: Maragos, unpub. data. 

8

7

)0

6

00,1/

5

( 2 m

4

c - a

3

erA

2

1

0

5

0

0

0

0

0

5

0

0

0

1-

-1

-2

-4

-8

6

1-

1

1

6-

1-2

4

6

1

1

1

1-

1

2

4

1-

1

2

8

Coral Size Distribution (cm)

Pocillopora Porites Psammocora

2002 2006

30

25

)000,20 1/( 2 m

15

c - aer10

A

5

0

-5 

0 0 0 0 

0

0

5 

0 0 0

0

1

-

0

0

6-1

-2-4

66

1

1248

111-8

66

-1

1

-

>

61-1-1-

24

1

24

1-1

1

1

1

>

8

8

Coral Size Distribution (cm)

Cyphastrea Montipora Pocillopora Porites

2002 2006

25

20

)000,1/( 15

2 mc - a10 erA

5

0

0

1-5 

0 

00

0

-5

0

000

0

0

6-1

1-2

-4

8

1

4

1-

6

-

-2

1-1-8

6

6

-1

1

16

1

-1

1

1241

1241

>

8

8

Coral Size Distribution (cm)

Cyphastrea Montipora Pocillopora Porites

2002 2006

30

25

)000, 20 1/( 2 m

15

c - aer10

A

5

0

-5

0

0

0

0

0

1

6-1

-2

8

1-5

0

0

0

0

4

1

2

4

8

6

1

1-

1-

6-

1-

1-

1-

1

2

4

1

2

4

1-1 8

Coral Size Distribution (cm)

Pocillopora Porites Psammocora

2002 2006

A B

C D

Midway Atoll

Eleven permanently marked transects 

were established at Midway Atoll National Wildlife Refuge between 2000-

2002. Eight sites were resurveyed in 

September 2006 and are shown in Figures 4.26 and 4.27. Five of the resurveyed sites are situated on the northern 

and eastern back reefs (MID 1Pa, 2P, 

7P and 17P), two on the NW back reef 

(MID 18P, 20P), one near the southwest 

reef crest (MID 19P) and one on a central lagoon patch reef (MID 14P).

Figure 4.26. Percent change in coral cover at Midway Atoll between 2002 

and 2006. Source: Maragos, unpub. data; map: L. Wedding. 

0.5

1

1.5

2

2.5

Area - cm2 (/1,000)

Cyphastrea Montipora Palythoa Pavona Pocillopora Porites

2002 2006

2

4

6

8

10

12

14

16

Area - cm2 (/1,000)

Montipora Pocillopora Porites

2002 2006

E F
Benthic Communities

E F 

2006 

2 

1.5 

1 

-5

0 

0 

0

-5

0 

0 

0 

0 

5 

1

-1

-2

-4

1

-1

-2

1-

10 

20 

5 

-4

-8

40 80 

1-

10 

20 40 

80 

6

1

1

6

1

1

1

6-

1

2

2

4

11-21-41-

6-

1

11-21-41-

70 

5 1-

1020 40 80 

6-

160

21-41-

81-

>160 

5 1-

10 2040 80 

6-

160

11-11-21-41-

81-

>160 

Cyphastrea Montipora Palythoa Pavona Pocillopora Porites Montipora Pocillopora Porites 

2.5 16 

14 2006 2002 2002 /1,000) 12 

10 

/1,000) (

 (

2

2

 cm

m

8 

 - c

ea -

a

6 e

rA

Ar

4 0.5 

2 

0 0

/1,000) ( 2 m - caeAr

Coral Size Distribution (cm) Coral Size Distribution (cm) 

G Montipora Pocillopora Porites 

60 2002 2006

50 

40 

30 

20 

10 

0 

Coral Size Distribution (cm) 

Figure 4.27 (continued). Changes in the proportion of each genus, size distribution, and cover for corals reported at 7

permanent sites at Midway: E) 18P, F) 19P and G) 20P. Source: Maragos, unpub. data. 

Figure 4.28. In 2006 both Cyphastrea ocellina (left) and Psammocora stellata (right) were reported for the first time at Midway Atoll. Photos: J. Maragos.

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

125 

Overall, coral populations showed mixed 

trends during the four year period. The

abundance and numbers of Porites

lobata and P. compressa decreased

slightly. The rose coral Pocillopora spp

showed no clear trend, and the abundance of Montipora capitata and M. cf.

turgescens generally increased from

2002-2006. The small brain coral (Cyphastrea ocellina) and small branching coral (Psammocora stellata) were

reported for the first time at several

transects in 2006 (Figure 4.28). Overall there were no trends for coral mean diameter or frequencies over the 

four year period, although generic diversity per transect increased at most sites. 

The eastern back reef site MID-1Pa showed increases at smaller size classes but declines in larger corals. 

The neighboring east back reef site 17P showed major declines in all size classes and genera. Finger coral 

(Porites compressa) at the southeast lagoon site MID-7P were abundant in 2002, but in 2006 were all dead 

but still standing. The southwest reef crest/back reef site MID-19P also showed catastrophic declines in all 

corals. In contrast, the two northern back reef sites MID-20P and MID-18P dominated by Montipora showed 

major increases over the four year period. In 2002, Montipora at these sites were especially hit hard by coral 

bleaching, but now have rebounded to levels comparable if not higher than those reported earlier. The reasons 

for the major coral declines at sites MID-7P, -1P and -17P are not clear but warrant continued monitoring. The 

declines may be related to the residual effects of WWII and post WWII military construction at Midway, which 

resulted in the dredging of a deep channel between the lagoon and ocean and the likely change in lagoon 

circulation and water levels. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Descriptive Statistics for Corals from 2006 Rapid Ecological Assessment Data 

Mokumanamana 

In 2006 only two stations were sampled 

at Mokumanamana Island (Table 4.8, 

Figure 4.29). Average coral species 

richness ( x = 11.5, SD ± 2.1) ranked 

the highest among all reefs surveyed. 

Percent live coral cover was 22.1% (SD 

± 15.9) and ranked forth overall. Density of coral colonies (number/m-2) also 

ranked first among all locations sampled 

in 2006 with a mean density of 6.9 colonies m-2. 

126 

Table 4.8. Descriptive statistics for corals from 2006 REA data at Mokumanamana Island. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 95% 95% 

MEAN 

Richness 2 11.5 2.12 1.5 -7.56 30.56 

Coral cover (%) 2 22.06 15.94 11.28 -121.2 165.32 

Density (no. m-2) 2 6.89 0.55 0.39 1.93 11.85 

Figure 4.29. Mokumanamana coral statistics and distribution for 2006. Species richness (top left), percent coral cover (top

right) and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

French Frigate Shoals 

French Frigate Shoals ranked third overall in coral species richness with an average of 9.9 coral species per transect 

(Table 4.9, Figure 4.30). Percent live 

coral cover was 29.7% and also ranked 

third among all locations surveyed in 

2006. Coral colony density was 4.82 

m-2 and again ranked third among locations. 

Table 4.9. Descriptive statistics for corals from 2006 REA data at French 

Frigate Shoals. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 95% 95% 

MEAN 

Richness 10 9.9 3.07 0.97 7.7 12.1 

Coral cover (%) 10 29.71 18.68 5.91 16.3 43.07 

Density (no. m-2) 10 4.82 2.37 0.75 3.12 6.52 

Figure 4.30. French Frigate Shoals coral statistics and distribution for 2006. Species richness (top left), percent coral

cover (top right) and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

127 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Maro Reef 

Species richness at Maro Reef was 9.1 

per transect and ranked fourth overall 

(Table 4.10, Figure 4.31). Coral cover 

was high ( x = 33.3, SD ± 17.8) and 

ranked second overall. Density was the 

second highest among all sites and averaged 5.43 colonies/m-2. 

128 

Table 4.10. Descriptive statistics for corals from 2006 REA data at Maro 

Reef. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 95% 95% 

MEAN 

Richness 9 9.11 1.45 0.48 7.99 10.23 

Coral cover (%) 9 33.29 17.85 5.95 19.6 47.01 

Density (no. m-2) 9 5.43 1.47 0.49 4.3 6.56 

Figure 4.31. Maro reef coral statistics and distribution for 2006. Species richness (top left), percent coral cover (top right)

and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 
Benthic Communities

Table 4.11. Descriptive statistics for corals from 2006 REA data at Laysan 

Island. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 

MEAN 

95% 95% 

Richness 3 8 1 0.58 5.52 10.48 

Coral cover (%) 3 17.65 12.86 7.42 -14.3 49.59 

Density (no. m-2) 3 2.84 1.06 0.61 0.2 5.48 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Laysan Island 

Lasyan Island had limited sampling effort in 2006 (Table 4.11; Figure 4.32). 

There were an average of 8.0 species 

recorded from transects, ranking fifth 

overall. Coral cover was also intermediate (fifth in rank) with an average cover 

of 17.7%. The density of coral colonies 

was low (seventh in overall rank) with 

an average of 2.8 coral colonies/m-2. 

Figure 4.32. Laysan Island coral statistics and distribution for 2006. Species richness (top left), percent coral cover (top

right) and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

129 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Lisianski-Neva Shoals 

Lisianski-Neva Shoals averaged 10.8

coral species per transect and ranked

second overall (Table 4.12, Figure 4.33).

It ranked first in coral cover with an average of 36.7%. Density of coral colonies

was intermediate with 4.3 colonies/m-2. 

130 

Table 4.12. Descriptive statistics for corals from 2006 REA data at 

Lisianski. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 95% 95% 

MEAN 

Richness 9 10.78 2.28 0.76 9.03 12.53 

Coral cover (%) 9 36.74 20.77 6.93 20.8 52.71 

Density (no. m-2) 9 4.27 1.54 0.51 3.08 5.45 

Figure 4.33. Lisianski-Neva Shoals coral statistics and distribution for 2006. Species richness (top left), percent coral

cover (top right) and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 
Benthic Communities

Table 4.13. Descriptive statistics for corals from 2006 REA data at Lisianski. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 95% 95% 

MEAN 

Richness 9 4.44 1.24 0.41 3.49 5.4 

Coral cover (%) 9 13.81 17.74 5.91 0.17 27.44 

Density (no. m-2) 9 2.68 1.98 0.66 1.15 4.2 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Midway Atoll 

Species richness of corals at Midway

was the lowest of any reef surveyed in 

2006 with an average of four species

per transect (Table 4.13, Figure 4.34).

Coral cover was 13.8% and ranked sixth 

overall. The density of coral colonies

was 2.7/m-2, which was also the lowest 

among all location. 

Figure 4.34. Midway Atoll coral statistics and distribution for 2006. Species richness (top left), percent coral cover (top 

right) and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

131 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Kure Atoll 

Kure had the second lowest coral species richness with an average of six 

species per transect (Table 4.14, Figure 

4.35). Coral cover was second lowest 

after Midway at 13.7%. Colony density 

was intermediate at 4.3 colonies/m-2 

and ranked fourth overall. 

132 

Table 4.14. Descriptive statistics for corals from 2006 REA data at Kure 

Atoll. Source: NWHI RAMP, unpub. data. 

CHARACTERISTIC NUMBER MEAN STD STD LOWER UPPER 

DEV ERR 95% 95% 

MEAN 

Richness 9 6 2.24 0.75 4.28 7.72 

Coral cover (%) 9 13.67 9.34 3.11 6.5 20.85 

Density (no. m-2) 9 4.29 2.54 0.85 2.33 6.24 

Figure 4.35. Kure Atoll coral statistics and distribution for 2006. Species richness (top left), percent coral cover (top right) 

and coral density (number m-2; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Changes In Coral Cover Over Time From Rapid Ecological Assessment Data 

Most regions have low coral cover 

(<20%), with higher values at Maro, Lisianski and French Frigate Shoals. Coral cover values determined from REA 

surveys showed the highest coral cover 

values at Maro and Lisianski though 

their magnitude (>60%) was greater 

than the values derived from the lineintercept method in 2004-2006 (Figure 

4.36). At each region, the coral cover 

values computed from the different survey years (2004, 2005 and 2006) are 

highly similar, indicating little change 

overall in each region. 

Coral Settlement and Recruitment 

In fall 2001 an array of recruitment plates 

was attached to the base of CREWS 

moorings at French Frigate Shoals, 

Maro, Lisianski, Pearl and Hermes, Midway and Kure to assess larval recruitment. The plates were collected in fall 

2002 and fresh arrays were deployed 

which, in turn were collected in 2003. 

Coral recruits present on the plates 

were counted and measured with the 

use of a dissecting microscope. While 

the second cohort of plates were in the 

water for a shorter time period than the 

first cohort of recruitment plates that 

had been deployed between 2001 and 

2002 (293 versus 376 days, respectively), the number of recruits was higher in 

2003 (382) than in 2002 (Figure 4.37). 

Plates at Maro showed the highest 

number of recruits in both years. Nearly 

all juvenile recruits were from the family 

Pocilloporidae, though members of the 

families Acroporidae and Poritidae were 

also found on plates from French Frigate Shoals and Maro. 

Figure 4.36. Differences in coral cover among regions within the NWHI.

Not all regions were surveyed in all three years. Coral cover was calculated

from the line-intercept method at 0.5 m intervals. Data are mean and standard error. Source: NWHI RAMP, unpublished data; map: L. Wedding. 

133 

Figure 4.37. Density of coral recruits on plates deployed at six locations in

the NWHI in 2002 and 2003. Source: NWHI RAMP; map: L. Wedding. 
Benthic Communities

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

134 

Coral Bleaching 

Mass coral bleaching affected numerous 

shallow reefs through the NWHI in 2002 

and 2004 (Figure 4.38). In both years, 

the incidence of bleaching was greater 

at the three northern atolls (Pearl and 

Hermes, Midway and Kure) than at Lisianski and farther south. At the three 

northern atolls, bleaching was most severe in shallow back reef and lagoon 

habitats. In both years, colonies in the 

genus Montipora and Pocillopora sustained the highest levels of bleaching 

(Kenyon et al., 2006; Kenyon and Brainard, 2006). In comparison, only low 

levels of bleaching were observed during 2006 surveys (Figure 4.38), which 

were conducted at the same time of 

year (September) as those in 2002 and 

2004. Colonies in the genus Montipora 

were again most affected by bleaching 

in 2006. 

In 2004, visual estimates of mortality 

and algal overgrowth of Montipora capitata and M. cf. turgescens at back reef sites at the three northern atolls conservatively exceeded 50%, with 

nearly complete mortality of surface-facing portions of colonies at numerous sites. The shallow crest of a large 

central patch reef system at Kure Atoll, previously referred to as “the coral gardens” due to its luxuriant growth 

of montiporids and pocilloporids, was heavily bleached in 2002. In 2004, only a few branches of Porites compressa remained alive and the dead coral skeletons were thickly covered in turf and macroalgae. Little change 

was seen in this reef’s condition in 2006. A striking shift occurred at this location from a system dominated by 

coral in 2001 to a system dominated by algae in 2004 (Figure 4.39). 

Figure 4.38. Percentage of colonies with bleached tissue within belt

transects surveyed in 2002, 2004 and 2006. Minimal bleaching was seen at

Gardner Pinnacles and French Frigate Shoals, which are not shown to reduce the complexity of the figure. Source: NWHI RAMP; map: L. Wedding. 

Figure 4.39. Phase shift on a patch reef at Kure Atoll from a benthos dominated by coral to one dominated by algae after 

a bleaching event in 2002. Photos: J. Kenyon. 

Distribution of Coral Disease 

Coral disease has emerged as a serious threat to coral reefs worldwide and a major cause of reef deterioration (Weil et al., 2006). The numbers of diseases and coral species affected, as well as the distribution of diseases, have all increased dramatically within the last decade (Porter et al., 2001; Green and Bruckner, 2000; 

Sutherland et al., 2004; Weil, 2004). Changing climatic conditions as well as local anthropogenic stressors 

have been implicated in increased disease levels but our ability to fully understand recent disease outbreaks 

is hampered by the paucity of baseline and epidemiological information on the normal disease levels in the 

ocean (Harvell et al., 1999, 2002). The NWHI is considered to be one of the last relatively pristine large coral 
Benthic Communities

100 

90 

80 

70 

ites (%) 

60 

roportion of S 50 

40 

P30 

20 

10 

0 

Por Trm Por TLS Por Por Por GA Mont Mont Mont Acro Acro Poc Poc GA 

DTTS BND TLS Wspt GA WS GA WBD 

Figure 4.40. Frequency of occurrence of different coral diseases within the

NWHI. Data based on 33 REA surveys conducted in 2005. Source: NWHI 

RAMP, unpub. data. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

reef ecosystems remaining in the world. 

As such, it provides the unique opportunity to document the normal levels of 

disease in a coral reef system exposed 

to limited human influence and the potential of understanding disease dynamics in response to changing climatic 

conditions. 

During a multi-agency cruise conducted 

in September 2002, disease investigation was incorporated into the protocol 

and a characterization of coral diseases 

was initiated. In 2003, baseline coral

disease surveys were conducted at 73 

permanent monitoring sites throughout 

the NWHI and have since been surveyed annually. Twelve disease states

have now been documented in the four 

major genera of coral (Porites, Montipora, Pocillopora and Acropora) on the 

reefs of the NWHI (Figure 4.40). The

distribution and frequency of occurrence of the different coral diseases varied widely within the nine islands/atolls 

of the NWHI (Table 4.15; Figure 4.41). 

The most common disease is Porites 

trematodiasis (Figure 4.42) caused by

the digenetic trematode, Podocotyloides 

stenometra (Aeby, 1998). This disease

is widespread (69.8% of the sites in

2003) and is known to exclusively affect

Porites sp. coral (Aeby, 2006). Other

diseases are less common, such as Porites brown necrotizing disease, which

only occurred at only 3.2% of the sites in

2003 (Aeby, 2006). Patterns in disease

prevalence among the coral genera

suggest Acropora is highly susceptible

to disease and Pocillopora appears to

be very resistant. Acropora comprised only 2.2% of the overall coral community along transects, yet showed 

high overall prevalence of disease (Aeby, 2006). In contrast, pocilloporids are a common coral in the NWHI 

(21.1% of the overall coral community along transects) yet seldom showed signs of disease (Aeby, 2006). In 

contrast, Willis et al. (2004) found pocilloporids on the Great Barrier Reef to have the highest prevalence of 

disease among all coral families surveyed despite pocilloporids having the lowest coral cover. 

Although coral disease was found to be widespread on the reefs of the NWHI, disease prevalence (proportion of colonies affected) for most coral diseases, with the exception of Porites trematodiasis, was found to 

be low in a healthy ecosystem (2005: average prevalence = 0.43% SE ± 0.1%; n = 37 sites surveyed; Figure 

4.43). In contrast, the average prevalence of Porites trematodiasis in 2005 was 12.5% (SE ± 3.2%; n=36 sites 

surveyed). Porites trematodiasis is an unusual coral disease, in that, it is caused by a larval trematode, which 

is transmitted through the food chain and requires multiple hosts (coral, mollusk, fish) for completion of its life 

cycle (Aeby, 1998). In contrast, most coral diseases are caused by bacteria or viruses that can be transmitted 

directly (host to host) or through the water column. For Porites trematodiasis, prevalence of the disease is de135 

Table 4.15. Distribution on of twelve coral diseases based on REA surveys 

conducted between 2002-2005. Source: Aeby, unpub. data. 

MMM FFS GAR MAR LAY LIS PHR MID KUR 

Por TRM X X X X X X X X X 

Por TLS X X X X X X X 

Por DTTS X X X X X X X 

Por BND X X 

Por GA X X X 

Mont WS X X X X X X 

Mont MFTL X X X 

Mont GA X X X X 

Acroporid WS X 

Acro GA X 

Poc WB X X 

Poc GA X 

Total # Diseases 2 6 1 7 5 5 8 5 7 

Coral disease abbreviations: Por = Porites, Mont = Montipora, Acro =Acropora, Poc = Pocillopora, TRM = trematodiasis, WS = white syndrome, WB = white

band,TS = tissue loss syndrome, DTTS = discolored tissue thinning syndrome,

BND = brown necrotising disease, GA = growth anomaly, MFTL = multifocal 

tissue loss 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

136 

pendent upon and thus reflective of the 

abundance of its three hosts. Hence it 

is not surprising to find high prevalence 

of this disease on the pristine reefs of 

the NWHI where host abundance is 

high. Similarly, Aeby (2007) examined 

the prevalence of Porites trematodiasis 

in Kaneohe Bay, Oahu which has a distinct north-south gradient in rural to urbanized watersheds. Most of the human 

population in surrounding watersheds is 

concentrated in the southern sector and 

so the south Bay has been most affected by impacts of urbanization (Maragos 

et al., 1985; Hunter and Evans, 1995). 

Aeby (unpub. data) found disease levels to be higher in the north Bay than in 

the south Bay and concluded that host 

abundance, not environmental stressors, was the primary factor affecting 

prevalence of Porites trematodiasis in 

Kaneohe Bay. Prevalence of disease 

varied among islands (Figure 4.44) and 

differed among coral genera at each 

island. In 2005, Maro had the highest prevalence of montiporid disease 

whereas Kure had the highest level of 

poritid disease. It is not yet clear why 

differences in disease prevalence occur 

among islands. Understanding patterns 

of disease occurrence will require much 

more information on disease epizootiology such as etiology and mode of transmission. 

Prevalence of the disease is dependent upon and thus reflective of the 

abundance of its three hosts. Hence it 

is not surprising to find high prevalence 

of this disease on the pristine reefs of 

the NWHI where host abundance would 

also be high. One exception to the pattern of healthy levels of coral disease on the reefs of the NWHI is an outbreak of Acropora white syndrome (AWS) that was first documented at French Frigate Shoals in 2003 (Aeby, 

2006b). AWS has caused significant coral loss on reefs at French Frigate Shoals (Aeby, unpub. data), as well 

as in other areas of the Indo-Pacific (Willis et al., 2004; Jacobson, 2006). As of 2006, studies found the disease 

to have spread to seven reefs within French Frigate Shoals. Acroporids have also been greatly affected by 

disease in Australia (Willis et al., 2004) and the Marshall Islands (Jacobson, 2006) and have been decimated 

by disease in the Caribbean (Green and Bruckner, 2000; Porter et al., 2001; Patterson et al., 2004; Weil, 

2004). Acroporids were one of the major frame-building corals in the Florida Keys, but losses of acroporids 

are now averaging 87% or greater (Miller et al., 2002; Patterson et al., 2002). Research is desperately needed 

to understand disease processes to prevent the acroporid reefs of the Monument and neighboring Johnston 

Atoll National Wildlife Refuge from following the same path as the acroporid reefs of the Florida Keys. More 

research is also needed to understand disease transmission dynamics across Indo-Pacific and the impact 

climate change will have on the health of coral reef ecosystems. 

Figure 4.41. Frequency of occurrence of different coral diseases within the

NWHI. Data based on 33 REA surveys conducted in 2005. Source: Aeby; 

unpub. data; map: L. Wedding. 

Figure 4.42. Porites trematodiasis is caused by a larval trematode, which is

transmitted through the food chain and requires multiple hosts (coral, mollusk, fish) for completion of its lifecycle. Photo: G. Aeby. 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

137Benthic Communities

Figure 4.43. Coral disease for French Frigate Shoals, Gardner Pinnacles, Maro Reef, Laysan, Lisianski and Pearl and 

Hermes. Source: Aeby, unpub. data; maps: L. Wedding.

166°6'W

166°6'W

166°12'W

166°12'W

166°18'W

166°18'W

166°24'W

166°24'W

N'45°32

N'45°32

N'84°32

N'84°32

N'24°32

N'24°32

0 2 4 ± Kilometers

Land

 Coral Disease

(Presence/Absence)

Water <20 m

Acropora

Porites Trematod.

Porites other

Montipora

167°59'40"W

167°59'40"W

168°W

168°W

168°0'20"W

168°0'20"W

N"02'0°52

N°52

N°52

N"04'95°42

N"04'95°42

0 0.1 0.2 ± Kilometers

Land

 Coral Disease

(Presence/Absence)

Water <20 m

Acropora

Porites Trematod.

Porites other

Montipora

170°24'W

170°24'W

170°30'W

170°30'W

170°36'W

170°36'W

170°42'W

170°42'W

N'03°52

N'03°52

N'42°52

N'42°52

N'81°52

N'81°52

0 2 4 ± Kilometers

Land

 Coral Disease

(Presence/Absence)

Water <20 m

Acropora

Porites Trematod.

Porites other

Montipora

171°42'W

171°42'W

171°45'W

171°45'W

171°48'W

171°48'W

171°39'W

N'84°52

N'84°52

N'54°52

N'54°52

N'24°52

0 1 2 ± Kilometers

Land

 Coral Disease

(Presence/Absence)

Water <20 m

Acropora

Porites Trematod.

Porites other

Montipora

173°48'W

173°48'W

173°54'W

173°54'W

174°0'W

174°0'W

174°6'W

174°6'W

N'6°62

N'6°62

N'0°62

N'0°62

N'45°52

0 1.5 3 ± Kilometers

Land

 Coral Disease

(Presence/Absence)

Water <20 m

Acropora

Porites Trematod.

Porites other

Montipora

175°42'W

175°42'W

175°48'W

175°48'W

175°54'W

175°54'W

176°W

176°6'W 176°W

N°82

N'45°72

N'45°72

N'84°72

N'84°72

0 2 4 ± Kilometers

Land

 Coral Disease

(Presence/Absence)

Water <20 m

Acropora

Porites Trematod.

Porites other

French Frigate Gardner Pinnacles

Shoals

Maro Reef Laysan

Lisianski Pearl and 

Hermes

Montipora
Benthic Communities

 

177°27'W 177°24'W 177°21'W 178°24'W 178°21'W 178°18'W 

Midway Atoll Kure Atoll 27'N 28°

15'N 

27'N 

28°

28°

15'N 28°

 Coral Disease 

24'N 

 Coral Disease 

(Presence/Absence) (Presence/Absence) 28°

12'N 

Acropora Acropora 

28°

Porites Trematod. Porites Trematod. 

24'N 

Porites other Porites other 

28°

Montipora 

± Montipora 

Land 

12'N 

Land 

Water <20 m

28°

Water <20 m

0 1 2 0 0.5 1 ± Kilometers Kilometers 

177°27'W 177°24'W 177°21'W 177°18'W 178°24'W 178°21'W 178°18'W 

Figure 4.43 (continued). Coral disease at Midway and Kure atolls. Source: Aeby, unpub. data; maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

138 

50 

45 

40 

35 

30 

25 

20 

15 

10 

5 

0 

FFS MAR PHR MID KUR 

Porites 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0.0 

FFS MAR PHR MID KUR 

Acropora 

0.030 

0.025 

0.020 

0.015 

0.010 

0.005 

0.000 

FFS MAR PHR MID KUR 

Pocillopora 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0.0 

FFS MAR PHR MID KUR 

Prevalence (%) 

Montipora

Figure 4.44. Prevalence of coral disease among locations by major coral genera. Note the differences in y-axis among

genera. Source: G. Aeby, unpub. data. 

Coral Predators 

The Crown-of-thorns starfi sh (COTS; Acanthaster planci; Figure 4.45) and Drupellid snails (Drupella sp.) 

are both corallivores that have caused significant coral damage in other areas of the Indo-Pacific, and were 

monitored on the reefs of the NWHI during benthic (COTS and Drupellid snails) and towed-diver surveys 

(COTS). Towed-diver surveys report COTS to be present on the reefs of the NWHI but to occur at low levels 

(average=0.65 COTS/km; NWHI Reef Assessment and Monitoring Program or RAMP, unpub. data). During annual benthic monitoring surveys it was found that the frequency of occurrence (the number of sites with animals 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

or feeding scars/total sites surveyed) for 

Drupella sp. was low (3% in 2004, 15.4% 

in 2005) (Aeby, unpub. data). Drupella 

were usually found feeding at the base 

of branches of cauliflower coral (Pocillopora meandrina). For COTS, frequency of occurrence was also low with reports of COTS observed at 4.5% of the 

monitoring sites in 2004 and 28.2% in 

2005 (Aeby, unpub. data). COTS were 

usually found as single animals. 

Figure 4.45. Crown-of-thorns sea star in the NWHI. Photo: J. Kenyon. 

ALGAE 

Although the NWHI represent one of the last relatively intact tropical reef ecosystems in the world, macroalgal community dynamics of the 10 atolls, islands, and reefs situated in the NWHI Marine National Monument 

remain poorly understood. A study published in conjunction with the Northwestern Hawaiian Islands’ third Scientific Symposium (Vroom and Page, 2006) was the first to provide distributional maps of common algal species, statistically compare sites from differing habitats and islands based on relative abundance of macroalgae 

and look for temporal differences in macroalgal populations. Findings revealed that the abundance of most 

macroalgal genera was low across the archipelago, but that members of certain green algal genera including 

Halimeda and Microdictyon (Figure 4.46) can be extremely common and in some cases form dense monotypic 

meadows on the reef, especially in fore reef areas (Microdictyon) and lagoons (Halimeda). Other genera, such 

as the brown algae Stypopodium and Lobophora, and the red alga Laurencia, become increasingly prevalent 

in the three northwestern-most atolls of the Hawaiian archipelago (Kure, Midway, and Pearl and Hermes). 

Relative abundance of macroalgae across the NWHI chain as a whole remained relatively static for the years 

surveyed; however, slight changes occurred at Kure and Midway atolls where coral bleaching events were 

documented in 2002 and 2004. 

Figure 4.46. Halimeda velasquezii at Maro Reef (left). H. velasquezii is the most common species of Halimeda in the 

NWHI. Microdictyon is also very common in some regions of the NWHI. A close-up photo of a Microdictyon setchellianum

(right) field at Gardner Pinnacles. Photos: P. Vroom. 

139 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

140 

A study recently completed at Pearl and Hermes Atoll (Page, 2006) used detailed species-level percent cover 

analyses coupled with environmental variables to better understand the mechanisms that determine distributional patterns of organisms, particularly algae. Benthic community composition was examined along a wave 

exposure gradient using multivariate statistical analyses with the hypothesis that sites with similar levels of 

wave exposure would exhibit similar benthic communities. Species richness of coral and macroalgae were 

also compared to determine if sites with intermediate levels of wave exposure would contain the highest diversity of benthic organisms. To test these hypotheses, percent cover of benthic organisms was determined 

at 34 sites in four wave exposure categories: high, intermediate-high, intermediate-low and low. Multivariate 

statistical analyses revealed that sites from each wave exposure category differed significantly, and a nonmetric multi-dimensional scaling ordination (nMDS) and cluster diagram grouped sites from low, high, and 

intermediate-high wave disturbance areas into three relatively discrete clusters. However, sites experiencing 

intermediate-low wave exposure did not group together in the nMDS ordination or cluster diagram, suggesting 

variability in benthic compositions among these sites. Coral and macroalgal species richness was significantly 

higher at sites with intermediate-high and intermediate-low levels of wave exposure than at sites with low wave 

exposure, although not significantly higher than sites with high wave exposure. 

An article appearing in American Scientist magazine (Vroom et al., 2006) compared percent cover of macroalgal, turf algal, crustose coralline algal and coral populations at eight islands across the Pacific Ocean basin, 

including two from the NWHI. The NWHI are documented to contain the highest percent cover of algal species 

when compared to other geographic locations, and the lowest percent cover of living coral. This is likely due 

to the subtropical location of the NWHI and cool SSTs that bathe biological communities during winter months. 

Despite high algal populations, the NWHI remain healthy and thriving marine ecosystems that are dominated 

by top predators and high fi sh populations. 

Algal diversity appears similar across 

the NWHI chain even though brown algae tend to be more abundant at Midway and Kure atolls when compared to 

most other islands (Figure 4.47). The 

lower abundance of green algae at Midway may be tied to lower apex predator biomass and higher herbivorous fish 

densities at this atoll system, suggesting 

possible top-down control of the benthic habitat (DeMartini and Friedlander, 

2004, 2006). 

Although the mix of macroalgal species 

is relatively similar throughout the NWHI 

chain, certain species (e.g., Stypopodium flabelliforme, Laurencia galtsoffii) 

are more abundant in the northwesternmost atolls where SSTs experience the 

greatest annual fl uctuation. While S. 

flabelliforme is a major component of 

shallow reef systems at Kure Atoll, it is a 

minor component of reefs at most other 

islands and atolls in the NWHI. Because brown algae are known to predominate over other algal lineages in 

cool, temperate environments (Cheney, 1977), it is possible that the cooler SSTs found at Kure and Midway 

atolls during winter months may favor a higher abundance of brown algal species (Figure 4.47). 

Figure 4.47. Prevalence of major algal lineages in the Northwestern Hawaiian Islands. Bars represent standard deviation. Source: NWHI RAMP, 

unpub. data; map: L. Wedding. 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

141 

Algae Data: 2006

Mokumanamana 

Only two stations were assessed for 

algae at Mokumanamana in 2006 (Figure 4.48; located on pages 144-145). It 

is a composite of maps illustrating the 

percent frequency of occurrence of major algae by island). Four algal groups 

were present with Halimeda occurring in 

100% of the samples, followed by Laurencia (91.7%), crustose coralline red 

algae (12.5%) and Jania (8.3%; Table 

4.16). 

Table 4.16. Summary statistics for algal groups at Mokumanamana Island 

in 2006. Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 0 0 0 0.00% 

Halimeda 100 0 2 100.00% 

Microdictyon 0 0 0 0.00% 

Neomeris 0 0 0 0.00% 

Jania 8.33 11.79 1 50.00% 

Laurencia 91.67 11.79 2 100.00% 

Non-geniculate branched coralline red

algae 

0 0 0 0.00% 

Crustose coralline red algae 12.5 17.68 1 50.00% 

Lobophora 0 0 0 0.00% 

Padina 0 0 0 0.00% 

French Frigate Shoals 

Ten stations were sampled in 2006 at 

French Frigate Shoals with seven algal 

groups present on quantitative surveys 

(Table 4.17, Figure 4.48). Laurencia 

was present all stations and found, on 

average, in 77% of quadrats. Halimeda 

was present at 90% of the stations and 

found, on average, in 62% of the quadrats. Jania was found at half the stations 

but on occurred in 9% of the quadrats, 

on average. 

Table 4.17. Summary statistics for algal groups at French Frigate Shoals 

in 2006. Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 1.67 5.27 1 10.00% 

Halimeda 62.5 38.14 9 90.00% 

Microdictyon 15.83 21.68 4 40.00% 

Neomeris 0 0 0 0.00% 

Jania 9.17 15.44 5 50.00% 

Laurencia 76.67 20.71 10 100.00% 

Non-geniculate branched coralline red algae 0 0 0 0.00% 

Crustose coralline red algae 0 0 0 0.00% 

Lobophora 30 32.68 8 80.00% 

Padina 2.5 7.91 1 10.00% 

Maro Reef 

Nine stations were sampled at Maro 

Reef in 2006 with six algal groups present (Table 4.18, Figure 4.48). Halimeda 

was present at all stations and found, on 

average, in 91% on the quadrats. Laurencia was also found at all stations and 

occurred in 75% of the quadrats. Crustose coralline red algae were found at 

three-quarters of the stations surveyed 

and appeared an average of 34% of the 

quadrats. 

Table 4.18. Summary statistics for algal groups at Maro Reef in 2006. 

Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 5.56 8.33 4 44.44% 

Halimeda 90.74 6.51 9 100.00% 

Microdictyon 0 0 0 0.00% 

Neomeris 0 0 0 0.00% 

Jania 12.96 19.59 4 44.44% 

Laurencia 75 19.09 9 100.00% 

Non-geniculate branched coralline red

algae 

0 0 0 0.00% 

Crustose coralline red algae 34.26 36.43 6 66.67% 

Lobophora 27.78 30.33 6 66.67% 

Padina 0 0 0 0.00% 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

142 

Laysan Island 

Three stations were surveyed at Lasyan 

Island in 2006 with eight algal groups 

observed in these surveys (Table 4.19, 

Figure 4.48). Halimeda and Laurencia 

were found at all stations and were the 

dominant groups being found, on average, in 89% and 86% of all quadrats, respectively. Crustose coralline red algae 

occurred at two of the three stations and 

were present in 44% of the quadrats, on 

average. 

Table 4.19. Summary statistics for algal groups at Laysan Island in 2006. 

Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 0 0 0 0.00% 

Halimeda 88.89 19.25 3 100.00% 

Microdictyon 19.44 33.68 1 33.33% 

Neomeris 2.78 4.81 1 33.33% 

Jania 8.33 14.43 1 33.33% 

Laurencia 86.11 17.35 3 100.00% 

Non-geniculate branched coralline red

algae 

0 0 0 0.00% 

Crustose coralline red algae 44.44 38.49 2 66.67% 

Lobophora 19.44 4.81 3 100.00% 

Padina 5.56 9.62 1 33.33% 

Lisianski-Neva Shoals 

Eight stations were sampled at Lisianski-Neva Shoals in 2006 with eight algal 

groups present in those surveys (Table 

4.20, Figure 4.48). Halimeda occurred 

at all stations and in nearly all quadrats 

(94%). Other important genera included 

Laurenica, which was present in 78% of 

the quadrats, and Jania, which occurred 

in 42% of the quadrats. Both genera 

were present at 89% of the stations surveyed. 

Table 4.20. Summary statistics for algal groups at Lisianski-Neva Shoals 

in 2006. Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 12.96 13.89 6 66.67% 

Halimeda 93.52 8.1 9 100.00% 

Microdictyon 25 33.59 5 55.56% 

Neomeris 10.19 11.62 5 55.56% 

Jania 42.59 33.19 8 88.89% 

Laurencia 77.78 31.18 8 88.89% 

Non-geniculate branched coralline red

algae 

0 0 0 0.00% 

Crustose coralline red algae 1.85 5.56 1 11.11% 

Lobophora 25 16.14 8 88.89% 

Pearl and Hermes Atoll 

A total of 12 stations were sampled at 

Pearl and Hermes in 2006 with nine 

algal groups present in those surveys 

(Table 4.21; Figure 4.48). Laurencia occurred at the greatest number of stations 

(92%), followed by Halimeda (75%), 

Microdictyon (67%), Dictyosphaeria 

(67%) and Lobophora (58%). On average Halimeda was present in 49% of 

quadrats, followed by Microdictyon with 

42%, and Laurencia with 40%. Although 

Dictyosphaeria had a high frequency of 

occurrence, it was only present in 12% 

of the quadrats, on average. 

Table 4.21. Summary statistics for algal groups at Pearl and Hermes Atoll 

in 2006. Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 11.81 12.54 8 66.67% 

Halimeda 49.31 39.64 9 75.00% 

Microdictyon 41.67 44.1 8 66.67% 

Neomeris 4.86 10.33 3 25.00% 

Jania 20.14 23.15 6 50.00% 

Laurencia 40.28 31.15 11 91.67% 

Non-geniculate branched coralline red

algae 

0 0 0 0.00% 

Crustose coralline red algae 18.75 32.4 4 33.33% 

Lobophora 29.86 36.66 7 58.33% 

Padina 10.42 26.38 3 25.00% 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Midway Atoll 

Sampling at Midway Atoll in 2006 included six stations with eight algal groups 

present (Table 4.22, Figure 4.48). Laurencia was found at all stations and 39% 

of the quadrats. Lobophora was found 

at 83% of the stations and occurred in 

47% of the quadrats, on average. Microdicyton was found at half the stations 

and occurred in 22% of the quadrats. 

Padina was present at two-thirds of the 

stations (19% of the quadrats). 

Table 4.22. Summary statistics for algal groups at Midway Atoll in 2006. 

Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 6.94 13.35 2 33.33% 

Halimeda 11.11 16.39 3 50.00% 

Microdictyon 22.22 32.77 3 50.00% 

Neomeris 0 0 0 0.00% 

Jania 1.39 3.4 1 16.67% 

Laurencia 38.89 19.48 6 100.00% 

Non-geniculate branched coralline red algae 0 0 0 0.00% 

Crustose coralline red algae 12.5 16.46 3 50.00% 

Lobophora 47.22 24.53 5 83.33% 

Padina 19.44 21.52 4 66.67% 

143 

Kure Atoll 

Eight stations were sampled at Kure 

Atoll in 2006 with eight algal groups 

present (Table 4.23, Figure 4.48). Microdictyon was the most abundant genera, occurring at all stations and in 62% 

of all quadrats. Halimeda also was present at all stations but in a lower percentage of quadrats (25%). Jania and Lobophora were both present at 87% of the 

stations. 

Table 4.23. Summary statistics for algal groups at Kure Atoll in 2006. 

Source: NWHI RAMP, unpub. data. 

STATIASTICS MEAN SD FREQ % FREQ 

Dictyosphaeria 10.42 19.8 4 50.00% 

Halimeda 25 23.15 8 100.00% 

Microdictyon 62.5 26.35 8 100.00% 

Neomeris 0 0 0 0.00% 

Jania 20.83 15.43 7 87.50% 

Laurencia 43.75 37.73 6 75.00% 

Non-geniculate branched coralline red algae 0 0 0 0.00% 

Crustose coralline red algae 31.25 36.39 4 50.00% 

Lobophora 30.21 27.44 7 87.50% 

Padina 6.25 11.57 3 37.50% 
54'N

166°24'W 166°18'W 166°12'W 166°6'W 

54'N 

French Frigate Mokumanamana 23°

23°

Shoals 

48'N

48'N 

23°

23°

% Freq. of Algae 

Dictyosphaeria
 

Halimeda
 

Microdictyon
 

Neomeris
 

42'N

Jania
 

23°

Laurencia
 

42'N 23°

crustose coralline
 

Lobophora
 

Padina
 

Land 

Water <20 m 

024 1 ± Kilometers 

166°24'W 166°18'W 166°12'W 166°6'W 

170°48'W 170°42'W 170°36'W 170°30'W 171°46'W 171°44'W 171°42'W 48'N

Maro Reef 

25°

Laysan Island 

48'N 

30'N

25°

25°

30'N 25°

% Freq. of Algae % Freq. of Algae 46'N25°

24'N25°

s phaeri

46'N 

Dictyo phaeria Dictyos a 

25°

Halimeda 

24'N 

Halimeda 

Microdictyon 

25°

Microdictyon 

Neomeris Neomeris 

Jania Jania 

Laurencia Laurencia 

crustose coralline crustose coralline 

Lobophora Lobophora 

Padina 

±
 Padina 

Land 

44'N

18'N

Land 

Water <20 m 

25°

Water <20 m 

25°

024 1 

±

18'N 

0 0 0.4 .8 1.6 Kilometers 

44'N 

Kilometers 

25°

25°

170°42'W 170°36'W 170°30'W 171°46'W 171°44'W 171°42'W 

174°6'W 174°0'W 173°54'W 176°6'W 176°W 175°54'W 175°48'W 

6'N 

N 28°

26°

Lisianski 

6'N 

Pearl and 

26°

Hermes 

54'N 27°

54'N 27°

% Freq. of Algae % Freq. of Algae 

0'N 

Dictyosphaeria Dictyosphaeria 

26°

Halimeda Halimeda 

Microdictyon Microdictyon 48'N 0'N 27°

Neomeris Neomeris 26°

Jania Jania 

Laurencia Laurencia 

48'N 

crustose coralline crustose coralline 

27°

Lobophora Lobophora 

na 

and ± Padi Padina 

Land L

Water <20 m 

Water <20 m 0 2 1 4 ± 0 2 1 4 42'N

Kilometers Kilometers 27°

174°6'W 174°0'W 173°54'W 176°W 175°54'W 175°48'W 175°42'W 

Figure 4.48. Percent frequency of occurrence of major algal groups by island in 2006. Source: NWHI RAMP, unpub. data; 

maps: L. Wedding. 

Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

144 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

177°21'W 

177°21'W 

177°24'W 

177°24'W 

177°27'W 

177°27'W 

177°18'W 

28°15'N 

28°15'N 

28°12'N 

28°12'N 

0 1 2 0.5 Kilometers 

± Water <20 m 

Land 

% Freq. of Algae 

Halimeda 

Neomeris 

Jania 

Laurencia 

Lobophora 

Padina 

crustose coralline 

Microdictyon 

Dictyosphaeria 

178°18'W 

178°18'W 

178°21'W 

178°21'W 

178°24'W 

178°24'W 

28°27'N 

28°27'N 

28°24'N 

28°24'N 

0 1 2 0.5 Kilometers 

Water <40 m ± Land 

% Freq. of Algae 

Halimeda 

Neomeris 

Jania 

Laurencia 

Lobophora 

Padina 

crustose coralline 

Microdictyon 

Dictyosphaeria 

Midway Kure 

Figure 4.48 (continued). Percent frequency of occurrence of major algal groups by island in 2006. Source: NWHI RAMP, 

unpub. data; maps: L. Wedding. 

INVERTEBRATES 

Census of Coral Reef Ecosystems (CReefs) 

The international CoML is a global effort to assess the diversity, distribution and abundance of ocean life and 

explain how it changes over time. Over 1,700 scientists from 73 countries are pooling their findings to create a comprehensive and authoritative portrait of life in the oceans today, yesterday and tomorrow. As one 

of 17 projects of the CoML, the goals of the CReefs are to increase tropical taxonomic expertise, conduct a 

taxonomically-diversified global census of coral reef ecosystems, and improve access to and unify coral reef 

ecosystem information scattered throughout the world. 

As part of the CReefs effort, NOAA’s Pacific Islands Fisheries Science Center Coral Reef Ecosystem Division 

led a multi-institutional team of international taxonomists on a 23-day research expedition in October 2006 to 

explore the biodiversity of small, understudied, or lesser known invertebrate, algal and microbial species at 

French Frigate Shoals. In an effort to maximize the ability to document biodiversity, surveys were conducted 

at over 50 different sites representing 14 habitat types using 12 diverse sampling methods (including baited 

traps, rubble brushing, rubble extraction, underwater vacuuming with gentle suction, plankton tows, light traps, 

sediment and water sampling) specifically designed to minimize habitat impacts while maximizing the number 

of ecological niches sampled. 

During the three week cruise, scientists documented more than 1,000 species at French Frigate Shoals. For 

comparison, this corresponds to around 20% of the Hawaiian marine invertebrate fauna documented over 

the past 200 years. These new findings indicate just how little is known about tropical marine invertebrates in 

general and especially within the NWHI, and may offer clues to the extent of undiscovered diversity at French 

Frigate Shoals. Collected species were photo-documented for future study. Many species had never been 

photographed, fresh or alive, and thus represent the first documentation of their living color and appearance. 

DNA samples were also collected to facilitate DNA-based identification of Hawaiian and tropical Pacifi c invertebrates in the future. 

Thorough taxonomic identifications and molecular analyses of the samples collected are still being analyzed 

and will take many years to complete. However, preliminary findings suggested that approximately 2,300 

unique morpho-species were collected and photographed during the 16 days of sampling (Figure 4.50). To 

improve the long-term ability to monitor biodiversity, tissue samples for molecular barcoding were collected 

from about 60% of the unique morpho-species. An estimated 30-50 collected specimens are thought to be new 

species to science, including new species of crabs, corals, sea cucumbers, sea quirts, worms, sea stars, snails 

and clams. From this expedition, well over a hundred new species records from sponges, corals, anemones, 

flatworms, segmented worms, hermit crabs, crabs, sea slugs, bivalves, gastropods, octopus, sea cucumbers, 

145 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

146 

sea stars and sea squirts, will likely be 

identified for French Frigate Shoals. The 

highest sampled diversities at French 

Frigate Shoals were in the phylums Anthropoda and Mollusca. By habitat type, 

lagoon patch reefs, La Perouse Pinnacle 

(basalt), back reef and deep fore reefs 

had the highest diversity. Due to the 

high level of taxonomic expertise available on the cruise, hand collection was 

the most effective sampling methodology, following by rubble extraction, rubble 

brushing and use of baited traps. 

Some anecdotal figures indicate the degree of novelty. For example, of the six 

specimens of octopus collected three 

species may be new to science (Figure 

4.50). In comparison, 15 species of octopus were previously known from the Hawaiian Islands. Additionally, there were at least 25 species of sea 

cucumbers documented; three are new species and two are new records for Hawaiian fauna (Figure 4.50). 

Previously, about 30 species of shallow water holothurians have been documented from Hawaiian waters. 

800 

700 

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Figure 4.49. Unique morphospecies collected at French Frigate Shoals by

phylum from CReefs cruise. Source: CoML, unpub. data.

Figure 4.50. Six species of octopus (left) were collected during the mission, three of which maybe new to science. The

right photo shows a newly discovered species of sea cucumber. Photos: G. Paulay. 

Though relatively high diversity was found for sponges, bryozoans, eulimid gastropods, hermit crabs, echinoderms, ascidians and other invertebrates (including corallimorph anemones, galatheid squat lobsters, porcellanid crabs, pea crabs and coral barnacles), had strikingly low diversity or were absent. Interestingly, about 

one third of all invertebrate morphospecies collected were either found only once or found at only one site. A 

possible new family of ascidian for the NWHI, Mogulidae, was collected. Likewise, a new species of coral that 

could not even be identified to family level was found and photographed, since coral collections were not authorized under this permit. An estimated 48 new species records of Opisthobranch molluscs for French Frigate 

Shoals were collected, 27 of which appear to be new records for the NWHI. 

Other Invertebrate Surveys 

Recent efforts to quantify the non-coral invertebrate populations in the NWHI included two broad-scale toweddiver surveys conducted in 2004 and 2006 (Figure 4.51) and a REA survey conducted in 2005. Surveys were 

focused on collecting information on three target classes of invertebrates: Echinoidea, Holothuroidea and Asteroidea. Towed-diver surveys found densities of echinoids and holothuroids to be highest at the northernmost 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 4.51 Mean density of Echinoids, Asteriods and Holothuroids per m2 from towed diver surveys. Sources: NWHI

RAMP, Brainard et al., in prep.; maps: L. Wedding. 

islands/atolls. Sea urchins were the most common invertebrate observed during these surveys, with Kure 

(2004 and 2006) and Midway (2006) reporting the highest densities in the island chain (>1,600 urchins/ha). 

Sea cucumbers were present at all islands but in low densities, with the exception of the northern atolls. The 

highest sea cucumber density was recorded at Kure in 2006. COTS were in relatively low abundance throughout the archipelago with the highest density recorded in 2004 at Pearl and Hermes. Though abundance of 

COTS was relatively low in comparison with reported infestation levels in higher coral cover areas, such as the 

Great Barrier Reef, the impacts of these abundances could be significant due to the relatively low coral cover 

found throughout much of the NWHI. 

Data collected during REA surveys included species level information on the three target classes of invertebrates and followed the general patterns of the towed-diver data. The most common echinoid throughout the 

NWHI was the burrowing sea urchin, Echinostrephus sp., with the highest densities recorded at Midway and 

Kure (>12 individuals/m2

). As in towed-diver surveys, sea cucumbers were present at all islands/atolls but in 

low densities. The most common sea cucumber was Actinopyga obesa, with a density of .03 individuals/ m2 at 

Kure. The most common sea-star was Linckia multifora. 

147 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

148 

EXISTING DATA GAPS 

Effective management decisions are based on reliable information on the biological characteristics of the organisms, their ecological relationships and understanding of the natural temporal variations that characterize 

their ecosystems. Overall there is a need for basic information on all living resources at the NWHI. Taxonomy 

studies should provide knowledge of all species presents to develop a baseline and facilitate identifi cation of 

new species records and which ones are endemic, rare and worthy of special attention. Life history studies 

are needed to provide information on essential habitat requirements (reproduction, recruitment and feeding) 

for all life stages, environmental tolerance, larval dispersal mechanisms and other parameters (age structure, 

growth, mortality, etc.) for key native species. Specific research opportunities include: 

• Developing a comprehensive catalog of native species that include: ecological requirements, georeferenced habitat use during different life stages, life history metrics (population age/size distributions, 

growth rates, size/age of maturity, mortality rates, etc.); 

• Comparing native species habitats and ecological requirements to a catalog of anthropogenic threats in 

order to identify native species vulnerable to anthropogenic stress; 

• Developing comparative life history studies between NWHI and MHI to determine anthropogenic effects 

on growth, maturation, and reproductive success of native species; 

• Documenting the trophic dynamics of key native species; 

• Developing a comprehensive species list of algal taxa for the NWHI; 

• Determining habitat distribution/availability, especially that essential to reproduction, recruitment, and 

feeding; 

• Characterizing the genetic structure of specific populations; and 

• Determining the functional ecological roles of native species. 

Monitoring programs require research to determine priority parameters and indicators to be measured for 

changes to ecosystems and ecological processes. Research also needs to indicate the scale, resolution and 

frequency of sampling that will contribute to meaningful monitoring, and the kinds of tools and technology that 

can best obtain the desired data. There are key gaps in the development and implementation of monitoring 

programs, including the need to determine: 

• The variables, scale and the spatial and temporal resolution at which ecological processes and connectivity can be monitored to support management needs; 

• The existing parameters and indicators of existing monitoring programs and identify gaps as the basis 

for more comprehensive monitoring of ecosystem change; and 

• The spatial and temporal basis of ecological processes to identify ecological boundaries between subregions. 

There are also key research issues that have been identified as important for monitoring and modeling, including: 

• Which environmental conditions, e.g., temperature, flow, geomorphology, have a mitigating infl uence on 

survival in a changed environment; 

• To what extent the reduction or expansion of one or more segments of the community assemblage result 

in competitive top down pressure or an increase in bottom up production; 

• How ecosystem acclimation to change varies among taxa and in relation to both survival and the ability 

to effectively reproduce; 

• The degree to which variability in an ecosystem may determine its capacity for resilience; 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

• How the rebound of an ecosystem depends on maintenance of established pathways of energy fl ow, 

which provide the system a stable means of recovery rather than risk a transition to a different state of 

equilibrium; 

• To what extent reducing fish populations of the ecosystem undermine or realign energy flow and trophic 

stability; 

• The other key aspects that affect ecosystem stability and resilience need to be identified, e.g., rates of 

energy flow, oceanographic conditions, nutrient levels and recruitment; 

• The spatial and temporal patterns of plankton and larval dispersal, sources and sinks and 

• The size, location and effectiveness of closed areas, e.g., MPAs. 

As with monitoring of ecosystems and ecological processes, there is a need for research on the parameters 

and indicators most appropriate and practical for measuring changes to species populations and habitats. Research needs to address both marine terrestrial biodiversity and communities and seek to identify the scale, 

resolution and frequency of sampling that will contribute to meaningful monitoring of flora and fauna, as well 

as the most useful tools and technology for gathering the data. Important gaps in the development and implementation of monitoring programs include the need to determine: 

• The variables, scale and the spatial and temporal resolution at which biodiversity and habitats should be 

monitored to support management needs; 

• The existing parameters and indicators of existing monitoring programs and identify gaps as the basis 

for more comprehensive monitoring; and 

• What spatial and temporal parameters distinguish sub-populations of species or differentiate habitats in 

the NWHI. 

There are also specific research issues that have been identified as important for monitoring biodiversity and 

habitats, including the need to: 

• Determine the priority species for monitoring in relation to anticipated short-term impacts, including from 

management actions, and long-term change; 

• Document ‘hot spots’ of adult population abundance; 

• Determine the movement of key species into the NWHI and within the NWHI; 

• Assess priority species populations as a basis for monitoring and developing recovery models and projections of future population levels; 

• Undertake life history studies for all priority species to provide information on essential habitat requirements (reproduction, recruitment and feeding) for all life stages; 

• Determine essential habitat and ecological requirements of protected species to minimize anthropogenic 

threats and the effect of catastrophic events; 

• Determine which likely effects of climate change on protected species are priorities for monitoring, e.g., 

the effect of sea level rise on nesting site of the green sea turtle and Hawaiian monk seal; and 

• Evaluate exiting and potential diseases affecting priority species and habitats of the NHWI and develop 

appropriate methods to monitor the presence and impact of these on terrestrial and marine biodiversity. 

149 
Benthic Communities

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

APPENDIX 

Distribution of corals and anemones reported in the NWHI during 1907-2006 compiled by Maragos from Dana (1846),

Vaughan (1907), Dana (1971), Maragos et al. (2004), and the unpublished records of G. Aeby, J. Asher, J. Kenyon, J. 

Maragos, B. Vargas and B. Zgliczynski. Endemics in bold and asterisks (*) indicate undescribed species. 

150 

STONY CORALS NIH NEC FFS GAR MAR LAY LIS PHR MID KUR N 

*Coral unid., seen first by J. Starmer, sp.18 x 1 

Acropora cerealis x x x 3 

A. cytherea x x x x x 5 

A. gemmifera x x 2 

A. humilis x x x 3 

A. nasuta x x x 3 

A. paniculata x 1 

*A. sp.1 (prostrate) x x 2 

*A. sp.28 cf. retusa x 1 

A. valida x x x x x 5 

*A. sp.29 (table) x 1 

*A. sp.30 cf. palmerae x 1 

A. sp. 20 (neoplasia/tumor?) x 1 

A. sp.26 cf. loripes x 1 

Montipora capitata x x x x x x x x x x 11 

M. flabellata x x x x x x x x x 9 

M. patula x x x x x x x x x x 10 

*M. sp.4 cf. incrassata x x x x 4 

M. dilatata x x 2 

*M. sp.6 cf. dilatata x 1 

*M. sp.7 (foliaceous) x x x x 4 

*M. sp.2 (ridges) x x 2 

*M. sp.5 (branching) x 1 

*M. sp.14 (nodular) first seen by B. Vargas x 1 

M. tuberculosa x x x x x x x 7 

*M. sp.24 (irregular) x 1 

*M. sp.3 cf. turgescens x x x x x x 6 

M. verrilli x x x x x x x 7 

Gardineroseris planulata x 1 

Leptoseris hawaiiensis x x 2 

L. incrustans x x x x 4 

*L. sp.22 cf. incrustans x 1 

L. mycetoseroides x 1 

*L. cf. papyracea sp19 x 1 

*L. cf. scabra sp17 x x 2 

Pavona clavus x x x 3 

P. duerdeni x x x x x x x x x x 10 

P. maldivensis x x x x x x 6 

P. varians x x x x x x x x x x 10 

*Balanophyllia sp. (pink) x x x 3 

Cladopsammia eguchii x x x x x x x 7 

Tubastraea coccinea x x x x x x x x 9 

Cyphastrea ocellina x x x x x x x x x x 10 

Leptastrea agassizi x x x 3 

L. bewickensis x x x 3 

L. purpurea x x x x x x x x x 9 

L. pruinosa x x x x 4 

*L. sp.8 cf. F. hawaiiensis x x x x x 5 

*Cycloseris tenuis 

*C. vaughani 

x 

x 

x x 

x 

x 

x x 

4 

4 

Diaseris distorta x x 2 
Benthic Communities

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Continued from previous page, distribution of corals and anemones reported in the NWHI during 1907-2006 compiled

by Maragos from Dana (1846), Vaughan (1907), Dana (1971), Maragos et al. (2004), and the unpublished records of G. 

Aeby, J. Asher, J. Kenyon, J. Maragos, B. Vargas and B. Zgliczynski. Endemics in bold and asterisks (*) indicate undescribed species. 

STONY CORALS NIH NEC FFS GAR MAR LAY LIS PHR MID KUR N 

Fungia scutaria x x x x x x x x x 9 

F. granulose x x x 3 

Pocillopora damicornis x x x x x x x 8 

P. eydouxi x x x x x x x x x 9 

P. sp.10 cf. laysanensis x x x 4 

P. ligulata x x x x x x x x x x 11 

P. meandrina x x x x x x x x x x 10 

P. molokensis x x x x x x x x 9 

P. sp.32 cf. verrucosa x x x 3 

P. sp.33 cf. zelli x 1 

*P. sp.11 cf. capitata x x x x x x x 8 

*Porites sp.12 cf. annae x x x 3 

*P. sp. 15 (paliform lobes) x 1 

Porites brighami x x x x x x x x x 9 

P. compressa x x x x x x x x x x 11 

*P. sp.23 (arthritic fingers) x 1 

P. duerdeni x x x x x x 6 

P. evermanni x x x x x x x x x x 10 

P. hawaiiensis x x x x x x x x 8 

P. lobata x x x x x x x x x x 10 

*P. sp. 21 cf. lobata x 1 

*P. sp.16 cf. lutea x 1 

P. rus x 1 

*P. sp.27 (columns) x 1 

*P. sp.13 cf. solida x x x x x x 6 

Psammocora explanulata x 1 

P. nierstraszi x x x x x x x x 8 

P. stellata x x x x x x x x x 10 

P. verrilli x x x 3 

Total 17 21 66 29 41 34 37 43 33 36 

Endemic 4 8 27 7 12 11 15 14 8 15 Mean 

Percent endemic 23.5 38.1 40.9 24.1 29.3 32.3 40.5 32.6 24.2 41.7 32.8 

Non-stony corals and anemones. 

Non-Stony Corals & Anemones NIH MMM FFS GAR MAR LAY LIS PHR MID KUR 

Palythoa tuberculosa x x x x x x x x x x 

P. sp. x 

Zoanthus pacificus x x x x 

Zoanthus sp (Kure) x 

Zoanthus sp ("B") x x x x x 

*Sinularia sp (yellow) x x x x x 

*Sinularia (purple) x x 

*Sinularia (brown) x 

*Sinularia (pink) x 

Acabaria bicolor x x 

Cirrhipathes sp x x 

Heteractis malu x x x x x 

Total Species Per Island 4 3 9 4 4 2 3 3 1 6 

151 
Benthic Communities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

152 

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high-latitude reefs in the Hawaiian Archipelago. Proceedings of the 10th International Coral Reef Symposium Okinawa 

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Management 34(3): 339-349. 

Kenyon, J.C., M.J. Dunlap, and G.S. Aeby. 2008a. Community structure of hermatypic corals at Kure Atoll in the Northwestern Hawaiian Islands: stemming the shifting baseline. Atoll Research Bulletin. 

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Kenyon, J.C., C.B. Wilkinson, M.J. Dunlap, G.S. Aeby, and C. Kryss. 2007b. Community structure of hermatypic corals at 

Laysan Island and Lisianski Island/Neva Shoal in the Northwestern Hawaiian Islands: a new layer of scientifi c exploration. 

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Kenyon, J.C., C.B. Wilkinson, and G.S. Aeby. 2008b. Community structure of hermatypic corals at Maro Reef in the Northwestern Hawaiian Islands: a unique open atoll. Atoll Research Bulletin. 

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141-150. 

Maragos, J., C. Evans, and P. Holthus. 1985. Reef corals in Kaneohe Bay six years before and after termination of sewage (Oahu, Hawaiian Archipelago). Pp: 189-194. In: Proc. 5th Intl. Coral Reef Congress, Tahiti, 4. 

Maragos, J.E., D.C. Potts, G.S. Aeby, D. Gulko, J.C. Kenyon, D. Siciliano, and D. VanRavenswaay. 2004. 2000-2002 

Rapid Ecological Assessments of corals (Anthozoa) on shallow reefs of the Northwestern Hawaiian Islands. Part 1: species and distribution. Pacific Science 58(2): 211-230. 

Miller, M., A. Bourgue, and J. Bohnsack 2002. An analysis of the loss of acroporid corals at Looe Key, Florida US: 1983-

2000. Coral Reefs 21:179-182. 

Page, K.N. 2006. Factors influencing benthic distributional patterns in a near-pristine coral reef ecosystem: Pearl and

Hermes Atoll. Master’s Thesis, University of Hawaii, Honolulu. 

Patterson, K.L., J.W. Porter, K.B. Ritchie, S.W. Polson, E. Mueller, E.C. Peters, D.L. Santavy and G.W. Smith. 2002. The 

etiology of white pox, a lethal disease of the Caribbean elkhorn coral, Acropora palmata. Proceedings of the National

Academy of Sciences of the United States of America 99:8,725-8,730. 

PIFSC-CRED, Honolulu, Hawaii. 

Porter, J., P. Dustan, W. Jaap, K. Patterson, V. Kosmynin, O. Meier, M. Patterson, and M. Parsons 2001. Patterns of 

spread of coral disease in the Florida Keys. Hydrobiologia 460: 1-14. 

Randall, J.E. 2007. Reef and shore fishes of the Hawaiian Islands. Bull. Mar. Sci. 41:490-502. 

Rohmann, S.O., J.J. Hayes, R.C. Newhall, M.E. Monaco, and R.W. Grigg. 2005. The area of potential shallow-water

tropical and subtropical coral ecosystems in the United States. Coral Reefs 24:370-383. 

Siciliano D. 2005. Latitudinal limits to coral reef accretion: Testing the Darwin Point Hypothesis at Kure Atoll, Northwestern 

Hawaiian Islands, using new evidence from high resolution remote sensing and in situ data. Ph.D. Dissertation, University

of California, Santa Cruz, 30-154. 

Sutherland, K., J. Porter, and C. Torres 2004. Disease and immunity in Caribbean and Indo-Pacific zooxanthellate corals. 

Marine Ecol Progress Series 266: 273-302. 

Vaughan, T. F. 1907. Recent Madreporaria of the Hawaiian Islands and Laysan. Bull. U.S. Natl. Mus. 59:1-427. 

Veron, J.E.N. 1995. Corals in space and time. Cornell University Press, Ithaca, NY. 321 pp. 

Vroom, P.S. and K.N. Page 2006. Relative abundance of macroalgae (RAM) on Northwestern Hawaiian Island reefs. Atoll 

Research Bulletin 543: 533-548. 

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Vroom, P.S., K.N. Page, J.C. Kenyon, and R.E. Brainard. 2006. Algae-Dominated Reefs. American Scientist 94: 429-

437. 

Weil, E. 2004. Coral reef diseases in the wider Caribbean. Pp: 35-68. In E. Rosenberg and Y. Loya (eds). Coral Health 

and Disease. Springer-Verlag, Germany.
 

Weil, E., G. Smith, and D. Gil-Agudelo. 2006. Status and progress in coral reef disease research. Dis Aquat Org 69: 1-7. 

Willis, B., C. Page, and E. Dinsdale 2004. Coral disease on the Great Barrier Reef. Pp: 69-104. In: E. Rosenberg and Y.

Loya (eds). Coral Health and Disease. Springer-Verlag, Germany. 

PERSONAL COMMUNICATIONS 

Maragos, J.E. U.S. Fish and Wildlife Service, Honolulu, HI, U.S.A. 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Fishes 

Alan Friedlander1,2, Edward DeMartini3, Lisa Wedding1,4 and Randy Clark1 

BIOGEOGRAPHY OF FISHES 

The Hawaiian Archipelago is among the most isolated on earth and exhibits the highest level of marine fish 

endemism of any archipelago in the Pacific (Randall, 1995, 1998, 2007; Randall and Earle, 2000; Allen, 2002). 

Owing to limited human influence, the Northwestern Hawaiian Islands (NWHI) reefs are nearly pristine and 

represent one of the last remaining intact large-scale, predator-dominated coral reef ecosystems on earth 

(Friedlander and DeMartini, 2002). Because of its high level of endemism and the near pristine nature of its 

reefs, the NWHI represents an important global biodiversity hot spot and provides a view of what reefs in the 

may have MHI looked like before human contact. 

Despite centuries of exploitation, the MHI today has even higher biodiversity of fishes than the NWHI. Randall 

et al. (1993) reported 258 species of reef and shore fishes from Midway Atoll compared with 612 species in 

the MHI (Randall, 2007). Mundy (2005) lists 21 species that are known from the NWHI, but not the MHI (Table 

5.1). Of these, most are either deep-water or mesopelagic and therefore poorly sampled waifs, or species with 

poor taxonomic resolution. In contrast, 406 species are known from the Main Hawaiian Islands (MHI) but not 

the NWHI and overall richness and diversity are greater in the MHI compared with the NWHI (Mundy, 2005). 

Table 5.1. Fish species known from the NWHI but not found in the MHI. Source: Mundy, 2005. 

FAMILY SPECIES COMMON NAME LOCATIONS HABITAT 

Scyliorhinidae Apristurus spongiceps Spongehead catshark Nihoa Deep-water 

Muraenidae Gymnothorax atolli Atoll moray Pearl and Hermes to Midway Cryptic 

Platytroctidae Mentodus mesalirus Tubeshoulders Pearl and Hermes to Midway Deep-water 

Stomiidae Astronesthes nigroides Dragonfish Pearl and Hermes to Midway Mesopelagic 

Eustomias cancriensis Scaleless black dragonfish Pearl and Hermes to Midway Mesopelagic 

Ophidiidae Bassozetus zenkevitchi Cusk-eel Midway to Kure Deep-water 

Spectrunculus grandis Cusk-eel Maro Deep-water 

Macrouridae Cetonurus crassiceps Grenadier, Rattail Pearl and Hermes Deep-water 

Holocentridae Myripristis murdjan Blotcheye soldierfish Midway to Kure Shallow reefs 

Fistulariidae Fistularia petimba Serrate coronetfish Nihoa to Kure Mod-deepwater 

Laysan Scorpaenopsis pluralis Laysan scorpionfish Lasyan Deep-water 

Callanthiidae Grammatonotus macrophthalmus Splendid perch French Frigate Shoals Deep-water 

Epigonidae Epigonus devaneyi Deepwater cardinalfish Mokumanamana to Maro Deep-water 

Carangidae Caranx lugubris Black trevally Mokumanamana to Midway Shallow to 

deep 

Carangidae Decapterus macrosoma Shortfi n scad Maro Pelagic 

Pomacanthidae Centropyge interruptra Japanese angelfish Kure and Midway Shallow reefs 

Kyphosidae Girella leonina Blackedge nibbler Midway Waif 

Labridae Epibulus insidiator Slingjaw wrasse French Frigate Shoals north

to Kure 

Shallow reefs 

Ammodytidae Lepidammodytes macrophthalmus Sand lance Maro Poorly known 

Ephippidae Platax boersii Boer’s spadefish Midway Waif 

Luvaridae Luvarus imperialis Louvar Laysan Epipelagic 

155 

1. NOAA/NOS/NCCOS/CCMA Biogeography Branch

2. The Oceanic Institute 

3. NOAA/NMFS/Pacific Islands Fisheries Science Center, Coral Reef Ecosystem Division

4. University of Hawaii at Manoa 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

156 

The few demersal species found in the 

NWHI but not the MHI include the blotcheye soldierfi sh (Myripristis murdjan), an 

Indo-Pacific species but restricted to the 

NWHI in the Hawaiian archipelago, and 

the Japanese angelfish (Centropyge 

interruptra; Figure 5.1) which is known 

only from the NWHI and Japan (Mundy, 

2005). Evidence of larval pelagic transport from Japan to the NWHI via the 

Kuroshio and North Pacific Currents is 

supported by the presence of a number 

of species that are common only off Japan and the northwestern end of the Hawaiian Archipelago (Randall, 2007). In addition to the Japanese angelfish, these include two lizardfishes (Synodus lobelia and S. ulae), the manyspine squirrelfish (Sargocentron 

spinosissimum), two species of knifejaws (Oplegnathus fasciatus and O. punctatus) and the blackedge nibbler 

(Girella punctata , family Girellidae), a close relative of the chubs of the family Kyphosidae (Randall, 2007). 

Two species, the slingjaw wrasse (Epibulus insidiator) and the chevron butteryflyfi sh (Chaetodon trifascialis), 

are associated with Acropora corals that occur only in the central portion of the NWHI, and although these fish 

species are occasionally observed in the MHI and the far northern end of the chain, they are most abundance 

from French Frigate Shoals to Pearl and Hermes (Mundy, 2005). Despite the taxonomic similarity with the MHI 

fauna, the NWHI fish assemblage differs from that of the MHI at various ecological and demographic levels owing to oceanographic conditions (e.g., water temperature), habitat (e.g., coral and reef type) and anthropogenic 

influences (e.g., effects of fishing in the MHI). 

There are a variety of environmental and 

other reasons for lower reef fi sh diversity in the NWHI versus MHI. Many shallow-water fish species that are adapted 

to warmer water cannot survive in the 

NWHI since winter water temperatures 

can be as much as 7oC cooler than the 

MHI (Mundy, 2005). Some shallow-water species are adapted to cooler water 

and can be found in deeper waters at 

the southern end of the archipelago. 

This phenomenon known as tropical 

submergence is exemplifi ed by species 

such as the yellowfi n soldierfi sh (Myripristis chryseres), the endemic Hawaiian grouper (Epinephelus quernus), 

and the masked angelfi sh (Genicanthus personatus), all of which occur in shallow water at Midway but are 

restricted to much greater depths in the MHI (Figure 5.2; Randall et al., 1993; Mundy, 2005). Other reasons for 

the lower number of species in the NWHI include insufficient sampling effort and the lack of many high island 

habitats such as estuaries and rocky shorelines 

Some of the non-endemic species abundant at higher latitude reefs in the NWHI have antitropical distributions and are thought to have established themselves in the archipelago when surface waters were previously 

cooler (Randall, 1981). The Hawaiian morwong, (Goniistius vittatus) for example, may be a cryptic species that 

diverged during the late Miocene-early Pliocene from the lineage presently represented by nominal conspecifics in the southern hemisphere (Burridge and White, 2000). Interestingly, most Hawaiian endemic species do 

not appear to exhibit submergence (greater depth distributions) in the MHI, although rigorous comparisons are 

lacking (DeMartini and Friedlander, 2004). 

Figure 5.1. The Japanese angelfi sh (Centropyge interruptra; left) and the

spotted knifejaw (Oplegnathus punctatus; right) are known only from the

NWHI and Japan, although the latter is occasionally observed in the MHI.

Photo: J. Watt. 

Figure 5.2. The endemic masked angelfi sh (Genicanthus personatus, left)

and Hawaiian grouper (Epinephelus quernus, right) are found in shallower

water at Midway Atoll but are restricted to deeper depths in the MHI. Photos: J. Watt (left); J. Maragos (right). 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Fish Species Richness 

Despite lower species richness in the 

NWHI as compared with the MHI (Mundy 2005), the total number of species 

(210) observed on quantitative transects 

in the NWHI (DeMartini and Friedlander, 

2004) was similar to the number of species (215) reported in a recent comprehensive quantitative study around the 

MHI (Friedlander et al., 2007). The lowest overall fish species richness in the 

NWHI occurs at the small basalt islands 

(Mokumanamana, Gardner and Nihoa; 

Figure 5.3) and highest at French Frigate Shoals and Pearl and Hermes. The 

former may be related to the higher coral richness and greater diversity of habitats (Maragos et al., 2004), while the latter is likely related to large size, habitat 

diversity and presence of subtropical 

and temperate species which occur at 

much greater depths southward in the 

chain of islands. 

Total species richness observed on 

surveys (y) showed a positive, linear 

relationship (y=8.05 * ln(x+1) + 112.2, 

R2

=0.51, p=0.02, Table 5.2, Figure 5.4) 

with a logarithmic function of total reef 

area less than 10 fathoms (x). This relationship is consistent with the general 

theory of island biogeography and likely 

reflects the greater diversity of habitats 

present in larger reef areas. 

Figure 5.3. Total fish species richness at each of 10 emergent NWHI reefs.

Source: NWHI RAMP, unpub. data; map: L. Wedding. 

Table 5.2. Results of least squares linear regression model for total number of species by ln (total reef area within 10 fathoms +1). R2

 = 0.51, N = 

10. Source: NWHI RAMP, unpub. data. 

ANALYSIS OF VARIANCE 

Source DF Mean Square F Ratio Prob > F 

Model 1 2105.32 8.20 0.0211 

Error 8 256.85 

C. Total 9 

PARAMETER ESTIMATES 

Term Estimate Standard Error t Ratio Prob>|t| 

Intercept 112.21 12.3 9.12 <0.001 

Ln (area) 8.052 2.81 2.86 0.0211 

157 

Figure 5.4. Relationship between cumulative number of fish species at

each reef and total reef area (km2) within 10 fathoms. Source: Friedlander

et al., in prep. 

ln[(reef area (km2) < 10 fm) + 1] 

0 2 4 6 

Total number of species 

40 

60 

80 

100 

120 

140 

160 

180 

200 

220 

Observations 

Linear regression 

95% Confidence Band 

95% Prediction Band 
Fishes

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

158 

Endemism 

The Hawaiian Island chain is among the most isolated on earth and exhibits the highest level of marine fish 

endemism of any archipelago in the Pacific (Randall, 1995, 1998; Randall and Earle, 2000; Allen, 2002). Endemism is a key attribute of biotic communities that is generally a great concern of conservation ecology. One 

reason of general biogeographic interest is that speciation and the origin and maintenance of biodiversity are 

undoubtedly related to degrees of isolation and endemism (Gray, 1997). Because of the decline in global marine biodiversity, endemic “hot spots” like Hawaii are important areas for global biodiversity conservation. The 

endemic fishes of Hawaii are small bodied and have very restricted geographic ranges of less than 50,000 km2 

(Roberts et al., 2002). Small body size, per se, may be associated with higher extinction risk because smallbodied species tend to have narrower habitat requirements (Hawkins et al., 2000). Therefore both body size 

and endemic status argue for the conservation of these species. 

Based on species-presence, endemism is equivalent for fishes in the NWHI (20.6% using all available data) 

and the MHI (MHI, 20.9%; DeMartini and Friedlander, 2004). On average, percentage endemism was much 

higher based on numerical densities (52%) and biomass (37%) which increased with latitude, and was especially pronounced at the four northernmost reefs that are the oldest emergent geological features of the archipelago (Figure 5.5). Greater endemism towards Midway and Kure appears related to consistently higher rates 

of replenishment by young-of-the-year (YOY) upchain following dispersal as pelagic larvae and/or juveniles. 

There were significant positive relationships between number and biomass of endemics with latitude (Tables 

5.3, 5.4, 5.5; Figures 5.6). However endemism based on species presence was not significantly correlated with 

latitude (Figure 5.7). 

Figure 5.5. Percent endemism based on numerical densities (top left), biomass (top right) and species richness (bottom

left) at each of 10 emergent NWHI reefs. Source: DeMartini and Friedlander, 2004; maps: L. Wedding. 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Endemic reef fishes are appreciably smaller bodied than nonendemics within the NWHI (DeMartini and Friedlander, 2004). Median body size does not vary with latitude and longitude for either endemics or nonendemics, which obviates possibly confounding environmental effects. Reef fish populations at higher latitude reefs 

included larger proportions of YOY recruits. YOY length frequencies did not differ for most species between 

northern and southern reefs, suggesting that a seasonal lag in spawning and recruitment at higher latitudes 

cannot explain the greater YOY densities observed. Disproportionate recruitment at higher-latitude reefs may 

be related to better growth and survivorship after settlement onto reefs, higher levels of within-reef and regional reseeding at higher latitudes, or other factors. 

Table 5.3. Results of least squares linear regression model 

for total number of species by ln (total reef area within 10 

fathoms +1). R2 = 0.51, N = 10. Source: DeMartini and 

Friedlander, 2004. 

ANALYSIS OF VARIANCE 

Source DF Mean F Ratio Prob > F 

Square 

Model 1 962.8 15.86 0.004 

Error 8 60.72 

C. Total 9 

PARAMETER ESTIMATES 

Term Estimate Standard t Ratio Prob>|t| 

Error 

Intercept -89.86 34.15 -2.63 0.0301 

Latitude 5.28 1.32 3.98 0.004 

Table 5.4. Results of least squares linear regression model 

for total number of species by ln (total reef area within 10

fathoms +1). R2 = 0.51, N = 10. Source: DeMartini and 

Friedlander, 2004. 

ANALYSIS OF VARIANCE 

Source DF Mean F Ratio Prob > F 

Square 

Model 1 1817.66 14.7374 0.005 

Error 8 123.34 

C. Total 9 

PARAMETER ESTIMATES 

Term Estimate Standard t Ratio Prob>|t| 

Error 

Intercept -153.734 48.67219 -3.16 0.0134 

Latitude 7.249942 1.888528 3.84 0.005 

Table 5.5. Results of least squares linear regression model 

for total number of species by ln (total reef area within 10

fathoms +1). R2 = 0.51, N = 10. Source: DeMartini and 

Friedlander, 2004. 

ANALYSIS OF VARIANCE 

Source DF Mean F Ratio Prob > F 

Square 

Model 1 8.18 3.53 0.0971 

Error 8 2.32 

C. Total 9 

PARAMETER ESTIMATES 

Term Estimate Standard t Ratio Prob>|t| 

Error 

Intercept 13.77 6.67 2.06 0.0729 

Latitude 0.49 0.26 1.88 0.0971 

159 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

160 

Latitude 

22 24 26 28 

Percent Endemism (Number of Individuals) 

0 

20 

40 

60 

80 

100 

Observations 

Linear regression line 

95% Confidence Band 

95% Prediction Band 

Latitude 

22 24 26 28 

Percent Endemism by Biomass 

-40 

-20 

0 

20 

40 

60 

80 

100 

Observations 

Linear regression line 

95% Confidence Band 

95% Prediction Band 

Figure 5.6. Least squares linear regression model for percent endemism by numerical abundance versus latitude (left).

Least squares linear regression model for percent endemism by biomass versus latitude (right). Source: DeMartini and

Friedlander, 2004. 

Latitude 

22 23 24 25 26 27 28 29 

Percent Endemism by Species 

22 

23 

24 

25 

26 

27 

28 

29 

30 

Observations 

Figure 5.7. Least squares linear regression model for percent endemism by

species versus latitude. Source: DeMartini and Friedlander, 2004 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

LATITUDINAL AFFINITIES AMONG FISHES
 

Biogeographic forces may promote disparate abundance patterns among some 

species at opposite ends of the archipelago owing to differences in temperature 

and other environmental factors. Some 

species might have a temperate or subtropical bias, whereas others might be 

better suited to more tropical conditions. 

To identify latitudinal gradients of abundance, numerical densities as a function of latitude was examined within the 

NWHI using Spearman rank correlation. 

Positive correlations indicated a temperate affinity, while negative correlations 

indicated a tropical affi nity. The percentage of individuals with either temperate/ 

subtropical or temperate affinities is an 

indication of the total fi sh assemblage 

affinity at each reef (Table 5.6; Figure 

5.8). 

Thirty species showed a significant positive correlation (Spearman Rank Correlation, p<0.05) with latitude based on 

numerical density from quantitative fish 

surveys conducted between 2000 and 

2002 (Table 5.7). Of these, 17 (57%) 

were endemics. Wrasses (Labridae) had 

the greatest number of species (eight) 

showing higher latitude affi nity followed 

by damselfishes (Pomacentridae) with 

four species. Several other species 

such as knifejaws (Oplegnathus spp.) 

and boarfi sh (Evistias acutirostris) were 

more abundant at higher latitudes but 

their low numbers during surveys made 

the results inconclusive statistically. 

Table 5.6. Percentage of numerical abundance at each reef that consisted 

of species that showed either a temperate/subtropical (northerly) affinity

or tropical (southerly) affinity in abundance. Source: Friedlander et al., in 

prep. 

REEF TEMPERATE/SUBTROPICAL AFFINITY TROPICAL AFFINITY 

NIH 12.97% 16.35% 

MMM 28.01% 28.44% 

FFS 27.45% 8.57% 

GAR 24.52% 14.15% 

MAR 51.94% 4.27% 

LAY 44.91% 10.24% 

LIS 52.90% 3.22% 

PHR 52.34% 1.99% 

MID 56.08% 0.93% 

KUR 63.43% 1.24% 

Island/atoll abbreviations used throughout this chapter: NIH = Nihoa Island; MMM = 

Mokumanamana, FFS = French Frigate Shoals; GAR = Gardner Pinnacles; MAR = Maro

Reef; LAY = Laysan Island; LIS = Lisianski Island; PHR = Pearl and Hermes; MID = Midway Atoll; KUR = Kure Atoll 

Figure 5.8. Percentage of total numerical abundance (numbers m-2) for species showing a significant latitude gradient of distribution. Source: Friedlander et al., in prep. 

Table 5.7. Species with temperate/subtropical affinity (positive correlation with latitude). Endemics in bold. Source:

Friedlander et al., in prep. 

FAMILY TAXON NAME COMMON NAME HAWAIIAN NAME 

Synodontidae Synodus ulae Ulae Lizardfish ulae 

Holocentridae Sargocentron xantherythrum Hawaiian Squirrelfish alaihi 

Scorpaenidae Pterois sphex Hawaiian Turkeyfish 

Serranidae Epinephelus quernus Hawaiian Grouper hapuu 

Priacanthidae Priacanthus meeki Hawaiian Bigeye aweoweo 

Chaetodontidae Chaetodon auriga Threadfi n Butterflyfish kikakapu 

Pomacanthidae Genicanthus personatus Masked Angelfish 

Pomacentridae Abudefduf abdominalis Sargent Major mamo 

Pomacentridae Chromis hanui Chocolate-dip Chromis 

161 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 5.7 (continued). Species with temperate/subtropical affinity (positive correlation with latitude). Endemics in bold.

Source: Friedlander et al., in prep. 

162 

FAMILY TAXON NAME COMMON NAME HAWAIIAN NAME 

Pomacentridae Chromis ovalis Oval Chromis 

Pomacentridae Stegastes fasciolatus Pacifi c Gregory 

Cirrhitidae Paracirrhites forsteri Blackside Hawkfish hilu pili koa 

Labridae Anampses cuvier Pearl Wrasse opule 

Labridae Coris flavovittata Yellowstrip coris hilu 

Labridae Gomphosus varius Bird Wrasse hinaleaiiwi, akilolo 

Labridae Labroides phthirophagus Hawaiian Cleaner Wrasse 

Labridae Stethojulis balteata Belted Wrasse omaka 

Labridae Thalassoma ballieui Blacktail Wrasse 

Labridae Thalassoma duperrey Saddle Wrasse hinalea lauwili 

Labridae Thalassoma purpureum Surge Wrasse hou 

Scaridae Calotomus zonarchus Yellowbar Parrotfish 

Scaridae Chlorurus perspicillatus Spectacled Parrotfish uhu uliuli 

Scaridae Scarus dubius Regal Parrotfish lauia 

Cheilodactylidae Cheilodactylus vittatus Hawaiian Morwong 

Acanthuridae Acanthurus nigroris Bluelined Surgeonfish maiko 

Acanthuridae Zebrasoma veliferum Sailfi n tang maneoneo 

Gobiidae Coryphopterus sp. Goby oopu 

Gobiidae Gnatholepis anjerensis Eyebar goby 

Balistidae Xanthichthys mento Crosshatch Triggerfish 

Diodontidae Diodon holocanthus Spiny Puffer oopu okala 

Over 63% of the total numerical abundance of fishes at Kure Atoll was composed of species with a high latitude correlation (Figure 5.8). The percentage of high latitude affinity individuals was also substantial at Midway 

Atoll (56%), Pearl and Hermes Atoll (52%) and Lisianski Island-Neva Shoals (53%). The major break occurs 

between Maro Reef and Gardner Pinnacle where the numerical abundance of high latitude affi nity species 

dropping from 52% to 25% between these two locations. The lowest percentage of high latitude affi nity individuals was observed at Nihoa Island (13%). There was a relatively large shift towards more high latitude affinity individuals between Nihoa and Mokumanamana (28%). 

Twenty-one species were significantly and positively correlated (p<0.05) with low latitudes based on numerical 

density estimated on surveys conducted between 2000-2002 (Table 5.8). Only two of these species (9%) were 

endemics in contrast to the species with high latitude bias, where 54% were found to be endemic. Based on 

total numerical abundance, the highest percentage of low latitude species was observed at Mokumanamana 

Table 5.8 Species with tropical affinity (negative correlation with latitude). Endemics in bold. Source: Friedlander et al.,

in prep. 

FAMILY TAXON NAME COMMON NAME HAWAIIAN NAME 

Carcharhinidae Carcharhinus amblyrhynchos Gray Reef Shark mano 

Carcharhinidae Triaenodon obesus Whitetip Reef Shark mano lalakea 

Lutjanidae Aphareus furca Smalltooth Jobfish wahanui 

Lethrinidae Monotaxis grandoculis Bigeye Emperor mu 

Mullidae Parupeneus bifasciatus Doublebar Goatfish munu 

Mullidae Parupeneus multifasciatus Manybar Goatfish moano 

Chaetodontidae Chaetodon multicinctus Multiband Butterflyfish kikakapu 

Chaetodontidae Chaetodon quadrimaculatus Fourspot Butterflyfish lau hau 

Pomacentridae Plectroglyphidodon imparipennis Brighteye Damselfish 

Cirrhitidae Paracirrhites arcatus Arc-eye Hawkfish pili koa 

Scaridae Calotomus carolinus Stareye Parrotfish 

Acanthuridae Acanthurus blochii Ringtail Surgeonfish pualu 
Fishes

Latitude 

Figure 5.9. Relationship between latitude and numerical abundance of

species with temperate/subtropical and tropical affinities. Results of least 

squares linear regression. Temperate/subtropical = -1.56 + 0.07*Latitude, 

Tropical = 1.00 - 0.03*Latitude. Source: Friedlander et al., in prep. e cnundab Alcaireumon NitoporPr

22 24 26 28 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

-0.2 

Temperate/subtropical 

Tropical 

Linear regression temperate 

95% Confidence Band 

Linear regression tropical 

95% Confidence Band 

Table 5.9. Least squares linear regression model for species exhibiting temperate/subtropical affinity and latitude. Source: Friedlander et al., in prep. 

ANALYSIS OF VARIANCE 

Source DF Mean F Ratio Prob > F 

Square 

Model 1 0.20 33.57 0.0004 

Error 8 0.01 

C. Total 9 

PARAMETER ESTIMATES 

Term Estimate Standard t Ratio Prob>|t| 

Error 

Intercept -1.57 0.34 -4.57 0.0018 

Latitude 0.08 0.01 5.79 0.0004 

Table 5.8 (continued). Species with tropical affinity (negative correlation with latitude). Endemics in bold. Source: Friedlander et al., in prep. 

FAMILY TAXON NAME COMMON NAME HAWAIIAN NAME 

Acanthuridae Acanthurus nigrofuscus Brown Surgeonfish maiii 

Acanthuridae Acanthurus olivaceus Orangeband Surgeonfish naenae 

Acanthuridae Naso lituratus Orangespine Unicornfish umaumalei 

Monacanthidae Cantherhines sandwichiensis Squaretail Filefish oili lepa 

Balistidae Melichthys niger Black Durgon humuhumuelele 

Monacanthidae Pervagor aspricaudus Lacefi n Filefish 

Balistidae Rhinecanthus rectangulus Reef Triggerfish humuhumunukunukuapuaa 

Balistidae Suffl amen bursa Lei Triggerfish humuhumulei 

Tetraodontidae Canthigaster amboinensis Ambon Toby 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

(28%) and Nihoa (14%; Figure 5.8). Less 

than 1% of the number density of fishes 

counted at Midway consisted of species 

with a low latitude preference. Similarly, Kure Atoll (1.2%) Pearl and Hermes

Atoll (2.0%) and Lisianski Island-Neva

Shoals (3.2%) had low numbers of more 

tropical affi nity individuals. 

There is a strong positive linear relationship between the percentage of

individuals with temperate/subtropical

affinities and latitude (Table 5.9, Figure 

5.9), while there is a strong negative

linear relationship with the percentage

of individuals with tropical affi nities and 

latitude (Table 5.10, Figure 5.9). A major faunal break occurred around Maro

and Laysan, where the numerical abundance of northern and southern affinity species were more similar. Although

species with northern affinities were still

more abundant than species with southern affinities south of Maro, the overall

numerical abundance of these northern

species averaged 23% south of Maro,

but 54% to the north. Species with tropical affinities account for 17% of fish 

numbers south of Maro, but only 4% to

the north. 

163 
Fishes

Figure 5.11. Time series of the estimated mean numerical density of YOY

of all taxa at French Frigate Shoals and Midway during each survey year. 

Each vertical bar represents one southeast of the estimated survey year

grand mean for both major habitats. Source: DeMartini, 2004. ) 

2 10 m/n (ytisDen

1992 1993 1994 1995 1996 1997 1998 1999 2000 

10 

8 

6 

4 

2 

0 

FFS 

Midway 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

164 

Fish Recruitment 

The planktonic dispersal of reef fishes 

is an important process linked to the 

persistence of benthic reef populations. 

Recruitment of reef fishes increased 

with latitude, and was especially pronounced at the four northernmost reefs 

that had a larger proportion of YOY recruits (DeMartini and Friedlander, 2004). 

During 2000-2002, recruit fi sh densities 

were generally greater upchain to the 

northwest (versus downchain) and a 

larger number of endemic (versus nonendemic) species recruited to a greater extent upchain in the NWHI (Figure 

5.10; DeMartini and Friedlander, 2004). 

YOY recruit length frequencies did not 

differ for most species between northern and southern reefs, suggesting that 

a seasonal lag in spawning and recruitment at higher latitudes cannot explain 

the greater YOY densities observed 

there. Disproportionate recruitment at 

higher-latitude reefs may be related to 

higher levels of within-reef and regional reseeding at higher latitudes. This 

was first indicated by survey data collected during the 1990s at French Frigate Shoals and Midway (DeMartini et 

al., 2002; DeMartini, 2004). During this 

period, there was consistently higher 

recruitment of YOY life stages of fishes 

at Midway Atoll versus French Frigate 

Shoals despite the generally greater 

densities of older-stage fishes at French 

Frigate Shoals (Figure 5.11). 

Table 5.10. Least squares linear regression model for species with tropical 

affinity and latitude. Source: NWHI RAMP, unpub. data. 

ANALYSIS OF VARIANCE 

Source DF Mean 

Square 

F Ratio Prob > F 

Model 1 0.04 14.17 0.0055 

Error 8 0.01 

C. Total 9 

PARAMETER ESTIMATES 

Term Estimate Standard 

Error 

t Ratio Prob>|t| 

Intercept 1.01 0.24 4.12 0.0033 

Latitude -0.04 0.01 -3.76 0.0055 

Figure 5.10. Geographic patterns of the Recruit Index (ratio of YOY sized to 

larger individuals) for all pooled major species of endemic and non-endemic

reef fishes. Source: DeMartini and Friedlander, 2004; map: L. Wedding. 
100 

)

80 

%( ecnani

60 

 Dom

Nihoa 

Mokumanamana 

vei

French Frigate Shoals 

tal

40 Gardner u

Maro 

Cum

Laysan 

Lisianski 

20 Pearl and Hermes 

Midway 

Kure 

0

1 10 1

Species Rank 

Figure 5.12. Ordinary dominance curve for each reef based on biomass.

Source: NWHI RAMP, unpub. data. 

Transform: Log(X+1)
 

Resemblance: S17 Bray Curtis Similarity
 

Similarity 

Figure 5.13. Bray Curtis similarity dendrogram showing similarities among

reef based on biomass. Source: NWHI RAMP, unpub. data. 

Stress: 0.07 

MMM LIS 

MAR PHR FFS 

LAY 

GAR NIH MID 

KUR 

Figure 5.14. Nonmetric multi-dimensional scaling plot of reef similarities

derived from biomass abundance of species. Similarities based on BrayCurtis Similarity Index. Biomass abundance ln(x+1) transformed. Source:

NWHI RAMP, unpub. data. 

Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

GENERAL FISH ASSEMBLAGE STRUCTURE 

Dominance by species was revealed by 

plotting relative percent contribution by 

each species to total biomass at each 

reef. A limited number of species accounted for the majority of the biomass 

for most locations. Giant trevally (ulua, 

Caranx ignobilis) was the dominant species by weight at Lisianski (50% of total biomass), Pearl and Hermes (43%), 

Laysan (32%) and Maro (30%; Figure 

5.12). Chub (nenue, Kyphosus spp.) 

is the most dominant taxa by weight at 

Nihoa and accounts for 35% of the biomass. 

The similarity of fish assemblages 

among reefs in the NWHI was compared based on biomass density for

each species at each reef (Figures 5.13, 

5.14). Two atolls (Kure and Midway) had 

high concordance and formed a distinct 

cluster relative to all other islands. The

two basalt islands (Nihoa and Mokumanamana) were also distinct in their fish 

assemblages while Gardner Pinnacles,

the other basalt rock, was unique in its

fish assemblage based on biomass.

Pearl and Hermes and Lisianski were

the most similar based on fi sh assemblage biomass but also cluster at lower 

levels with Maro, Laysan, and to a lesser extent, French Frigate Shoals. 

Similarity based on numerical abundance showed two distinct clusters with 

Nihoa being an extreme outlier (Figures 5.15, 5.16). Midway and Pearl and 

Hermes exhibited similar assemblage

structure, as did French Frigate Shoals 

with Maro, and Kure with Lisianski. Mokumanamana, Gardner, and to a lesser 

extent, Laysan, exhibited similar assemblage structure but were less correlated 

than those in the other cluster. Nihoa

was unique in its assemblage structure 

based on numerical abundance. 

00 

165 
Fishes

Stress: 0.07 

NIH 

MID 

PHR FFS 

MAR MMM KUR LIS 

LAY 

GAR 

Figure 5.16. Nonmetric multi-dimensional scaling plot of reef similarities

derived from numerical abundance of species. Similarities based on BrayCurtis Similarity Index. Numerical abundance fourth root transformed.

Source: NWHI RAMP, unpub. data. 

Transform: Fourth Root 

Resemblance: S17 Bray Curtis Similarity 

Similarity

Figure 5.15. Bray Curtis similarity dendrogram showing similarities among

reef based on numerical abundance. Source: NWHI RAMP, unpub. data. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

166 

Trophic Structure 

Overall, apex predators accounted for

47% of total fish biomass, followed by

herbivores (31%) and secondary consumers (22%). Pearl and Hermes had

the highest percentage of apex predators (67%), with French Frigate Shoals

(61%) and Lisianski-Neva Shoal (58%)

also having substantial apex predator

biomass (Figure 5.17). More than 65%

of the apex predator biomass observed

within the NWHI consisted of giant trevally. 

Apex predator biomass increases up the 

chain reaching a maximum at Pearl and

Hermes Atoll before declining dramatically at Midway and Kure atolls (Figure

5.17; DeMartini and Friedlander, 2004).

The extremely low biomass of apex

predators at Midway and Kure has been 

attributed to previous extractive fishing 

activities at both locations as well as a

tag-and-release recreational sport fishery at Midway (DeMartini et al., 2002;

DeMartini et al., 2005). 

Herbivores were dominant in terms of

biomass at Nihoa (56%) and Midway

(56%). Chubs accounted for most of the

herbivore biomass at Nihoa while the

endemic spectacled parrotfi sh (Chlorurus perspicillatus) was most predominant at Midway and Kure. The lowest

total biomass was recorded at Mokumanamana (0.45 t ha-1) while Pearl and

Hermes had the lowest percentage of

herbivores (11%). Secondary consumer

biomass ranged from a high at Midway (0.91 t ha-1) and Pearl and Hermes (0.89 t ha-1) to a low at Mokumanamana (0.26 t ha-1). The saddle wrasse was the dominant species among secondary consumers at both Midway 

and Pearl and Hermes. 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

167 

Figure 5.17. Percent biomass by consumer groups at each reef. Bubbles are proportional to total biomass (t ha-1).

Source: NWHI RAMP, unpub. data. 

Biomass Size Spectra 

Biomass densities of pooled taxa were 

evaluated as size spectra relative to 

standardized length classes; our analysis revealed that there were relatively 

more and greater numbers of large individual fish at Pearl and Hermes and 

French Frigate Shoals than elsewhere 

in the NWHI (Figure 5.18). Overall, 

biomass based on the intercept of the 

biomass-to-body size relation (i.e. 

abundance at the midpoint of the length 

distribution) was lowest at Kure, Mokumanamana and Nihoa (Figure 5.19). 

Figure 5.18. Biomass size spectra for all fishes greater than 15 cm at each

of the major reefs in the NWHI. Source: NWHI RAMP, unpub. data. 

Standardized size class (cm) 

-100 -50 0 50 100 

Log10 biomass (kg ha-1) 

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 Kure 

Midway 

PHR 

Lisianski 

Laysan 

Maro 

Gardner 

FFS 

Mokumanamana 

Nihoa 
Fishes

1.5 

1.4 

1.3 

t p

e

1.2 

cret

1.1 

ni1.0 Y

-0.006 0.9 

-0.008 

0.8 

-0.010 e 

0.7 p

-0.012 lo

NIH 

M

S

MM

S FF

R GA

-0.014 

MAR

LAY

SLI

PHR

D MI

R

-0.016 

KU

Figure 5.19. Plot of slope and y-intercept from size spectra regressions.

Source: NWHI RAMP, unpub. data. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

168 

Shark Distribution Patterns 

Sharks are an important component of 

the reef fish assemblage in the NWHI 

accounting for 28% of apex predator 

biomass and 13% of total reef fi sh biomass on the fore reef. Grey reef (Carcharhinus amblyrhynchos, 8.4%), Galapagos (Carcharhinus galapagensis, 

10.2%; Figure 5.20) and whitetip reef 

sharks (Triaenodon obesus, 8.6%; Figure 5.20) comprised similar percentages of total apex predator biomass while 

blacktip reef sharks (Carcharhinus melanopterus) were much less abundant 

than the other three species and comprised only 0.3% of total biomass and 

0.6% of apex predator biomass in the 

fore reef habitats. The biogeographic 

distribution patterns of gray reefs and 

Galapagos sharks were markedly different within the NWHI (Figure 5.21). Gray 

reef sharks were replaced by Galapagos sharks moving northward along the 

NWHI chain. Galapagos sharks are less 

abundant at Nihoa, Mokumanamana, and French Frigate Shoals but are very abundant northwest of Gardner 

Pinnacles. Gray reefs become less abundant northward. Papastamatiou et al. (2006) examined data from 

the Hawaii Shark Control Program between 1967 and 1980 and found Galapagos and tiger sharks (Galeorcerdo cuvier) to be more abundant in the NWHI compared to the MHI, while sandbar sharks (Carcharhinus 

plumbeus) were more common in the MHI compared with the NWHI. These data showed gray reef sharks 

were more numerous in the NWHI compared with the MHI. Within the NWHI, this species was more abundant 

at Mokumanamana and French Frigate Shoals at the lower end of the NWHI and less abundant at the northern 

reefs of Maro and Midway. Interspecific competition, owing to dietary overlap, perhaps influences the distribution of these sharks throughout the Hawaiian Islands (Papastamatiou et al., 2006). 

Figure 5.20. Galapagos sharks (left) and a whitetip shark (right). Photos: J. Maragos and A. Friedlander. 
Fishes

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

169 

Figure 5.21. Biogeographic distribution of sharks in the NWHI based on number of individuals ha-1. Values are numbers 

ha-1 and are for fore reef habitats only. Source: NWHI RAMP, unpub. data. 

Influence of Influence of Predators 

on Prey Fishes 

The effects of apex predation, primarily by giant trevally, are pervasive. Apex 

predators structure prey population sizes and age distributions and strongly influence the reproductive and growth dynamics of other harvested species (such 

as parrotfish) as well as smaller-bodied, 

lower-trophic-level fishes on shallow 

NWHI reefs (DeMartini and Friedlander, 

2006). Perhaps the strongest evidence 

for the controlling influence of apex predation on the structure of fi sh assemblages in the NWHI is provided by data 

on the size, composition and spatial distribution of prey species (Figure 5.22; 

DeMartini et al., 2005). 

Figure 5.22. Scatterplot of the ranks of prey population attributes (median

body length at sex change in the four major labroid species, median body

lengths of all eight select species of labroids, and median body length of

all other prey fishes) versus the ranks of giant trevally densities. Source:

Demartini et al., 2005. 

Rank Giant Trevally Density 

1 2 3 4 5 6 

Rank Prey Population Attribute 

1 

2 

3 

4 

5 

6 

Median TL at sex change 

Median TL of all select labroids 

Median TL of all other prey fishes 

MID 

KUR 

MAR 

FFS 

LIS 

PHR 
Fishes

170 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

DeMartini (2004) documented the

habitat-specific spatial distributions of 

juvenile and other small-bodied fishes 

particularly susceptible to predation and 

recognized the importance of back reef, 

lagoon patch reef and other sheltered 

(wave-protected) habitats as nursery areas for juvenile reef fishes (Figure 5.23). 

This study, based on re-analyses of data 

collected at French Frigate Shoals and 

Midway Atoll during the 1990s, has contributed substantially to development of 

both “essential fish habitat” and “habitat 

areas of particular concern” concepts 

in recognizing the greater per-unit-area 

value of atolls due to their larger proportion of sheltered juvenile nursery habitats (DeMartini, 2004). 

Updated Comparison of Fish Assemblage Metrics Among NWHI Reefs 

Based on data collected from initial surveys in 2000, 2001, 2002 and new sites 

surveyed in 2007, fish assemblage characteristics were compared among all

reefs. Fish species richness appeared

highest at Nihoa, Gardner and Laysan

and lowest at Mokumanamana, Maro

and Kure but these differences were not 

significant (Table 5.11, Figure 5.24). The 

number of individual fishes observed on

transects differed signifi cantly different 

among reefs (Table 5.12, Figure 5.25,).

Midway, followed by Pearl and Hermes

had the highest number of individuals

while Mokumanamana and Maro had

the lowest. Biomass also differed significantly different among reefs (Table 5.13, 

Figure 5.26; F9,409 = 3.64, p < 0.001) with 

the highest biomass at Gardner, Nihoa

and Pearl and Hermes. The lowest fish 

biomass was recorded at Kure and Mokumanamana. 

Figure 5.23. Percentage contribution of YOY to overall YOY plus olderstage densities. Source: adapted from DeMartini, 2004. 

45 

40 

l a

35 

to Tf30 otne25 rc Pe

20 

sYOY a15 

10 

5 

0 

Exposed Semi-sheltered Sheltered 

FFS Midway 

Table 5.11. Fish species richness Analysis of Variance among reefs. 

Source: NWHI RAMP, unpub. data. 

SOURCE DF SUM OF MEAN F RATIO PROB > F 

SQUARES SQUARE 

Reef 9 686.699 76.3 1.64 0.1005 

Error 400 18548.44 46.37 

C. Total 409 19235.14 

Figure 5.24. Mean species richness per transect from REA data from 2000-

2002 and 2007. Error bars are standard error of the mean. Source: NWHI 

RAMP, unpub. data. 

30 

F9,409 = 1.65 

p = 0.10 

25 

es 

20 

ecip of S 15 erbNum 10 

5 

0 

KUR MID PHR LIS LAY MAR GAR FFS MMM NIH 
Fishes

1.6 

1.4 

1.2 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

F9,409 = 3.674 

p < 0.001 

-1 (ln[x+1]) Biomass t ha

KUR MID PHR LIS LAY MAR GAR FFS MMM NIH 

Figure 5.26. Mean biomass in t ha-1 (ln[x+1]) per transect from REA data 

from 2000-2002 and 2007. Error bars are standard error of the mean. 

Source: NWHI RAMP, unpub. data. 

Table 5.13. Fish biomass in t ha-1 (ln[x+1]) Analysis of 

Variance among reefs. Comparisons for all pairs using 

Tukey-Kramer HSD. Levels not connected by same letter 

are significantly different. Source: NWHI RAMP. 

ANALYSIS OF VARIANCE 

Source DF Sum of Mean F Prob 

Squares Square Ratio > F 

Reef 9 9.30 1.03 3.64 0.0002 

Error 400 113.64 0.28 

C. Total 409 122.93 

Level Multiple Com- Mean 

parisons 

Gardner AB 1.26 

Lisianski A 1.14 

Laysan AB 1.13 

Midway A 1.12 

Nihoa AB 1.11 

PHR A 1.09 

FFSs A 1.01 

Maro AB 0.97 

MMM AB 0.74 

Kure B 0.70 

Table 5.12. Fish biomass in t ha-1 (ln[x+1]) Analysis of 

Variance among reefs. Comparisons for all pairs using 

Tukey-Kramer HSD. Levels not connected by same letter 

are significantly different. Source: NWHI RAMP. 

ANALYSIS OF VARIANCE 

Source DF Sum of Mean F Prob 

Squares Square Ratio > F 

Reef 9 6.78 0.75 6.18 <.0001 

Error 400 48.80 0.12 

C. Total 409 55.58 

Level Multiple Mean 

Comparisons 

Midway A 1.20 

PHR AB 0.99 

Lisianski BC 0.87 

FFS BC 0.86 

Gardner ABC 0.83 

Kure BC 0.83 

Laysan BC 0.83 

Nihoa BC 0.81 

Maro BC 0.79 

MMM C 0.58 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

171 

1.4 

F9,409 = 6.18; p < 0.001 

1.2 

Number of Individuals (ln[x+1]) 1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

KUR MID PHR LIS LAY MAR GAR FFS MMM NIH 

Figure 5.25. Mean number of individuals per transect from REA data from 

2000-2002 and 2007. Error bars are standard error of the mean. Source: 

NWHI RAMP, unpub. data. 
Fishes

Average 

Table 5.14. Rank values for fish assemblage metrics among the 10 emer- Rank 

gent reefs of the NWHI. Source: NWHI RAMP, unpub. data. Biomass Predator Apex

RecruitmentMean

Reef 

Pearl and Hermes 10 9 4 9 10 10 6 8.29 Biomass* Total 

Midway 7 8 6 10 9 3 8 7.29 Number

French Frigate Shoals 5 10 7 7 8 8 5 7.14 Individuals

Lisianski 9 2 5 8 4 9 10 6.71 

Gardner 3 1 9 6 7 6 3 5 # Species

Laysan 4 5 8 4 5 7 1 4.86 Total 

Kure 8 7 3 5 2 1 7 4.71 Species

Nihoa 1 4 10 3 6 2 4 4.29 Endemism

Maro 6 6 2 2 3 5 2 3.71 

Mokumanamana 2 3 1 1 1 4 9 3 

*Total biomass excludes back reef and lagoon habitats to reduce bias and compares habitat types. 

172 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Comparisons of fish assemblage characteristics among reefs in the NWHI revealed Pearl and Hermes Atoll to have

the highest average rank among the

seven metrics examined (Table 5.14,

Figure 5.27). Pearl and Hermes yielded the highest endemism, highest total

biomass, and highest apex predator

biomass among all reefs. Midway and

French Frigate Shoals was second and 

third highest rank with Midway having

the greatest number of individuals and

French Frigate Shoals having the highest richness. Lisianski-Neva Shoals had 

the highest recruit index (ratio of YOY to 

older sized individuals). 

Mokumanamana had the lowest rank

integrated over all fish assemblage metrics and had the lowest number of species per transect and the lowest number 

of individuals per transect. Maro Reef

and Kure Atoll also had low values for

most fish assemblage metrics. Since

all sampling was conducted within the

boundaries of each Special Preservation Area (SPA), these rankings by reef

should also serve as a ranking by SPA. 

Comparisons with the MHI 

The most conspicuous biological patterns observed in the NWHI was the

strikingly higher numerical and biomass 

densities and greater average body sizes of reef fishes in the NWHI compared 

to the MHI, particularly for large jacks,

reef sharks and other apex predators

(Figure 5.28). Also notable is the overall reduced numbers and biomass density of lower trophic level fishes 

in the MHI, including lower-level carnivores. Differences in fish biomass density between the MHI and NWHI 

represent both the severe depletion of apex predators from fishing and the heavy exploitation of other species, 

primarily lower trophic-level carnivores on shallow reefs of the MHI (Friedlander and DeMartini, 2002). Fish 

densities at less exploited sites (such as uninhabited Kahoolawe and no-take areas) within the MHI further 

reinforce the conclusions that these differences are caused by fishing. Recent comparisons of fi sh biomass 

and size structure among accessible sites and inaccessible sites near versus distant from population centers 

in the MHI further indicate that depressed MHI stocks are primarily the result of fishing rather than other anthropogenic stressors such as poorer habitat quality (Williams et al., 2008). Were it not for extraction, reef fish 

productivity in the MHI should be higher (not lower) than in the NWHI as a result of greater terrigenous nutrient 

input and more diverse juvenile nursery habitats at the vegetated, high windward islands. Other anthropogenic 

stressors insufficiently explain the lower densities of reef fishes in the MHI (Friedlander and DeMartini, 2002; 

Friedlander and Brown, 2004). The differences in fish assemblage structure provide evidence of the high level 

of exploitation in the MHI. Further, the sharp contrast between the two areas in terms of fish density and composition provides a valuable perspective for developing ecosystem-level management of reef systems in the 

MHI and the NWHI (Friedlander and DeMartini, 2002). 

Figure 5.27. Mean rank values for fish assemblage metrics among the 10

emergent reefs of the NWHI. Source: NWHI RAMP, unpub. data. k ane RgaervA

e Kur y 

i

r 

a

a 

idwa

PHR

o

nsk

aysan

Mar ne

FFS 

d

man

i o

M

isia

Gar

mana

N h

L

L

ku Mo

10 

8 

6 

4 

2 

0 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

173 

Catalogue of the NWHI Fish Assemblages 

We conclude this chapter with a characterization of the fish assemblages at 

each of the 10 NWHI reefs, ordered from 

from Nihoa Island to Kure Atoll. The assemblages at each reef are described

in terms of three basic metrics (species 

richness and numerical and biomass

densities), with the latter two metrics

examined for dominant species. 

Nihoa Island 

Despite its small size (Figure 5.29),

Nihoa Island ranked first overall in fish 

species richness per transect among all

reefs surveyed in the NWHI. This is in

contrast to the total species richness,

which ranked amongst the lowest in the

NWHI. High species richness is related

to the proximity to MHI and our observation of the highest percentage of species with a tropical-biased distribution.

Species richness ranged from to 36.6

to 8.6 ( x =22.8, SD ± 11.02; Table 5.15,

Figure 5.30). 

Numerical abundance of fi shes ranked 

eighth overall and ranged from 5.32 to

0.14 individuals m-2 ( x =1.61, SD ± 1.57; 

Table 5.15, Figure 5.30). The blackfin 

chromis (Chromis vanderbilti), a planktivorous damselfish, comprised 35% of

the total numerical density, followed by

chubs (16%), and the brown surgeonfi sh (Acanthurus nigrofuscus, 6%). The

highest species richness, biomass, and

numerical abundance were observed

off the leeward side of the island where

high complexity basalt benches provided good quality habitat for a diversity of

species of various sizes. 

Biomass ranked fifth overall. Mean biomass per station was 2.88 t ha-1 (SD ± 

3.37) and ranged from a high of 12.03 to 

a low of 0.39. Chubs accounted for 43% 

of the total biomass at Nihoa Island, followed by whitetip reef sharks (7%), the 

introduced blueline snapper (Lutjanus 

kasmira, 7%) and black durgons (Melichthys niger, 5.5%). 

Table 5.15. Fish assemblage characteristics for Nihoa Island. Source: 

NWHI RAMP, unpub. data 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95% 

Species 11 22.8 11.02 3.32 15.4 30.21 

Number of 11 1.61 1.57 0.47 0.55 2.66 

Individuals (m2

) 

Biomass (t ha-1) 11 2.88 3.37 1.01 0.62 5.14 

Figure 5.28. Comparisons of total biomass and biomass among consumer

groups between the NWHI and MHI. Source: Friedlander and DeMartini,

2002. 

Figure 5.29. Aerial image of Nihoa Island. Photo: J. Maragos. 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

174 

Figure 5.30. Fish assemblage characteristics for Nihoa Island. Species richness (top left), number of individuals (top

right), and biomass (t ha-1; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

Mokumanamana 

Mokumanamana yielded the lowest

species richness per transect ( x =17.8, 

SD ± 4.45) among all reefs (Table 5.16, 

Figure 5.31, SD ± 4.45). Higher species 

richness was observed on the northwestern portion of the island. 

Mokumanamana also had the lowest

numerical density of fi shes observed 

among reefs in the NWHI (0.81 individuals/m2

, SD±0.35) and ranged from 1.49 to 0.43. The planktivorous 

blackfin chromis accounted for 19% of total numerical density, followed by the saddle wrasse (Thalassoma 

duperrey,18%) and the orangeband surgeonfi sh (Acanthurus olivaceus, 10%). The low overall values for fish 

assemblage characteristics at Mokumanamana are likely the result of low habitat complexity where the majority of stations having extremely low relief. For example, Shark Bay, located on the northern portion of the 

island, exhibited substrate of flat planed surfaces as a result of scouring by surge and sediment suspension. 

Fish biomass also ranked lowest at Mokumanamana. The distribution of biomass was extremely variable (CV 

= 0.85) but was highest off the points on the north and eastern parts of the island. Biomass ranged from 4.11 

to 0.36 t ha-1 with a grand mean of 1.25 (SD ± 1.06). Apex predators accounted for 43% of the total biomass 

Table 5.16. Fish assemblage characteristics for Mokumanamana Island. 

Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95% 

Species 15 17.82 4.45 1.15 15.36 20.29

Number of 15 0.81 0.35 0.09 0.61 1

Individuals (m2

) 

Biomass (t ha-1) 15 1.25 1.06 0.27 0.67 1.84 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 5.31. Fish assemblage characteristics for Mokumanamana. Species richness (top left), number of individuals (top

right), and biomass (t ha-1; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

and were dominated by grey reef sharks with 25% of total fish biomass. Other important contributors to fish 

biomass included orangeband surgeonfish (17%), black durgons (17%), giant trevally (6%) and whitetip reef 

sharks (5%). 

French Frigate Shoals Fish 

Species richness at French Frigate

Shoals averaged 21.8 (SD ± 7.7) and

was the forth highest among all reefs

surveyed (Table 5.17, Figure 5.32). Fore 

reef habitats had the highest species

richness ( x = 26.1), followed by back

reef ( x = 20.7), and lagoon habitats ( x

= 19.3). Species richness tended to be 

higher on the windward fore reef (Table 

5.18). 

Fish density ranged from 12.0 to 0.26 individuals/m2 and averaged 1.69 (SD ± 1.8). Numerical abundance 

was highest in lagoon habitat (1.77 individuals/m2 ) and was dominated by the domino damselfi sh (Dascyllus 

albisella, 9%), saddle wrasse (8%) and goldring surgeonfi sh (Ctenochaetus strigosus, 7%). Density was lowTable 5.17. Fish assemblage characteristics for French Frigate Shoals 

across all habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95% 

Species 93 21.78 7.73 0.8 20.19 23.37

Number of 93 1.69 1.83 0.19 1.31 2.07

Individuals (m2

) 

Biomass (t ha-1) 93 2.28 2.22 0.23 1.83 2.74 

175 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

176 

Figure 5.32. Fish assemblage characteristics for French Frigate Shoals: species richness (top row), number of individuals

(middle row), and biomass (t ha-1, bottom row). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 5.18. Fish assemblage characteristics for French Frigate Shoals for 

each major habitat type. Source: NWHI RAMP, unpub. data. 

BACK REEF NUMBER MEAN STD 

DEV 

STD 

ERR 

MEAN 

LOWER 

95% 

UPPER 

95% 

Species 2 20.67 0.47 0.33 16.43 24.9 

Number of 

Individuals (m2

) 

2 1.55 0.68 0.48 -4.52 7.61 

Biomass (t ha-1) 2 0.97 0.1 0.07 0.06 1.87 

LAGOON 

Species 58 19.34 6.83 0.9 17.54 21.14 

Number of 

Individuals (m2

) 

58 1.77 2.16 0.28 1.2 2.34 

Biomass (t ha-1) 58 1.87 1.72 0.23 1.42 2.33 

FORE REEF 

Species 33 26.13 7.63 1.33 23.43 28.84 

Number of 

Individuals (m2

) 

33 1.56 1.12 0.19 1.16 1.96 

Biomass (t ha-1) 33 3.08 2.8 0.49 2.09 4.08 

est on the fore reef ( x = 1.55 m2), where 

the blackfin chromis and saddle wrasse 

each accounted for 10% of the total number of individuals. Numerical abundance 

on the back reef habitat ( x = 1.55) was 

composed of the saddle wrasse (12%), 

the introduced blueline snapper (9%)

and blackfin chromis (8%). The greatest 

number of individuals was observed at

stations near Tern Island at the northern 

portion of the atoll and at the southern

pass near Disappearing Island. 

Fish biomass density (t ha-1) was highest on the fore reef ( x = 3.08 t ha-1) and 

was dominated by giant trevally (26%)

and grey reef sharks (21%). French

Frigate Shoals ranked third in total fore 

reef biomass among all locations. Species composition by weight in the lagoon ( x = 1.87) primarily consisted of giant trevally (13%), followed by grey 

reef sharks (6%), the endemic spectacled parrotfish (6%) and bluespine unicornfi sh (Naso unicornis, 6%). The 

back reef habitat yielded the lowest biomass ( x = 0.97) where giant trevally (25%), bluelined snappers (14%) 

and grey reef sharks (10%) comprised nearly half of the total biomass. Biomass was highest near Tern Island 

at the northern portion of the atoll and at the southern pass near Disappearing Island. 

Gardner Pinnacles 

A total of 10 stations were sampled for 

fishes at Gardner Pinnacles with the 

sampling effort representing a large portion of the hard bottom habitat less than 

18.2 m in depth including windward and 

leeward exposures. Mean species richness was 22.5 (SD ± 6.5) with a range 

from 36 to 13.3 species per transect. 

Gardner ranked second in mean species richness even though total species richness was low (Table 5.19 and Figure 5.33). 

Despite its small size, the biomass density of fishes at Gardner Pinnacles ranked fourth overall. Fish biomass 

ranged from 7.68 to 0. 29 t ha-1 ( x = 2.99, SD ± 2.11; Table 5.19, Figure 5.33). Chubs dominated by weight, 

comprising 17% of the total fish biomass. This species was followed by bluefin trevally (Caranx melampygus, 

11%) and grey reef sharks (10%). Highest biomass was observed off the northwest basalt pinnacle where 

large boulders formed a highly complex habitat with a vertical wall down to the reef pavement at 18.2 m. This 

station was dominated by bluefin (25%) and giant trevally (13%). 

Fish density ranged from 2.88 to 0.62 individuals/m2 ( x = 1.39, SD ± 0.73). Chubs accounted for 16% of total 

numerical abundance, followed by saddle wrasse (9%), and oval chromis (Chromis ovalis, 7%). The drop-off 

at the northwest sea stack harbored a large number of planktivores including oval chromis and milletseed 

butterflyfi sh (Chaetodon miliaris). These two species comprised 32% of the numerical density of fishes at this 

station. 

Table 5.19. Fish assemblage characteristics for Gardner Pinnacles across 

ll habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV 

Species 10 22.55 6.48 

Number of 10 1.39 0.72 

MEAN 

2.05 

0.23 

95% 

17.91 

0.88 

95% 

27.19

1.91

Individuals (m2

) 

Biomass (t ha-1) 10 2.99 2.11 0.67 1.48 4.5 

a

177 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

178 

Figure 5.33. Fish assemblage characteristics for Gardner Pinnacles. Species richness (top left), number of individuals

(top right), and biomass (t ha-1; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

Maro Reef 

Maro Reef was second only to Mokumanamana Island in having the lowest

mean species richness observed on

quantitative surveys (Table 5.20, Figure

5.34). Mean species richness was 18.6

(SD ± 4.6) and ranged from 27.67 to

12.56 per station. Relatively high species numbers were recorded at stations

along the westernmost, leeward reef

sections. 

The number of individual fish observed on transects at Maro was also low compared with other reefs in the 

NWHI ( x = 1.3, SD ± 0.5). Small resident species such as saddle wrasse (16%), Pacific Gregory (Stegastes 

fasciolatus,13%) and juvenile parrotfishes (11%) comprised much of the numerical density observed at Maro. 

Several stations on the windward, northeast side of the reef possessed higher numbers of individuals compared to other stations and were dominated by small juvenile parrotfishes. 

Biomass also was low compared to most other locations and ranked second lowest after Mokumanamana Island. Biomass density ranged from 6.12 to 0.41 t m-2 ( x = 1.9, SD ± 1.7); and similar to the observed richness 

Table 5.20. Fish assemblage characteristics for Maro Reef across all habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95% 

Species 42 18.65 4.58 0.71 17.22 20.08

Number of 42 1.26 0.51 0.08 1.1 1.42

Individuals (m2

) 

Biomass (t ha-1) 42 1.92 1.7 0.26 1.39 2.46 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

179Fishes

patterns, relatively high biomass was observed along the westernmost, leeward reef sections. More than 25% 

of the biomass at Maro Reef consisted of giant trevally, followed by spectacled parrotfish (11%), Galapagos 

sharks (7%), bullethead parrotfish (Chlorurus sordidus, 6%) and whitetip reef sharks (6%).

Laysan Island Fish 

Laysan Island ranked third in mean species richness ( x = 22.4, SD ± 5.2; Table

5.21, Figure 5.35), ranging from 32.7 to

13.3. The highest species richness occurred on the windward fore reef, off the

northeast corner of the island. 

Numerical abundance ranged from 2.46

to 0.42 individuals m-2 ( x = 1.3, SD ±

0.5) and was dominated by saddle wrasses (18%), followed by convict tangs (Acanthurus triostegus, 11%), 

and Pacific Gregory (7%), respectively. No strong spatial patterns to numerical abundance were observed 

among the sampling stations at Laysan.

Figure 5.34. Fish assemblage characteristics for Maro Reef. Species richness (top left), number of individuals (top right), 

and biomass (t ha-1; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding.

Table 5.21. Fish assemblage characteristics for Laysan Island across all 

habitat types. Source: NWHI RAMP, unpub. data.

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95%

Species 20 22.37 5.19 1.16 19.94 24.79

Number of 20 1.34 0.53 0.12 1.1 1.59

Individuals (m2

)

Biomass (t ha-1) 20 2.55 2.09 0.47 1.58 3.53
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

180 

Figure 5.35. Fish assemblage characteristics for Laysan Island. Species richness (top left), number of individuals (top

right), and biomass (t ha-1; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

Laysan Island ranked sixth in mean biomass ( x = 2.5, SD ± 2.1), ranging from 5.15 to 0.85 t ha-1. The windward, northeast fore reef harbored the highest biomass. Giant trevally comprised 37% of total biomass, followed by whitebar surgeonfi sh (Acanthurus leucopareius, 6%) and the endemic spectacled parrotfi sh (6%). 

Lisianski Island-Neva Shoals 

Lisianski Island-Neva Shoals ranked 

sixth in mean species richness per station ( x = 21.2, SD ± 4.13) and ranged 

from 24.7 to 20.7 (Table 5.22, Figure 

5.36). The greatest number of species 

per station was observed on the leeward 

side (northwest and west) of Lisianski. 

Numerical abundance at Lisianski Island-Neva Shoals ranked third overall. Mean fish density was 1.45 individuals/m2

 (SD ± 0.5) and ranged from 1.66 to 0.99 individuals/m2. Dominant species include saddle wrasse 

(12%), goldring surgeonfish (11%), Pacific Gregory (11%) and juvenile parrotfish (8%). No spatial patterns 

were observed for fish density across the reef system. 

Table 5.22. Fish assemblage characteristics for Lisianski Island-Neva 

Shoals across all habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95% 

Species 32 21.23 4.13 0.73 19.75 22.72 

Number of 32 1.45 0.53 0.09 1.26 1.64 

Individuals (m2

) 

Biomass (t ha-1) 32 2.47 1.71 0.3 1.85 3.08 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 5.36. Fish assemblage characteristics for Lisianski Island-Neva Shoals. Species richness (top left), number of

individuals (top right), and biomass (t ha-1; bottom left). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 

Lisianski Island-Neva Shoals ranked seventh in mean biomass compared to all other reefs. Mean fi sh biomass 

was 2.5 t ha-1 (SD ±1.7) and ranged from 5.15 to 0.8. Biomass was highest along the southeast portion of 

Neva Shoals, in an area of high coral cover and high habitat complexity. Giant trevally accounted for the majority (51%) of the total biomass. This was followed in importance by three species of parrotfishes: the endemic 

spectacled parrotfish (8%), bullethead parrotfish (4%) and the endemic regal parrotfi sh (Scarus dubius, 4%). 

Pearl and Hermes Atoll 

Mean species richness at Pearl and 

Hermes Atoll was 20.1 (SD ± 7.2) and 

ranked seventh overall (Table 5.23, Figure 5.37). Species richness was significantly higher (F291 = 24.49, p<0.001) on 

the fore reef ( x = 24.0, SD ± 6.9) compared with the lagoon ( x = 16.9, SD ± 

6.0) and back reef ( x = 17.0, SD ± 4.6) 

habitats (Table 5.24). 

Table 5.23 Fish assemblage characteristics for Pearl and Hermes Atoll 

across all habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD 

DEV 

STD ERR 

MEAN 

LOWER 

95% 

UPPER 

95% 

Species 91 20.12 7.21 0.76 18.62 21.62 

Number of 

Individuals (m2

) 

91 1.82 0.83 0.09 1.65 1.99 

Biomass (t ha-1) 91 2.78 3.75 0.39 2 3.56 

181 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

182Fishes

Figure 5.37. Fish assemblage characteristics for Pearl and Hermes Atoll. Species richness (top row), number of individuals (middle row) and biomass (t ha-1, bottom row). Source: NWHI RAMP, unpub. data; maps: L. Wedding.
Fishes

 

Table 5.24. Fish assemblage characteristics for Pearl and Hermes Atoll for 

each major habitat type. Source: NWHI RAMP, unpub. data. 

BACK REEF NUMBER MEAN STD 

DEV 

STD ERR 

MEAN 

LOWER 

95% 

UPPER 

95% 

Species 7 17 4.59 1.74 12.75 21.25 

Number of 

Individuals (m2

) 

7 1.88 0.55 0.21 1.37 2.39 

Biomass (t ha-1) 7 1.05 0.85 0.32 0.26 1.83 

LAGOON 

Species 43 16.91 5.99 0.91 15.07 18.76 

Number of 

Individuals (m2

) 

43 1.63 0.78 0.12 1.39 1.87 

Biomass (t ha-1) 43 2.02 3.02 0.46 1.09 2.95 

FORE REEF 

Species 41 24.02 6.91 1.08 21.84 26.2 

Number of 

Individuals (m2

) 

41 2.01 0.88 0.14 1.73 2.29 

Biomass (t ha-1) 41 3.88 4.42 0.69 2.49 5.28 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

The numerical density of fishes at Pearl 

and Hermes ranked second overall ( x

= 1.8, SD ± 0.8). Overall, planktivores 

comprised a third (37%) of total density, which included oval chromis (11%) 

blackfin chromis (7%) and chocolate 

dip chromis (Chromis hanui, 5%). The 

number of individuals observed on the 

fore reef ( x = 2.1, SD ± 0.9) was significantly higher (p<0.05) than the back 

reef ( x = 1.9, SD ± 0.6) and lagoon ( x

= 1.6, SD ± 0.8) habitats. 

Pearl and Hermes ranked fi rst in fish 

biomass on the fore reefs ( x = 3.9, 

SD± 4.4) among all locations. Biomass 

was significantly higher on the fore reef 

(p < 0.05) than the lagoon ( x = 2.0, SD 

± 3.0), which, in tern, was significantly higher (p < 0.05) than at back reef ( x = 1.0, SD± 0.9). Apex predators 

dominated the fish biomass, with giant trevally accounting for 48%, followed by whitetip reef sharks (6%), and 

Galapagos sharks (5%). Stations with the highest biomass were located along the leeward, southwest fore 

reef. 

Midway Atoll 

Midway ranked fifth in species richness 

among all reef locations (Table 5.25, 

Figure 5.38). The mean number of species per transect differed significantly 

(p<0.05) among all three habitats. Fore 

reef habitats harbored 27.0 (SD ± 6.0) 

species, followed by back reefs ( x = 

19.1, SD ± 4.8), and lagoon habitats ( x

= 15.8, SD ± 6.1). Richness was highest along the southern fore reef (Table 

5.26). 

Midway ranked first in numerical density 

( x = 2.7 individuals/m2

, SD ± 2.0). The 

lagoon harbored the greatest number 

of individuals ( x = 2.9 individuals/m2

, 

SD ± 2.7) consisting of damselfishes 

(oval chromis – 11%, Pacific Gregory – 

10%, domino damselfish – 5%, blackfin 

chromis – 5% and chocolate dip chromis 

– 5%). All except the Pacifi c Gregory 

are planktivores. Saddle wrasse (13%) 

and schools of convict tangs (6%) also 

contributed to the large number of individuals observed at Midway. Numerical 

abundance was highest on the northwestern leeward fore reef and in Welles 

Harbor. 

183 

Table.5.25. Fish assemblage characteristics for Midway Atoll across all 

habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD 

DEV 

STD ERR 

MEAN 

LOWER 

95% 

UPPER 

95% 

Species 37 21.59 7.97 1.31 18.94 24.25 

Number of 

Individuals (m2

) 

37 2.69 2.04 0.34 2.01 3.37 

Biomass (t ha-1) 37 2.5 2.14 0.35 1.78 3.21 

Table 5.26. Fish assemblage characteristics for Midway Atoll for each 

major habitat type. Source: NWHI RAMP, unpub. data. 

BACK REEF NUMBER MEAN STD 

DEV 

STD 

ERR 

MEAN 

LOWER 

95% 

UPPER 

95% 

Species 4 19.08 4.79 2.4 11.45 26.71 

Number of 

Individuals (m2

) 

4 1.59 0.46 0.23 0.85 2.32 

Biomass (t ha-1) 4 1.46 0.65 0.33 0.42 2.49 

LAGOON 

Species 15 15.76 6.14 1.59 12.35 19.16 

Number of 

Individuals (m2

) 

15 2.9 2.69 0.69 1.41 4.39 

Biomass (t ha-1) 15 1.58 1.22 0.31 0.91 2.26 

FORE REEF 

Species 18 27.02 6.05 1.43 24.01 30.03 

Number of 

Individuals (m2

) 

18 2.76 1.58 0.37 1.97 3.54 

Biomass (t ha-1) 18 3.49 2.52 0.59 2.24 4.74 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

184 

Figure 5.38. Fish assemblage characteristics for Midway Atoll. Species richness (top row), number of individuals (middle 

row) and biomass (t ha-1; bottom row). Source: NWHI RAMP, unpub. data; maps: L. Wedding. 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Biomass at Midway averaged 2.5 t ha-1 (SD ±2.1) and ranked second overall among locations. There were large 

differences in biomass among habitat types with biomass on the fore reef ( x = 3.5, SD ± 2.5) more than two 

times higher than the back reef ( x = 1.5, SD ± 0.7), and the lagoon ( x = 1.6, SD ± 1.2). Herbivores accounted 

for the majority of the biomass (57%) with considerable contributions from the spectacled parrotfi sh (13%), 

whitebar surgeonfish (8%), convict tang (7%), and bluespine unicornfish (6%). Galapagos sharks (8% ) and giant trevally (5%) were the major predators by weight. The highest biomass was observed along the northwest 

fore reef where the reef crest becomes submerged and along the southern fore reef off Sand Island. 

Kure Atoll 

Species richness at Kure was low ( x

= 19.6, SD ± 6.3) ranking eighth overall 

(Table 5.27, Figure 5.39). Significantly 

higher (p<0.05) numbers of species 

were observed on the fore reef ( x = 

21.5, SD ± 6.3) compared to the lagoon 

( x = 17.4, SD ± 6.0) and back reef ( x

= 15.3, SD ± 2.0). Richness was high 

around the entire fore reef (Table 5.28). 

An average of 1.4 individuals/m-2 were 

observed at Kure (sixth overall). Saddle 

wrasse (20%), oval chromis (12%), Pacific Gregory (9%) and chubs (6%) were 

most important numerically. No strong 

patterns in the distribution of individuals was observed and no signifi cant difference among habitat types (p>0.05) 

were detected. The fore reef averaged 

1.6 individuals/m-2, followed by lagoon 

( x = 1.3, SD ± 1.1) and back reef ( x

= 1.1, SD ± 0.2). Fish density was highest on the leeward fore reef and central 

western patch reefs. 

Kure had the second lowest biomass of 

any location ( x = 1.2, SD ± 1.1) and the 

lowest proportion of apex predators (16%). Spectacled parrotfish (17%), chubs (10%) and giant trevally (5%) 

were most important by weight. There were no strong patterns in the spatial distribution of biomass. Unlike 

other locations, the lagoon ( x = 1.2, SD ± 1.5) and fore reef ( x = 1.3, SD ± 0.9) biomass estimates were very 

similar. 

Table 5.27. Fish assemblage characteristics for Kure Atoll across all habitat types. Source: NWHI RAMP, unpub. data. 

LEVEL NUMBER MEAN STD STD ERR LOWER UPPER 

DEV MEAN 95% 95% 

Species 59 19.6 6.32 0.82 17.96 21.25 

Number of 59 1.41 0.81 0.1 1.2 1.62 

Individuals (m2

) 

Biomass (t ha-1) 59 1.22 1.13 0.15 0.93 1.51 

Table 5.28. Fish assemblage characteristics for Kure Atoll for each major 

habitat type. Source: NWHI RAMP, unpub. data. 

BACK REEF NUMBER MEAN STD 

DEV 

STD 

ERR 

MEAN 

LOWER 

95% 

UPPER 

95% 

Species 5 15.27 2.05 0.92 12.73 17.81 

Number of 

Individuals (m2

) 

5 1.11 0.21 0.09 0.85 1.37 

Biomass (t ha-1) 5 0.61 0.19 0.09 0.38 0.85 

LAGOON 

Species 20 17.42 5.96 1.33 14.63 20.21 

Number of 

Individuals (m2

) 

20 1.31 1.09 0.24 0.8 1.82 

Biomass (t ha-1) 20 1.22 1.53 0.34 0.5 1.94 

FORE REEF 

Species 34 21.53 6.3 1.08 19.33 23.73 

Number of 

Individuals (m2

) 

34 1.52 0.65 0.11 1.29 1.75 

Biomass (t ha-1) 34 1.31 0.91 0.16 0.99 1.63 

185 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

186Fishes

Figure 5.39. Fish assemblage characteristics for Kure Atoll. Species richness (top row), number of individuals (middle 

row) and biomass (t ha-1; bottom row). Source: NWHI RAMP, unpub. data; maps: L. Wedding.
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

EXISTING DATA GAPS 

Two major issues dominate the management and conservation of reef resources in the NWHI and throughout the Hawaiian Archipelago. The dispersal, connectivity, and genetic exchange between reef populations 

of NWHI and MHI organisms is undoubtedly the issue of greatest consequence for future management and 

conservation of reef fish and other resources in the NWHI as well as the MHI. Much recent progress has been 

made obtaining the empirical data needed to begin unraveling patterns of planktonic dispersal and more directed adult movements of fishes in the NWHI (see the Connectivity and Integrated Ecosystem Studies chapter of this document). The habitat relations of fishes are arguably the second most important issue to consider 

for fishes in the NWHI. Habitat alterations (sea level rise, warming, acidification) resulting from global climate 

change are expected to be the most significant impacts and likely to occur in the NWHI (Selkoe et al., 2008). 

Although the effects of global warming and coral bleaching on coral reef fishes are of concern worldwide 

(Pratchett et al., 2008a), they are relatively more important in the NWHI where resources are now protected 

from other human impacts by establishment of the Monument. 

The prevalence and dynamics of coral and related substrata (e.g., algal secondary cover) represent the most 

obvious habitat issues for shallow-water reef fishes in the NWHI. Although corals are important as a food 

source only for relatively few, specialized fishes in tropical reef ecosystems including Hawaii (Cole et al. 2008), 

corals provide exceedingly important shelter resources (Caley and St. John, 1996). These shelter resources 

are especially important for the relatively small-bodied and predator-vulnerable juvenile life stages of reef 

fishes, particularly early YOY near the time when they settle from the plankton as “recruits” to benthic populations (Jones et al., 2004; DeMartini and Anderson, 2007). Coral shelter is nonetheless also important for larger, 

older juveniles and adults (Beukers and Jones, 1997). 

A comprehensive and systematic characterization of the habitat relations of Hawaiian reef fishes is lacking and 

needed. The only published work to date is limited to finger coral habitat on shallow (10 m) fringing reefs of 

the leeward Big Island and further restricted to the recruits of a suite of summer-recruiting species, primarily 

tangs of the family Acanthuridae (DeMartini and Anderson, 2007). Work is in progress to expand this catalogue 

both taxonomically and across additional habitats, with initial emphasis on the diverse labroids (parrotfishes, 

wrasses) that recruit in spring-summer to very shallow (1-3 m deep) and wave-protected coral rubble habitats. 

Several recent case studies exemplify the need for distinguishing habitat relations between juvenile and adult 

conspecifics (Pratchett et al., 2008b; Wellenreuther and Clements, 2008). For this reason, the habitat relations 

of adult as well as juvenile Hawaiian reef fishes are being described. 

187 
Fishes

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

188 

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Allen, G.R. 2002. Indo-Pacifi c coral-reef fishes as indicators of conservation hotspots. Proc 9th Int Coral Reef Symp 2:

921-926. 

Beukers J.S. and G.P. Jones. 1997. Habitat complexity modifies the impact of piscivores on a coral reef fi sh population. 

Oecologia 114: 50-59. 

Burridge, C.P. and R.W.G. White. 2000. Molecular phylogeny of the antitropical subgenus Goniistius (Perciformes: Cheilodactylidae: Cheilodactylus): evidence for multiple transequatorial divergences and non-monophyly. Biol J Linn Soc 70: 

435–458. 

Caley, M.J. and J. St. John. 1996. Refuge availability structures assemblages of coral reef fishes. J Anim Ecol 65: 414­

428. 

Cole, A.J., M.S. Pratchett, and G.P. Jones. 2008. Diversity and functional importance of coral-feeding fishes on tropical

coral reefs. Fish and Fisheries 9: 286-307. 

Cowen, R.K., C.B. Paris, and A. Srinivasan. 2006. Scaling of connectivity in marine populations. Science 311: 522-527. 

DeMartini, E.E. 2004. Habitat and endemism of recruits to shallow reef fish populations: selection criteria for no-take

MPAs in the NWHI Coral Reef Ecosystem Reserve. Bull Mar Sci 14: 185–205. 

DeMartini, E.E. and T.W. Anderson. 2007. Habitat associations and aggregation of recruit fishes on Hawaiian coral reefs. 

Bull Mar Sci 81: 139-152. 

DeMartini, E.E. and A.M. Friedlander. 2004. Spatial pattern of endemism in shallow water reef fish populations of the

Northwestern Hawaiian Island. Mar. Ecol. Prog. Ser. 271: 281-296. 

DeMartini, E.E. and A.M. Friedlander. 2006. Predation, endemism, and related processes structuring shallow-water reef 

fish assemblages of the NWHI. Atoll Research Bulletin 543: 237-257. 

DeMartini E.E., A.M. Friedlander, and S.R. Holzwarth. 2005. Size at sex change in protogynous labroids, prey body size 

distributions, and apex predator densities at NW Hawaiian atolls. Marine Ecology Progress Series 297: 259-271. 

DeMartini, E.E., F.A. Parrish, and R.C. Boland. 2002. Comprehensive evaluation of shallow reef fish populations at French

Frigate Shoals and Midway Atoll, Northwestern Hawaiian Islands (1992/93, 1995–2000). NOAA Technical Memorandum 

NOAA-TM-NMFS-SWFSC-347NOAA Fisheries, Southwest Fisheries Science Center, Honolulu. 

DeMartini, E.E., B.J. Zgliczynski, R.C. Boland, and A.M. Friedlander. In review. Influences of wind-wave exposure on

the distribution and density of recruit reef fishes at Kure and Pearl and Hermes atolls, Northwestern Hawaiian Islands. 

Environ. Biol. Fish. 

Ehler, R. 2004. Socio-economic assessment of commercial bottomfishing in the Northwestern Hawaiian Islands. Report

to NOAA,NOS, National Marine Sanctuary Program. Pp 46. 

Friedlander, A.M., and E. Brown . 2004.Marine Protected Areas and community-based fisheries management in Hawaii.

Pp. 208-230. In: A.M. Friedlander (ed.), Status of Hawaii’s Coastal Fisheries in the New Millenium. 2nd ed. Proceedings 

2001 Fisheries Symposium sponsored by the American Fisheries Society, Hawaii Chapter. Honolulu, Hawaii. 

Friedlander A.M., E.K. Brown, and M.E. Monaco. 2007. Coupling ecology and GIS to evaluate efficacy of marine protected areas in Hawaii. Ecol. Appl. 17: 715-30. 

Friedlander, A.M. and E.E. DeMartini. 2002. Contrasts in density, size, and biomass of reef fishes between the Northwestern. and the Main Hawaiian Islands: the effects of fishing down apex predators. Mar. Ecol. Prog. Ser. 230: 253-264. 

Gray, J.S. 1997. Marine biodiversity: patterns, threats and conservation needs. Biodiversity and Conservation 6:153­

175. 

Hawkins, J.P., C.M. Roberts, and V. Clark. 2000. The threatened status of restricted range coral reef fi sh species. Anim 

Conserv 3: 81–88. 

Jones, G.P., M.I. McCormick, M. Srinivasan, and J.V. Eagle. 2004. Coral decline threatens fish biodiversity in marine

reserves. Proc Nat Acad Sci USA 101: 8251-8253. 

Maragos, J., D. Potts, G. Aeby, D. Gulko, J. Kenyon, D. Siciliano, and D. VanRavensway. 2004. 2000-2002 Rapid Ecological Assessment of Corals (Anthozoa) on shallow reefs of the Northwestern Hawaiian Islands, Part I: Species and Distribution. Pacific Science 58(2): 211-230. 

Mundy, B.C. 2005. Checklist of the fishes of the Hawaiian archipelago. Bishop Museum Bulletin in Zoology 6. Bishop

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Papastamatiou, Y.P., B.M. Wetherbee, C. Lowe, and G.L. Crow. 2006. Distribution and diet of four species of carcharhinid 

shark in the Hawaiian Islands: evidence for resource partitioning and competitive exclusion. Mar. Ecol. Pro. Ser. 320: 

239-251. 

Pratchett, M.S., M.L. Berumen, M.J. Marnane, J.V. Eagle, and D.J. Pratchett. 2008. Habitat associations of juvenile versus adult butterflyfishes. Coral Reefs 27: 541-551. 

Pratchett, M.S., P.L. Munday, S.K. Wilson, N.A.J. Graham, J.E. Cinner, D.R. Bellwood, G.P. Jones, N.V.C. Polunin, and 

T.R. McClanahan. 2008. Effects of climate induced coral bleaching on coral-reef fishes — ecological and economic consequences. Oceanogr Mar Biol Annu Rev 46: 251-296. 

Randall, J.E. 1981. Examples of antitropical and antiequatorial distribution of Indo-West-Pacific fishes. Pac Sci 35: 197– 

209. 

Randall, J.E. 1987. Introductions of marine fishes to the Hawaiian Islands. Bull Mar Sci 41: 490-502. 

Randall J.E. 1995. Zoogeographic analysis of the inshore Hawaiian fish fauna. Pp:193-203. In: Maragos J.E., Peterson

M.N.A., Eldredge L.G., Bardach J.E., and Takeuchi H.F. (eds.) Marine and coastal biodiversity in the tropical island Pacific 

region: Vol. 1, Species systematics and information management priorities. East-West Center, Honolulu. 

Randall J.E. 1998. Zoogeography of shore fishes of the Indo-Pacific region. Zool Stud (Taiwan) 37: 227–268. 

Randall J.E. 2007. Reef and shore fishes of the Hawaiian Islands. Sea Grant College Program, University of Hawaii,

Honolulu. 546 pp. 

Randall J.E., and J.L. Earle. 2000. Annotated checklist of the shore fishes of the Marquesas Islands. Occas Pap Bishop

Museum 66: 1–39. 

Randall, J.E., J.L. Earle, R.L. Pyle, J.D. Parrish, and T. Hayes. 1993. Annotated checklist of the fishes of Midway Atoll, 

Northwestern Hawaiian Islands. Pac Sci 47: 356–400. 

Roberts, C.M., C.J. McClean, J.E.N. Veron, J.P. Hawkins and 8 others. 2002. Marine biodiversity hotspots and conservation priorities for tropical reefs. Science 295: 1280–1284. 

Selkoe, K.A., B.S. Halpern, and R. Toonen. 2008. Evaluating anthropogenic threats to the Northwestern Hawaiian Island 

Aquatic Conservation: Marine and Freshwater Ecosystems 18:1149-1165. 

Wellenreuther, M. and K.D. Clements 2008. Determinants of habitat association in a sympatric clade of marine fishes. 

Mar Biol 154: 393-402. 

Williams, I.D., W.J. Walsh, R.E. Schroeder, A.M. Friedlander, B.L. Richards, and K.A. Stamoulis. 2008. Assessing the 

importance of fishing impacts on Hawaiian coral reef fish assemblages along regional-scale human population gradients.

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Marine Protected Species 

Charles Littnan1, Marie (Chapla) Hill2, Stacy (Kubis) Hargrove1, Kaylene E. Keller3 and Angela D. Anders4 

INTRODUCTION 

The Monument protects habitat for

many marine mammal species ,including 24 species of cetaceans that have

been sighted in the Hawaiian Islands

Exclusive Economic Zone (EEZ), and

the critically endangered Hawaiian

monk seal. (Figure 6.1). Twenty three

species of cetaceans were observed

and identified to the species level during a 2002 survey (Barlow et al., 2004).

Four of these species are on the U.S.

Endangered Species list, including the

humpback whale (Megaptera novaeangliae), sperm whale (Physeter macrocephalus), fin whale (Balaenoptera physalus) and sei whale (Balaenoptera borealis; http://www.nmfs.noaa. 

gov/pr/species/esa/mammals.htm). In addition, the false killer whale (Pseudorca crassidens) is listed as a 

strategic stock under the 1994 amendments to the Marine Mammal Protection Act (MMPA). Each of these species has been observed within the Monument boundaries (Barlow et al., 2004; Johnston et al., 2007; NMFS, 

unpublished data). Several of the cetacean species observed within the Hawaiian Islands EEZ are found there 

year-round (e.g., spinner dolphins, false killer whales, rough-toothed dolphins). Others occur there only seasonally and in some cases are known to migrate long distances to use the area for breeding (e.g., humpback 

whales). 

Figure 6.1. The Monument protects habitat for many marine mammal species, including several species of dolphins and whales. A spinner dolphin 

(left) and humpback whales (right) are pictured here. Photos: PIFSC and

D. Shapiro. 

In addition to providing important habitat 

to cetaceans, the Monument is also the

primary habitat for the federally endangered Hawaiian monk seal (Monachus

schauinslandi; Figure 6.2). The six main

Hawaiian monk seal subpopulations are 

completely contained within the Monument boundaries. The Hawaiian monk

seal population is estimated to have

declined by 60% since the 1950s (Antonelis et al., 2006), and is currently estimated at just under 1,200 individuals.

Because of its small population size and

swift rate of decline, the Hawaiian monk

seal is the focus of intense conservation

efforts. 

Finally, the Monument provides the primary nesting habitat for the green turtle (Chelonia mydas; Figure 6.2) 

in the Hawaiian Archipelago, listed as Threatened under the U.S. Endangered Species Act (ESA). Green, 

loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea) and 

1. NOAA/NMFS/Pacific Islands Fisheries Science Center 

2. Joint Institute for Marine and Atmospheric Research 

3. NOAA/NOS/ONMS/Papahanaumokuakea Marine National Monument

4. Clancy Environmental Consultants, Inc. 

Figure 6.2. The Monument is home to the six primary Hawaiian monk seal

subpopulations (left). The area also protects nesting habitat of the green

turtle (right). The Hawaiian monk seal is listed as endangered and the

green turtle is listed as threatened under the U.S. Endangered Species Act. 

Photos: J. Watt. 

191 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

192 

olive ridley (Lepidochelys olivacea) turtles use the Monument for foraging habitat and as migration pathways. 

Although the Hawaiian green turtle population has been increasing over the past three decades, individuals 

still nest primarily at French Frigate Shoals in the Northwestern Hawaiian Islands (NWHI). 

CETACEANS 

Available Data 

Most of what is known about cetaceans found within the Hawaiian EEZ comes from data collected within the 

waters surrounding the Main Hawaiian Islands (MHI). Although somewhat limited, information on the occurrence of cetacean species within the Monument comes from historical whaling records, documented opportunistic sightings and stranding records, data collected during ship-based surveys, and species-specifi c (e.g., 

spinner dolphin) photo-identification and genetic research. 

Charles Townsend (1935) used whaling logbooks to record locations of certain whale species onto charts of 

both the Atlantic and Pacific Oceans. The Wildlife Conservation Society digitized the charts and made them 

available to the general public (http://www.wcs.org/sw-high_tech_tools/landscapeecology/townsend_charts). 

Data on sperm whale sightings within the Hawaiian EEZ, including the Monument, are extracted from these 

records (see Species Descriptions section, sperm whale). 

Edward W. Shallenberger (1981) collected information from published and unpublished literature, fi eld notes, 

ships’ logs, and interviews with knowledgeable people in order to document the occurrence and status of cetacean species found in Hawaiian waters, including the NWHI. 

The Atoll Research Bulletin produced a series of publications on the natural history of the NWHI in which records of cetacean species were documented from opportunistic sightings and stranding events (Rice, 1960; 

Amerson, 1971; Woodward, 1972; Amerson et al., 1974; Nitta and Henderson, 1993). These records are more 

anecdotal in nature and lack precise location data (i.e., latitude/longitude points), however, they are useful for 

generalizing about the occurrence of certain species within the Monument. 

Precise data regarding the occurrence of 

cetaceans in the Monument come from 

recent ship-based surveys within the 

200 nm EEZ surrounding the Hawaiian 

Islands (Barlow et al., 2004; Johnston 

et al., 2007; NMFS, unpublished data). 

In 2002, Barlow et al. (2004) conducted 

standard ship-based visual line-transect 

surveys, from two ships, for all cetacean 

species in the Hawaiian Islands EEZ. 

Search effort included a total of 24,738 

km (13,357 nm) over 157 survey days. 

Acoustic monitoring, photo-documentation, biopsy and behavioral studies were 

conducted concurrently. Line-transect 

surveys resulted in observations of 23 

cetacean species within the Hawaiian 

Islands EEZ, with 15 of those species 

seen within the boundaries of the Monument (see Species Descriptions section 

and Figure 6.3; Barlow et al., 2004). 

Abundance estimates and densities per 

1,000 km2

 were calculated for 19 of the 23 cetacean species observed (Table 6.1; see Cetaceans Abundance 

Estimates section on page 210; Barlow, 2006). 

Figure 6.3. Cetacean Observations and Survey Transects . Sources: Barlow et al., 2004; Johnston et al., 2007; NMFS, unpublished; Townsend, 

1935; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 6.1. Estimated abundance of 19 cetacean species in the MHI and outer Hawaiian Islands EEZ. Overall abundances, 

overall densities, and coefficients of variation (CV) are pooled from the MHI and outer EEZ estimates. Pooled abundance

and density estimates are given for delphinids and beaked whales. Asterisk (*) indicates a more recent estimate of false 

killer whale abundance in offshore waters of the Hawaiian EEZ (484 individuals, CV=0.93) comes from Barlow and Rankin

(2007). Source: Barlow, 2006. 

SPECIES MAIN ISLAND 

ABUNDANCE 

(n) 

OUTER EEZ 

ABUNDANCE 

(n) 

OVERALL 

ABUNDANCE 

(n) 

OVERALL DENSITY 

PER 1,000 km2 

(D) 

CV 

Offshore spotted dolphin 4,283 4,695 8,978 3.66 0.48 

Striped dolphin 660 12,483 13,143 5.36 0.46 

Spinner dolphin 1,488 1,863 3,351 1.37 0.74 

Rough-toothed dolphin 1,713 6,997 8,709 3.55 0.45 

Bottlenose dolphin 465 2,750 3,215 1.31 0.59 

Risso’s dolphin 513 1,859 2,372 0.97 0.65 

Fraser’s dolphin 0 10,226 10,226 4.17 1.16 

Melon-headed whale 0 2,950 2,950 1.20 1.17 

Pygmy killer whale 956 0 956 0.39 0.83 

False killer whale * 0 236 236 0.10 1.13 

Short-finned pilot whale 3,190 5,680 8,870 3.62 0.38 

Killer whale 0 349 349 0.14 0.98 

Sperm whale 126 6,793 6,919 2.82 0.81 

Pygmy sperm whale 0 7,138 7,138 2.91 1.12 

Dwarf sperm whale 0 17,519 17,519 7.14 0.74 

Blainville’s beaked whale 0 2,872 2,872 1.17 1.25 

Cuvier’s beaked whale 0 15,242 15,242 6.21 1.43 

Longman’s beaked whale 0 1,007 1,007 0.41 1.26 

Bryde’s whale 0 469 469 0.19 0.45 

Delphinids pooled 13,267 50,087 63,354 25.83 

Beaked whales pooled 371 19,121 19,492 7.95 

The work of Johnston et al. (2007) focused on visual and acoustic observations of humpback whales from 

Oahu to Midway Atoll in the NWHI during March and April 2007. Search effort covered 1,690 km over 12 survey days. Surveys were focused on areas near atolls and islands, and tracklines generally followed the 183 

m (1,000 fathom) isobath, however, some tracklines were in deeper waters (Johnston et al., 2007; NMFS, 

unpublished data). Observations were conducted following standard distance sampling/line transect methods 

for cetaceans, similar to those employed in Barlow et al. (2004). During the surveys, sightings of all cetaceans 

were recorded, including location and group size estimates (NMFS, unpublished data). Additionally, acoustic 

monitoring, photo-documentation and biopsy sampling were conducted. These surveys resulted in the detection of 44 groups of eight cetacean species. Seven of these species were observed within Monument boundaries (Johnston et al., 2007; NMFS, unpublished data). In the Species Description section (below) these surveys 

will be referred to as the NWHI survey. 

Other species-specific cetacean work within the Monument includes research on the social patterns and population structure of spinner dolphins (Stenella longirostris) at Midway Atoll (Karczmarski et al., 1998; 1999; Rickards et al., 2001; Karczmarski et al., 2005) and the genetic diversity of spinner dolphins within the Hawaiian 

Archipelago (Andrews et al., 2006). The photo-identification and behavioral research at Midway Atoll consisted 

of land and small boat-based surveys conducted in 1998 through 2001, totaling 1,104 effort hours. Results of 

this work indicate that a resident spinner dolphin population is present at Midway, but that movement of individuals between Midway, Kure Atoll, and Pearl and Hermes Atoll occurs (Karczmarski et al., 1998; 1999; Rickards et al., 2001; Karczmarski et al., 2005). The analysis of biopsy samples taken from various locations within 

the Hawaiian Archipelago (e.g., Hawaii, Maui/Lanai, Oahu, Niihau, French Frigate Shoals, Pearl and Hermes 

Atoll, Midway Atoll and Kure Atoll) indicates a genetic distinction among separate spinner dolphin populations 

(Andrews et al., 2006). 

193 
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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

194 

Species Descriptions 

Description, range and habitat information is taken from the following sources: Tomich (1986), Ridgeway and 

Harrison (1994), Ridgeway and Harrison (1999), Perrin et al. (2002), Reeves et al. (2002), and OBIS SEAMAP 

(an online data source that compiles information from various published sources, http://seamap.env.duke. 

edu/). 

Offshore Pantropical Spotted Dolphin (Stenella attenuata) 

Three subspecies of the pantropical spotted dolphin are recognized worldwide and differ in body size, coloration and skull characteristics. Their lengths range from 1.6 m to 2.6 m and their average weight is 114 kg. 

In general, the pantropical spotted dolphin has a moderately slender body; a relatively small dorsal fi n that 

is strongly falcate (back-curved or shaped like a sickle); and a long, slender beak. The basic color pattern 

includes a dark gray dorsal cape that dips low onto the sides below and forward of the dorsal fin and a lighter 

gray ventral (belly) color that widens along the sides of the peduncle, or tailstock. Adults have a black “mask” 

and a dark jaw-to-flipper stripe. The pattern of spotting and striping on adults can be extremely complex and 

variable; in Hawaii animals have very little dorsal spotting. Calves are born without spots, and juveniles develop them first on their ventral side. The tip of the beak is white and more conspicuous in some populations, 

including those found in the waters surrounding the Hawaiian Archipelago. 

Pantropical spotted dolphins are found in all tropical to warm temperate oceanic waters between 40°N and 

40°S. In the Pacific Ocean, the stocks are separated into the offshore eastern tropical Pacific, the coastal waters between Baja California and the northwestern coast of South America, and the near-shore waters around 

the Hawaiian Islands. 

Pantropical spotted dolphins are found 

throughout the Hawaiian Archipelago 

and are common on the leeward sides 

of the islands as well as at shallow offshore banks (Shallenberger, 1981; Tomich, 1986). A series of 12 aerial surveys (1993-1998) within 46 km of the 

coastline surrounding the MHI resulted 

in observations of 23 groups of spotted 

dolphins, with an average size of 42.8 individuals (Mobley et al., 2000). Baird et 

al. (2003) recorded 25 sightings around 

the MHI in May and June of 2003 with 

a mean group size of 77.1 individuals. 

Baird et al. (2006) determined that the 

peak in sighting rates off the MHI occurred in water depths of 1,000-2,000 

m. Within the Hawaiian EEZ, during the 

2002 (August –November) ship-based 

survey, Barlow et al. (2004) recorded 12 

sightings of spotted dolphins in groups 

as large as 80 individuals (Figure 6.4). One sighting of 74 individuals occurred within the Monument boundaries (Barlow et al., 2004). 

Striped Dolphin (Stenella coeruleoalba) 

The striped dolphin reaches a maximum length of 2.7 m and a maximum weight of 160 kg. It has a small to 

medium-sized robust body; a prominent falcate dorsal fin; and a long, well-defined beak. The color pattern is 

a combination of bluish-gray and white. The cape, beak, fins and tail are dark blue-gray. The ventral side, or 

belly, is white. On each side of the body a narrow black stripe runs from the beak to the eye and then diverges; 

one branch runs from to the pectoral flipper and the other continues along the side to the anal region. A bluish 

Figure 6.4. Pantropical spotted dolphin observations from 2002 survey of

the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

or light gray shoulder blaze is present above the side stripe and below and anterior to the dorsal fi n. The markings and boldness of the stripes vary with individual and geographical location. 

Striped dolphins are primarily found in 

tropical and warm temperate waters 

that are oceanic and deep from 50°N 

to 40°S. They occur in the U.S. off the 

west coast, in the northwestern Atlantic, 

in the Gulf of Mexico and in the waters 

off of the Hawaiian Islands. This species associates with upwelling areas 

and convergence zones. 

Striped dolphins are considered rare in 

Hawaiian waters (Shallenberger ,1981; 

Tomich, 1986). Baird et al. (2005a) suggested that they are likely to “use the 

[Hawaiian] islands seasonally (in warmwater periods).” In June 2003, Baird et al. 

(2003) recorded one sighting of striped 

dolphins off of Niihau, in approximately 

2,800 m depth, with a mean group size 

of 45. Barlow et al. (2004) recorded 12 

sightings of striped dolphins within the 

Hawaiian EEZ, between August and 

November, with a mean group size of 12.8 individuals (Figure 6.5). Three of these sightings occurred within 

the Monument boundaries (Barlow et al., 2004). 

Spinner Dolphin (Stenella longirostris) 

Four subspecies of spinner dolphins are recognized worldwide and include Stenella longirostris longirostris 

(Hawaiian or Gray’s), S.l. orientalis (Eastern), S.l. centroamericana (Central American) and S.l. roseiventris 

(Dwarf). They vary regionally in both form and color pattern. Generally, the spinner dolphin body is slender 

and small, reaching maximum lengths of 2.4 m and 78 kg. The melon is relatively flat and the beak is long and 

slender. The dorsal fin shape varies from moderately falcate to triangular. The color pattern is defined by a dark 

dorsal cape that does not dip low along the sides (like the spotted dolphin, a similar-looking species), lighter 

gray sides, and a light gray or white ventral side. 

Spinner dolphins are found in all tropical and subtropical oceans between 30°N and 30°S. Stenella longirostris 

longirostris is the most widely spread subspecies and is typically found around oceanic islands in the Atlantic, 

Indian, western and central Pacific Oceans. Spinner dolphins associated with the islands in the Hawaiian Archipelago often use shallow inshore waters to rest and socialize during the day and move offshore at night to 

feed (Norris and Dohl, 1980). 

Hawaiian spinner dolphins are resident throughout the Hawaiian Islands, including the NWHI (Norris and Dohl, 

1980; Shallenberger, 1981; Tomich, 1986; Karczmarski, 2005). Historical reports demonstrate the presence 

of spinner dolphins in the NWHI at French Frigate Shoals, Pearl and Hermes Atoll and Kure Atoll (Amerson, 

1971; Woodward, 1972; Amerson et al., 1974). According to Amerson et al. (1974), prior to 1968 there had 

been no reported sightings of spinner dolphin at Pearl and Hermes Atoll. Photo-identification research (2006­

2008) indicates the presence of a resident population at Pearl and Hermes Atoll (NMFS, unpublished data). 

Shallenberger (1981) recorded sightings at Laysan, Lisianski and Maro Reef. However, photo-identification 

and behavioral research at Midway Atoll (1998-2001) demonstrated that a resident population of spinner dolphins was present, but the population size changed from 1998 (n= 260 individuals) to 2001 (n=140 individuals) 

due to the immigration of individuals to Kure Atoll (Rickards et al., 2001; Karczmarski et al., 2005). During the 

Figure 6.5. Striped dolphin observations from 2002 survey of the Hawaiian

Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 

195 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

196 

2002 (August – November) Hawaiian 

EEZ survey, eight sightings of spinner 

dolphins were recorded; three of these 

sightings were within the Monument 

boundaries (Barlow et al., 2004; Figure 6.6). During the 2007 (March-April) 

NWHI survey, two groups of spinner 

dolphins were observed at Gardener 

Pinnacles (NMFS, unpublished data). 

Genetic data from spinner dolphins in 

the MHI suggest that limited genetic exchange is occurring from one island to 

the next (Andrews et al., 2006; Baird et 

al., 2005a; Galver, 2002). Andrews et al. 

(2006) also found that the spinner dolphin populations in the NWHI (Midway, 

Pearl and Hermes and Kure) are genetically homogenous and distinct. 

Rough-toothed Dolphin 

(Steno bredanensis) 

The rough-toothed dolphin has a moderately robust body shape; it reaches a maximum length of 2.7 m and a 

maximum weight of 160 kg. The dorsal fi n is tall, moderately falcate and located at mid-back. The pectoral flippers are relatively large. The head is small and lacks a crease between the melon and the long beak. The color 

pattern is muted but defined by a dark dorsal cape, lighter gray sides and a white belly. Most rough-toothed 

dolphins have a mottled appearance from dark spotting on the sides, throat and belly. White scarring (from 

cookie cutter shark bites or other rough-toothed dolphins) is typical. The upper surface of the beak is dark and 

the lips and ventral surface are white. 

Rough-toothed dolphins occur in deep warm temperate and tropical waters worldwide, between 45°N and 

35°S. 

Rough-toothed dolphins are observed 

in deep water around all of the MHI 

(Shallenberger, 1981; Tomich, 1986; 

Figure 6.7). Research conducted between 2000 and 2006 in the MHI (Baird 

et al., in press b) demonstrated that 

rough-toothed dolphins use the area 

year-round and are most commonly 

found in waters greater than 1,500 m 

deep. Within the waters of the NWHI, 

Shallenberger (1981) noted sightings of 

rough-toothed dolphins as far north as 

Mokumanamana. Nitta and Henderson 

(1993) reported a sighting at French 

Frigate Shoals. During the 2002 (August 

– November) Hawaiian EEZ survey, 19 

groups of rough-toothed dolphins were 

observed ranging in size from two to 

15 individuals; three of these sightings 

were within the Monument boundaries 

(Barlow et al., 2004). During the 2007 

Figure 6.6. Spinner dolphin observations in Hawaiian Island EEZ. Sources:

Barlow et al., 2004; Johnston et al., 2007; NFMS, unpublished; map: K.

Keller. 

Figure 6.7. Rough-toothed dolphin observations in Hawaiian Island EEZ

Sources: Barlow et al., 2004; Johnston et al., 2007; NFMS, unpublished;

map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

(March-April) NWHI survey, one group of rough-toothed dolphins was observed near Lisianski Island (NMFS, 

unpublished data). 

Bottlenose Dolphin (Tursiops truncatus) 

The bottlenose dolphin is characterized by coastal and offshore ecotypes that are morphologically distinct, in 

which the offshore animals tend to be larger in size. In general, the bottlenose dolphin has a wide head and 

robust body that reaches a length of 2.5 m to 3.8 m and a maximum weight of 500 kg. Males are typically larger 

than females. The beak is short, and there is a distinct crease where it meets the melon. The pectoral flippers 

are long, and the dorsal fin is moderately tall and falcate. The color pattern ranges from a dark gray dorsal cape 

to lighter gray sides but lacks a distinct demarcation. The belly tends to be off-white or pinkish. 

The bottlenose dolphin occurs worldwide in tropical and temperate waters within the range of 45°N and 45°S. 

Coastal populations are found along continents and around most oceanic islands, where they move into or 

reside in bays, estuaries and lower bodies of rivers. Pelagic, or offshore populations tend to reside far offshore 

as in the Gulf Stream of the North Atlantic and the eastern tropical Pacific. 

Bottlenose dolphins are distributed 

throughout the Hawaiian Archipelago 

and occur regularly in the waters surrounding the MHI (Shallenberger, 1981; 

Tomich, 1986). Research within the MHI 

suggests that individuals are resident to 

particular islands, not mixing between 

islands (Baird et al., 2003; Baird et al., 

2006; Baird et al., in press a). Sightings 

of dolphins in the MHI occurred in average depths of 222 m (Baird et al., 2003). 

Baird et al. (2006) demonstrated that off 

Kauai and Niihau there are two existing 

populations of bottlenose dolphins that 

are distinguished by depth preference, 

however, they are not reproductively 

isolated as individuals move between 

the two populations. Historical reports 

demonstrate the presence of bottlenose 

dolphins in the NWHI at Laysan Island, 

French Frigate Shoals, Kure Atoll, and 

Pearl and Hermes Atoll (Rice, 1960; 

Amerson, 1971; Woodward, 1972; Amerson et al., 1974). During the 2002 (August – November) Hawaiian EEZ 

survey, 14 groups of bottlenose dolphins were observed and ranged in size from 4 to 28 individuals; one of 

these sightings was within Monument boundaries, southeast of Midway Atoll (Barlow et al., 2004; Figure 6.8). 

During the 2007 (March-April) NWHI survey, three groups of bottlenose dolphins were observed near Nihoa, 

Mokumanamana and Laysan Islands (NMFS, unpublished data). 

Risso’s Dolphin (Grampus griseus) 

The Risso’s dolphin has a bulbous, beakless head with a distinguishable longitudinal crease along the center 

of the melon. It has a robust body that tapers to a narrow tailstock and reaches a length of 2.6 m to 4 m and a 

weight of 300 to 500 kg. The dorsal fin is tall, erect and moderately falcate; and the pectoral fins are long and 

sickle-shaped. The color pattern can be variable from black, dark gray, brown or white and typically lightens as 

an individual ages. Most adults are heavily scarred with teeth rakes of other dolphins, cookie cutter shark bites 

and circular marks from their prey (e.g., squid). 

197 

Figure 6.8. Bottlenose dolphin observations in the Hawaiian Island EEZ

Sources: Barlow et al., 2004; Johnston et al., 2007; NMFS, unpublished;

map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

198 

Risso’s dolphins are extensively distributed throughout tropical and warm temperate waters. They are generally found 

in offshore waters deeper than 1,000 m 

and with surface temperatures of 10 to 

28°C. Although migration patterns are 

unknown, seasonal shifts in population 

density are recognized and presumed to 

be related to changes in water temperature and prey (e.g., squid) abundance. 

Sightings of Risso’s dolphins are rare in 

Hawaiian waters (Shallenberger, 1981; 

Tomich, 1986). During a series of aerial 

surveys (in 1993, 1995 and 1998) in 

the MHI only two individuals were seen 

(Mobley et al., 2000), however, these 

surveys only covered waters within 46 

km (25 nm) of the coast. Stranding records from five events also demonstrate 

the presence of Risso’s dolphins within 

the MHI (Nitta, 1991; Maldini, 2005). During the 2002 (August-November) Hawaiian EEZ survey, seven groups 

of Risso’s dolphins were observed (Figure 6.9). In five of these sightings, other cetacean species were present and included short-finned pilot whales, bottlenose dolphins, sei or Bryde’s whales, and unidentifi ed small 

dolphins (Barlow et al., 2004). In October 2002, a group of eight individuals was seen south of Lisianski Island 

(Barlow et al., 2004). 

Fraser’s Dolphin (Lagenodelphis hosei) 

The Fraser’s dolphin has a stocky body and grows to a maximum length of 2.7 m and a maximum weight of 

210 kg. It has small appendages and a small, well-defined beak. The dorsal fin is triangular to slightly falcate 

and is more erect in males than females. The color pattern is characterized by a dark, grayish-blue dorsal cape; 

lighter gray sides; a whitish belly; a distinctive dark stripe on each side that runs from the eye to the anus; and 

a dark flipper stripe that merges with the 

side stripe along the lower jaw. 

The Fraser’s dolphin is a pantropical 

species that is generally found between 

30°N and 30°S. It is primarily an oceanic species and found in waters deeper 

than 1,000 m, however, it has also been 

found in areas where deep water approaches the coast. 

The first documentation of Fraser’s 

dolphins in Hawaiian waters occurred 

during the 2002 Hawaiian EEZ survey 

(Barlow et al., 2004; Figure 6.10). Two 

groups, comprised of 47 and 171 individuals, were observed within the Hawaiian EEZ (outside of Monument waters) in November (Barlow et al., 2004). 

Figure 6.9. Risso’s dolphin observations from 2002 survey of the Hawaiian 

Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 

Figure 6.10. Fraser’s dolphin observations from 2002 survey of the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Melon-headed Whale (Peponocephala electra) 

The melon-headed whale has a moderately robust body that tapers at both ends. This whale can reach a 

length of 2.7 m and a weight of 275 kg. The head is narrow, triangular shaped, and has no beak. The dorsal fin 

is tall (as much as 30 cm), falcate and positioned at mid back. The general color pattern has an overall gray or 

black appearance with variable lighter gray ventral markings and white lips. The face has a dark mask over the 

eyes, which helps to distinguish this species from others that are similar looking (e.g., pygmy killer and false 

killer whales). 

The melon-headed whale is a pantropical species that is found in deep waters between 40°N and 35°S. 

Melon-headed whales have been observed somewhat regularly in the waters surrounding the MHI (Shallenberger, 1981; Mobley et al., 2000; Baird et 

al., 2003; Baird et al., 2005a). The first 

record is from Hilo Bay in 1841 when a 

group of 60 animals were driven ashore 

by natives (Tomich, 1986). Shallenberger (1981) noted that a group of 75-150 

melon-headed whales was seen regularly off the Kohala coast of Hawaii. During 12 aerial surveys (within 46 km from 

the coast of the MHI) in 1993-1998, 

Mobley et al. (2000) observed three 

groups with an average of 13.5 individuals per group. Between 2000 and 2005, 

Baird et al. (2005a) observed 18 groups 

with an average of 305 individuals per 

group (in the MHI). Three sightings within 2003 were in an average water depth 

of 1,100 m (Baird et al., 2003). During 

the 2002 (August-November) Hawaiian EEZ survey, Barlow et al. (2004) observed one group of 171 melonheaded whales within the northwestern portion of the EEZ (outside of Monument waters; Figure 6.11). 

Pygmy Killer Whale 

(Feresa attenuata) 

The pygmy killer whale has a moderately robust body that tapers more toward 

the back half. It grows to a length of 2.6 

m and a weight of 170 kg. The head is 

rounded with no beak. The dorsal fi n is 

tall, falcate and positioned slightly behind the mid back. The color pattern 

is mostly dark gray to black with white 

markings on the lips and belly. Areas of 

lighter gray extend along the sides from 

the eye to the anus. 

The pygmy killer whale is a pantropical 

species that is found between 40°N and 

35°S. It is one of the most poorly known 

species of odontocetes. 

Figure 6.11. Melon-headed whale observations from 2002 survey of the 

Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 

199 

Figure 6.12. Pygmy killer whale observations from 2002 survey of the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

200 

Pygmy killer whales have been observed off the leeward coasts of Oahu and Hawaii on numerous occasions 

in groups as large as 100 individuals, but typically in groups smaller than 50 individuals (Shallenberger, 1981; 

Tomich, 1986). Between 2000 and 2005, six groups of pygmy killer whales with an average group size of 11.5 

individuals were observed in the MHI (Baird et al., 2005a). Baird et al. (2003) observed one group of 13 individuals off of Kauai/Niihau in 613 m depth. A long-term study of opportunistic sightings of pygmy killer whales 

suggests that a small population of year-round residents is located off the island of Hawaii (McSweeney et al., 

in press) Barlow et al. (2004) observed three groups of pygmy killer whales within the Hawaiian EEZ (Figure 

6.12). One group of five individuals was seen within the Monument boundaries near Midway Atoll (Barlow et 

al., 2004). 

False Killer Whale (Pseudorca crassidens)
 

The false killer whale has a relatively slender body that grows to a length 6 m and a weight of 2,000 kg. The 

head is small and conical with the melon overhanging the tip of the lower jaw. The dorsal fin is moderately tall, 

falcate and positioned at mid back. The flippers are broad at the base, narrow at the tip and have a bulge in the 

middle of the leading edge that is a distinguishing feature. The color pattern appears dark gray to black over 

the entire body with lighter gray patches on the throat and chest. 

False killer whales are distributed throughout all tropical and warm-temperate waters, generally occurring between 50°N and 50°S. They are typically found in waters deeper than 1,000 m.
 

Two populations of false killer whales 

are recognized within the Hawaiian 

EEZ (Chivers et al., 2007). Genetic and 

photographic evidence demonstrate 

the presence of an offshore population closely related to animals found in 

the eastern North Pacific (and Palmyra 

Atoll), and an inshore population that is 

demographically distinct (Chivers et al., 

2007; Baird et al., 2008). Both populations are listed as one strategic stock 

under the amendments to the MMPA
 

as a result of interactions with Hawaii 

longline fisheries (http://www.nmfs.
 

noaa.gov/pr/species/esa/mammals.
 

htm). According to Baird et al. (2008), 

false killer whales are observed infrequently in the nearshore waters of the 

MHI. Between 1986 and 2006, only 50 

groups of false killer whales were encountered (Baird et al., 2008). During 

aerial surveys within 46 km of the coastline (1993-1998) Mobley et al. (2000) observed 21 groups. Baird et al. (2008) encountered false killer whales 

in depths between 48 m and 4,331 m depth. During the 2002 survey, Barlow et al. (2004) observed two groups 

of two and 19 individuals within the northwestern portion of the Hawaiian EEZ in August and September 2002, 

respectively (Figure 6.13). During the 2007 NWHI survey, one group of false killer whales was observed near 

Lisianski Island (NMFS, unpublished data).
 

Figure 6.13. False killer whale observations from 2002 survey of the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Short-finned Pilot Whale (Globicephala macrorhynchus) 

The short-finned pilot whale has a large, bulbous head in which the melon protrudes beyond the mouthline. 

The beak is very short and the mouthline is noticeably upturned toward the eye. The dorsal fin is falcate, set 

forward of the midbody, broad at the base and long relative to its height. Males have distinctly broader dorsal 

fins than females. The species is relatively large with females reaching lengths of 5.5 m and weights of 1,000 

kg and males reaching lengths of 6.1 m and weights of 3,000 kg. The color pattern is generally black or dark 

brown with a light gray throat patch, saddle behind the dorsal fin and streak behind the eye. 

The short-fi nned pilot whale is a tropical to warm-temperate species found between 50°N and 40°S. They typically occur in deep water. 

Short-finned pilot whales are seen 

throughout the year in the MHI (Shallenberger ,1981; Mobley et al., 2000; Baird 

et al., 2003). Shallenberger (1981) noted that group sizes were often greater 

than 100 individuals and rarely smaller 

than 30 individuals. Aerial surveys conducted within 46 km of the coastline 

within the MHI (1993-1998) resulted in 

73 observed groups of pilot whales with 

an average group size of 8.4 individuals (Mobley et al., 2000). A summary of 

sighting data from 2000 to 2005 resulted 

in 80 observed groups of pilot whales 

with an average of 20 individuals per 

group (Baird et al., 2005a). Data from 

May and June of 2003 demonstrated 

that the average depth of sighting locations for 17 groups of pilot whales within 

the MHI was 1,142 m (Baird et al., 2003). 

During the 2002 survey of the Hawaiian 

EEZ, Barlow et al. (2004) observed 25 

groups of pilot whales, ranging in size from 2 to 28 individuals (Figure 6.14). Four sightings were within the 

Monument boundaries (Barlow et al., 2004). During the 2007 (March-April) NWHI survey, four groups of pilot 

whales were observed within the Monument between Pearl and Hermes Atoll and Midway Atoll, near French 

Frigate Shoals and at Gardener Pinnacles (NMFS, unpublished data). 

Killer Whale (Orcinus orca) 

The killer whale has a stocky body with a conical shaped head that lacks a prominent beak. This is the largest 

of the delphinid species with females growing to a maximum length of 8.0 m and an average weight of 3,000 

kg and males growing to a maximum length of 9.0 m and an average weight of 6,000 kg. The dorsal fin is large, 

ranging in size from 0.9 m for females to 1.8 m for males. The shape of the dorsal fin is variable, from falcate in 

females and juveniles to tall and erect in males. The color pattern of the killer whale is its most distinctive feature. The dorsal side of the body is black, as are the pectoral fl ippers. The ventral side of the body is white and 

lobes extend from the belly along each side behind the dorsal fin. Distinct white patches are located slightly 

above and behind the eyes. A gray to white shaded saddle is located on the back behind the dorsal fin. 

Killer whales are considered the most widespread cetacean. They can be found in any marine region but 

are more abundant in cool temperate regions. In the Pacific Northwest, two different groups of killer whales 

have been identified. Both the “transients” and “residents” are present year-round, however the “transients” 

have larger home ranges and prey on marine mammals, while resident pods target fish as their primary prey. 

Whether this pattern is universal is unknown. Movements of killer whales appear to be driven by food availability (American Cetacean Society, 1995 -2007). 

Figure 6.14. Short-finned pilot whale observations in the Hawaiian Island

EEZ. Sources: Barlow et al., 2004; Johnston et al., 2007; NFMS unpublished; map: K. Keller. 

201 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

202 

Although infrequent, sightings of killer 

whales have been documented in the 

Hawaiian EEZ (Shallenberger, 1981; 

Tomich, 1986; Baird et al., 2005b). Baird 

et al. (2005b) reported 21 records of 

killer whale sightings within the Hawaiian EEZ between 1994 and 2004. During an aerial survey in March of 2000, 

Mobley et al. (2001) observed a group 

of killer whales west of Niihau. In May 

of 2003, Baird et al. (2003) observed 

one group of four individuals off the 

west side of the island of Hawaii in 773 

m depth. Barlow et al. (2004) observed 

two groups of killer whales, each consisting of two individuals, in September 

and November of 2002 (Figure 6.15). 

The November sighting occurred just 

north of French Frigate Shoals (Barlow 

et al., 2004). 

Sperm Whale (Physeter macrocephalus) 

The sperm whale is large and distinctive, with a huge square head comprising approximately one-third of its 

total length. Adult females can reach 12 m in length and 24,000 kg in weight. Adult males are larger, reaching 

18 m and weighing up to 57,000 kg. The blowhole is set at the front of the head and skewed to the left. The 

dorsal fin is small and rounded. The skin behind the head is wrinkled. The color pattern is black to brownishgray with white around the mouth and belly. 

Sperm whales are cosmopolitan in their distribution and inhabit waters from the equator to the edge of the polar 

ice packs. Only adult male sperm whales will move between higher and lower latitudes, while females, calves 

and juveniles are generally found in more topical and subtropical waters year around. The breeding grounds 

are located in the tropical and subtropical waters of the lower latitudes. Sperm whales are primarily found in 

waters greater than 600 m deep. 

Data from the Townsend (1935) charts 

indicate that occurrences of sperm 

whales around the Hawaiian archipelago were common (Figure 6.16). 

The whaling industry decimated their 

numbers, and currently the species is 

listed as Endangered under the ESA 

(http://www.nmfs.noaa.gov/pr/species/ 

esa/mammals.htm). Shallenberger 

(1981) reported occasional sightings 

and stranding events within the MHI. 

Sperm whales were the most frequently 

observed species within the Hawaiian 

EEZ between August and December 

2002 (Barlow et al., 2004). Barlow et al. 

(2004) observed 46 groups ranging in 

size from one to six individuals. Twelve 

of these sightings were within the Monument boundaries (Barlow et al., 2004). 

Figure 6.15. Killer whale observations from 2002 survey of the Hawaiian

Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 

Figure 6.16. Sperm whale observations around the Hawaiian archipelago

Sources: Barlow et al., 2004; Johnston et al., 2007; NFMS, unpublished;

Townsend, 1935; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

During the 2007 (March-April) NWHI survey, seven groups of sperm whales were observed within the Monument (NMFS, unpublished data). 

Pygmy Sperm Whale (Kogia breviceps)
 

The pygmy sperm whale has a small, robust body with a bulbous, square-shaped head with a pointed snout, 

a narrow mouth and undershot lower jaw. It ranges from 2.8 m to 3.5 m in length and reaches a maximum 

weight of 450 kg. The blowhole is set far back on the head and offset to the left. The dorsal fin is small, falcate 

and located behind the midpoint of the body. The pectoral flippers are small and located unusually close to the 

head. Coloration ranges from a dark gray on the back to pinkish-white on the belly, and there are half-moon 

shaped markings between the eye and the flipper, sometimes referred to as “false-gills”. The pygmy sperm 

whale closely resembles the dwarf sperm whale. 

The pygmy sperm whale occurs in tropical to temperate regions worldwide and is generally found in deep waters seaward of the continental shelf. Pygmy sperm whales are thought to be non-migratory and are generally 

found singly or in small groups up to fi ve individuals. 

Pygmy sperm whales are observed 

occasionally within Hawaiian waters. 

Shallenberger (1981) combines the two 

Kogia species into one section because 

of the possible misidentification of each 

species. Most data come from strandings in the MHI, which have occurred on 

Kauai, Oahu, Molokai and Maui (Shallenberger, 1981). In June 2003, Baird 

et al. (2003) observed one group of two 

individuals between Kauai and Niihau 

in 700 m depth. Two lone individuals 

were observed within the northwestern 

portion of the Hawaiian EEZ by Barlow 

et al. (2004; Figure 6.17) in November 

2002. Within the Monument there is a 

single record, from 1923, of a beach 

cast skeleton that was identified as a 

pygmy sperm whale (Amerson, 1971). It 

was this event that led to the naming of 

Whale Island at French Frigate Shoals 

(Amerson, 1971).
 

Dwarf Sperm Whale (Kogia sima)
 

The dwarf sperm whale is nearly identical in appearance to the pygmy sperm whale; however, the dwarf sperm 

whale has a dorsal fi n that is more prominent and positioned further forward on its back. Additionally, the dwarf 

sperm whale is a smaller whale, reaching a length of 2.7 m and weighing approximately 275 kg.
 

The dwarf sperm whale is a tropical and temperate species, generally found in offshore waters, but somewhat 

more coastal than the pygmy sperm whale. There is no evidence to suggest that the dwarf sperm whale migrates. 

Shallenberger (1981) combines the two Kogia species into one section because of the possible misidentification of each species. Stranding events have been recorded on Oahu and Hawaii (Tomich, 1986). In May and 

June of 2003, Baird et al. (2003) encountered eight groups of dwarf sperm whales near Lanai, Kauai and Niihau. The average group size was two individuals, and they were observed in waters with an average depth of 

203 

Figure 6.17. Pygmy sperm whale observations from 2002 survey of the

Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

204 

2,004 m (Baird et al., 2003). Barlow et al. 

(2004) observed dwarf sperm whales on 

five occasions within the Hawaiian EEZ 

in October and November 2002 (Figure 

6.18). The species was observed singly 

or in groups of up to three individuals 

(Barlow et al., 2004). 

Blainville’s Beaked Whale 

(Mesoplodon densirostris) 

The Blainville’s beaked whale, sometimes called the dense-beaked whale, 

has a robust body that is compressed 

laterally. It is a medium-sized whale that 

reaches 5.8 m in length and 3,500 kg in 

weight. The dorsal fin is small, falcate 

and positioned approximately two-thirds 

down the length of the body. The color 

pattern is silver-gray to brown on the 

dorsal surface with lighter gray to white 

on the belly. Blainville’s beaked whales are typically covered with white or pale-gray circular marks or scars 

that are likely caused by cookie cutter sharks. They have a distinct mouthline that sweeps up at the middle of 

the lower jaw. Males have a tooth protruding from each side of the lower jaw at this site. 

Blainville’s beaked whales are a tropical and temperate species and are considered the most widely distributed 

mesoplodont. They are found primarily in deep waters, 500-1,000 m. There is no evidence of seasonal movements or migrations. 

Blainville’s beaked whales have been 

observed in the MHI off of Oahu, Hawaii, Kauai and Molokai (Shallenberger, 1981; Tomich, 1986; Mobley et al., 

2000, Baird et al., 2003). Group sizes 

range from two to seven individuals 

(Shallenberger, 1981; Tomich, 1986; 

Mobley et al., 2000; Baird et al., 2003). 

Five groups observed by Baird et al. 

(2003) were in average water depths of 

1,304 m. Recent satellite tagging studies off the west coast of the island of 

Hawaii suggest that this population of 

Blainville’s beaked whales is island-associated and exhibits strong site fidelity 

(Schorr et al., In press). Within the Monument boundaries, the earliest record 

of Blainville’s beaked whales is from 

a stranding event of two individuals at 

Midway Atoll in April 1961 (Galbreath, 

1963; Shallenberger, 1981). Barlow et 

al. (2004) observed Blainville’s beaked whales (one to two individuals per sighting) within Monument waters in 

September and October 2002 (Figure 6.19). 

Figure 6.18. Dwarf sperm whale observations from 2002 survey of the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 

Figure 6.19. Blainville’s beaked whale observations from 2002 survey of 

the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Cuvier’s Beaked Whale (Ziphius cavirostris) 

Cuvier’s beaked whale has a long, stocky body. Adults range in length from 5 m to 7.5 m and weigh from 2,000 

kg to 3,000 kg. The head is small, the melon is steeply tapered and the beak is short and poorly-defi ned. Mature males have two teeth protruding from the front of the lower jaw. The dorsal fin is small, falcate and located 

approximately two-thirds back along the length of the body. The color pattern varies from dark gray to light 

brown, with the head and neck, and eventually the body, becoming lighter in color as the whale ages. This is 

particularly pronounced in males. Scars from cookie cutter sharks can give a mottled appearance to the sides 

and belly. 

Cuvier’s beaked whales occur in all offshore waters except those in the polar regions. They are primarily found 

in waters greater than 1,000 m deep. 

Cuvier’s beaked whales are observed 

infrequently within the Hawaiian EEZ. 

Shallenberger (1981) noted two sightings off of Lanai and Maui. Aerial surveys 

of the MHI conducted during 1993, 1995 

and 1998 resulted in seven observed 

groups of Cuvier’s beaked whales with 

an average group size of three individuals (Mobley et al., 2000). During a 10 

year period (1990-2006), McSweeney 

et al. (2007) encountered Cuvier’s 

beaked whales on 35 occasions off the 

west coast of the island of Hawaii. Resightings of individuals during this time 

suggest some degree of site fidelity and 

the presence of a resident population. 

Stranding events at Midway Atoll and 

Pearl and Hermes Atoll demonstrate 

the presence of Cuvier’s beaked whales 

within the Monument (Shallengberger, 

1981). In addition, Barlow et al. (2004) 

observed groups within the Monument, 

at Gardener Pinnacles and north of Mokumanamana in August of 2002 (Figure 

6.20). 

Longman’s Beaked Whale 

(Indopacetus pacificus) 

The Longman’s beaked whale, sometimes referred to as the tropical bottlenose whale, can reach 9 m in length. 

It has a bulbous head and moderately 

long beak, from which two teeth erupt 

in males. The dorsal fin is pointed, falcate, and located behind the midpoint of 

the body. The color varies from brown to 

bluish gray, and the head and sides can 

be a lighter color in younger animals. 

This species has been misidentifi ed as 

the southern bottlenose whale. 

205 

Figure 6.20. Cuvier’s beaked whale observations from 2002 survey of the 

Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 

Figure 6.21. Longman’s beaked whale observations from 2002 survey of 

the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

206 

Little is known about the range of Longman’s beaked whale, but it is thought to occur primarily in pelagic waters 

within the Indo-Pacifi c region. 

Longman’s beaked whale is rare in Hawaiian waters. There are only two confirmed sightings within the Hawaiian EEZ. The first was made in November 2002 when Barlow et al. (2004) observed one group of four individuals within the northwestern portion of the EEZ (Figure 6.21). The second confirmed sighting was a group of 

30-35 individuals off of the west coast of the island of Hawaii in 2007 (http://www.cascadiaresearch.org/robin/ 

August2007.htm). 

Minke Whale (Balaenoptera acutorostrata) 

Minke whales are the smallest of the baleen whales. At least two subspecies of the common minke whale are 

recognized and include the North Pacifi c (B.a.scammoni) and North Atlantic (B.a. acutorostrata). The dwarf 

minke whale is considered a potential third subspecies but has not been given an offi cial scientifi c name. The 

common minke whale has a small, slender body and a pointed triangular head with a well-defi ned longitudinal 

ridge along the rostrum. Adults range in length from 7 m to 10.7 m and weigh as much as 9,200 kg. Females 

are slightly longer than males. The falcate dorsal fin is set approximately two-thirds back along the length of 

the body. The color pattern is black or dark gray on the dorsal side with a lighter gray chevron across the back 

and white on the belly. A white band across the middle of the pectoral flippers is a distinctive characteristic of 

this species. 

Common minke whales occur in the 

North Atlantic and North Pacific and migrate from the polar and temperate waters in the summer to the tropical waters 

in the winter. They are frequently observed in coastal or shelf waters, rather than deep offshore habitats. In the 

eastern Pacific, minke whales are found 

from the Bering Sea south to the coast 

of Baja California, and in the western 

Pacific they are found from the Sea of 

Okhotsk to the Sea of Japan. The winter distribution of North Pacifi c minke 

whales can be inferred from the distribution of their distinctive calls (termed 

“boings”). Boings are heard primarily between 15°N and 30°N in the months of 

November through March (Rankin and 

Barlow 2005). Shallenberger (1981) lists 

the minke whale under “animals sighted 

in Hawaiian waters but not considered 

part of the normal cetacean fauna.” One 

minke whale was observed within the Hawaiian EEZ by Barlow et al. (2004) in November 2002 (Figure 6.22). 

Bryde’s Whale (Balaenoptera edeni) 

The Bryde’s whale has a long, slender body with a pointed rostrum. Females are larger than males and can 

reach a length of 15.5 m and a weight of 40,000 kg. Three ridges extend from the blowhole to the tip of the 

rostrum, which is a diagnostic feature of this species. The dorsal fin is extremely falcate, tall (up to 45 cm), and 

positioned two-thirds of the way along the length of the body. The color pattern is gray on the dorsal side and 

white on the belly, sometimes with banding or chevrons. 

Figure 6.22. Minke whale observations from 2002 survey of the Hawaiian

Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Bryde’s whales are found in tropical and subtropical waters of the Pacific, Atlantic and Indian Oceans. They are 

rarely seen north or south of 40°. The whales are often seen at nearshore upwellings but are also occasionally found offshore. Some evidence suggests that there are two forms of the Bryde’s whale, an inshore and an 

offshore that may differ in reproductive cycles and diet. The Bryde’s whale is not as migratory as the sei whale, 

but limited migration does take place in some populations (offshore form), while other populations are resident 

year-around (inshore form). 

Shallenberger (1981) listed the Bryde’s 

whale as a rare species in Hawaiian 

waters. He noted one confi rmed sighting 87 km southeast of Nihoa in April 

of 1977 (Shallenberger, 1981). Tomich 

(1986) cites Leatherwood et al. (1982) 

as noting that Bryde’s whales are “relatively abundant over shallows northwest 

of Hawaii and near Midway Islands.” 

During the 2007 NWHI survey, a single 

Bryde’s whale was observed off the east 

coast of Niihau (NMFS, unpublished 

data). During August through October 

of the 2002 Hawaiian EEZ survey, Barlow et al. (2004) observed 14 groups of 

Bryde’s whales (Figure 6.23). With the 

exception of two sightings, in which 

there were two whales present, all were 

of single whales. Six of the sightings 

were within the Monument boundaries 

(Barlow et al., 2004). 

Sei Whale (Balaenoptera borealis) 

Sei whales are similar in appearance to Bryde’s whales, with a gray dorsal and white ventral surface, and with 

the dorsal fin rising at a steep angle from 

the back. Adults reach a maximum of 

20 m in length, and may weigh as much 

as 45,000 kg. Sei whales have only a 

single rostral ridge and lack the two additional parallel longitudinal ridges that 

are evident in the Bryde’s whales. 

Sei whales are found from the tropics to 

polar regions in the northern and southern hemispheres, but most often occur 

in the mid-latitude temperate zones. 

They are migratory open-ocean whales, 

not often observed near the coasts. The 

species is listed as Endangered under 

the ESA (http://www.nmfs.noaa.gov/pr/ 

species/esa/mammals.htm). 

Neither Shallenberger (1981) nor Tomich (1986) mention sei whales. Individual sei whales were observed on 

several occasions within the Hawaiian 

Figure 6.23. Byrde’s whale observations in the Hawaiian Island EEZ. 

Sources: Barlow et al., 2004; Johnston et al., 2007; NMFS, unpublished;

map: K. Keller. 

207 

Figure 6.24. Sei whale observations in the Hawaiian Island EEZ. Sources:

Barlow et al., 2004; Johnston et al., 2007; NMFS, unpublished; map: K.

Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

208 

EEZ (but outside of Monument waters) by Barlow et al. (2004) in November 2002 (Figure 6.24). In April 2007, 

during the NWHI survey a single sei whale was observed between Laysan and Lisianski Islands (NMFS, unpublished data). 

Fin Whale (Balaenoptera physalus) 

Similar to the Bryde’s and sei whales, fin whales are dark brown or gray dorsally and white ventrally. Fin whales 

are significantly larger reaching a length of 24 m and a weight of 120,000 kg. The dorsal fin is variable and either pointed or falcate. Fin whales have a distinctive asymmetrical color pattern on the lower jaw; the right side 

(including baleen) is white and the left side is dark gray or black. In addition, most individuals have a v-shaped 

chevron across the back of the head and a swirled blaze on the right side of the head. 

Fin whales are found in all oceans of the world, but primarily occur in cooler temperate regions and concentrate 

on shelf and in coastal waters. They can be found over a broad latitudinal range throughout the year, however, 

some appear to migrate, spending the summer in the northern polar region and the winter in warmer waters of 

lower latitudes. Like the sei whale, fin whales are listed as Endangered under the ESA (http://www.nmfs.noaa. 

gov/pr/species/esa/mammals.htm). 

Shallenberger (1981) listed fi n whales 

as rare in Hawaiian waters. He reported on two sightings off of Oahu and 

one stranding on Maui (Shallenberger, 

1981). In February 1994, a single fin 

whale was observed near Kauai (Mobley et al. 1996). Acoustic recordings 

have also detected the presence of fin 

whales off Oahu and Midway (Thompson and Friedl, 1982; McDonald and 

Fox, 1999). During the period of September through November 2002, Barlow et al. (2004) observed fi ve groups 

of fin whales within the Hawaiian EEZ 

(Figure 6.25). A single individual was 

observed within the Monument between 

Maro Reef and Laysan Island (Barlow 

et al., 2004). 

Humpback Whale (Megaptera novaeangliae) 

The humpback whale has a large, robust body that reaches a maximum length of 17 m and a maximum weight 

of 40,000 kg. Females are slightly larger than males. Humbacks have very long flippers (up to one-third the 

length of the body). The head and lower jaw are covered in tubercles. The dorsal fin is variable from tall and 

falcate to a small hump. The large flukes are concave with a serrated trailing edge. The color pattern is variable. It can be black on the dorsal side and black, white, or mottled black and white on the ventral side. 

Humpback whales are found in all of the major oceans and occur primarily in coastal waters (Figure 6.26). 

They are a migratory species and spend the summer in the polar regions and the winter in tropical waters. 

Four stocks are believed to occur in the North Pacific, including one that winters in the central North Pacific 

and Hawaii. Multiple stocks also occur in the North Atlantic, Northern Indian Ocean and in the southern hemisphere. Humpback whales are listed as Endangered under the ESA (http://www.nmfs.noaa.gov/pr/species/ 

esa/mammals.htm). 

Humpback whales within the MHI have been extensively studied for nearly four decades (Herman and Antinoja, 

1977; Shallenberger, 1977; Herman et al., 1980; Shallenberger, 1981; Calalmonkidis et al., 2008) and individFigure 6.25. Fin whale observations from 2002 survey of the Hawaiian Island EEZ. Source: Barlow et al., 2004; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 6.26. Humpback whale modeled habitat. A = Nihoa; B = Mokumanamana; C = Gardner Pinnacles; D = Maro Reef; 

E = Laysan Island; F = Lisianski Island; G = Pearl and Hermes Atoll; H = Midway Atoll; and I = Ladd Seamount. Map: 

Johnston et al., 2007. 

209 

ual whales photographed in Hawaii are 

also known from records in the northern 

feeding grounds in Alaska and British 

Columbia (Calambokidis et al., 2008). 

The whales migrate to the waters surrounding the Hawaiian Islands beginning in November and remain there until late May (Shallenberger, 1981). While 

in Hawaiian waters, they are found exclusively in shallow waters less than 

183 m (Shallengberger, 1981; Johnston 

et al., 2007). Humpback whales may 

use the waters of the NWHI throughout 

the winter months, and were observed 

within the Monument boundaries near 

Nihoa, Mokumanamana, Gardner Pinnacles, Maro Reef and Lisianski Island 

(Johnston et al., 2007). Nine groups 

were observed, two of which contained 

calves (Johnston et al., 2007; Figure 

6.27). Johnston et al. (2007) modeled 

the availability of humpback whale wintering habitat within the Monument based on bathymetric and sea surface temperature data. This modeling indicates potential available humpback whale habitat at all islands and atolls in the NWHI (and at Maro Reef and 

Ladd Seamount) south of the 21.1°C sea surface temperature cline. These areas in 2007 totaled 14,700 km2

, 

compared to 7,200 km2

 of humpback wintering habitat available in the MHI (Johnston et al., 2007). Surveys 

(aerial and ship-based) of the NWHI conducted in 1976-1977 (November-April) returned no sightings of humpFigure 6.27. Humpback whale observations in the Hawaiian Island EEZ.

Sources: Barlow et al., 2004; Johnston et al., 2007; NMFS, unpublished;

map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

210 

back whales (Herman et al., 1980). However, since the mid-1990s, regular sightings of humpback whales each 

year from January through March have been made by U.S. Fish and Wildlife Service staff stationed at French 

Frigate Shoals (A. Anders, pers. comm.). One reported opportunistic sighting of a mother and calf at French 

Frigate Shoals in February 1977 was dismissed as a “straggler” (Herman et al., 1980). This may suggest that 

the NWHI provide winter habitat for an expanding humpback whale population (Johnston et al., 2007). 

Additional Cetacean Species 

In addition to the 23 species described above, two other cetacean species have been detected within the Hawaiian Islands EEZ, including the North Pacific right whale (Eubalaena japonica) and blue whale (Balaenoptera 

musculus; Barlow, 2006). North Pacific Right whales have been observed in the waters surrounding the MHI 

on two confirmed occasions (Rountree et al.,1980; Tomich, 1986). The first record comes from a whaling ship’s 

logbook from 1851 in which a single “straggler” was observed 250 nm west of Maui (Rountree et al., 1980). 

Tomich (1986) noted a sighting of an individual right whale swimming among a group of humpback whales 

between Maui and Lanai in March 1979. Blue whales have been detected, based on vocalizations, off of the 

coast of Oahu and it was suggested that they migrate past the Hawaiian Islands twice a year (Thompson and 

Friedl, 1982). Twenty hertz signals, similar to those recorded by Thompson and Friedl (1982), have also been 

reported near Midway Atoll (Tomich, 1986). 

Cetacean Abundance Estimates 

The 2002 cetacean survey conducted by Barlow et al. (2004) in the Hawaiian Islands EEZ allowed for the calculation of abundance and density estimates for 19 of the 23 species observed (see Barlow 2006 for description of analytical methods). 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

PINNIPEDS 

The Hawaiian monk seal (Monachus 

schauinslandi; Figure 6.28) was listed 

as Depleted under the MMPA and Endangered under the ESA in 1976. The 

current population estimates are around 

1,100-1,200 individual seals, the majority of which live in the NWHI. 

The genus Monachus is a wide ranging 

species and is found in several different geographic areas around the world 

(Figure 6.29). The genus includes the 

Mediterranean monk seal (Monachus 

monachus), the Caribbean monk seal 

(Monachus tropicalis) and the Hawaiian 

monk seal. The Mediterranean monk 

seal is critically endangered and the 

Caribbean monk seal is assumed to 

have gone extinct in the last 50 years 

(Kenyan, 1977; see Boyd and Stanfield). The Hawaiian monk seal populations are estimated to have declined by 

60% since the 1950s (Antonelis et al., 

2006). 

Range 

Based on anatomical features and DNA 

analysis researchers estimate that Hawaiian monk seals arrived in Hawaii 

14-15 million years ago (Repenning et 

al., 1979) and split from the Monachus 

ancestors around 11.8 to 13.8 million 

years ago (Flyer et al., 2005). Hawaiian 

monk seals occur within the Hawaiian 

EEZ and the main subpopulations occur in the NWHI. A smaller but potentially increasing population of seals 

inhabit the MHI and there have been 

occurrences including a documented 

pupping and relocations of aggressive 

males to Johnston Atoll. The monk seal 

metapopulation can be divided into six 

major and two smaller subpopulations 

in the NWHI and one in the MHI (Figure 

6.30). These subpopulations are further 

grouped into management units. 

Figure 6.28. There are an estimated 1,200 Hawaiian monk seals, the majority of which live in the NWHI. In 1976 the species was listed as Endangered under the ESA. Photo: J. Watt. 

Figure 6.29. Worldwide distribution of monk seals. Source: ESRI; map: K.

Keller. 

211 

Figure 6.30. Hawaiian monk seal subpopulations. Source: NMFS, unpub

data; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

212 

Available Data 

The U.S. Fish and Wildlife Service conducted periodic monitoring of Hawaiian monk seals from the late 1950s 

until the late 1970s when the National Marine Fisheries Service (NMFS) assumed responsibility for recovery of 

the species and commenced monitoring activities. NMFS began an annual monitoring of Hawaiian monk seals 

at most major sites in the early 1980s. There is no historic data for estimating population size prior to the surveys of the 1950s or to estimate carrying capacity. It is likely that upon arriving in the MHI, Polynesian settlers 

extirpated the local population of seals. The surveys of the NWHI in the 1950s were too soon after World War 

II for the population to have plausibly recovered from the impact of the military disturbance, and some military 

presence was still having a negative effect on the monk seals at that time. 

The first range-wide surveys of Hawaiian monk seals were conducted in the 

late 1950s (Kenyon and Rice, 1959; 

Rice, 1960). Additional counts were 

conducted at Midway Atoll in 1956­

1958 (Rice, 1960) and at Kure Atoll in 

1963-1965 (Wirtz, 1968). Surveys were 

repeated throughout the 1960s and 

1970s, and while the methods were not 

standardized, complete beach counts 

are roughly comparable between the 

two survey periods. 

Since the early 1980s NMFS has been 

conducting annual surveys using standardized methods to estimate the population of Hawaiian monk seals. The work 

is conducted at field camps that are active from approximately April through 

August (Figure 6.31). All of the field 

camps collect information on the numbers of seals in the subpopulations based on counts of uniquely-identified seals. In addition any births, deaths, 

serious injuries and entanglements are documented. Necropsies are conducted on dead seals and seal feces 

are collected to evaluate dietary information. 

Habitat Use and Foraging Behavior 

Between 1996 and 2002, the movements and diving patterns of 147 Hawaiian monk seals have been monitored with satellite-linked radio transmitters at the six breeding colonies in the NWHI (42 adult males, 35 adult 

females, 29 juvenile males, 14 juvenile females, 12 weaned male pups, 15 weaned female pups; Abernathy 

and Siniff,1998; Stewart, 2004a, b; Stewart and Yochem, 2004a, b, c). 

Parrish et al. (2000) attached animal borne imaging systems (Crittercams) to 24 adult and subadult male monk 

seals at French Frigate Shoals. The Crittercams recorded the habitat depth and bottom type at locations where 

monk seals were seen capturing prey items. Recent studies have focused on characterizing juvenile monk 

seal habitat use and foraging behavior at French Frigate Shoals using Crittercams and time-depth recorders 

(TDRs). 

Abundance 

NMFS field camps were initiated in the early 1980s using systematic surveys for estimating abundance of 

the Hawaiian monk seal populations. The abundance of monk seals at the six main reproductive sites in the 

NWHI is estimated by direct enumeration. At those locations the majority of individual seals can be identifi ed by 

flipper-tags that have routinely been applied to weaned pups since the early 1980s, bleach marks placed annuFigure 6.31. Hawaiian monk seal field camps. Map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

ally, and by natural features such as scars and distinctive pelage patterns (Harting et al., 2007). The methods 

are different at Mokumanamana and Nihoa Islands because they are difficult to reach and there are no regular 

field camps at those sites. 

The methods used to derive estimates of monk seal abundance, and the abundance at locations within the 

Monument and in the MHI are as follows: 

• Main reproductive sub-populations in the NWHI of French Frigate Shoals, Laysan, Lisianski, Pearl and 

Hermes Atoll, Midway Islands and Kure Atoll: total enumeration of individuals when possible, otherwise 

capture-recapture estimates or minimum abundance (Baker, 2004; Baker et al., 2006). 

• Mokumanamana and Nihoa Islands: corrected mean beach counts made during most recent five years at 

Mokumanamana and Nihoa Islands. A correction factor (2.89 ± 0.06; NMFS, unpubl. data) derived from 

observations at the main reproductive sites is applied. 

• MHI: Minimum abundance consisting of the total number of uniquely identifiable seals observed alive during a calendar year. Sightings are non-systematic and collected by NMFS, and reported by volunteers, 

partner agencies and the general public. 

Beach Counts 

Methods 

Beach counts are conducted at least eight times annually per site to calculate a mean value that serves as a 

trend index for long-term comparisons. The beach counts include a count of all the seals found on the island 

or group of islands within an atoll during a single mid-day survey. 

Uses 

Direct enumeration data cannot be used for comparing historical counts; however, a measure of long-term 

trend is derived from the mean of all of the beach counts that have been conducted with varying frequency 

since the late 1950s. These beach counts provide a useful index because the general methodologies of counts 

during these 45 years are roughly comparable. 

Limitations 

A consideration when interpreting the mean beach counts is that the relationship between the mean beach 

counts and the actual population size is uncertain. That is, all of the factors that might cause beach counts to 

deviate from the true abundance (for example, changes in haul out patterns over time) are not known, and 

hence appropriate correction factors have not been determined. Eberhardt et al. (1999) concluded that, “beach 

counts may be very poor guides to year-to-year trends. However, beach counts are valuable indicators of 

long-term trends.” NMFS is currently investigating other approaches for estimating total abundance to better 

characterize long- and short-term trends. 

Habitat Use 

Terrestrial Habitat Use 

Monk seals use terrestrial habitat for haul-out areas to rest and pupping. Haul-out areas for resting generally 

consist of sandy beaches, but virtually all substrates, including emergent reef and shipwrecks, are used at various islands. Monk seals also use the vegetation behind the beaches, when available, as a shelter from wind 

and rain. Pups are born on various substrates; however, sandy beaches with shallow protected water near 

shore seem to be preferred habitat for pupping and nursing (Westlake and Gilmartin, 1990). 

Marine Habitat Use 

Monk seals spend approximately two-thirds of their time in the marine habitat (MMRP, unpublished data). They 

are primarily benthic foragers (Goodman-Lowe et al., 1998), and will search for food in coral reef habitat and 

on substrate composed of talus and sand on marine terraces of atolls and banks to depths exceeding 500 

m (Parrish et al., 2000, 2002: Parrish and Abernathy, 2006). Parrish et al. (2002) also described monk seals 

foraging in corals below 300 m in subphotic zones (Parrish et al., 2002). 

213 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

214 

The largest study of monk seal foraging 

ranges and diving behavior was conducted using tagging information from 

1996 to 2002 (Abernathy and Siniff, 

1998; Stewart 2004a, b; Stewart and 

Yochem, 2004a, b, c). During this time 

the movements and diving patterns of 

147 Hawaiian monk seals were monitored with satellite-linked radio transmitters at the six breeding colonies in 

the NWHI. Spatial dispersal of foraging seals indicates that they forage extensively within the lagoons at French 

Frigate Shoals, Pearl and Hermes Atoll, 

Midway Atoll and Kure Atoll, and on the 

outer slopes of those atolls and seaward of Laysan and Lisianski Island. 

Seals also foraged along the submarine 

ridges between these atolls and islands 

and at virtually all nearby seamounts. 

A fixed kernel density estimate method 

was used to determine the extent of foraging areas (Stewart et al., 2006; Figure 6.32). Primary foraging occurred in areas with high bathymetric relief or focused within the lagoon areas. At the majority of the islands 

and atolls 95% of the foraging occurred within 38 km and 75% occurred within 20 km of center of the island or 

atoll (Stewart et al., 2006). French Frigate Shoals did not follow this same pattern, however, with 95% of the 

foraging occurring within 50-58 km of the center of the atoll (Stewart et al., 2006). Seals at all of the colonies 

foraged outside of the colonies but there was no distinct pattern (Stewart et al., 2006; Table 6.2). Distances 

traveled to forage from haul out sites also varied with a seal’s age and sex and with the seal’s colony of seal 

origin. Foraging distances ranged overall from less than 1 km up to 217 km (Abernathy, 1999; Stewart, 2004a, 

b; Stewart and Yochem, 2004a, b, c; Stewart et al., 2006) 

In addition to looking at the distances seals foraged from their colonies, the diving behavior was also monitored (Stewart et al., 2006; Table 6.2). Most frequently, seals dove to depths less than 150 m, though there 

were secondary diving modes at various depths up to 500 m. There was some variation in seals foraging 

depth between the island and atolls. At 

Pearl and Hermes Atoll 90 % of dives 

and at French Frigate Shoals 60 – 80% 

of dives were to depths of less than 40 

m. The remaining 10 – 20% of dives occurred in depths greater than 40 m with 

some occurring as deep at 500 m. At 

Kure Atoll, Midway Atoll, Lisianski Island 

and Laysan Island seals regularly dived 

to depths greater than 40 m (Stewart et 

al., 2006). 

Foraging areas seem to vary between 

age groups, islands and individuals 

(Figure 6.33). Weaned pups at Kure 

Atoll and Midway Atoll did not range as 

far as adults whereas at Lisianski Island 

and Laysan Islands, adults and weaned 

pups exhibited similar foraging distances (Stewart et al., 2006). Further analyFigure 6.32. Hawaiian monk seal foraging ranges. Source: Stewart et al.,

2006; map: K. Keller. 

Figure 6.33. Examples of individual seal movements at Lisianski Island.

Source: NMFS, unpub data; Stewart et al., 2006; map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 6.2. Percentages of monitored Hawaiian monk seals at each colony that foraged at various sites in the NWHI. 

Source: Stewart et al., 2006. 

FEATURE 

NAME 

KURE 

ATOLL 

MIDWAY 

ATOLL 

PEARL AND 

HERMES 

ATOLL 

LISIANSKI 

ISLAND 

LAYSAN ISLAND FRENCH 

FRIGATE 

SHOALS 

WP 

(5) 

J 

(11) 

AM 

(4) 

AF 

(4) 

WP 

(4) 

J 

(8) 

AM 

(2) 

AF 

(3) 

J 

(6) 

AM 

(9) 

AF 

(9) 

WP 

(8) 

J 

(9) 

AM 

(4) 

AF 

(5) 

WP 

(10) 

J 

(10) 

AM 

(5) 

AF 

(5) 

AM 

(17) 

AF 

(17) 

Un-named 

Kure 

Seamount 1 

50 

Un-named 

Kure 

Seamount 2 

50 

Un-named 

Kure 

Seamount 3 

50 

Kure Atoll 100 100 100 100 13 50 33 

Nero 

Seamount 

25 25 13 50 33 

Midway Atoll 25 100 100 100 66 

Ladd 

Seamount 

25 33 100 100 100 

Pearl andHermes 

Atoll 

33 

Un-named 

PHR 

Lisianski/

Neva Shoals 

100 100 100 100 

Pioneer 

Bank 

38 22 20 

Northampton W 

11 30 30 20 40 

Northampton E 

11 40 40 

Laysan 22 20 100 90 100 100 

Un-named 

Laysan 1 

11 

Maro Reef 22 70 60 60 80 

Raita Bank 30 30 40 40 

Gardner 

Pinnacles 

6 30 

St. Rogatien

Banks 

12 10 

Brooks Bank 59 30 

French Frigate Shoals 

100 80 

Mokumanamana 

10 

sis was conducted to examine the relationship between habitat use and diet composition. In the early 1990s 24 

seals were tracked with satellite receivers and depth recorders at French Frigate Shoals (Parrish et al., 2000). 

In this study habitat use and diet of the monk seals were compared at different ecological zones. The analysis 

indicates that the seals foraging was focused more on the transitional slope areas. Generally the seals used all 

of the ecological zones proportionally to available habitat. The study also looked at the seals’ diet and the availability of prey species in each zone. The diet derived from scat analysis did not correlate with the prey species 

composition in any of the individual zones which was expected as seals generally used multiple habitats over 

the course of foraging trips. An analysis of the dissimilarity index of prey biomass density found that the prey 

guilds documented in the bank and slope areas had the least deviation (Parrish and Abernathy, 2006). 

215 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

216 

Satellite tagging data provide basic information on where the seals travel but do not provide specifi c information about seal behavior during their dives so seal mounted video cameras were utilized to examine habitat 

use, prey selection, and foraging behavior. Parrish et al. (2000) found that the diurnal pattern of foraging by 

male adults occurred mainly at the 60 m isobath using data collected from Crittercams. A few seals foraged 

at depths of more than 300 m. 

Crittercams also showed that even though much of the seals’ time was spent in the shallow areas (<10 m) 

near colonies, the majority of the time searching occurred at greater depths (50 – 60 m). In addition, there 

was evidence of seals consuming prey at deeper depths. Seals targeted habitats that were low-relief and 

areas composed of loose talus fragments provided the best foraging habitat. In this habitat seals are able to 

dislodge the talus fragments and easily locate the prey species. The second most searched habitat type was 

sand-dominated areas where prey was easily accessible. These two habitats were more frequently searched 

and potentially provide higher return of prey for search effort than more complex coral habitats that offer more 

hiding locations for prey species (Parrish et al., 2000). 

Recent studies have focused on characterizing juvenile monk seal habitat use and foraging behavior at French 

Frigate Shoals using Crittercams and TDRs. Juvenile seals forage in the same habitats commonly used by 

adults, but may lack the size and strength to forage as successfully as their adult counterparts (Parrish et al., 

2005). Dive records have indicated that most dives occurred at depths less than 200 m, but occasionally some 

exceeded 200 m. Substantial variability among the pups in depth, duration and temporal patterns of dives was 

noted (NMFS, unpublished data). 

Population Status and Trends

Current Abundance and Distribution of Populations 

Hawaiian monk seals occur as a single meta-population, with subpopulations distributed among eight NWHI 

locations from Nihoa Island to Kure Atoll, as well as a small and likely growing subpopulation in the MHI. There 

has been variation in the population dynamics between the subpopulations, with differences in environmental 

conditions and levels of human disturbance contributing to this variation (NMFS, 2007; Figure 6.34). 

0 

50 

100 

150 

200 

250 

300 

350 

1956 

1959 

1962 

1965 

1968 

1971 

1974 

1977 

1980 

1983 

1986 

1989 

1992 

1995 

1998 

2001 

2004 

2007 

Mean Total Beach Counts 

French Frigate Shoals 

0 

50 

100 

150 

200 

250 

300 

350 

1956 

1959 

1962 

1965 

1968 

1971 

1974 

1977 

1980 

1983 

1986 

1989 

1992 

1995 

1998 

2001 

2004 

2007 

Mean Total Beach Counts 

Laysan 

0 

50 

100 

150 

200 

250 

300 

1956 

1959 

1962 

1965 

1968 

1971 

1974 

1977 

1980 

1983 

1986 

1989 

1992 

1995 

1998 

2001 

2004 

2007 

Mean Total Beach Counts 

Lisianski 

0 

50 

100 

150 

200 

250 

300 

350 

195619591962196519681971197419771980198319861989199219951998200120042007 

Mean Total Beach Counts 

Pearl and Hermes 

Figure 6.34. Population trend index (mean beach counts) from individual Hawaiian monk seal subpopulations (--ο-- indicates less reliable historical counts). Source: NOAA PIFSC, unpublished data. 
Marine Protected Species 

Necker

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

0 

50 

100 

150 

200 

250 

300 

350 

195619591962196519681971197419771980198319861989199219951998200120042007 

Mean Total Beach Counts 

Midway 

0 

50 

100 

150 

200 

250 

300 

350 

195619591962196519681971197419771980198319861989199219951998200120042007 

Mean Total Beach Counts 

Kure 

0 

50 

100 

150 

200 

250 

300 

350 

195619591962196519681971197419771980198319861989199219951998200120042007 

Mean Total Beach Counts 

0 

50 

100 

150 

200 

250 

300 

350 

195619591962196519681971197419771980198319861989199219951998200120042007 

Mean Total BeachCounts 

Mokumanamana Nihoa

Figure 6.34 (continued). Population trend index (mean beach counts) from individual Hawaiian monk seal subpopulations

(--ο-- indicates less reliable historical counts). Source: NOAA PIFSC, unpublished data. 

Population Trends Across the Northwestern Hawaiian Islands 

The six major subpopulations in the 

NWHI can be divided into the three western subpopulations at Kure Atoll, Midway Atoll and Pearl and Hermes Atoll; 

and the more geographically isolated 

populations found at Laysan and Lisianski Islands, as well as French Frigate 

Shoals. The higher exchange of individuals between the western subpopulations may contribute to observed similarities in population dynamics among 

these sites, and these islands may, in 

certain circumstances, be considered a 

single management unit. Table 6.3 illustrates the variation in abundance estimates between the different islands and 

atolls in 2007. 

The estimated probabilities of sighting an animal is 90% for all years of data at French Frigate Shoals, Laysan 

Island, Midway Atoll and Kure Atoll, approximately 85% at Lisianski Island, and approximately 80% at Pearl 

and Hermes Atoll (Harting, 2002). Therefore, the numbers may underestimate the size of those sub-populations by 10%-20%. The methods used for the other population components (Mokumanamana, Nihoa and the 

MHI), while somewhat less accurate, are the best possible under current budget and logistical constraints. 

Because the other population segments represent relatively small proportions of the total population, errors in 

their abundance estimates do not greatly distort the estimated total population size. For example the best estimate of the total population size in 2005 was 1,247 seals. To determine a minimum population estimate (Nmin) 

for the total population that accounts for the statistical uncertainty in the abundance estimates, as is done for 

Table 6.3. Estimated 2007 monk seal abundance for each population segment. Nmin calculated at Mokumanamana and Nihoa Islands according 

to the methods of Wade and Angliss (1997). Source: NMFS, unpublished 

data. 

SITE ESTIMATION METHOD Nmin Nbest 

French Frigate Shoals Minimum 228 228 

Laysan Island Minimum 209 209 

Lisianski Island Total enumeration 174 174 

Pearl and Hermes Atoll Minimum 154 154 

Midway Island Minimum 65 65 

Kure Atoll Minimum 105 105 

Mokumanamana Corrected beach counts 31.4 42 

Nihoa Island Corrected beach counts 72.2 78.7 

Main Hawaiian Islands Minimum 88 88 

Total 1,126.60 1,143.70 

217 
Marine Protected Species 

218 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

stock assessment reports required by the MMPA (Wade and Angliss, 1997), a combination of enumeration 

and minimum estimates was used. The number of seals identified in 2005 at the main reproductive sites was 

1,065 seals, including 163 pups. Minimum population sizes for Mokumanamana and Nihoa Islands (based on 

the formula provided by Wade and Angliss, 1997) were 34 and 39, respectively, and a total of 77 seals were 

identified in the MHI. Using that procedure, minimum population size estimate for the total population is the 

sum of these estimates, or 1,215 seals. 

Long-term and Recent Population Trends 

Beach counts are used as an index of the population size. Based on the beach counts from the 1950s to 2001 

it appears that the species declined by approximately 50% between the late 1950s and the mid 1970s (Kenyon, 1973; Johnson et al., 1982). Beach counts of non-pups (juveniles, sub-adults and adults) declined by 

68% between the years 1958 and 2005. 

Based on the very limited window of data availability, the largest counts of monk seals observed at many 

islands were obtained around 1958. Three exceptions to this were French Frigate Shoals, where the maximum count was obtained in 1985, Mokumanamana where the maximum was obtained in 1977, and Nihoa 

where the maximum was obtained in 1991. The sum, across all sites in the NWHI, of the maximum counts, 

whenever obtained, totals 1,541, corresponding, after a very uncertain correction, to an estimated population size of 

around 3,000. There is evidence, at a 

minimum, that the available habitat was 

probably capable of supporting at least 

3,000 monk seals in the NWHI plus an 

unknown number in the MHI. 

More recent data indicate that non-pup 

beach counts declined rapidly from 

1985 to 1993, became relatively stable 

for several years, then declined again 

beginning in 1998. Models estimate that 

the total counts declined 8.1% per year 

until 1993 (Carretta et al., 2005). The 

trend in total abundance of Hawaiian 

monk seals is shown in Figure 6.35. A 

log-linear regression of estimated abundance from 1998 (the first year for which 

a reliable total abundance estimate has 

been obtained) to 2006 estimates that 

abundance declined -3.9% yr -1 (NMFS, 

unpublished data). 

1000 

1100 

1200 

1300 

1400 

1500 

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 

Estimated Abundance 

Error bars indicate +2 SE, 

and either -2 SE or known Nmin 

-3.9% per year 

Figure 6.35. The long-term combined trend at the main NWHI sites masks

a diversity of trends within the individual Hawaiian monk seal sub-populations. The population dynamics at the different atolls have varied considerably and current demographic variability among the island populations

probably reflects a combination of human and environmental/natural influences. Source: Gerrodette and Gilmartin, 1990; Polovina et al., 1994; Craig

and Ragen, 1999; Ragen, 1999. 

The Population Trends by Island and Atoll 

In addition to examining the overall trend in the Hawaiian monk seal population it is also important to examine 

each island and atoll. Each subpopulation exhibits different population dynamics that reflect their unique histories and environmental conditions (Figure 6.34). 

Kure Atoll 

The Hawaiian monk seal population at Kure Atoll has been impacted over the years by human disturbance. 

Beginning with sailors stranded after the ship wreck of the Parker who killed seals for food and continuing with 

disturbance caused by the U.S. Coast Guard (USCG) LORAN station. In the late 1970s NMFS began efforts 

with the USCG to reduce the level of disturbance to the Hawaiian monk seals. USCG decommissioned the 

LORAN station in 1992. Since 1992 state of Hawaii Department of Land and Natural Resources and the Ma­
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

rine Mammal Research Program (MMRP) field camps are the only human presence at Kure Atoll during the 

summer months. 

The population dynamics of monk seals have varied with these changes in human disturbance at Kure Atoll 

(Figure 6.34). After the construction of the LORAN station in the late 1950s and early 1960s the seal population declined abruptly. As efforts were made in the 1980s to reduce disturbance to the seals there was a corresponding increase in pup survival (Gerrodette and Gilmartin, 1990; Gilmartin, pers. comm.). From 1983-2000 

the beach count data shows a 5% increase per year. Since 2000 as seen at other islands and atolls there has 

been high juvenile mortality. The increase in the population until 2000 has been attributed to the reduction of 

human disturbance by USCG regulations and the closure of the LORAN station (Gilmartin et al., 1986). In addition 54 immature female seals were released at Kure and reached reproductive maturity by the early 1990s. 

(NMFS, 2007). Recent trends indicate a decline in the Kure population. 

Midway Atoll 

Midway Atoll has also had a history of human disturbance, starting in 1859, which has impacted the Hawaiian 

monk seal population (Figure 6.34). The monk seal population was depleted by the late 1800s and partially 

recovered in the early 1900s. Human activities in the early 1900s included attempts to blast a ship channel, 

installation of a cable station, construction of an airport and other World War II military activities. After World 

War II the human population peaked at 3,500 and was reduced to 250 by 1978 (NMFS, 2007). The 1957-1958 

monk seal surveys recorded a mean of 57 seals but by 1968 only one seal was observed (Kenyon, 1972). 

There were occasional sightings in low numbers during the 1980s (NMFS, 2007). Midway’s small monk seal 

population saw increases in the early 1990s as management efforts were increased to reduce disturbance. By 

1988 the U.S. Fish and Wildlife Service (USFWS) was actively participating in the management of wildlife at 

Midway Atoll in conjunction with the U.S. Navy. Since 1988, the USFWS has restricted the numbers of staff and 

visitors to Midway Atoll. Hawaiian monk seal beach counts increased during the 1990s but this was primarily 

due to immigration of individuals from Pearl and Hermes Atoll and Kure Atoll. In addition to immigrants, there 

were increases in total births. In 1996 the Navy transferred Midway Atoll to the USFWS and further measures 

were put in place to reduce disturbance to monk seals. There was a short five year increase in beach counts 

from 1995 – 2000 followed by a decline since 2000. 

Pearl and Hermes Atoll 

Impacts on the seal population at Pearl and Hermes Atoll started in 1859 when a sealing expedition visited the 

atoll. In the late 1920s pearl oysters were harvested and construction occurred on the islands. The U.S. military 

occupied the atoll in 1961 during construction of an observation tower. The atoll is now unoccupied except for 

NMFS summer fi eld camps. 

The Pearl and Hermes Atoll seal population declined by an estimated 90% after the 1950s (Figure 6.34). From 

the mid-1970s to 2000 beach counts have increased. Specifically from 1983 to 2000 counts increased an average of 6%. As seen at Kure Atoll and Midway Atoll counts have declined since 2000. 

Lisianski Island 

Lisianski Island is the site of many 1900s ship wrecks and as seen with other wreck sites stranded sailors 

relied on monk seals as well as other species for food. Harvesting expeditions also occurred during this time. 

Today the island is unoccupied except for monk seal fi eld camps. 

Beach counts have declined since the late 1950s and have remained low since then (Figure 6.34). The island 

is estimated to be below the carrying capacity but the cause for low population size is unknown. 

Laysan Island 

The 1857 Hawaiian vessel Manuokawai reported Hawaiian monk seals at Laysan Island. By the 1900s seal 

expeditions and guano miners had nearly extirpated the seal population. For several years the Japanese 

collected eggs and feathers from the island but since this collection was halted in 1915, the island has been 

relatively undisturbed by human presence. The only activities since that time have been survey and scientific 

219 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

220 

expeditions. Beginning in the early 1990s the USFWS has had a small year round field camp on Laysan, and 

NMFS has conducted seasonal field camps on the island. 

As on other islands, Laysan’s monk seal population declined in the late 1950s. The population has seen some 

increases but is still below the historic high. Ciguatera is suspected in a mass die off of 50 seals in 1978, but 

was not conclusively proven. In the early 1980s the sex ratio at Laysan was male biased resulting in 45 confirmed deaths due to male aggression from 1982 – 1994. From 1983 – 1994 an average of 4% of the Laysan 

adult females died from injuries related to male aggression (Johanos et al., 1999). Interventions to remove 

subordinate males and correct the sex ratio were successfully undertaken in the mid-90s and have resulted 

in substantially fewer occurrences of male aggression. Even though juvenile survival at Laysan is better than 

French Frigate Shoals there are still concerns about food limitations. There is still not a good understanding of 

the underlying causes or the lack of recovery of the monk seal population at Laysan Island. 

French Frigate Shoals 

French Frigate Shoals did not have the same guano resources that other islands in the NWHI did. As a result, 

the atoll was not mined; however, there is still documentation of harvesting occurring in 1882 of sharks, turtles, 

beche-de-mer and birds. The highest level of use occurred during World War II when a Naval airbase was built 

on Tern Island in 1942. A USCG LORAN station was established and maintained on East Island from 1943 - 

1952. The Naval airbase on Tern Island was decommissioned in 1946 but the USCG maintained the island as 

a LORAN station from 1952-1979. Since the closure of the USCG LORAN station the USFWS has operated a 

field station on Tern Island. 

French Frigate Shoals currently supports the largest monk seal colony in the NWHI (Figure 6.34). The monk 

seal population at East Island and Tern Island were impacted by disturbances caused by the military and 

USCG presence; however, after the closure of the LORAN station in East Island, numbers of monk seals using the island increased until the 1980s. After the USCG left Tern Island the presence of seals at the island 

increased until 1989. Since 1989 the French Frigate Shoals population has declined by as much as 75%. 

Juvenile survival rates have declined during this time. Survival in the mid-1980s for weaning to age two was 

as high as 90% but dropped to a low of 8% in 1997. One result of the low survival rates is an imbalance in the 

age structure of the population. The overall population is expected to decline in coming years as fewer females 

reach reproductive age and older females die. 

Mokumanamana and Nihoa Island 

Population monitoring visits to Mokumanamana and Nihoa Islands are infrequent and brief, so enumeration 

is not possible at these sites. Counts of seals at those islands tended to increase from approximately 1970 

to 1990 (Figure 6.34). The increase in counts may have been due to an influx of seals from French Frigate 

Shoals, which was growing at that time. During a seven-day period at Mokumanamana in 1993, 14 tagged 

seals were sighted, all of which had been marked as pups at French Frigate Shoals (Finn and Rice, 1994). 

During the same period, 12 tagged seals were sighted at Nihoa Island, 10 of which were from French Frigate 

Shoals (Ragen and Finn, 1996). 

The Main Hawaiian Islands 

The number of documented monk seal sightings in the MHI increased during the 1990s. Historical abundance 

data for the MHI are limited, as there were no systematic surveys of monk seals conducted prior to 2000. Births 

in the MHI have become more frequent. The known number of annual births in the MHI before and during the 

1990s was usually zero and never exceeded four, but seven births were recorded in 2000 and 12 in 2001 

(Baker and Johanos, 2004). More recently, a minimum of 88 individual seals have been identified in the MHI 

(NMFS, unpublished data). 
Marine Protected Species 

Figure 6.36. Leatherback turtles (left) and the Hawaiian green turtle (right) 

can be found in the Monument. Photos: NOAA National Marine Sanctuaries. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

MARINE TURTLES 

Covering more than 360,000 km2 of 

subtropical waters in the North Pacific, 

the Monument provides critical breeding 

and nesting habitat for the green turtle 

(Figure 6.36), and foraging habitat 

and migration pathways for green 

loggerhead, hawksbill and leatherback 

(Figure 6.36) turtles. Although olive ridley 

turtles have not been sighted within the 

Monument, their known distribution in 

the tropical Pacific indicates that they 

likely also use waters of the NWHI 

(Papahanaumokuakea Marine National 

Monument, 2008). These five marine 

turtle species are all protected under 

the ESA due to threats to beach nesting 

habitat and from incidental bycatch, 

marine debris entanglement, and vessel 

strikes (http://www.nmfs.noaa.gov/pr/ 

species/turtles/). 

Although four marine turtle species have 

been documented in Monument waters, 

the extensive nesting of green turtles in 

the NWHI has allowed for multi-island 

surveys, capture-mark-recapture work 

and long-term population studies of this 

species (Figure 6.37). Based on green 

turtle basking and nesting surveys 

across islands/atolls and over time, the 

species basks throughout the NWHI 

(Figure 6.38), but nests at only a subset 

of the islands (Figure 6.39). 

Monitoring Efforts by Island: Data and Methodology

French Frigate Shoals 

More than 90% of Hawaiian green turtle nesting occurs at French Frigate Shoals, with over 50% of nesting 

occurring on East Island. In addition to intensive study of green turtles at this atoll, annually since 1973, early 

observations were made by military personnel, fishermen and scientists at French Frigate Shoals beginning 

in 1859. Amerson (1971) summarizes all known observations of basking green turtles and nest attempts from 

1859 through 1969. 

The largest data set on green turtles in the NWHI consists of 35 years of research, beginning in 1973, on the 

nesting population on East Island, French Frigate Shoals (Balazs and Chaloupka, 2006). Between 1973 and 

1981, the work was a partnership between the Hawaii Institute of Marine Biology (University of Hawaii) and the 

USFWS, and since 1982 a collaboration between USFWS and the NOAA Pacific Islands Fisheries Science 

Center (PIFSC). From 1973 through the present time, annual surveys have been conducted on the number of 

individual female turtles going ashore each night during the nesting season (Balazs, 1976, 1980; Wetherall et 

al., 1998). Prior to 1996, unique individuals were identified based on double-tagging with external fl ipper tags; 

since that year, all individuals have been double-tagged with passive integrated transponders. Tagging studies 

have shown that nesting-island site fidelity is very high within the Hawaiian rookery, such that annual nesting 

221 

Figure 6.37. Locations of green turtle basking and nesting attempt surveys

conducted within the NWHI. Map: K. Keller. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

222 

abundance and trend estimates are not 

confounded by substantial immigration 

or emigration (Dizon and Balazs, 1982; 

Niethammer et al., 1997). 

Annual nesting abundance at East 

Island, French Frigate Shoals, has 

been estimated by the PIFSC using a 

Horvitz-Thompson type estimator: Ni

 = 

ni

/pi, where Ni = number female nesters in year i, ni

 = number of uniquelyidentified female nesters in year i, and 

pi = probability of sighting a unique female that nests in year i. The value pi 

was estimated based upon census data 

from >1,100 nesters during a five-year 

season-long saturation tagging and resighting program at the atoll from 1988-

1992. Trends in nester abundance from 

1973-2004 were estimated by Balazs 

and Chaloupka (2004, 2006) using a 

Bayesian smoothing spline regression 

that was fitted to the Horvitz-Thompson 

nest abundance series (Balazs and Chaloupka, 2004, 2006). 

Other Islands and Atolls 

Data on the number of green turtle pits 

and number of basking turtles at other 

islands and atolls in the northwestern 

chain have been collected in some 

years from 1982 through 2008. Number of pits does not indicate a specific 

number of nesting attempts by turtles, 

as each nesting attempt may consist 

of one too many pits; however, pits 

are likely indicative of some level of attempted nesting on the islands on which 

they have been observed (S. Kubis Hargrove, pers. comm.). On Laysan Island, 

NMFS personnel counted the number 

of turtle pits and basking turtles from 

March through June 1982 (Kam, 1986). In 2007, USFWS personnel surveyed the perimeter of Laysan Island 

regularly throughout the green turtle nesting season and monitored active nests for hatching (Payne et al., 

2007). On Lisianski Island, NMFS personnel counted the number of pits dug and number of basking turtles 

through various portions of the nesting season each year from 1982 to 1987, and 2006 and 2007 (Kam, 1985; 

Kam, 1986; Alcorn et al., 1988; Johanos and Withrow, 1988; Westlake and Siepmann, 1988; Kubis, 2008; M. 

Snover, pers. comm.). Similar counts were done at Pearl and Hermes Atoll in 1982, 1990, 1991, 2006, and 

2007 (Kam, 1986; Finn et al., 1993; Kubis, 2008; M. Snover, pers. comm.). At Midway Atoll, the fi rst observation of nesting occurred in 2006, and nests were also documented in 2007 and 2008 (John Klavitter, pers. 

comm.). In addition to pit counts at these islands and atolls, in 2006 NMFS personnel quantified the mean 

numbers of basking turtles from May through August at all islands and atolls north of Mokumanamana (B. 

Becker, M. Snover, pers. comm.). 

Figure 6.38. Islands and atolls at which green turtles have been observed

to bask. Map: K. Keller. 

Figure 6.39. Islands and atolls at which green turtle nesting attempts (pits)

have been observed. Map: K. Keller. 
Marine Protected Species 

600

A 

500 

Female Nesters

400 

300 

200 

100 

0 

6.5 

6.0

Ln(Nesters) 

B 

5.5 

5.0 

4.5 

4.0 

3.5 

Figure 6.40. Trends in green turtle nester abundance at East Island, French 

Frigate Shoals, 1973-2004. Panel A shows time series plot of the HorvitzThompson estimate of number of female turtles nesting each year over the

32-year period. Panel B shows estimated long-term trend in nester abundance derived using Bayesian smoothing spline regression model, which 

was fitted to the Horvitz-Thompson nester series shown in panel A. Red 

curve is mean annual nester abundance. Source: Balazs and Chaloupka,

2006. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

223 

Results and Discussion 

French Frigate Shoals 

Amerson (1971) reports that green turtles were first recorded at French Frigate Shoals by personnel on the 

USS Fenimore Cooper in 1859. In 1882, the crew of the Japanese-owned schooner Ada reported collecting 

1,543 pounds of turtle shell and 47 gallons of turtle oil from approximately 350 turtles. In 1914, green turtles 

were observed basking at French Frigate Shoals by the USS Rainbow’s hydrographic survey team, and in 

1923, members of the Tanager Expedition also reported observing turtles and turtle eggs at the atoll. They also 

reported evidence of previous turtle slaughter (Amerson, 1971). 

From the early 1920s through the late 1960s, U.S. Department of Interior, NOAA and the Smithsonian Institution personnel reported observing green turtles basking on most of the islands within French Frigate Shoals, 

including Tern, Trig, Whaleskate, Round, East, Gin, Little Gin and Disappearing Islands. The largest numbers of baskers during this time period were reported on East Island in the 1960s, with the highest number 

recorded (86 turtles) in September 1966. Turtle pits were also recorded through the late 1960s on Tern, Trig, 

Whaleskate, Round, East, Gin and Little Gin Islands (Amerson, 1971). 

More recently, NOAA personnel have quantified the number of green turtles basking on all islands within 

French Frigate Shoals during the nesting season. In 2006, an average of 143 turtles was observed basking at 

any one time. 

Results of Balazs and Chaloupka’s research on green turtles nesting at East 

Island, French Frigate Shoals, indicate 

annually variable nesting population sizes, ranging from just under 100 to more 

than 500 female turtles each year from 

1973 to 2004 (Figure 6.40). Estimation 

of nesting population trends indicates

an increase in annual population size of 

approximately 5.7% per year (95% CI: 

5.3 - 6.1%) over that 32-year time period (Figure 6.40; Balazs and Chaloupka, 

2006). 

The increase in green turtle nesting population size at French Frigate

Shoals (Figure 6.41) may be attributed 

in part to increased protections under

the ESA, as harvesting of turtles on land 

or in waters surrounding the Hawaiian 

Islands was prohibited beginning in the 

late-1970s. However, human impacts

on beach nesting habitat at French Frigate Shoals also changed dramatically

over the last half of the 20th century.

From the late 1930s to early 1950s, the 

U.S. Navy and USCG operated Naval

Air and Long Range Navigation stations

on East Island; during that time, turtle

nesting and basking reportedly greatly

decreased (Amerson, 1971). After the

decommissioning of the Naval Air Station and relocation of the USCG LORAN

station from East Island to Tern Island in
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

224 

1954, numbers of nest attempts on East 

Island began to increase through the late 

1960s (Amerson, 1971). The number of 

nest at French Frigate Shoals continued to increase through 2004 (Balazs 

and Chaloupka, 2006), and during the 

2008 season, an estimated 589 females 

nested at East Island (G. Balazs, pers. 

comm.). 

Other Islands and Atolls 

Numbers of green turtle nesting and 

basking are much lower at the other 

islands and atolls in the northwestern 

chain, relative to French Frigate Shoals. 

The islands of Nihoa and Mokumanamana contain only small areas of basking habitat, while Laysan, Lisianski, and the islands of Pearl and Hermes Atoll have small numbers of nesting 

green turtles each year (fewer than 100 turtle pits per island or atoll). Midway and Kure Atolls have relatively 

extensive areas of beach habitat, but only one nest per year has been observed at Midway Atoll since 2006 

(John Klavitter, USFWS, pers. comm.), and nesting has never been observed at Kure Atoll (Kubis, 2008). The 

following sections provide results of pit and basking turtle counts for Nihoa, Mokumanamana, Laysan, Lisianski, Pearl and Hermes Atoll, Midway Atoll and Kure Atoll for some years from 1982 through 2008. 

Nihoa and Mokumanamana 

The two high islands of the northwestern chain, Nihoa and Mokumanamana, each contain habitat for basking 

and/or nesting, although consisting of only several square meters. There is a small sand beach at Nihoa, but 

only rocky shoreline on Mokumanamana. Green turtles have not been observed nesting on either of these 

islands, but basking has been observed (Kubis, 2008). In 1983, NOAA personnel recorded a mean of 1.5 basking turtles per day on Mokumanamana from 24 July through 6 August (Morrow and Buelna, 1985). 

Laysan Island 

In 1982, NOAA personnel on Laysan Island observed 12 green turtle nest excavations, consisting of 45 pits, 

between 25 May and 30 June. In addition, a mean of 2.6 turtles were observed basking each day during the 

period 16 March through 30 June (Kam, 1986).
 

In 2005 and 2006, USFWS personnel noted a “few” green turtle pits on Laysan from April through October (C. 

Rehkemper, USFWS, pers. comm.), and in 2006 NMFS personnel recorded 0.2 turtles basking at any one time 

during the nesting season (M. Snover, 

NMFS, pers. comm.).
 

In 2007, USFWS located a total of 50 

green turtle nests on Laysan (Figure 

6.42). Of 24 nests that were monitored 

from May through early September, an 

estimated 1,403 eggs were laid, with 

clutch sizes ranging from 55 to 111
 

(mean = 87.8, n = 16 nests). Hatching 

success at the 24 monitored nests was 

85.6%. Incubation periods ranged from 

60-75 days (mean = 67.5), with incubation period shortening over the course 

of the season (Payne et al., 2007).
 Figure 6.42. Green turtle nest on Laysan Island, 26 June 2007. Photo: US- FWS. 

Figure 6.41. Green turtle laying eggs, French Frigate Shoals, June 2002.

Photo: NOAA. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Lisianski Island 

NMFS personnel counted turtle pits and basking green turtles on Lisianski Island during parts of the nesting 

season in some years between 1982 and 2007. Results of these counts indicate a range of 15 to 47 pits observed per year, and a mean of 2.0 to 5.4 turtles basking on the island per day (Table 6.4). Figure 6.43 indicates the locations of pits observed on Lisianski Island in 1982 and 1983. 

Table 6.4. Observations of pits and basking green turtles on Lisianski Island, 1982–2007. 

YEAR DATES OBSERVATIONS REFERENCE 

1982 May – Aug 23 excavation sites consisting of 47 pits Kam (1986) 

1982 8 Jul – 13 Sep Mean of 5.4 baskers/day Kam (1986) 

1983 31 May – 9 Aug 19 pits (Figure 6.43) Kam (1985) 

1984 2 Jul – 6 Aug 91 pits Alcorn et al. (1988) 

1985 17 Jun – 20 Jul 78 pits Alcorn et al. (1988) 

1986 5 – 26 Aug 15 pits Westlake and Siepmann (1988) 

1987 1 – 4 Jun; 5 – 29 Aug 34 pits Johanos and Withrow (1988) 

1987 7 – 27 Aug Mean of 2.0 baskers/day Johanos and Withrow (1988) 

2006 May – Aug Mean of 2.9 baskers/day Melissa Snover, NMFS (pers. comm.) 

2007 May – Jun Nests observed but not counted Kubis (2008) 

225 

Figure 6.43. Locations of green turtle pits on Lisianski Island May – August 

1982 and May – August 1983. Sources: Kam, 1986 and1985. 
Marine Protected Species 

226 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Pearl and Hermes Atoll 

NMFS personnel observed turtle pits 

and basking green turtles at Pearl and 

Hermes Atoll (on North, Southeast and 

Seal Kittery Islands) during parts of the 

nesting season in some years between 

1982 and 2007 (Kam, 1986; Finn et al., 

1993; Kubis, 2008). Count data indicate 

a range of one to 13 pits observed per 

year, and a mean of 10.0 to 12.6 turtles 

basking on North and Southeast Islands 

per day (Table 6.5). Figure 6.44 indicates the locations of pits observed on 

North and Southeast Islands in 1982. 

Midway Atoll 

One green turtle nest per year has been 

found at Midway Atoll since 2006. In 

2006, a single nest was located on Spit 

Island, and in 2007 and 2008 one nest 

per year was found on Sand Island (J. 

Klavitter, USFWS, pers. comm.). All 

three nests (2006, 2007, and 2008) 

hatched successfully. The nest laid in 

2008 was estimated to have contained 

89 eggs, 65 of which hatched successfully (J. Klavitter, USFWS, pers. comm.; 

Figures 6.45 and Figure 6.46). In 2006, 

NMFS personnel observed 4.5 basking 

turtles at any one time at Midway Atoll 

(M. Snover, pers. comm.). 

Kure Atoll 

Nesting by green turtles has never been 

observed at Kure Atoll (Kubis, 2008). 

Biological monitoring and research on 

other species has been conducted by 

NMFS and Hawaii Department of Land 

and Natural Resources personnel at 

Kure over a period of many years, so 

it is unlikely that nesting has occurred 

but has remained unobserved. Green 

turtles have been observed basking at 

Kure Atoll in small numbers. In 2006, 

NMFS personnel observed 0.7 basking turtles at any one time during a total 

of eight observation days (M. Snover, 

NMFS, pers. comm.). 

Table 6.5. Observations of pits and basking green turtles at Pearl and 

Hermes Atoll, 1982–2007. 

YEAR DATES ISLAND OBSERVATIONS REFERENCE 

1982 5 Jul North Island 13 pits

(Figure 6.44) 

Kam (1986) 

1982 2 – 5 Jul Southeast 

Island 

9 pits

(Figure 6.44) 

Kam (1986) 

1982 2 – 6 Jul North and 

Southeast 

Mean of 10 

baskers/day 

Kam (1986) 

1990 8 – 9 Jun North Island 2 pits Finn et al. (1993) 

1991 1 Aug – 13 

Sep 

Southeast 

Island 

1 pit Finn et al. (1993) 

2006 May - Aug Not specified 12.6 baskers/day Melissa Snover, 

NMFS (pers. comm.) 

2007 May-Jun Not specified Nests observed 

but not counted 

Kubis (2008) 

North Island 

Southeast Island 

Southeast Island North Island

A 

B C

Figure 6.44. Panel A: locations of green turtle pits observed at Pearl and 

Hermes atoll in 1982. Panel B indicates locations of pits on Southeast Island; panel C indicates pit locations on North Island. Source: Kam, 1986. 

Figure 6.45. Green turtle tracks and nest on Sand Island, Midway Atoll, May 

2008. The left panel shows turtle tracks and the right panel shows an active

nest. Photos: T. Summers, USFWS. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Conclusions and Management 

Action 

Green turtles have been observed 

basking at all of the islands and atolls 

within the Monument, but nesting attempts have been limited to the islands 

and atolls from French Frigate Shoals to 

Midway Atoll. As previously described, 

more than 90% of green turtle nesting 

occurs at French Frigate Shoals, with 

a range of approximately 100 to 550 

females digging approximately 450 to 

2,500 nests each year (Table 6.6). In 

contrast, between 15 and 91 pits have 

been observed on Laysan and Lisianski Islands in any one year, 1-13 pits 

per island at Pearl and Hermes Atoll 

per year, and only one nest per year at 

Midway Atoll between 2006 and 2008 

(Table 6.5). As the number of nesting 

females on East Island, French Frigate Shoals has increased over the last 

three decades, the numbers of nests 

at Laysan, Lisianski, and Pearl and 

Hermes Atoll may have also increased over time. Additional periodic counts of pits and/or mark-resighting of 

nesting females at those locations in future years will help to more precisely estimate the subpopulation sizes 

of nesting green turtles throughout the Monument. 

Table 6.6. Numbers of green turtle nest pits observed on all islands and atolls in the NWHI between 1982 and 2008. 

Dash (-) indicates data not collected or not available; plus sign (+) indicates observed pits but not counted; and zero (0)

indicates true count of zero. 

Figure 6.46. Location of green turtle nest on Sand Island, Midway Atoll, in 

2008. Source: J. Klavitter; map: K. Keller. 

227 

ISLAND/ATOLL 1982 1983 1984 1985 1986 1987 1990 1991 2006 2007 2008

Nihoa 0 0 0 0 0 0 0 0 0 0 0 

Mokumanamana 0 0 0 0 0 0 0 0 0 0 0 

French Frigate Shoals: East

Island† 

585* 158* 896* 729* 311* 644* 675* 482* 1,904* 1,566* 2,430* 

Laysan 45 - - - - - - - - 50 -

Lisianski 47 19 91 78 15 34 - - - + -

Pearl and Hermes Atoll: 

North Island 

13 - - - - - 2 - - + -

Pearl and Hermes Atoll: 

Southeast Island 

9 - - - - - - 1 - + -

Midway Atoll: - - - - - - - - - - -

Spit Island 0 0 0 0 0 0 0 0 1 0 0 

Midway Atoll: 

Sand Island 0 0 0 0 0 0 0 0 0 1 1 

Kure Atoll 0 0 0 0 0 0 0 0 0 0 0 

†Pits have also been observed but not counted in all years on Tern, Trig, Gin and Little Gin Islands at French Frigate Shoals. 

*Numbers of pits at East Island, French Frigate Shoals, are estimates based upon numbers of nesting females (Stacy Kubis Hargrove, pers. comm.). Individual turtles lay three to six (mean = 4.5) clutches per season (http://www.fpir.noaa.gov/PRD/prd_green_ 

sea_turtle.html), so estimates of number of nest pits was obtained by multiplying the number of nesting females per year by 4.5. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

228 

Papahanaumokuakea Marine National Monument’s Draft Management Plan (PMNM, 2008) describes a strategy and three activities to manage green turtle habitat within the Monument, based upon the Recovery Plan 

for U.S. Pacific Populations of the Green Turtle (Chelonia mydas; NMFS and USFWS,1998). Strategy TES-3 

of the Monument’s Draft Management Plan is to “Ensure that nesting populations of green turtles at source 

beaches are stable or increasing over the life of the plan” (the life of the plan being 15 years). The fi rst activity 

planned to achieve this strategy includes the continuation of data collection to monitor nesting turtles on East 

Island, French Frigate Shoals (with the largest numbers of nesting turtles in the Monument), and the periodic 

reassessment of the distribution of nesting activity on the other islands and atolls within the NWHI (PMNM, 

2008). The second activity to achieve Strategy TES-3 is the protection and management of nesting habitat, including prevention of introduction of mammalian predators such as rats, reduction of artificial light near nesting 

beaches, prohibition of habitat alteration, and the regulation of human access and activities. Management actions to delay habitat loss due to sea level rise are also advised, but specific activities related to the slowing of 

climate-change-induced habitat loss are not described (PMNM, 2008). Finally, Strategy TES-3 will be attained 

by protecting and managing foraging areas and migration routes within the Monument, including identification 

and mapping of these areas, and management of vessel transit and discharge, and minimization of the introduction of contaminants (PMNM, 2008). 

EXISTING DATA GAPS 

It is important to develop and regularly update a database of population structure and dynamics for protected 

species. The database will help managers make effective decisions and determine the effects of previous decisions and events (e.g., climate events, management decisions, research programs, disease outbreaks, etc.). 

Specific opportunities include research to improve the understanding of: 

• The essential habitats and ecological requirements of protected species, to minimize anthropogenic 

threats and the effect of catastrophic events; 

• The diet and foraging behavior of the Hawaiian monk seals throughout different life stages in order to 

understand the effect of food availability on the population; 

• Time budgets, diving, and movement characteristics and energetics of the Hawaiian monk seal, stratified 

by representative sub-populations, age, and sex classes; 

• An appropriate and sensitive assay for biotoxins and metabolites in tissue of monk seals and prey species; 

• The effects of climate change on nesting sites of protected species, e.g., the effect of sea level rise on 

nesting sites of the green sea turtle and Hawaiian monk seal; 

• The Allee effect (i.e., that for smaller populations, the reproduction rates and survival of individuals decrease) and thresholds for phase shift; 

• Cetacean presence and behavior in the NWHI at different times of the year; and 

• The presence/absence of other turtle species and nesting sites at other locations in the NWHI. 
Marine Protected Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Seabirds
 

Kaylene E. Keller1, Angela D. Anders2, Scott A. Shaffer3, Michelle A. Kappes3, Beth Flint4 and Alan Friedlander5,6 

INTRODUCTION 

The Northwestern Hawaiian Islands 

(NWHI) provide habitat for an estimated 

5.5 million nesting seabirds representing 22 different species (see Figures 

7.1 and 7.2 and Fefer et al., 1984). For 

many of these species, the Monument 

provides the majority of available nesting habitat. Nesting occurs throughout 

the year, varying by species and within 

species, and by annual food availability 

(Harrison, 1990). The largest breeding 

populations occur at Midway Atoll, Laysan Island and Nihoa (USFWS, 2005). 

While the Monument protects seabird 

breeding and nesting habitat, the foraging ranges for most of these species 

extend beyond the Monument’s boundaries, with foraging distances ranging 

from 3 km to several thousand kilometers (e.g., Fernández et al., 2001). Some 

seabird species occur year-round in the 

Monument, while others migrate to other parts of the Pacific when not breeding. Juvenile birds may also remain at 

sea for several years before returning 

to their breeding colonies inside Monument water. Overall, the NWHI provide 

high-quality breeding habitat, with low 

predation risk and low disturbance conditions (Table 7.1). 

The distribution of seabirds within the 

Monument reflects, to some extent, the 

nesting habitat currently available on 

the islands (Tables 7.2 and 7.3). Nesting distribution has also been affected by human disturbance in the late 

19th and 20th centuries, including egg and feather hunting, and destruction of habitat due to military activities 

during and after World War II. For example, populations of many of the seabird species on Laysan Island are 

likely still recovering after the devegetation of the island by guano miners and hunter-introduced feral rabbits in 

the early 1900s (Ely and Clapp, 1973). Further habitat losses have occurred from the introduction of non-native 

plants like golden crown-beard (Verbisena encelioides) and rodent pests like rats and mice. Numbers of nesting adults of some species are also still increasing on Tern and East Islands at French Frigate Shoals after the 

decommissioning of Naval and Coast Guard stations following World War II (Amerson, 1971). 

235 

Figure 7.1. A Red-footed Booby. Red-footed Boobies nest on all islands 

and atolls in the NWHI. Photo: J. Watt. 

Figure 7.2. Brown Noddy Terns and Brown Boobies at Pearl and Hermes 

Atoll. Photo J. Watt. 

1. NOAA/NOS/ONMS/Papahanaumokuakea Marine National Monument

2. Clancy Environmental Consultants, Inc.

3. University of California Santa Cruz

4. U.S. Fish and Wildlife Service 

5. NOAA/NOS/NCCOS/CCMA Biogeography Branch

6. The Oceanic Institute 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

236 

BREEDING PERIOD FEEDING

BEHAVIOR 

ESTIMATED

FORAGING RANGE

FROM COLONIES

CommonName 

ProtectionStatus 

IUCN ESA Primary

Months ofPresence 

Months WhenBreeding 

Fish Fish

Eggs 

Cephaopods(squid, octopus) 

Ephausiids (krill) Crus­ taceans Feeding Habits Feeding Activity Distance Source Eggs Chicks 

Procellariiformes (Albatrosses, Petrels and Shearwaters)LaysanAlbatross 

Highly Imperiled and HighConcern 

VU A4bd Nov - Jul Nov-Feb Jan-Jul X X X Surface feeding Nocturnal 1,000 km 

BlackfootedAlbatross 

Highly Imperiled and HighConcern 

EN A3bd Oct - Jul Oct-Feb Jan-Jul X X X Surface feeding Diurnal 700 km 

Short-tailedAlbatross 

VU D2 Endangered Nov - Feb Oct-Jan Jan-Jun X X X Surface feeding Diurnal Unknown 

BoninPetrel 

ModerateConcern 

LC Aug - Jun JanMarch Feb-Jun X X X Surface feed­ ing Nocturnal Unknown 

Bulwer’sPetrel 

ModerateConcern 

LC Apr - Oct May-Jul Jul-Oct X X X X Surface feeding Nocturnal Unknown 

WedgetailedShearwater 

Low or NotCurrently atRisk 

LC May - Dec May-Aug AugDec X X Contact dip­ ping / associated with large

predatory fi sh 

Diurnal 480 km 

ChristmasShearwater 

Highly Imperiled and HighConcern 

LC Feb - Oct April-Jul Jun-Oct X X Contact dipping and pursuit plunging /

associated withlarge predatoryfi sh 

Nocturnal Unknown 

Tristram’s StormPetrel 

Highly Imperiled and HighConcern 

NT Oct - May Dec-Feb FebMay X X Surface feed­ ing Nocturnal Unknown 

Pelecaniformes (Tropicbirds, Boobies and Frigatebirds)Red-footedBooby 

Low or NotCurrently atRisk 

LC Jan - Dec Jan -

Aug 

Mar -Dec 

X X Plunge diving /

associated withlarge predatoryfi sh 

Diurnal 276 km Flint 

MaskedBooby 

ModerateConcern 

LC Dec - Oct Jan - Jul Mar -

Oct 

X X Plunge diving /

associated withlarge predatoryfi sh 

Diurnal 158 km Flint 

BrownBooby 

ModerateConcern 

LC Jan - Oct Feb -

Aug 

April -Oct 

X X Plunge diving /

associated withlarge predatoryfi sh 

Diurnal 80 km USFWS,

2005 

GreatFrigatebird 

ModerateConcern 

LC Jan - Dec Feb - Jul April -

Nov 

X X Surface feeding / associated with large

predatory fi sh 

Diurnal 612 km Weimerskirch

et al.,2004 

Table 7.1. Life history and management Information for selected seabirds of the NWHI. Source: USFWS, unpub. data. 
Table 7.1 (Continued). Life history and management Information for selected seabirds of the NWHI. Source: USFWS, unpub. data. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

237 

BREEDING PERIOD FEEDING

BEHAVIOR 

ESTIMATED

FORAGING RANGE

FROM COLONIES

CommonName 

ProtectionStatus 

IUCN ESA Primary

Months ofPresence 

Months WhenBreeding 

Fish Fish

Eggs 

Cephaopods(squid, octopus) 

Ephausiids (krill) Crus­ taceans Feeding Habits Feeding Activity Distance Source Eggs Chicks 

LesserFrigatebird 

LC Feb - Jul Feb - Jul X X Surface feeding / associated with large

predatory fi sh 

Diurnal Unknown 

Red-tailedTropicbird 

ModerateConcern 

LC Feb - Nov Mar -

Aug 

April -Nov 

X X Plunge diving Diurnal 468 km Flint 

WhitetailedTropicbird 

LC Jan - Dec Jan -

Dec 

Jan -Dec 

X X Plunge diving Diurnal 374 km Flint 

Charadriiformes (Terns and Noddies)BlackNoddy 

ModerateConcern 

LC yeararound Nov - Jun Dec - Aug X X X Surface feed­ ing / associated with large

predatory fi sh 

Diurnal 80 km USFWS,

2005 

BrownNoddy 

Low or NotCurrently atRisk 

LC yeararound Jan - Oct Feb - Nov X X Surface feed­ ing / associated with large

predatory fi sh 

Diurnal 163 km Flint 

BlueNoddy 

HighlyImperiled andHigh Concern 

LC yeararound Jan ­ May Jan - Jun X Surface feed­ ing Diurnal Near- shore 

White Tern Moderate

Concern 

LC yeararound Jan - Dec Jan - Dec X X Surface feed­ ing / associated with large

predatory fi sh 

Diurnal Nearshore 

Sooty Tern Moderate

Concern 

LC Mar - Sep Mar - Jul April -

Sep 

X X Surface feeding / associated with large

predatory fi sh 

Primarilynocturnal 

740 km Flint,

1991 

GraybackedTern 

ModerateConcern 

LC Feb - Oct Feb -

Aug 

April -Oct 

X X X X Surface feeding / associated with large

predatory fi sh 

Diurnal 370 km USFWS,

2005 

Little Tern Moderate

Concern 

LC Feb - Oct Feb -

Aug 

April -Oct 

X X Plunge diving Diurnal 3 km USFWS,

2005 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

238 

NIHOA

ISLAND 

MOKUMANAMANA 

FRENCH FRIGATE SHOALS 

GARDNER

PINNACLES MARO REEF LAYSAN ISLAND LISIANSKI ISLAND 

PEARL AND HERMES ATOLL MIDWAY ATOLL KURE ATOLL 

Disappearing

Island 

Little Gin Island 

Gin Island 

Le Perouse

 Pinnacle 

East Island 

Round Island 

Shark Island 

Tern Island 

Trig Island 

Seal Kittery

Island 

Grass Island 

Southeast 

Island 

Bird Island 

Little North 

Island 

North Island 

Spit Island 

Eastern Island 

Sand Island 

Sand Island 

Green Island 

Black-footedAlbatross X X X X X X X X X X X X X X X X X X X LaysanAlbatross X X X X X X X X X X X X X X X X X X X Short-tailedAlbatrossBonin Petrel X X ? X X X X X X X X 

Bulwer’sPetrel X X X X X X X X X 

Wedge-tailed Shearwater X X X X X X X X X X X X X 

ChristmasShearwater X ? X X X X X X ? X X Tristram’sStorm-Petrel X X X X X X ? X X Red-tailedTropicbrid X X X X X X X X X X X X X X X White-tailedTropicbird X MaskedBooby X X X X X X X X X X X X X X X X X X X Brown Booby X X X X X X X X X X ? X X 

Red-footedBooby X X X X X ? X X X X X X X X X GreatFrigatebird X X X X X X X X X X ? X Lesser Frigate Bird X Little Tern X X X 

Grey-backedTern X X X X X X X X X X X X X X ? X X Sooty Tern X X X X X X X X X X 

BrownNoddy X X X X X X X X X X X X X X X X X X Black Noddy X X X X X X X X ? X X X 

Blue Noddy X X X X 

White Tern X X X X X X X X X 

Table 7.2. Seabird nesting distribution in the NWHI. Source: USFWS, unpub. data. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 7.3. Distribution of seabirds in the Pacific, Main Hawaiian Islands (MHI) and the NWHI. Source: USFWS, 2005. 

COMMON NAME SCIENTIFIC NAME NWHI MHI USPI 

Procellariiformes (Albatrosses, Petrels and Shearwaters) 

Black-footed Albatross Phoebastria nigripes B B B 

Laysan’s Albatross Phoebastria immutabilis B B B 

Short-tailed albatross Phoebastria albatrus b 

Hawaiian Petre Pterodroma sandwichensis B 

Herald Petrel Pterodroma arminjoniana B 

Tahiti Petrel Pterodroma rostrata B 

Bonin Petrel Pterodroma hypoleuca B Ex B 

Phoenix Petrel Pterodroma alba Ex 

Bulwer’s Petrel Bulweria bulwerii B B B 

Wedge-tailed Shearwater Puffi nus pacifi cus B B B 

Christmas Shearwater Puffi nus nativitatis B B B 

Newell’s Shearwater Puffinus auricularis newelli B1 

Audobon’s Shearwater Puffi nus lherminieri B 

Band-rumped Storm-Petrel Oceanodroma castro B B 

Black Storm-Petrel Oceanodroma melania B 

Tristram’s Storm-Petrel Oceanodroma tristrami B B 

Polynesian Storm-Petrel Nesofregetta fuliginosa B 

Pelecaniformes (Tropicbirds, Boobies and Frigatebirds) 

White-tailed Tropicbird Phaethon lepturus dorothea B B B 

Red-tailed Tropicbird Phaethon rubricauda melanorhynchos B B B 

Masked Booby Sula dactylatra personata B B? B 

Brown Booby Sula leucogaster plotus B B B 

Red-footed Booby Sula sula rubripes B B B 

Great Frigatebird Fregata minor palmerstoni B b B 

Lesser Frigatebird Fregata ariel ariel B 

Charadriiformes (Terns and Noddies) 

Little Tern Sterna albifrons sinensis B B 

Gray-backed Tern Sterna lunata B B? B 

Bridled Tern Sterna anaethetus B? 

Sooty Tern Sterna fuscata oahuensis B B? B 

Brown Noddy Anous stolidus pileatus B B B 

Black Noddy Anous minutus marcusi B B B 

Blue Noddy Procelsterna cerulea saxatilis B B? B 

White Tern Gygis alba alba B B B 

Note: 1Endemic 

Abbreviations: B = breeding; b = unsuccessful breeding attempts; B? = breeding suspected; Ex = extirpated breeders 

239 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

240 

PROCELLARIIFORMES (ALBATROSSES, PETRELS AND SHEARWATERS) 

Laysan Albatross (Phoebastria immutabilis) 

Laysan Albatrosses are a relatively small 

albatross species, with a body length of 

79-81 cm, a wingspan of 195-203 cm, 

and a mean body mass of 2.4 kg (Whittow, 1993; Suryan et al. 2008; Figure 

7.3). Like Black-footed Albatrosses (P. 

nigripes) and other Procellariiformes, 

males are slightly larger than females 

but feather plumage is identical for both 

sexes. Laysan Albatrosses have a white 

head, neck, and underparts, and sooty 

brown upper wings and trailing edges of 

under wings, and back. The legs, feet, 

and bill are pink but the bill also has a 

greenish tip (Whittow, 1993). 

When breeding, Laysan Albatrosses 

nest on all of the islands and atolls of 

the NWHI chain, and at discrete colonies on Kauai and Oahu, Torishima Island, Japan (Kurata, 1978), and off of 

the west coast of Baja, Mexico (USFWS, 

2005). A pair was also documented to 

have successfully bred on Wake Island 

in 2001 (USFWS, 2005; Figure 7.4). In 

the NWHI, egg laying and incubation 

are generally synchronous, occurring 

from November to January. Chicks are 

reared from late January to mid-July 

and fledge in mid to late July (USFWS, 

2005). Most birds breed every year but 

will occasionally skip a breeding event 

(Fisher, 1976). 

In the NWHI, predator control, including 

rat eradication, has reduced some of the 

threats to Laysan Albatrosses, but existing impacts to nesting habitat include 

the invasive wildflower golden crownbeard (Verbesina encelioides), other 

non-native plant species, obstacles to 

fl ying (USFWS, 2005), and lead toxicity in chicks at Midway from ingestion of lead paint chips from dilapidated 

buildings (Finkelstein et al., 2003). Threats at sea include the ingestion of marine debris (e.g., plastics), sea 

level rise and long-line bycatch (USFWS, 2005). 

When at sea, tracking studies reveal that Laysan Albatrosses are found throughout the North Pacific (including 

the Bering Sea) but generally range between 30°N and 55°N (Harrison, 1987; Fernandez et al., 2001; Hyrenbach et al., 2002; Shaffer et al., 2005). During the incubation period, adults conduct foraging excursions lasting 

10-30 days and may travel over 2,000 km from the nesting colony (Kappes et al., in review, Figures 7.4 and 

7.5). Albatrosses studied across several consecutive years (2002-2006) show that habitat use changes across 

years (Figure 7.5) but the environmental cues that putatively influence foraging effort remain the same across 

Figure 7.3. Laysan Albatross, Tern Island and French Frigate Shoals. Photo: C. Gregory. 

Figure 7.4. Laysan Albatross nesting sites and foraging areas in the NWHI. 

Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

years studied. That is, sea surface temperature (SST) and primary productivity levels appear to be the most 

important predictors of searching/foraging activity (Kappes et al., in review). During the chick-brooding period, 

adults are constrained by the need to provision their chick frequently so foraging excursions last only one to 

three days on average and range from the colony is typically less than 400 km (Kappes et al., unpublished 

data). When chicks are large enough to defend themselves and are thermally independent, both parents are 

able to forage simultaneously. During this period (i.e., chick-rearing), adults conduct both long and short duration foraging trips with some trips extending northward to the Aleutian Islands (Fernandez et al., 2001; Hyrenbach et al., 2002). When breeding is complete, adult Laysan Albatrosses depart the breeding colonies for cool 

waters of the Central and Western North Pacific including the Bering Sea and Aleutian Islands (Shaffer et al., 

submitted; Figure 7.5). Here, birds remain for most of the summer months while undergoing molt and recovering from breeding. Albatrosses return to the colonies in mid- to late-November to breed again. It is important 

to note the this species has only been tracked from a few of their breeding colonies, thus at sea distribution is 

not fully characterized. Laysan Albatrosses are surface feeders, with a diet consisting of squid, crustaceans, 

fish and flying fish eggs. At least 50% of the diet is composed of squid (USFWS, 2005). 

Figure 7.5. Laysan Albatross utilization distribution during brooding, incubation and postbreeding. Source: Shaffer et al., 

in review; maps: R. Clark. 

241 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

242 

Black-footed Albatross (Phoebastria nigripes) 

Black-footed Albatrosses are slightly 

larger than Laysan Albatrosses, with a 

body length of 64-74 cm, a wingspan of 

193-216 cm, and a mean body mass of 

2.8 kg (Awkerman et al., 2008; Suryan 

et al., 2008; Figure 7.6). Like Laysan 

Albatrosses, males are slightly larger 

than females but plumage is identical 

between the sexes. Black-footed Albatrosses are dusky-brown with white 

fringes around the base of the bill, under the eye, under the tail, and over the 

base of the tail (Harrison, 1987). 

Ninety eight percent of the breeding 

population occurs within the Monument. The species nests on all of the 

islands and atolls in the NWHI, with the 

majority of pairs nesting at Midway Atoll 

and on Laysan Island (USFWS, 2005; 

Figure 7.7). A few thousand (Awkerman 

et al., 2008) Black-footed Albatrosses 

also breed on discrete colonies in Japanese Islands, and several pairs have 

been observed prospecting at Guadalupe Island, Baja, Mexico. Within breeding colonies, Black-footed Albatrosses 

nest synchronously, with all females 

laying eggs within a few-week period. 

Throughout the Hawaiian archipelago, 

egg-laying and incubation generally occurs from October through December, 

and chicks are reared from January to 

June, with fledging occurring in midJune (Awkerman et al., 2008). Historical 

breeding areas include the Hawaiian archipelago and Marshall, Johnston, and 

Torishima Islands (Harrison, 1987). 

Within the Monument, many threats 

have been reduced over the years, but 

existing threats include ingestion of plastics, long-line bycatch, and sea level rise (USFWS, 2005; Lewison and 

Crowder, 2003). The Monument provides protection for breeding and nesting habitat, but only a small portion 

of the foraging range remains protected because of the wide ranging foraging behavior. 

When at sea, tracking studies reveal that Black-footed Albatrosses are found throughout the North Pacific 

(partially the Bering Sea) but generally they range between 25°N and 50°N (Harrison, 1987; Fernandez et 

al., 2001; Hyrenbach et al., 2002; Shaffer et al., 2005). During the incubation period, adults conduct foraging 

excursions lasting 10-20 days in duration and may travel over 1,500 km from the nesting colony (Kappes et 

al., in review; Figures 7.7 and 7.8). Adults tend to head north-northeast of the breeding islands to warmer waters along the southern edge of the North Pacific Current. Like Laysan Albatrosses, Black-footed Albatrosses 

studied across multiple consecutive years (2002-2006) use slightly different habitat across years (Figure 7.8) 

but the environmental cues that putatively influence foraging effort remain the same across years studied. That 

Figure 7.6. Black-footed Albatross, Tern Island and French Frigate Shoals. 

Photo: C. Gregory. 

Figure 7.7. Black-footed Albatross nesting sites and foraging areas in the 

NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

is, SST and primary productivity levels appear to the most important predictors of searching/foraging activity 

(Kappes et al., in review). During the chick-brooding period, adult Black-footed and Laysan Albatrosses experience the greatest overlap in their distribution because adults are constrained by the need to provision their 

chick frequently; thus foraging excursions last only one to three days on average and ranges are typically less 

than 300-400 km from the colony (Kappes et al., unpublished data). During the chick-rearing period, adults 

conduct both long and short duration foraging trips with some trips extending to the west coast of the U.S. and 

Canada (Fernandez et al., 2001; Hyrenbach et al., 2002). After breeding, adult Black-footed Albatrosses leave 

the breeding colonies for rich productive waters of the California Current and Aleutian Islands (Hyrenbach 

et al., 2006; Fischer, 2008; Shaffer et al., submitted; Figure 7.8). Thus, the spatial overlap with Laysan Albatrosses during the non-breeding period can be relatively minor (<10%; Shaffer et al., submitted). Black-footed 

Albatrosses remain along the West Coast of the U.S. or Aleutian Islands for most of the summer months while 

undergoing molt and recovering from breeding. Albatrosses return to breeding colonies in mid- to late-October 

to breed again. It is important to note the this species has only been tracked from a few of their breeding colonies, thus at sea distribution is not fully characterized. The species is a surface feeder, with a diet including 

fish eggs, squid, crustaceans, fish, and zooplankton. Forty percent of the diet is composed of flying fish eggs 

(USFWS, 2005). 

243 

Figure 7.8. Black-footed Albatross utilization distribution during brooding, incubation and postbreeding. Source: Shaffer 

et al., in review; maps: R. Clark. 
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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

244 

Short-tailed Albatross (Phoebastria albatrus) 

Short-tailed Albatrosses are larger than 

Laysan and Black-footed Albatrosses, 

with a mean wingspan of 237 cm and 

mean body mass of 4.3 kg (Brooke, 

2004; Suryan et al., 2008). Short-tailed 

Albatrosses are similar in appearance 

to Laysan Albatrosses, but are larger, 

with a heavier bright pink bill, and with 

a yellow wash on the white plumage of 

the head and neck (Harrison, 1990; Figure 7.9). 

Short-tailed Albatrosses historically 

ranged throughout the North Pacific, but 

current breeding sites include only Torishima and Minami-kojima, Japan (USFWS, 2005). Short-tailed Albatrosses periodically do attempt to breed at Midway 

Atoll, but there are no documented accounts of successful nesting (USFWS, 

2005). Eggs are laid from October to 

November and fledging occurs in June. 

The Short-tailed Albatross is listed as Endangered under the Endangered Species Act (ESA) throughout its 

range. Within the Monument, threats are minimal relative to other potential colony sites, and management actions are taking place to encourage nesting at Midway Atoll. Tracking studies show that these albatrosses generally remain in the Western Pacific when breeding, and then move further north into the Bering Sea and along 

the Aleutian Islands (Suryan et al., 2006). Based on the large body size of Short-tailed Albatrosses compared 

to Laysan and Black-footed albatrosses, Short-tailed Albatrosses would appear to have a more restricted 

range that occurs within regions of stronger winds and larger wave heights (Suryan et al., 2008). 

Bonin Petrel (Pterodroma hypoleuca) 

Bonin Petrels are 30 cm long with a 

wingspan of 63-71 cm and a mean body 

mass of 204 g. Plumage on the upper 

parts is blue- to silver-gray, with a sooty 

head and neck, and white forehead, 

chin and throat. Upper wings are gray 

with black primaries, and the underwing 

is white with black margins (Seto and 

O’Daniel, 1999; Figure 7.10). 

Bonin Petrels are found throughout the 

western north Pacific and breed in the 

NWHI and on Volcano and Bonin Islands 

in Japan. There are no breeding colonies of Bonin Petrels in the Main Hawaiian Islands (MHI; Harrison, 1987). 

In the NWHI, Bonin Petrels nest at 

French Frigate Shoals, Laysan Island, 

Lisianski Island, Pearl and Hermes Atoll, Midway Atoll and Kure Atoll. Gardner Pinnacles may also provide 

nesting habitat. Lisianski Island, Laysan Island and Midway Atoll support the largest colonies in the archipelaFigure 7.9. Short-tailed Albatross. Photo: J. Lloyd. 

Figure 7.10. Bonin Petrel. Photo: C. Gregory. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

go (Figure 7.11). In the NWHI, eggs are 

laid from December to March and chicks 

are reared from February to May. 

Bonin Petrels are nocturnal surface 

feeders, with a diet consisting mainly of 

fish (USFWS, 2005). 

Habitat loss from erosion and invasive 

plant species are some of the main 

threats to the populations in the NWHI. 

Historically, introduced Polynesian rats 

posed a serious threat to Bonin Petrel 

populations, but rats were extirpated in 

the NWHI by the year 2000. The U.S. 

Fish and Wildlife Service (USFWS) has 

also modified light sources at Midway 

Atoll and French Frigate Shoals to reduce impacts to nocturnal seabird species, including the Bonin Petrel. Figure 7.11. Bonin Petrel nesting sites in the NWHI. Source: USFWS, unpub. data; map: K. Keller. 

245 

Bulwer’s Petrel (Bulweria bulwerii)
 

The Bulwer’s Petrel is 26 cm long with 


a 67 cm wingspan (Harrision, 1987). 


Plumage is sooty brown, with a lighter brown face and chin (Megysi and 


O’Daniel, 1997; Figure 7.12).
 

The Bulwer’s Petrel is a wide-ranging 


species occurring in the tropical and 


subtropical waters of the Pacific, Atlantic and Indian Oceans (Harrision, 1987). 


In the Pacific, Bulwer’s Petrels breed in 


the Phoenix, Marquesas, Bonin, Volcano and Hawaiian Islands, including the 


NWHI and MHI (USFWS, 2005). From 


the little that is known about the species’ at-sea distribution, it appears that 


the Hawaiian populations travel to the 


central and eastern Pacific during the 


non-breeding period (USFWS, 2005).
 

In the NWHI, Bulwer’s Petrels have 


been found to breed at Nihoa Island, Mokumanamana, French Frigate Shoals, Laysan Island, Lisianski Island, 


Pearl and Herrmes Atoll and Midway Atoll (Figure 7.13). The largest breeding colony occurs on Nihoa Island. 


Bulwer’s Petrels lay eggs in the NWHI between May and July. Chicks are present from July to October, and 


fledging occurs by early October. 


Bulwer’s Petrels are nocturnal surface feeders, with a diet composed of fish, squid, crustaceans and sea-


striders. Most of the prey species are bioluminescent and are found in upwelling areas (USFWS, 2005).
 

Figure 7.12. Bulwer’s Petrel. Photo: USFWS. 
Seabirds

246 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

As seen with many of the seabirds in the 

NWHI, Bulwer’s Petrels suffered losses 

to Polynesian rat and ant introductions. 

Wedge-tailed Shearwater 

(Puffi nus pacifi cus) 

The Wedge-tailed Shearwater is 43 cm 

long, with a wingspan of 101 cm (Harrison, 1987; Figure 7.14), and a mean 

body mass of 390 g (Whittow, 1997). 

Light-morph shearwaters are grayish 

brown above, with white underparts, 

while dark-morph individuals are sooty 

brown above and below (Whittow, 

1997). 

Wedge-tailed Shearwaters occur 

throughout the tropic and subtropical 

Pacific and Indian Oceans, including the 

NWHI (Harrison, 1987). The Hawaiian 

populations most likely migrate to the 

Equatorial Countercurrent and east during the non-breeding period (USFWS, 

2005). This species aggregates into 

large multi-species feeding flocks, often 

associated with subsurface predators 

(e.g., tuna and dolphin). 

Wedge-tailed Shearwaters nest on all 

of the islands and atolls in the NWHI 

(Figure 7.15). The largest colonies within the archipelago are at Nihoa Island, 

Laysan Island and Lisianski Island. In 

the NWHI, eggs are laid from June to 

August and chicks are present from August to December, with the majority of 

fledging occurring in November. 

Wedge-tailed Shearwaters use contact 

dipping for feeding, and their diet in the 

Hawaiian Archipelago consists mainly 

of larval goatfi sh, fl ying fi sh, squirrelfi sh 

and squid (USFWS, 2005). 

Figure 7.13. Bulwer’s Petrel nesting sites in the NWHI. Source: USFWS, 

unpub. data; map: K. Keller. 

Figure 7.14. Wedge-tailed Shearwater light and dark morphs, Tern Island, 

French Frigate Shoals. Photo: USFWS. 

Figure 7.15. Wedge-tailed Shearwater nesting sites and foraging areas in 

the NWHI. Source: USFWS, unpub. data; map: K. Keller. . 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Christmas Shearwater (Puffi nus nativitatis) 

Christmas Shearwaters are 36 cm long 

with a 76 cm wingspan (Harrison, 1987), 

and a mean body mass of 354 g (Seto, 

2001). Plumage is dark brown throughout, with underparts slightly paler than 

upperparts (Seto, 2001; Figure 7.16). 

Christmas Shearwaters occur in the 

tropical and subtropical Pacific (Harrison, 1987). The species nests on all of 

the islands and atolls in the NWHI, with 

the largest breeding colonies occurring 

on Laysan Island and Lisianski Island 

(USFWS, 2005; Figure 7.17). Females 

lay eggs from April through July, and 

chicks are reared from June to October. 

Christmas Shearwaters use pursuit and 

plunge feeding behavior, with a diet 

composed of fi sh (goatfi sh, fl ying fi sh 

and scad) and squid (USFWS, 2005). 

Nesting habitat degradation due to the 

spread of non-native invasive plant species is the most significant threat to the 

species in the NWHI. 

Figure 7.16. Christmas Shearwaters, Tern Island and French Frigate 

Shoals. Photo: D. Wright. 

247 

Figure 7.17. Christmas Shearwaters nesting sites in the NWHI. Source:

USFWS, unpub. data; map: K. Keller. 
Seabirds

248 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Tristram’s Storm-petrel (Oceanodroma tristrami) 

The Tristram’s Storm-petrel is the smallest Procellariiformes species in the 

NWHI. It averages 24 cm in length, with 

a 56 cm wingspan and a mean body 

mass of 77-97 g. The species is brownish gray throughout, with a buffy brown 

wing bar across the upper wing (Slotterback, 2002; Figure 7.18). 

The Tristram’s Storm-petrel range includes the subtropical central and western Pacific and waters off of Japan. 

Breeding colonies occur in the NWHI, 

but there is no evidence of colonies in 

the MHI (USFWS, 2005). 

The species is found on Nihoa Island, Mokumanamana, French Frigate 

Shoals, Laysan Island, Lisianski Island, 

and Pearl and Hermes Atoll. The largest colonies are at Nihoa Island, Laysan 

Island, and Pearl and Hermes Atoll (Figure 7.19). In the NWHI, eggs are laid 

from December to February, and chicks 

are present from February to May. Most 

birds have dispersed by June. 

The feeding behavior of Tristram’s 

Storm-petrels consists of pattering and 

snatching prey from the surface. Generally, the diet in the NWHI consists of 

small fish and squid and sometimes 

planktonic halobates (insects) and crustaceans (USFWS, 2005). 

Breeding colonies were extirpated from 

Midway Atoll and Kure Atoll, most likely 

by the introduction of rats. Recolonization is possible due to the eradication 

of rats from these locations by the year 

2000. Nesting habitat degradation from 

invasive plant species continues to be a threat at Pearl and Hermes Atoll. 

Figure 7.18. Tristram’s Storm-petrel, Tern Island and French Frigate Shoals. 

Photo: C. Gregory. 

Figure 7.19. Tristram’s Storm-petrel nesting sites in the NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

PELECANIFORMES (BOOBIES, FRIGATEBIRDS AND TROPICBIRDS) 

Red-footed Booby (Sula sula rubripes) 

The Red-footed Booby is the smallest 

of the booby species worldwide, with a 

length of 69-79 cm and body mass of 

850-1,100 g (Schreiber et al.,1996; Figure 7.20). Females are slightly larger 

than males. Adults in the NWHI are 

white, often with a yellowish wash on 

the head and neck, with black primaries, 

secondaries and coverts. A tan morph 

also occurs in the NWHI, but is present 

in much lower numbers and is seen only 

rarely (A. Anders, pers. comm.). Bills of 

females are blue with a pink base, and 

those of males lighter blue with a lime 

green and pink base. Legs and feet 

are orange-red to red (Schreiber et al., 

1996). 

Red-footed Boobies are a pantropical species, with the largest breeding 

colonies occurring in Palmyra and the 

Hawaiian Islands. Red-footed Boobies 

nest on all of the islands and atolls in the 

NWHI, as well as on Kauai, Oahu and 

offshore islets in the MHI (Figure 7.21). 

The species lays eggs from March to 

August and chicks occur from May to 

December. 

The species forages farther than other 

boobies, ranging up to 276 km from the 

nesting colony (USFWS unpublished 

data; Figure 7.21). During the nonbreeding period, the birds have been 

observed to travel several hundred kilometers from land (USFWS, 2005). The 

Red-footed Booby is a plunge diver, with 

primary prey species including flying fish 

and squid. This species often forages in 

large, multi-species flocks associated 

with subsurface predator. 

Habitat destruction is the main threat to populations in the NWHI (USFWS, 2005). 

Figure 7.20. Red-footed Boobies, Tern Island, French Frigate Shoals. Photo: USFWS. 

249 

Figure 7.21. Red-footed boobies nesting sites and foraging areas in the

NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

250 

Masked Booby (Sula dactylatra personata) 

Masked Boobies are the largest of the 

booby species, with a body length of 

74-86 cm, and body mass of 1.2-2.4 

kg. As with many other Pelecaniformes 

species, females are slightly larger than 

males. Adults are white with black-brown 

primaries, secondaries and tail, and purplish orange feet (Anderson, 1993; Figure 7.22). 

Masked Boobies are a pantropical species, with the largest breeding colonies 

occurring on Howland, Baker and Jarvis. 

In the NWHI, the species occurs on all 

of islands and atolls (Figure 7.23). Eggs 

are present from January to July, and 

chicks occur from March to October. 

During the breeding season, birds forage up to 160 km from the breeding colonies (USFWS unpublished data; Figure 7.23), and during the non-breeding 

period individuals may travel from 1,000 

– 2,000 km from the breeding colonies 

(USFWS, 2005). Masked Boobies are 

plunge divers, with the majority of the 

diet consisting of fish, particularly flying 

fish and jacks. A very small portion of 

the diet is squid (USFWS, 2005). 

The primary threats to the Masked booby populations in the NWHI are habitat 

destruction and loss of nesting habitat 

due to invasive plants (USFWS, 2005). 

Figure 7.22. Masked Booby with chick, Tern Island, French Frigate Shoals. 

Photo: NOAA. 

Figure 7.23. Masked Booby nesting sites and foraging areas in the NWHI.

Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Brown Booby (Sula leucogaster plotus) 

The Brown Booby is a medium-sized 

booby, with a body length of 64-85 

cm, a wingspan of 132-155 cm, and 

body mass of 950-1,800 g (Schreiber 

and Norton, 2002). Females are markedly larger than males. Adults are deep 

brown on the back, head, neck and 

throat, with bright white underparts. In 

the NWHI, adults have a pale yellow bill 

with a light blue base, and bluish yellow 

legs and feet (A. Anders, pers. comm.; 

Schreiber and Norton, 2002; Figure 

7.24). 

The Brown Booby distribution overlaps 

with those of the masked and Red-footed Booby species, which are pantropical (USFWS, 2005). The largest brown 

booby populations occur in the Hawaiian Islands, including the NWHI and 

MHI. The species nests within all of the 

islands and atolls of the NWHI. Brown 

Boobies lay eggs from February to August, and chicks are present from April 

to October (Figure 7.25). 

Foraging occurs near shore, at 8-70 km 

from land (USFWS, 2005; Figure 7.25). 

The species has been known to travel 

2,000 km from breeding colonies during 

the nonbreeding season, but individuals 

generally remain within 80 km of land 

during the breeding period (USFWS, 

2005). Brown Boobies are plunge divers, with primary prey species consisting of flying fish, squid, mackerel scad 

and juvenile goatfish (USFWS, 2005). 

As with the other Booby species, the 

main threat to Brown Booby populations 

in the NWHI is habitat destruction (USFWS, 2005). 

Figure 7.24. Brown Booby, Tern Island, French Frigate Shoals. Photo: J. 

Drury. 

251 

Figure 7.25. Brown Booby nesting sites and foraging areas in the NWHI.

Source: USFWS, 2005; map: K. Keller. 
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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

252 

Great Frigatebird (Fregata minor palmerstoni) 

Frigatebirds have the largest wing-area 

to body mass ratio of any avian species: 

Great Frigatebirds, with a length of 85­

105 cm and wingspan of 205-230 cm, 

have a body mass of just 1-1.8 kg (Gauger Metz and Schreiber, 2002). Males are 

black or black-brown throughout, with a 

purple/blue/green sheen on the dorsal 

feathers of the neck and nape, and a 

red gular sac. The gular pouch is deflated and a pale pink-orange color during 

the non-breeding period, and becomes 

bright red and is inflated during display 

prior to the nesting period. Females are 

significantly larger than males, with a 

white throat, breast, and underparts 

and no (or a greatly reduced) gular sac 

(Gauger Metz and Schreiber, 2002; Figure 7.26). 

The distribution of Great Frigatebirds is 

pantropical, with the largest breeding 

populations occurring on Nihoa Island 

and Laysan Island (USFWS, 2005). 

Great Frigatebirds nest on all of the islands and atolls within the NWHI except 

Gardner Pinnacles and Kure Atoll (Figure 7.27). In the NWHI, eggs are laid 

between March and July, and chicks are 

present from April to November. 

Foraging ranges during the breeding 

season have been calculated to be up to 

612 km (Weimerskirch et al., 2004), but 

frigatebirds travel up to 7,000 km during the non-breeding period (Dearborn 

et al., 2003; Figure 7.27). Great Frigatebirds cannot swim or land on water, and 

thus use surface dipping and aerial pursuit to capture prey. The main prey species are flying fish and squid (USFWS, 

2005). 

The greatest threats to populations in the NWHI are habitat destruction and disturbance during nesting. 

Figure 7.26. Male Great Frigatebird with inflated gular pouch, Tern Island, 

French Frigate Shoals. Photo: D. Dearborn. 

Figure 7.27. Male Great Frigatebird nesting sites and foraging areas in the

NWHI. Source: Weimerskirch et al., 2004; map: K. Keller. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Lesser Frigatebird (Fregata ariel ariel) 

Lesser Frigatebirds are significantly 

smaller than Great Frigatebirds, with 

a mean body length of 75 cm (Lindsey, 1986). Male plumage is similar to 

that of the Great Frigatebird, but with 

overall body plumage of lessers being 

darker black and with a brighter purple 

and green irredescence to the dorsal 

neck and nape feathers (Figure 7.28). 

Lesser males also have a bright white 

line on the underside of the wing, providing an obvious distinction in flight to 

the male Great Frigatebird (A. Anders, 

pers. comm.). Female lesser plumage 

is similar to that of female Great Frigatebirds, but with darker black feathers 

dorsally, and a full black hood giving a 

black, rather than white, throat (A. Anders, pers. comm.). 

The pantropical distribution of Lesser 

Frigatebirds lies within that of Great 

Frigatebirds, with the largest breeding 

colonies occurring on Baker and Howland Islands (USFWS, 2005). Individuals are observed roosting regularly but 

in low numbers in the NWHI; successful nesting of a Lesser Frigatebird male 

and Great Frigatebird female (with production of hybrid offspring) has been 

observed in multiple years at French 

Frigate Shoals (Figure 7.29), and one 

pair of Lesser Frigatebirds has been 

documented nesting on Tern Island, although the nest failed prior to hatching 

(Dearborn and Anders, 2000). 

As with Great Frigatebirds, Lesser Frigatebirds use surface dipping to capture 

prey, and main food items include flying fish and squid. Lesser Frigatebirds 

travel thousands of kilometers from the breeding colonies during the non-breeding period, but are seen most 

often within 80 km of breeding and roosting islands (USFWS, 2005). 

Figure 7.28. Lesser Frigatebird. Photo: USFWS. 

253 

Figure 7.29. Lesser Frigatebird nesting sites in the NWHI. Source: USFWS,

unpub. data; map: K. Keller. 
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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

254 

Red-tailed Tropicbird (Phaethon rubricauda melanorhynchos)
 

Red-tailed Tropicbirds are a relatively 


small, stout Pelecaniformes species, 


with a body length of 44-47 cm (80-102 


cm including long central tail feathers), 


and body mass of 650-780 g (Schreiber 


and Schreiber, 1993). Plumage is white 


throughout, often with a pale pink wash. 


The bill is red-orange, and a black crescent eye ring extends to a short eye line 


(Figure 7.30). The tail is short and white, 


with two long red central rectrices.
 

The Red-tailed Tropicbird is distributed 


throughout the Indo-Pacific region between 35°N and 30°S. The largest concentration of breeding birds within the 


Pacific occurs in the NWHI at Midway 


Atoll and Laysan Island (Figure 7.31). 


Other smaller colonies are found on 


all of the other islands and atolls in the 


NWHI, in the MHI, and on other Pacific 


Islands such as Johnston Atoll, American Samoa, Wake and the Marianas 


(USFWS, 2005). Red-tailed tropicbirds 


lay eggs from March to August and 


chicks occur from April to November. 


Foraging ranges have been calculated 


to be approximately 470 km from the 


breeding colonies, which extends beyond the boundaries of the Monument 


(USFWS unpublished data; Figure 


7.31). Red-tailed Tropicbirds are solitary, plunge divers and feed mostly on 


flying fish. Other prey species include 


squid, mackerel scad, dolphinfish, truncated sunfish and balloonfish (USFWS, 


2005). They are not associated with 


subsurface predator schools.
 

In the NWHI, rats on Midway Atoll and 


Kure Atoll, along with invasive plants, 


were the main threats to the species. 


Rats have been eradicated, and USFWS is currently conducting native plant restoration and other alien species removal projects to increase available nesting habitat.
 

Figure 7.30. Red-tailed Tropicbird, Tern Island, French Frigate Shoals. Photo: C. Gregory. 

Figure 7.31. Red-tailed Tropicbird nesting sites and foraging areas in the 

NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

White-Tailed Tropicbird (Phaethon lepturus dorothea) 

White-tailed Tropicbirds are similar in 

appearance to Red-tailed Tropicbirds, 

but are smaller and more slender, with 

a total length of 60-80 cm (including the 

central rectrices), a wingspan of 90-95 

cm, and a mean body mass of 350 g 

(Lee and Walsch-Mcgehee, 1998). As 

with Red-tailed Tropicbirds, body plumage is white, often with a pink wash, but 

the long central rectrices are white, and 

the bill is more orange than red (Lee and 

Walsch-Mcgehee, 1998; Figure 7.32). 

White-tailed Tropicbirds range throughout the tropics with the exception of 

the eastern Pacific and northeastern 

Atlantic. The largest colonies in the 

Pacific occur on American Samoa and 

the MHI. Smaller colonies are found at 

Midway Atoll, Palmyra, Wake and the 

Marianas (USFWS, 2005). Within the 

NWHI, White-tailed Tropicbirds nest 

only at Midway Atoll, where a few pairs 

may breed throughout the year (Figure 

7.33). White-tailed Tropicbirds may be 

competitively excluded from other islands in the northwestern chain by Redtailed Tropicbirds; in areas of sympatry, 

the larger Red-tailed Tropicbirds do often outcompete White-tails for nest sites 

(Harrison, 1990). 

White-tailed Tropic birds forage at distances up to 120 km from nesting colonies (USFWS, 2005; Figure 7.33), such 

that the foraging range extends beyond 

the boundaries of the Monument. The 

species are solitary, plunge divers and 

feed mainly on flying fish without aggregations into multi-species feeding fl ocks 

with other seabirds. 

Introduced predators are the greatest 

threat throughout the breeding range. 

Figure 7.32. White-tailed Tropicbird, Sand Island, Midway Atoll. Photo: K. 

Starr. 

255 

Figure 7.33. White-tailed Tropicbird nesting sites and foraging areas in the 

NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

256 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

CHARADRIIFORMES (TERNS AND NODDIES) 

Black Noddy (Anous minutus marcusi) 

The Black Noddy is similar in appearance to the Brown Noddy, but with a 

smaller body size (length 35-40 cm, and 

body mass 85-140 g), and darker brown 

plumage throughout. The head is graybrown, fading to grayish-white on the 

forehead, and with a white crescent on 

the lower eye. The bill is black, and legs 

and feet are reddish brown to orange 

(Gauger, 1999; Figure 7.34). 

Black Noddies are a pantropical species, and the largest colonies in the 

NWHI are at Midway Atoll and Nihoa 

Island (USFWS, 2005; Figure 7.35). In 

the NWHI, Black Noddies can breed 

year around, but in general eggs are laid 

between October and June, and chicks 

are present from December to August. 

Breeding adults forage within 80 km of 

nesting colonies and often forage near 

shore <10 fm (USFWS, 2005; Figure 

7.35). Black Noddies feed by surface 

dipping, and prey species include juvenile and larval goatfish, lizardfish, herring, fl ying fi sh and gobies. 

Habitat loss, predation, invasive species and disturbance are all threats to 

Black Noddy populations. Introduced 

insects at Kure Atoll and increases in 

the invasive golden crown-beard have 

had negative impacts on nesting habitat 

(USFWS, 2005). 

Figure 7.34. Black Noddy, Tern Island, French Frigate Shoals. Photo: C. 

Gregory. 

Figure 7.35. Black Noddy nesting sites and foraging areas in the NWHI.

Source: USFWS, 2005; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Brown Noddy (Anous stolidus pileatus) 

Brown Noddies are a medium-sized 

tern species; they are slightly larger 

than Black Noddies, with a length of 40­

45 cm and a mean body mass of 180 

g. Body plumage is chocolate-brown 

throughout, with a gray-brown head, 

grayish-white forehead, and white eye 

ring. The bill is black, and legs and feet 

are dark gray to black (Chardine and 

Morris, 1996; Figure 7.36). 

Brown Noddies are a pantropical species, with breeding colonies occurring at 

American Samoa, the Marianas, Johnston Atoll and the NWHI. The largest 

colony in the NWHI is on Nihoa Island 

(USFWS, 2005; Figure 7.37). In the 

NWHI, females lay eggs between January and May, and chicks are present 

from February to November. 

Foraging during the breeding season 

occurs within sight of the nesting colonies. During the nonbreeding season, 

the birds are known to stay within 100 

km of the nesting colonies (USFWS, 

2005; Figure 7.37). Brown Noddies feed 

by surface dipping, and prey includes 

goatfish, lizardfish, mackerel scad, flying fish and squid. (USFWS, 2005) 

Predators are the greatest threat to 

Brown Noddy populations. 

Figure 7.36. Brown Noddy, Tern Island, French Frigate Shoals. Photo: 

NOAA. 

257 

Figure 7.37. Brown Noddy nesting sites and foraging areas in the NWHI.

Source: USFWS, 2005; map: K. Keller. 
Seabirds

258 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Blue Noddy of Blue-Gray Noddy (Procelsterna cerulea saxatilis) 

The Blue Noddy is the world’s smallest 

tern species. Body plumage is bluishgray throughout, with slightly lighter 

coloration on the head and ventral surfaces, and a white eye ring. Primaries 

and tail are dark gray. Bill and legs dark 

gray, and feet are gray with yellowgray webbing (http://www.state.hi.us/ 

dlnr/dofaw/cwcs/Conservation_need. 

htm#Species; A. Anders, pers. obs.; 

Figure 7.38). 

Blue Noddies are found throughout the 

Pacific, with the largest nesting colonies 

on Nihoa Island and Mokumanamana 

(USFWS, 2005). Blue Noddies nest in 

the eastern portion of the NWHI on Nihoa Island, Mokumanamana, French 

Frigate Shoals (on La Perouse Pinnacle) and Gardner Pinnacles (Figure 

7.39). On these islands, Blue Noddies 

lay eggs between January and May, 

and chicks are present from January to 

June. There is some variation in breeding times between islands. The species 

is generally considered a year-round 

resident to the Hawaiian Islands. 

Blue Noddies feed by surface dipping 

and feed mainly on larval lizardfishes, 

fl ounders, goatfi shes and fl ying fi sh. 

They have also been known to take 

squid, crustaceans and halobates (USFWS, 2005). 

Natural predators are the main threat to 

blue noddies. 

Figure 7.38. Blue Noddy, La Perouse Pinnacle, French Frigate Shoals. 

Photo: D. Wright. 

Figure 7.39. Blue Noddy nesting sites in the NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

White Tern (Gygis alba alba) 

White Terns are a medium-sized tern 

species, with a length of 27-33 cm, 

wingspan of 70-87 cm, and body mass 

of 77-157 g. Body plumage is entirely 

white, with a black eye ring. The bill is 

black, and legs and feet are gray-blue 

with yellow-white webs (Niethammer 

and Patrick, 1998; Figures 7.40). 

The White Tern is a pantropical species, 

with the largest colonies in the NWHI 

occurring on Nihoa Island and Midway 

Atoll (Figure 7.41). Other islands including American Samoa and the Marianas 

also support large populations (USFWS, 

2005). In the NWHI the species breeds 

year-around. 

White Terns forage in near-shore waters 

during the breeding season. The species forages by surface diving, plunging and dipping. Prey includes juvenile 

goatfish and flying fish, while a smaller 

portion of the diet is composed of squid, 

needlefishes, halfbeaks, dolphinfishes 

and blennies (USFWS, 2005). 

Figure 7.40. White Tern with chick, Tern Island, French Frigate Shoals. 

Photo: NOAA. 

259 

Figure 7.41. White Tern nesting sites in the NWHI. Source: USFWS, unpub. 

data; map: K. Keller. 
Seabirds

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

260 

Sooty Tern (Sterna fuscata oahuensis) 

The Sooty Tern is a medium-sized tern 

species, with a length of 36-45 cm, a 

wingspan of 82-94 cm, and mean body 

mass of 200 g (Schreiber et al., 2002). 

Body plumage is deep black dorsally 

and on the tail, with a highly-contrasting white face, throat, and underbelly. 

A white patch on the forehead extends 

to just above the eye, creating a black 

eyeline. The bill, legs, and feet are black 

(Schreiber et al., 2002; Figure 7.42). 

Sooty Terns are a pantropical species. 

The largest colonies in the NWHI occur 

at Laysan Island and Lisianski Island. 

Baker and Jarvis support equally large 

populations (USFWS, 2005; Figure 

7.43). Sooty Terns breed on all islands 

and atolls in the NWHI, with eggs laid 

between March and July and chicks 

present from April to September. 

Sooty Tern foraging distances have 

been calculated to be 740 km (USFWS, 

unpublished data) during the breeding 

season and 5,000 km during nonbreeding season (Figure 7.43). Sooty Terns 

feed by surface dipping, and main prey 

species include squid, goatfish, flying fish and mackerel scad (USFWS, 

2005). 

Introduced predators are a major 

threat to Sooty Terns. While rats have 

been eradicated from the NWHI, cattle 

egrets continue to take chicks at Midway Atoll (USFWS, 2005). In addition to 

introduced predators, native predators 

such as Great Frigatebirds and Laysan 

Finches also prey on Sooty Tern eggs 

and chicks. Figure 7.43. Sooty Tern nesting sites and foraging areas in the NWHI. 

Source: USFWS, unpub. data; map: K. Keller. 

Figure 7.42. A Sooty Tern at Tern Island, French Frigate Shoals. Photo: C. 

Gregory. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Gray-Backed Tern (Sterna lunata) 

Gray-backed Terns are a mediumsized Tern, with a length of 35-38 cm 

and body mass of 95-145 g. The upper 

wings, back, and tail are slate-gray, and 

the throat, belly, and underwings are 

white. The head is white with a full black 

cap and black eyeline, and the bill, legs, 

and feet are black (Mostello et al., 2000; 

Figure 7.44). 

Gray-backed Terns are found in the 

tropical and subtropical Pacific, with the 

largest breeding colonies at Lisianski 

Island, Nihoa Island and Laysan Island. 

Smaller colonies are found on Johnston, Wake and Jarvis (USFWS, 2005). 

Gray-backed Terns nest on all islands 

and atolls in the NWHI, with eggs laid 

from March to July, and chicks present 

from April to September (Figure 7.45). 

Gray-back Terns have been estimated 

to forage up to 370 km from land, which 

includes areas outside of the Monument 

(USFWS, 2005; Figure 7.45). Graybacked Terns feed by hovering and dipping; prey species include five-horned 

cowfi sh, juvenile fl ying fi sh, goatfi sh, 

herring and dolphinfish. Additional prey 

include squid, crustaceans, mollusks, 

and marine and terrestrial insects (USFWS, 2005). 

As with other seabird species, habitat destruction and disturbance are the 

greatest threats to this species in the 

NWHI (USFWS, 2005). 

Figure 7.44.. Gray-backed Tern. Photo: F. Starr. 

261 

Figure 7.45. Gray-backed Tern nesting sites and foraging areas in the 

NWHI. Source: USFWS, unpub. data; map: K. Keller. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

262 

Little Tern (Sterna albifrons sinensis) 

The distribution of Little Terns (Figure 

7.46) is pantropical; however, populations in the NWHI are very small and 

have been found only at Pearl and 

Hermes and Midway Atolls (USFWS, 

2005), and French Frigate Shoals (A. 

Anders, pers. comm.; Figure 7.47). Little Terns breed in the spring. 

During the breeding season, the species stays within 3 km of the breeding 

colonies while foraging. Little Terns are 

shallow-water plunge divers, with a diet 

consisting of small fi sh, crustaceans, insects, annelids and mollusks (USFWS, 

2005). 

Habitat destruction and disturbance are 

two of the threats faced by Little Terns. 

The breeding-season foraging range is 

completely protected within the boundaries of the Monument. 

Figure 7.46. Little Tern. Photo: D. Mason, www.realbirder.com. 

Figure 7.47. Little Tern nesting sites in the NWHI. Source: USFWS, unpub. 

data; map: K. Keller. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

POPULATION STATUS AND TRENDS 

Available Data 

Large-scale monitoring of seabird populations in the NWHI began in the early 1960s, with the Smithsonian 

Institution’s Pacific Ocean Biological Survey Program (POBSP). This program was followed by Tripartite Cooperative Agreement Studies in the late 1970s and early 1980s, and by the current long-term monitoring program initiated in 1980 by the USFWS at French Frigate Shoals, Midway Atoll and Laysan Island. The current 

USFWS seabird monitoring program provides information on seabird populations over time within French Frigate Shoals, Midway and Laysan, but geographical comparisons are difficult, as data collection methods have 

differed across these locations. 

Pacific Ocean Biological Survey Program 

The POBSP was conducted throughout the Pacific by the Smithsonian Institution from 1963-1970. The Smithsonian’s surveys included at-sea bird observations, as well as breeding population counts and banding on 

islands and atolls within the NWHI from 1963-1968 (King, 1974). The resulting data provide a general baseline 

for five species of seabirds that breed on Nihoa, Mokumanamana, French Frigate Shoals, Lisianski, Laysan, 

Pearl and Hermes Atoll, Midway Atoll and Kure Atoll, including Laysan and Black-footed Albatrosses, Wedgetailed Shearwaters, Red-tailed Tropicbirds and Sooty Terns (Table 7.4). Because the POBSP breeding population size data presented in King (1974) were not well documented in terms of the types and timing of the 

counts, it is not entirely clear if population estimates were total number of individuals or number of breeding 

pairs. It is thus difficult to compare the 1960s data to current population size estimates. However, the POBSP 

data do allow for general comparisons of population sizes between islands and atolls for the time period during 

which those data were collected (Table 7.5). 

Table 7.4. Smithsonian Institution Pacific Ocean Biological Survey Program Survey Sites. 

SITE 

BLACK-FOOTED 

ALBATROSS 

(Phoebastria nigripes) 

LAYSAN'S 

ALBATROSS 

(Phoebastria immutabilis) 

RED-TAILED 

TROPICBIRD 

(Phaethon rubricauda

rothschildi) 

SOOTY TERN 

(Sterna fuscata

oahuensis) 

WEDGE-TAILED 

SHEARWATER 

(Puffi nus pacifi cus 

chlororhynchus) 

French Frigate

Shoals 

X X X X X 

Kure X X X X X 

Laysan X X X X X 

Lisianski X X X X X 

Midway X X X X X 

Mokumanamana X X X X X 

Nihoa X X X X X 

Pearl and Hermes X X X X X 

263 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 7.5. POBSP Seabird Population Survey Results. 

264 

SITE SPECIES SCIENTIFIC NAME COMMON 

NAME 

DATE LOW_ 

VALUE 

HIGH 

VALUE 

UNITS 

Lisianski LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 8,000 10,000 Largest number of breeders 

Nihoa LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 -­ 38 Largest number of breeders 

Kure LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 -­ 3,200 Largest number of breeders 

MMM LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 -­ 1,650 Largest number of breeders 

FFS LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 -­ 1,000 Largest number of breeders 

Midway LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 -­ 110,000 Largest number of breeders 

Laysan LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 300,000 500,000 Largest number of breeders 

Pearl and 

Hermes 

LAAL Phoebastria immutabilis Laysan Albatross 1963-1968 -­ 30,000 Largest number of breeders 

MMM BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 375 Maximum number of breeding birds recorded 

FFS BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 3,100 Maximum number of breeding birds recorded 

Laysan BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 40,000 Maximum number of breeding birds recorded 

Nihoa BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 100 Maximum number of breeding birds recorded 

Lisianski BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 4,000 Maximum number of breeding birds recorded 

Pearl and 

Hermes 

BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 9,000 Maximum number of breeding birds recorded 

Midway BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 24,000 Maximum number of breeding birds recorded 

Kure BFAL Phoebastria nigripes Black-footed 

Albatross 

1963-1968 -­ 1,150 Maximum number of breeding birds recorded 

MMM WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 2,000 Maximum number recorded 

Kure WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 6,230 Maximum number recorded 

MMM SOTE Sterna fuscata 

oahuensis 

Sooty Tern 1968 -­ 50,000 Maximum number recorded 

Midway SOTE Sterna fuscata

 oahuensis 

Sooty Tern 1968 -­ 353,000 Maximum number recorded 

Laysan SOTE Sterna fuscata 

oahuensis 

Sooty Tern 1968 -­ 2,000,000 Maximum number recorded 

Nihoa SOTE Sterna fuscata 

oahuensis 

Sooty Tern 1968 -­ 100,000 Maximum number recorded 

Pearl and 

Hermes 

WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 22,400 Maximum number recorded 

Laysan WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 200,000 Maximum number recorded 

FFS SOTE Sterna fuscata 

oahuensis 

Sooty Tern 1968 -­ 250,000 Maximum number recorded 

Pearl and 

Hermes 

SOTE Sterna fuscata 

oahuensis 

Sooty Tern 1968 -­ 40,110 Maximum number recorded 

Nihoa WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 25,000 Maximum number recorded 

Kure SOTE Sterna fuscata oahuensis Sooty Tern 1968 -­ 48,000 Maximum number recorded 

Lisianski WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 60,000 Maximum number recorded 

Lisianski SOTE Sterna fuscata 

oahuensis 

Sooty Tern 1968 -­ 1,000,000 Maximum number recorded 

Midway WTSH Puffi nus pacifi cus 

chlororhynchus 

Wedge-tailed 

Shearwater 

1963-1968 -­ 3,000 Maximum number recorded 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 7.5. (continued). POBSP Seabird Population Survey Results. 

SITE SPECIES SCIENTIFIC NAME COMMON 

NAME 

DATE LOW_ 

VALUE 

HIGH 

VALUE 

UNITS 

Nihoa RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 500 Maximum population estimates 

Kure RTTR Phaethon rubricauda Maximum population estimates

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 2,500 

MMM RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 200 Maximum population estimates 

FFS RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 225 Maximum population estimates 

Laysan RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 4,000 Maximum population estimates 

Pearl and 

Hermes 

RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 165 Maximum population estimates 

Lisianski RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 3,000 Maximum population estimates 

Midway RTTR Phaethon rubricauda 

rothschildi 

Red-tailed 

Tropicbird 

1963-1968 -­ 7,500 Maximum population estimates 

Island/atoll abbreviations: MMM = Mokumanamana, FFS = French Fri

Species abbreviations: LAAL = Laysan’s Albatross; BFAL = Black-foote

Tern; WTSH = Wedge-tailed Shearwater; RTTR = Red-tailed Tropicbird 

gate Shoals 

d Albatross; WTSH = Wedge-tailed Shearwater; SOTE = Sooty 

Tripartite Cooperative Agreement Studies 

In 1975, the National Marine Fisheries Service, USFWS, and Hawaii Division of Aquatic Resources (then 

known as Division of Fish and Game) established a five-year Tripartite Cooperative Agreement to conduct surveys and assessments of the NWHI (Grigg and Tanoue, 1984). One of the publications resulting from this cooperative agreement included a summary of the seabird research that had been conducted in the northwestern 

islands, and included information on 18 species of seabirds that breed in the northwestern chain. From 1978 

to 1982, USFWS conducted field studies of variable length (from five weeks to year-around) at Nihoa Island, 

French Frigate Shoals, Laysan Island and Lisianski Island. In addition, short fi eld trips were conducted to most 

of the other islands and atolls, but these shorter trips did not produce detailed population evaluations. The data 

presented in the Tripartite Cooperative Agreement Studies report is a combination of POBSP data and the field 

data collected from 1978–1982. The report is limited in use for biogeographic comparisons between islands/ 

atolls because the dates and methods of data collection were not reported, but it is possible to use the data as 

a baseline for seabird breeding population sizes within islands and atolls (Fefer et al., 1984). 

USFWS Seabird Monitoring Program 

The USFWS has been conducting seabird monitoring at French Frigate Shoals and Midway Atoll since 1980. 

Various levels of population monitoring have been conducted at French Frigate Shoals for each of the following species: Laysan Albatrosses, Black-footed Albatrosses, Bonin Petrels, Bulwer’s Petrels, Wedge-tailed 

Shearwaters, Christmas Shearwaters, Tristram’s Storm-petrels, Red-footed Boobies, Masked Boobies, Great 

Frigatebirds, Red-tailed Tropicbirds, Black Noddies, Brown Noddies, White Terns and Gray-backed Terns. 

Monitoring at Laysan Island also occurs once a year, where data are collected on Laysan Albatrosses, Blackfooted Albatrosses, Red-footed Boobies and Great Frigatebirds (data from 1992-present are currently available). As time and funding allow, periodic monitoring also occurs on the other islands and atolls in the NWHI. 

The long-term data sets from French Frigate Shoals, Midway Atoll and Laysan Island provide information 

about the variability of the seabird populations within each of those islands/atolls over the past 27 years, but 

because monitoring methods have differed between locations, inter-island or-atoll comparisons for biogeographic assessment are limited. As a first step toward future biogeographic analysis, data layers of presence 

and absence of species are presented here, as are a subset of results from the long-term seabird monitoring 

program at French Frigate Shoals and Midway Atoll. Table 7.5 also indicates the types of monitoring data that 

have been collected at each island and atoll. 

265 
Seabirds

266 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

USFWS Monitoring at French Frigate Shoals

Methods 

Since 1980, the USFWS has conducted field monitoring on Tern Island, French Frigate Shoals, to estimate the 

minimum number of breeding pairs and annual reproductive success of a subset of the seabird species that 

breed on the island. Beginning in 1980-1981, minimum numbers of breeding pairs and reproductive success 

were estimated annually for Laysan and Black-footed Albatrosses, Red-footed Boobies, Red-tailed Tropicbirds, Black Noddies, and White Terns (Dearborn et al., 2001). USFWS has since expanded the monitoring 

program on Tern Island, such that minimum numbers of breeding pairs are now estimated annually, as of 

2008, for Laysan Albatrosses, Black-footed Albatrosses, Christmas Shearwaters, Bulwer’s Petrels, Tristram’s 

Storm-petrels, Red-footed Boobies, Masked Boobies, Great Frigatebirds, Red-tailed Tropicbirds, Black Noddies, Brown Noddies, White Terns and Gray-backed Terns (USFWS, 2008). In addition, annual reproductive 

success is now monitored for Laysan and Black-footed Albatrosses, Bulwer’s Petrels, Tristram’s Storm-petrels, 

Red-footed Boobies, Masked Boobies, Red-tailed Tropicbirds and Black Noddies (USFWS, 2008). 

Estimation of the minimum number of pairs breeding on Tern Island varies by species, depending primarily 

upon population size and the level of breeding synchrony exhibited by the species. For the Procellariiformes, 

including Laysan and Black-footed Albatrosses, Christmas Shearwaters, Bulwer’s Petrels, and Tristram’s 

Storm-petrels, population sizes are relatively small, and breeding synchrony is high. For these reasons, the 

number of breeding pairs nesting on Tern Island are counted directly each year for each of these species 

(numbers of breeding pairs of Laysan and Black-footed Albatrosses are also directly counted each year at all 

other islands within French Frigate Shoals, such that the number of breeding pairs for the entire atoll can be 

estimated for these two species). In contrast, breeding within the Pelecaniformes and Charadriiformes species is highly asynchronous, and population sizes are larger, such that direct counts of breeding pairs are not 

possible (with the exception of Masked Boobies, for which all breeding adults on Tern Island are banded, and 

the breeding population consists of only a few hundred pairs; A. Anders, pers. comm.). For these species, estimates of the minimum numbers of breeding pairs are based upon mean incubation count nest censuses: for 

each species, a count of all nests at which an adult is incubating is conducted at a periodicity that equals the 

mean incubation length for that species. For example, the mean incubation length of Great Figatebirds is 55 

days, so a count of all nests at which an egg is being incubated is conducted every 55 days (USFWS, 2008). 

Summing the mean incubation counts over an entire year then provides information on the minimum number of 

breeding pairs that attempted to nest in that year (the estimate is a minimum, as some nests are initiated and 

fail between mean incubation count periods, so these failed breeding pairs are not counted; there is also some 

error introduced by the fact that within some species, individuals or breeding pairs may attempt to re-nest after 

nest failure within a year). 

Finally, annual reproductive success is also monitored based upon species’ population sizes and level of 

breeding synchrony. For Laysan Albatrosses, Black-footed Albatrosses, Bulwer’s Petrels, Tristram’s Stormpetrels, Masked Boobies, White Terns, and Gray-backed Terns, breeding populations are small enough and/or 

breeding is synchronous enough that virtually all nests on Tern Island are monitored to obtain an annual estimate of nesting success. In contrast, for Red-footed Boobies, Red-tailed Tropicbirds, and Black Noddies, nests 

are monitored year-around within multiple randomly-chosen permanent plots on Tern Island, with all nests in all 

plots being checked every two to four days for failure, hatching, or fledging (Dearborn and Anders, 1996). For 

each of these species, the reproductive success plots include approximately 20-30% of all nests on Tern Island 

for that particular species (Dearborn et al., 2001). Randomly-chosen permanent nest monitoring plots were 

also set up for Laysan and Black-footed Albatrosses beginning in 2006, in order to obtain more precise estimates of nesting success on Tern Island for these two species (USFWS, 2008; A. Anders, pers. comm.). For 

all species, nest monitoring methods provide data for annual estimates of hatching success, fl edging success, 

and overall reproductive success for each species monitored. Estimates of minimum numbers of breeding 

pairs and for hatching, fledging, and overall reproductive success are available for all monitored species from 

1996 through the present from the Pacific Seabird Monitoring Database (Pacific Seabird Group and USGS, 

Alaska Biological Science Center, 2007). 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Results 

The following figures (Figure 7.48) indicate the minimum numbers of breeding pairs of Laysan Albatrosses and 

Black-footed Albatrosses each year at 

all islands within French Frigate Shoals 

from 1960 – 2007 (1962 data: Rice and 

Kenyon, 1962; 1960-1983 data: Harrison et al., 1983; 1980-2007 data: Pacific Seabird Group and USGS, 2007). 

For both species, breeding population 

size varies annually, but both species 

have exhibited population increases at 

French Frigate Shoals since 2004. 

Estimates of the minimum numbers of 

breeding pairs on Tern Island, French 

Frigate Shoals are presented in Figure 7.49 for Bulwer’s Petrels, Christmas Shearwaters, Red-footed Boobies, 

Masked Boobies, Red-tailed Tropicbirds, Great Frigatebirds, Black Noddies, Brown Noddies, White Terns and 

Gray-backed Terns from 1996 – 2006 

(Pacific Seabird Monitoring Database, 

2008). In 2006, Bulwer’s Petrel nest 

boxes were temporarily relocated during building construction on Tern Island, 

such that only natural crevices were 

available for nesting for this species 

in that year. The number of Christmas 

Shearwater breeding pairs appears to 

have declined in 2002-2006 relative to 1996-2001, and numbers of Masked Booby breeding pairs increased 

steadily over the 11-year period shown. All other species’ breeding population sizes have fluctuated annually 

or remained stable from 1996-2006. 

0 

500 

1000 

1500 

2000 

2500 

3000 

3500 

4000 

4500 

1962 

1960-1983

19801982198319841985198619871988198919901991199219931994199519961997199819992000200120022003200420052007 

Total Breeding Pairs 

Laysan Albatross 

0 

1000 

2000 

3000 

4000 

5000 

6000 

7000 

1960-1983

1980

19811983

1984

1985

1986

19871988

1989

1990

1991

1992

1993

1994

1995

1996

1997

19981999

2000

2001

2002

2003

2004

2005

2007 

Hatch Year 

Total Breeding Pairs 

Black-footed Albatross 

Figure 7.48. The minimum numbers of breeding pairs of Laysan Albatrosses and Black-footed Albatrosses each year at all islands within French Frigate Shoals from 1960 – 2007. Sources: Rice and Kenyon, 1962; Harrison,

1983; Pacific Seabird Monitoring Database, 2008. 

267 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

268 

0 

500 

1000 

1500 

2000 

2500 

3000 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

Red-footed Booby 

0 

20 

40 

60 

80 

100 

120 

140 

160 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Minimum Number of Breeding Pairs

Masked Booby 

0 

200 

400 

600 

800 

1000 

1200 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

Red-tailed Tropicbird 

0 

100 

200 

300 

400 

500 

600 

700 

800 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

Great Frigatebird 

0 

1000 

2000 

3000 

4000 

5000 

6000 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

Black Noddy 

0 

1000 

2000 

3000 

4000 

5000 

6000 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

Brown Noddy 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

White Tern 

0 

100 

200 

300 

400 

500 

600 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Minimum Number of Breeding Pairs

Gray-backed Tern 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

1996 

1997 

1998 

1999 

2000 

2001 

2002 

2003 

2004 

2005 

2006 

Minimum Number of Breeding Pairs

Bulwer's Petrel 

0 

10 

20 

30 

40 

50 

60 

1996 

1997 

1998 

1999 

2000 

2001 

2002 

2003 

2004 

2005 

2006 

Minimum Number of Breeding Pairs

Christmas Shearwater 

Figure 7.49. Estimates of the minimum numbers of breeding pairs on Tern Island, French Frigate Shoals from 1996-2006.

Source: Pacific Seabird Monitoring Database, 2007. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Reproductive Success 

Annual nesting success (total number of chicks fledged/total number of eggs laid) from 1996 – 2006 is presented in Figure 7.50 below for Laysan and Black-footed Albatrosses, Bulwer’s Petrels, Red-footed Boobies, 

Masked Boobies, Red-tailed Tropicbirds, Black Noddies, and Gray-backed Terns. Black-footed Albatross reproductive success has remained relatively stable – between approximately 70-80% - over the 11-year period, 

while Laysan Albatross success has been lower and more variable – between 30% and just over 70% - during 

the same time period. Reproductive success for Red-tailed Tropicbirds and Gray-backed Terns appears to 

have declined substantially after the 1996 and 1997 breeding seasons, while all other species’ nesting success 

fluctuated annually over that time period. Cause of the extremely low reproductive success for Black Noddies 

in 2002 is unknown, although for all species, overall nesting success is tied very closely to food availability in 

any given year (2002-2003 was an El Niño year, such that food availability may have been low for some seabird species during that time). 

0 

10 

20 

30 

40 

50 

60 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Overall Reproductive Success (%) 

Bulwer's Petrel 

0 

10 

20 

30 

40 

50 

60 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Overall Reproductive Success (%)

Red-footed Booby 

0 

10 

20 

30 

40 

50 

60 

70 

80 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Overall Reproductive Success (%)

Masked Booby 

0 

10 

20 

30 

40 

50 

60 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Overall Reproductive Success (%) 

Red-tailed Tropicbird 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

1996 1997 1998 2000 2001 2002 2003 2004 2005 2006 

Overall Reproductive Success (%) 

Black-footed Albatross 

0 

10 

20 

30 

40 

50 

60 

70 

80 

1996 1997 1998 2000 2001 2002 2003 2004 2005 2006

Overall Reproductive Success (%) 

Laysan Albatross 

0 

10 

20 

30 

40 

50 

60 

70 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 

Overall Reproductive Success (%)

Black Noddy 

0 

5 

10 

15 

20 

25 

30 

35 

40 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 

Estimated Reproductive Success (%) 

Gray-backed Tern 

269 

Figure 7.50. Annual nesting success (total number of chicks fledged/total number of eggs laid) from 1996 – 2006. Source: 

Pacific Seabird Monitoring Database, 2007. 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

270 

USFWS Monitoring at Midway Atoll

Methods 

Laysan and Black-footed Albatross 

nests have been counted at Midway 

Atoll since 1991, and beginning in 1997, 

reproductive success of both species 

has been monitored. Hatching success, 

fledging success, and overall reproductive success, have been estimated for 

both species from 2002 – 2008 (Klavitter et al., 2009). Red-tailed Tropicbird 

population parameters have also been 

studied at Midway Atoll since 1997, 

including reproductive success, adult 

survival, and overall population trends 

(Laniawe and Klavitter, 2009; Laniawe, 

2008). Seabird monitoring at Midway also currently includes population 

monitoring of Short-tailed Albatrosses, 

Brown Boobies, Masked Boobies, Bulwer’s Petrels, Tristram’s Storm-petrels, 

Least Terns and Little Terns (J. Klavitter, 

pers. comm.). 

Results 

Results of Laysan and Black-footed Albatross nest monitoring from 2002-2008 

are presented in Figure 7.51. For this 

seven-year period, mean Laysan Albatross hatching success was 82% and 

fledging success was 85%, leading to 

an overall reproductive success of 69%. 

Black-footed Albatrosses had similar 

population paramaters, with a hatching 

success of 83%, fledging success of 

83%, and overall reproductive success 

of 70% for the entire time period, In 

analyzing reproductive parameters between species and years, Black-footed 

Albatrosses had a slightly higher hatching success than Laysan Albatrosses, 

but the two species had similar fledging 

and overall reproductive success rates 

(Klavitter et al., 2009). 

The results of Red-tailed Tropicbird 

population monitoring at Midway Atoll 

from 1997-2007 are presented in Figure 7.52. Hatching, fledging, and overall 

reproductive success, as well as adult 

survival, varied between years, but for 

Figure 7.51. The top panel shows Laysan Albatross hatching, fledging, and 

overall reproductive success at Midway Atoll from 2002-2008.The bottom 

panel Black-footed Albatross hatching, fledging, and overall reproductive 

success at Midway Atoll from 2002-2008. Source: Klavitter et al., 2009. 

Laysan Albatross 

0.00 

0.10 

0.20 

0.30 

0.40 

0.50 

0.60 

0.70 

0.80 

0.90 

1.00 

2002 2003 2004 2005 2006 2007 2008 

Success 

Hatching Fledging Reproductive 

Black-footed Albatross 

0.00 

0.10 

0.20 

0.30 

0.40 

0.50 

0.60 

0.70 

0.80 

0.90 

1.00 

2002 2003 2004 2005 2006 2007 2008 

Success 

Hatching Fledging Reproductive 

Figure 7.52. Red-tailed Tropicbird reproductive success and survival estimates for Midway Atoll from 1997-2007. Source: Laniawe and Klavitter, 

2009. 

0.00 

0.10 

0.20 

0.30 

0.40 

0.50 

0.60 

0.70 

0.80 

0.90 

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 

Nesting Success & Survivorship 

Hatching Fledging Reproductive Survivorship 

Red-Tailed Tropicbird 

the entire 11-year period, reproductive success was 41%, and adult survival was 70%. These reproductive and 

survival rates led to an overall population trend of 0.82 for this time period, indicating that the Red-tailed Tropicbird population at Midway Atoll was declining during this time (Laniawe and Klavitter, 2009; Laniawe, 2008). 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

EXISTING DATA GAPS 

Spatial Distribution 

Limiting the population monitoring data to three of the islands/atolls within the NWHI reduces our ability to 

analyze population productivity, survival and community composition across the archipelago. The remoteness, 

year-around breeding, and underground nesting habits of some of the petrel species make breeding seabird 

surveys at all of the islands within the Monument logistically difficult. Nest density calculations at the various 

islands, along with information regarding available habitat (and the extent covered by introduced plants), might 

allow for analysis and predictions of future impacts from changing sea levels and vegetation change over time. 

In addition, standardized methods for monitoring reproductive success and survival at French Frigate Shoals, 

Laysan and Midway Atoll would allow for more comprehensive geographic comparisons of seabirds nesting 

within the Monument. The collection of at sea seabird survey data should be conducted on a regular basis in 

order to gain a better understanding of the at sea behavior and environmental conditions for foraging. Currently 

a single survey was conducted by the NOAA Pacific Southwest Fisheries Science Center in 2002. This type of 

survey needs to be conducted again and at different times of year in order to gain a better understanding of all 

the seabirds in the NWHI throughout the year. 

271 
Seabirds

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

272 

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Awkerman, J.A., D.J. Anderson, and G.C. Whittow. 2008. Black-footed Albatross (Phoebastria nigripes), The Birds of 

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Dearborn, D.C. and A.D. Anders. 1996. Reproductive success of Black Noddies, Red-footed Boobies, and Red-tailed 

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Dearborn, D.C. and A.D. Anders. 2000. Occurrence and breeding behavior of Lesser Frigatebirds (Fregata ariel) on Tern 

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(Phoebastria) species. J. Zool. London 254: 391-404. 

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Midway Atoll National Wildlife Refuge. Thesis. University of East Anglia, Norwich, England, UK. 

Laniawe, L. and J. Klavitter. 2009. Reproductive success, survivorship, and population trend of the red-tailed tropicbird 

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Hakodate, Hakkaido, Japan. 

Lee, D.S. and M. Walsh-Mcgehee. 1998. White-tailed Tropicbird (Phaethon lepturus), The Birds of North America Online 

(A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds. 

cornell.edu/bna/species/353. 

Lewison, R. and L.B. Crowder. 2003. Estimating fishery bycatch and effects on a vulnerable seabird population. Ecological Applications 13 (3): 743-753. 

Lindsey, T.R. 1986. The seabirds of Australia. Angus and Robertson, Australia. 

Megysi, J.L. and D.L. O’Daniel. 1997. Bulwer’s Petrel (Bulweria bulwerii), The Birds of North America Online (A. Poole, 

Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/ 

bna/species/281. 

Mostello, C.S., N.A. Palaia and R.B. Clapp. 2000. Gray-backed Tern (Sterna lunata), The Birds of North America Online 

(A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds. 

cornell.edu/bna/species/525. 

Niethammer, K.R. and L.B. Patrick. 1998. White Tern (Gygis alba), The Birds of North America Online (A. Poole, Ed.). 

Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/ 

species/371. 

Pacific Seabird Group and USGS, Alaska Biological Science Center, 2007 Pacific Seabird Monitroing Database. http:// 

www.absc.usgs.gov/research/psinfonet/psmdb/splashpsmdb.htm 

Rice, D. W. and K. W. Kenyon. 1962. Breeding distribution, history and populations of North Pacific Albatrosses. Auk 79: 

365–386. 

Schreiber, E.A., C.J. Feare, B.A. Harrington, B.G. Murray, Jr., W.B. Robertson, Jr., M.J. Robertson and G.E. Woolfenden. 

2002. Sooty Tern (Sterna fuscata), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; 

Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/665 

Schreiber, E.A. and R.L. Norton. 2002. Brown Booby (Sula leucogaster), The Birds of North America Online (A. Poole, 

Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/ 

bna/species/649 

Schreiber, E.A. and R.W. Schreiber. 1993. Red-tailed Tropicbird (Phaethon rubricauda), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds. 

cornell.edu/bna/species/043 

Schreiber, E.A., R.W. Schreiber and G.A. Schenk. 1996. Red-footed Booby (Sula sula), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds. 

cornell.edu/bna/species/241 

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Seto, N.W. 2001. Christmas Shearwater (Puffi nus nativitatis), The Birds of North America Online (A. Poole, Ed.). 

Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/ 

species/561 

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Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/ 

bna/species/385 

Shaffer, S.A., D.M. Palacios, Y. Tremblay, M.A. Kappes, D.G. Foley, S.J. Bograd, and D.P. Costa. (in review). A tale of two 

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bna/species/673b 

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Flint, B. U.S. Fish and Wildlife Service, Honolulu, HI, USA. 

Klavitter, J. USFWS, Honolulu, HI, USA. 

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www.absc.usgs.gov/research/psinfonet/psmdb/splashpsmdb.htm 
Nonindigenous and Invasive Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Nonindigenous and Invasive Species 

Kevin See

1

, Scott Godwin

2

 and Charles Menza3 

INTRODUCTION 

The Northwestern Hawaiian Islands (NWHI) represents a relatively pristine marine ecosystem with few nonindigenous and invasive species. Of the 343 nonindigenous species (NIS) found in the water’s of the Main 

Hawaiian Islands (MHI), only 13 have been detected in the NWHI (Eldredge and Carlton, 2002; Godwin et 

al., 2006; Godwin et al., 2008). This difference is likely due to the NWHI’s extreme remoteness, relatively low 

rates of visitation and concerted management efforts. Still, the threat of nonindigenous species spreading from 

the MHI to the NWHI and becoming invasive is a serious concern. The terms nonindigenous and invasive are 

both used to refer to species that are living outside of their historic native range. The difference is that invasive 

species have been shown to cause environmental or economic harm, while NIS have not. Most NIS currently 

found in the NWHI are in few locations and in low abundances. There is debate as to whether any are invasive, 

but this is an active area of research (Schumacher and Parrish, 2005). 

A total of 13 nonindigenous species have been authoritatively detected in the NWHI (Figure 8.1; Table 8.1). 

These species range from invertebrates to fish, and have a wide variety of life histories, likely modes of introduction and potential impacts. Some species have been found in only one or two locations (e.g., the red alga 

Hypnea musciformis), whereas others are widely distributed throughout most of the atolls and shoals (e.g., the 

blueline snapper Lutjanus kasmira). The difference in their distributions is related to their movement speeds, 

transport methods, ecological success and probability of detection. 

Figure 8.1. Documented distribution of nonindigenous and invasive species in the NWHI. Map: K. Keller. 

1. University of Washington

2. University of Hawaii

3. NOAA/NOS/NCCOS/CCMA Biogeography Branch 

275 
Nonindigenous and Invasive Species

Table 8.1. Marine nonindigenous and invasive species in the Northwest Hawaiian Islands. The table also includes information on their native range, where they have been seen in the NWHI, present population status and potential impacts.

Sources: Abbott, pers comm; DeFelice et al., 1998; DeFelice et al., 2002; Godwin et al., 2004; Godwin, 2008; Godwin, 

pers comm; Waddell et al., 2008; Zabin et al., 2004. 

SCIENTIFIC COMMON NATIVE PRESENT TAXA SIGHTINGS POTENTIAL IMPACT NAME NAME RANGE STATUS 

Change community structure and

Unknown; in diversity of benthic habitat, including Hypnea Unknown; Red alga Algae drift and on MMM overgrowing coral. Currently forms musciformis Cosmopolitan lobster traps large blooms, up to 7,465 kg (or

20,000 lbs), off the coast of Maui. 

Orange- Unknown; on Diadumene Fouling organism. Ecological impact is striped sea Anemone Japan derelict net PHR lineata unstudied but presumed minimal. anemone only 

MMM, FFS, Christ­ Competition for space with other inver­ Pennaria Unknown; GAR, MAR, mas tree Hydroid Established tebrates. Also stings humans, causing disticha Cosmopolitan LAY, LIS, PHR, hydroid a mild irritation. MID, KUR 

Fouling organism. Ecological impact

Amathia Bushy is unstudied but if it becomes estab­ Bryozoan Caribbean Established MID distans bryozoan lished in protected coastal areas it has

Fouling organism. Ecological impact

Schizoporella Branching unstudied, but observations suggest Bryozoan Mediterranean Established MID errata bryozoan some competition for space with other

fouling invertebrates. 

Balanus Established on Fouling organism. Ecological impact is Barnacle Barnacle Atlantic FFS reticulatus seawall unstudied but presumed minimal. 

Not estab­ Balanus Atlantic and Fouling organism. Ecological impact is Barnacle Barnacle lished; on ves­ MID venustus Caribbean unstudied but presumed minimal. sel hull only 

Serious nuisance fouling organism.

Competes for space and food resourc­ Chthamalus Caribbean Established in Barnacle Caribbean MID es with native species. Grows in such proteus barnacle harbor densities that it could exclude algal

grazers such as opihi. 

Autonomous The impacts of this species are Styelidae, Cnemido- Reef Monitor­ unknown but it has the capacity to solitary Tunicate Indo-Pacific FFS carpa irene ing Structures become a dominant fouling organism tunicate (ARMS) on any man-made substrate. 

This species has the capacity to

become an aggressive component of Styelidae, Indo-Pacific, Polycarpa a fouling community on man-made solitary Tunicate Western ARMS FFS aurita surfaces, and the potential for recruit­ tunicate Atlantic ment to natural habitats is always a

possibility. 

Toau or Could out-compete native species for Lutjanus Blackline Fish Indo-Pacific Established FFS resources, but current densities may fulvus Snapper be too low to see these effects. 

Could prey on or out-compete desirable fishery species. May also exclude Taape or NIH, FFS, Lutjanus more desirable species from fishing Blueline Fish Indo-Pacific Established MAR, LAY, kasmira gear through competition. Scientific snapper MID research into these effects is currently 

lacking. 

May predate on native species that Roi or Cephalopho- NIH, MMM, are targeted by aquariums, dive tours Peacock Fish Indo-Pacific Established lis argus FFS and fi shermen. Scientific research into grouper these effects is currently lacking. 

Has not been Overgrows black corals, killing them. Snowflake Five Fathom Carijoa riisei Octocoral Indo-Pacific seen in NWHI Competes for space with other inver­ coral Pinnacle yet tebrates. 

Has not been Change community structure and Acanthophora Red alga Algae Indo-Pacific seen in NWHI Kauai diversity of benthic habitat, including spicifera yet overgrowing coral. 

Island/atoll abbreviations found throughout this chapter: NIH = Nihoa, MMM = Mokumanamana, FFS = French Frigate Shoals, GAR = Gardner 

Pinnacles, MAR = Maro Reef, LAY = Laysan Island, LIS = Lisianski Island, PHR = Pearl and Hermes Atoll, MID = Midway Atoll, KUR = Kure Atoll 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

276 

the potential to overgrow coral reefs. 
Nonindigenous and Invasive Species 

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

All of the atolls and islands have at least one nonindigenous species, but several such as Midway Atoll (six 

species) and French Frigate Shoals (five species) have numerous. These two locations have been the foci of 

human activity for many years, especially during World War II when they were used as military bases. This activity probably meant greater ship traffic and food imports, both of which are considered principal NIS vectors. 

They are also two of the most studied locations and thus present NIS have a greater probability of detection. 

In addition to confirmed NIS observations in the NWHI, several unconfirmed reports of sightings exist and 

two other species (i.e., Carijoa riseii and Acanthophora Spicifera) have proven to be extremely successful 

invaders of the MHI, and therefore pose a serious threat to the NWHI. The red algae Hypnea musciformis and 

Acanthophora spicifera may have been sighted drifting on Maro Reef and sighted near Midway Atoll, respectively. The blackline snapper (Lutjanus fulvus) may have been spotted off Nihoa Island, and blueline snapper (L. kasmira) may have been seen off Mokumanamana, Lisianski Island, and Pearl and Hermes Atoll (Godwin 

et al., 2006, Draft Environmental Impact Statement, Draft Management Plan for the NWHI Proposed National 

Marine Sanctuary 2006, R. Kosaki, pers. comm.). 

Vectors 

Populations of nonindigenous marine species that have already colonized areas of the MHI represent the most 

likely source of nonindigenous species in the NWHI. This deduction is based on the proximity and pattern of 

ship movements among these two areas (Godwin et al., 2006). It is difficult to conclusively determine vectors 

of movement, but the most likely are: hull fouling, ballast water discharge and natural water currents. Recently, 

marine debris has been suggested as a vector and has shown the ability to transport nonindigenous species 

to the NWHI (Godwin et al., 2006). To date no records show any species were purposefully introduced into the 

NWHI, although they most certainly were to the MHI (e.g., blueline and blackline snapper, Peacock grouper). 

Data Collection 

To deal with the threat of NIS and invasive species, information about their biology and spatial distribution is 

critical. Sightings of marine invasive species in the NWHI come from a variety of sources (Table 8.2). Sources 

are typically biological inventories of particular areas (e.g., Midway Harbor Survey, French Frigate Shoals Survey) or are opportunistic (e.g., derelict fishing net removal project) and thus are limited in temporal and spatial 

scope. These types of data are useful for determining if a particular location has been invaded, or if a potential 

vector is acting as an invasive pathway. However, these data do not provide any indication of the severity of an 

invasion, whether an invasive population is growing or shrinking or the ability to complete a rigorous statistical 

comparison among locations. 

Currently, there is no systematic survey which covers all habitats likely to harbor NIS and invasive species. 

Most data are collected or informed by conventional SCUBA or snorkeling. As a result, most data are collected 

at depths shallower than 35 m. This is a concern since several nonindigenous species already detected in the 

NWHI or in the MHI have been detected well below this limit (e.g., blueline snapper – 256 m). To fill this gap 

Papahanaumokuakea Marine National Monument (PMNM) has begun assessing deep water survey technologies (C. Menza, pers. comm.). 

The NWHI Coral Reef Assessment and Monitoring Program (NOWRAMP) and lobster trap monitoring programs provide quantitative abundance data of NIS and can monitor changes over time (see Table 8.2 for 

details); however sampling is spatially biased. For example, NOWRAMP surveys are completed at permanent 

sites and thus may not be representative of larger populations and may not detect NIS that occur in unsampled 

habitats. Similarly, hull, net and trap inspections are tied to the distribution of invasive species and may provide 

biased population estimates of attached species. More intensive surveys in specific areas (e.g., Midway Harbor Survey) offer detailed fine spatial scale data and taxonomic resolution, but are time intensive and costly. 

277 
Nonindigenous and Invasive Species

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 8.2. Marine invasive species monitoring programs in the NWHI. 

278 

PROGRAM OBJECTIVES TIME 

PERIOD 

ISLANDS OR 

ATOLLS AGENCIES 

NOWRAMP Monitor fish, algae, coral and other

invertebrates 2000-2007 

NIH, MMM, 

FFS, GAR, 

MAR, LAY, LIS, 

PHR, MID, KUR 

NOAA-PMNM, 

PIFSC 

Midway Harbor Survey Survey the invertebrates on arti

ficial 

substrates in and around Midway Harbor 1998 MID 

USFWS, 

Bishop

Museum 

French Frigate Shoals

Survey 

Survey the seawall at Tern Island for 

nonindigenous species 2002 FFS 

USFWS, 

Bishop

Museum 

Derelict Fishing Net

Removal Project 

Remove derelict fishing nets on Kure, Pearl and

Hermes, Midway and Lisianski and determine if

any nets contained nonindigenous species 

2000 LIS, PHR, MID, 

KUR NOAA-NMFS 

Derelict Fishing Net

Removal Project 

Remove derelict fishing nets on French Frigate

Shoals and determine if any nets

contained nonindigenous species 

2007 FFS NOAA-NMFS 

Census of Coral Reefs Characterize invertebrate communities 2007 FFS NOAA-NMFS 

Hull Fouling Project Assess hull fouling as a mechanism for the dispersal of nonindigenous species 2003 MHI, MID HCRI-RP, 

HI-DLNR 

Lobster Trap Monitoring 

Monitor the population of spiny lobsters, and identify any algae that is growing on the

lobster traps 

1985-2007 MMM, MAR NOAA-PIFSC 

Abbreviations: NOWRAMP = Northwest Hawaiian Islands Rapid Assessment and Monitoring Program, MHI = Main Hawaiian Islands, NOAA = 

National Oceanic and Atmospheric Administration, PMNM = Papahanaumokuakea Marine National Monument, USFWS = U.S. Fish and Wildlife 

Service, NMFS = National Marine Fisheries Service, HI DLNR = Hawaii Department of Land and Natural Resources, PIFSC = Pacific Islands Fisheries Science Center, HCRI-RP = Hawaii Coral Reef Initiative Research Program 

MARINE ALGAE 

Nonindigenous algae in the NWHI are a major concern, because of the mobility of propagules, fast growth 

rate, potential ecological impacts to the native benthic community and presence in the MHI. One species of 

red algae, Hypnea musciformis, has been detected in the NWHI and another species, Acanthophora spicifera, 

is of particular concern because of its aggressive growth rate. Both species are present in the MHI and H. 

musciformis probably originated there. 

At least 19 species of macroalgae have been intentionally or passively introduced in Hawaii since the mid 

1950s (Doty, 1961; Brostoff, 1989; Rodgers and Cox, 1999; Russell, 1987, 1992; Woo, 1999; Smith et al., 

2002; Smith et al., in press) and at least five have successfully established themselves. These species are 

capable of moving to the NWHI. 

Red Algae, Spiny Algae (Acanthophora spicifera) 

This species of red algae has not yet been authoritatively recorded in the NWHI, but there has been one unconfirmed sighting at Midway and due to its success in the MHI, it is a species of particular concern. It is widely 

distributed among the MHI and throughout the tropics and subtropics. Introduction likely originated in Honolulu 

Harbor in the 1950s via a fouled barge originating in Guam (Doty, 1961). It has since spread to all the MHI, and 

is the most widespread invasive algae in the archipelago and is now a common component of the intertidal 

community (Smith et al., 2002). 

Movement and associated range extensions occur naturally through water movement, or anthropogenically 

through hull fouling. Fragments or spores move through advection and are likely the means of local dispersal 

in Hawaii (Kilar and McLachlan, 1986). Branches are brittle that often results in fragmentation. Fragments 

can accumulate forming large, freefloating populations and can drift for potentially long distances before settling and establishing new colonies. It is also frequently spotted fouling hulls throughout the MHI (Smith et al., 

2002). 
Nonindigenous and Invasive Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

A. spicifera can adapt to a variety of habitats and environmental conditions, and this is one of the reasons of its 

success throughout tropical and subtropical ecosystems. In Hawaii, it is abundant in protected areas where it 

is not exposed to high-energy wave action, such as rocky intertidal beaches, tide-pools and shallow reefflats. 

It attaches to hard substrates and is often found growing with the native algae species of Laurencia nidifica 

and Hypnea cervicornis (Botany UH, 2001). In other areas it has been found as an epiphyte on other algae 

species and as a free living drift alga. 

Potential impacts are poorly studied. It likely impacts the community structure and diversity of the benthic 

habitat through competition and smothering (Preskitt, 2002; Eldrege 2003), but these effects have not been 

well quantified (Shluker, 2003). A. spicifera can outcompete native algae such as L. nidifica and H. cervicornis 

(Russell, 1992). In the eastern tropical Pacific, blooms of A. spicifera covered by cyanobacterial epiphytes 

have been observed at several reefs and were associated with widespread coral mortality. 

Red Algae (Hypnea musciformis) 

In 2005, international press coverage 

drew attention to the potential spread of 

the red, invasive alga, Hypnea musci-

formis when large quantities were found 

entangled in lobster traps at depths from 

30 to 90 m near Mokumanamana (Godwin et al., 2006; Figure 8.2). The species was first recorded from deep water 

(>30 m) at Mokumanamana in 2002, 

and one small individual was found as 

part of a drift assemblage at Maro Reef 

(Friedlander et al., 2008). From 2002 

through 2004, small sprigs of the alga 

were commonly recorded on lobster 

traps at Mokumanamana. In spring to 

early summer of 2005, pounds of H. 

musciformis began to appear on lobster 

traps at Mokumanamana, generating 

concern about a large-scale epidemic 

of this nuisance alga. Later that year a 

special cruise was organized by PMNM 

to investigate the problem. Interestingly, 

no H. musciformis was discovered at 

Mokumanamana during the cruise, and 

continued investigations of algae associated with lobster traps in 2006 have failed to find any signifi cant population blooms other than a few small individuals similar to those documented in 2002 through 2004 (Friedlander et al., 2008). 

H. musciformis was intentionally introduced from its native range in Florida to Kaneohe Bay on Oahu in 1974 

for mariculture. It is commercially cultivated as a food source and for kappa carrageenan, a common food additive. Like A. spicifera, it spreads quickly and is distributed widely throughout the MHI where it is now found 

on Kauai, Oahu, Molokai and Maui, with the most abundant populations occurring on Maui (Botany UH, 2001). 

Populations are often found on calm intertidal and shallow subtidal reefflats where it either attaches to sandy flat rocks or is found as an epiphyte on other algae species, often on A. spicifera, Laurencia nidifica, Sargassum echinocarpum, and S. polyphyllum (http://hawaii.edu/reefalgae/invasive_algae/index.htm). 

Principal reasons for this species success are its high growth rate, ability to epiphytize other algae and frequent fragmentation. Russell (1992) estimated a growth rate between 10-50% per day. Drifting fragments 

can attach to other floating algae, like S. echinocarpum or S. polyphyllum, and float long distances before es279 

Figure 8.2. General location of the red algae Hypnea musciformis from 

NOAA/PIFSC lobster trap monitoring. 
Nonindigenous and Invasive Species

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

280 

tablishing new colonies. Attachment is 

aided by the presence of apical hooks 

(Figure 8.3). Fragments as small as 5 

mm proved viable, growing at a rate of 

200% a week (Smith et al., 2002). Besides fragmentation, H. musciformis 

also spreads through hull fouling. 

Potential impacts include competition 

with native algae and the creation of 

large dense surface mats. Like other 

invasive algae, it probably impacts the 

community structure and diversity of the 

benthic habitat, but these effects have 

not yet been quantified (Shluker, 2003). 

Russell (1992) found H. musciformis 

can outcompete the native algae H. cervicornis, especially in the presence of A. spicifera. H. musciformis can form large dense mats, which have 

been correlated with high levels of nutrient inputs from the coast. Similar nutrient inputs are not present in the 

NWHI, but mats located around the MHI are capable of supplying propagules for distribution to the NWHI. The 

presence of dense mats are also a concern, because in peak blooms tens of thousands of pounds of algae 

can wash ashore forming windrows 0.5 m high. The effect of these windrows on local biota like the Hawaiian 

monk seal or green sea turtle is unknown. 

H. musciformis now makes up a significant portion of the diet for the green sea turtle, sometimes composing 

as much as 99-100% of the seaweed mass in their stomachs. However, the nutritional value of H. musciformis 

has not yet been determined and so the long-term impact of incorporating this alga into the sea turtles’ diet is 

unknown (Botany UH, 2001). 

INVERTEBRATES 

Out of the all the different taxonomic groups of NIS, invertebrates represent the most species and are the least 

studied. Nine invertebrate species (one anemone, one hydroid, two bryozoans, three barnacles and two tunicates) have been detected in the NWHI. These invertebrates are typically cryptic and have been detected with 

the help of fine-scale surveys in targeted areas (e.g., Defelice et al., 1998, 2002). Most nonindigenous invertebrates have been detected at Midway Atoll and French Frigate Shoals, the two locations with the lion’s shares 

of survey effort and human activity. A tenth invertebrate species, the snowflake coral (Carijoa riseii), which has 

not been detected in the NWHI is described herein because it is a species of particular concern. 

Orange-striped Sea Anemone (Diadumene lineata) 

The orange-striped sea anemone is native to Japan, but has spread throughout the Pacifi c, Atlantic, Caribbean, the North Sea and the Mediterranean (Zabin et al., 2004). In 2000, about 100 individuals were identified 

in the lagoon at Pearl and Hermes Atoll attached to a derelict fishing net (Zabin et al., 2004; Figure 8.4). To 

date, no established adults have been seen in the NWHI. 

Although it can reproduce sexually, it likely spreads through asexual reproduction and hull fouling in the NWHI 

(Zabin et al., 2004). It exhibits a wide tolerance of temperature and salinity and is generally found on solid 

substrates, in intertidal pools or protected shallow waters such as bays and harbors. The orange-striped sea 

anemone is often found with mussels and oysters in other parts of its range (DeFelice et al., 2001), and could 

have been transported to Hawaii in an oyster shipment (Zabin et al., 2004). The impacts of this species in the 

NWHI remain unknown and unstudied. 

Figure 8.3. H. musciformis. The arrows point to the species’ distinctive 

hooks. Photo: P. Vroom. 
Nonindigenous and Invasive Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Christmas Tree Hydroid (Pennaria 

disticha) 

The Chrismas tree hydroid is native to 

the western Atlantic and has been reported in all of the NWHI except Nihoa 

(Godwin et al., 2006). It also is widely 

distributed among the MHI (DeFelice et 

al., 2001). It was first reported in the region during a survey of Pearl Harbor in 

1929 (DeFelice et al., 2001). 

It attaches to natural and artifi cial hard 

substrates where there is some water 

movement. It is very common in harbors in all the MHI and is often found 

in more protected areas such as cracks 

and crevices on reefs, at depths of 0–50 

m. The impacts of the Christmas tree 

hydroid are unstudied, but it is likely that 

it competes for space with other invertebrates. It also can sting humans, resulting in minor irritation (DeFelice et al., 

2001). 

Bushy Bryozoan (Amathia distans) 

In 1997 the bushy bryozoan was found 

at Midway Harbor, dominating many 

of the manmade structures that were 

surveyed (Figure 8.5). It formed large 

colonies on wood, concrete and metal 

pilings, as it does in harbors in the MHI 

(DeFelice et al., 1998). To date, this is 

the only location in the NWHI where it 

has been sighted. Its native range is the 

Caribbean, but it has spread over much 

of the tropics and subtropics including 

the western Atlantic, Mediterranean and 

Red Seas, eastern Pacifi c and coastal 

waters of Australia, New Zealand, Java 

and Japan (DeFelice et al., 2001). Movement is considered to be aided by hull 

fouling, ballast water discharge (larvae) 

or natural water movement (Shluker, 

2003). 

The bushy bryozoan was first spotted in the region at Kaneohe Bay in 1935, and has since spread to all the 

MHI (Shluker, 2003; Coles et al., 2004). It can be found in shallow water on hard anthropogenic substrates 

such as pilings and vessel hulls and natural substrates such as coral rubble. It is usually found inside harbors 

or embayments, or occasionally in more protected areas of the reef. The impacts of the bushy bryozoan are 

unknown and presumed minimal (DeFelice et al., 2001), probably including competition for space (Shluker, 

2003). 

Figure 8.4. General location of the orange-striped sea anemone (Diadumene lineata) from NOAA/PIFSC/CRED Marine Debris Program. 

281 

Figure 8.5. General locations of the bushy bryozoan (Amathia distans) at 

Midway Atoll. 
Nonindigenous and Invasive Species

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

282 

Branching Bryozoan (Schizoporella errata)
 

The branching bryozoan was recorded 

at Midway Harbor in 1997, where it was 

found occupying many of the same locations as the bushy brozoan, although 

not as abundant (DeFelice et al., 1998) 

(Figure 8.6). It is usually found inside 

harbors or embayments on man-made 

substrates, or occasionally in more protected areas of coral reefs (DeFelice et 

al., 2001). Its native range is the Mediterranean, but is now found worldwide, 

including all the MHI (DeFelice et al., 

2001) where it was first described at Pearl 

Harbor in 1933. It can be transported 

anthropogenically through hull fouling, 

which is likely how it was unintentionally 

transported to so many locations around 

the globe (Shluker, 2003). The impacts 

of this species are unknown, but likely 

include competition for space (DeFelice 

et al., 2001). 

Barnacle (Balanus reticulates) 

Although this species of barnacle has 

been found in the MHI on Kauai, Oahu, 

Maui and Hawaii (Coles et al., 2004), 

and was found on about 25% of the ship 

hulls in one hull fouling study (Godwin 

et al., 2004), it has only been spotted 

once in the NWHI, on a seawall at Tern 

Island in French Frigate Shoals in 2002 

(DeFelice et al., 2002; Figure 8.7). It is a 

fouling organism. Its ecological impact is 

presumed to be minimal, although there 

is little research to confirm this assumption.
 

Barnacle (Balanus venustus) 

This barnacle, native to the Atlantic and 

Caribbean oceans, has been seen once 

on a hull of a ship anchored at Midway 

Harbor in 2003 (Godwin et al., 2004), 

demonstrating this species’ ability to be 

transported through hull fouling. However, an established adult has never been seen in the NWHI. Its ecological impact is presumed to be minimal.
 

Caribbean Barnacle (Chthamalus proteus)
 

This barnacle from the Caribbean was found in Midway Harbor attached to pier pilings in 1997 (DeFelice et al., 

1998; Figure 8.8). It likely arrived in the region between 1973 and 1994, since it was first noticed at Kaneohe 

Bay, Oahu in 1995 and was not found during a comprehensive intertidal survey of Oahu in 1972. 

Figure 8.6. General locations of the branching bryozoan (Schizoporella errata) at Midway Atoll. 

Figure 8.7. General location of the barnacle Balanus reticulatus at Tern 

Island, French Frigate Shoals. 
Nonindigenous and Invasive Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

It was probably introduced through either hull fouling or ballast water, although 

Southward et al. (1998) argues that hull 

fouling is more likely. It is commonly seen 

above the waterline on inter-island ships 

(Zabin, 2007). Larval dispersal could 

also be a natural vector for spread between the islands of the Hawaiian archipelago, now that it is established there. 

Although there may be some peaks of 

larval production, larvae are found in the 

water column year-round. 

Surveys of MHI have found Caribbean barnacles around Kauai, Maui and 

Hawaii (DeFelice et al., 2001). It usually colonizes supratidal anthropogenic 

structures such as pier pilings and sea 

walls, although some individuals have 

been observed on intertidal boulders in 

the MHI. It is generally found in protected embayments and harbors, but small colonies have been found at one high energy site in Kaneohe Bay. This finding is a concern, because this species may be moving into habitat used by the native barnacle Nesochthamalus intertextus. At the moment, it seems the Caribbean barnacle is not competing with N. intertextus, 

but rather growing next to it. In addition, Caribbean barnacle individuals were quite small, so it was unclear 

whether there was an established population. 

The Caribbean barnacle has been implicated in displacing another nonindigenous barnacle, Balanus amphi-

trite, in the MHI demonstrating its competitive ability (Shluker, 2003). Its rapid proliferation may reflect that it is 

filling an unexploited niche in the Hawaiian archipelago, in the high intertidal and splash zones. The density of 

colonies and the rapid pace of reproduction make the Caribbean barnacle a good competitor for space. This 

proliferation could alter the community structure and potentially exclude algal grazers such as protected Hawaiian limpets (e.g., Cellana exarata, C. melanostoma, C. sandwicensis, C. talcosa). 

Styelidae, Solitary Tunicate (Cnemidocarpa Irene) 

This species is a widespread Indo-Pacific tunicate found in Japan, the Philippines, Australia, Micronesia and 

Melanesia. Large specimens may reach a length of 4 cm and have a dark brown to whitish tunic with deep 

wrinkles that are arranged to create irregularly shaped raised areas. This species is commonly associated with 

fouling communities located within man-made harbors and shallow benthic habitats with rubble substrate from 

Kauai to the island of Hawaii (Abbott et al., 1997). 

The larval stage of most solitary tunicates is brief; the larva does not feed, but concentrates on finding an appropriate place for the adult to live. The actual larvae are tadpole shaped and the muscular tail comprises twothirds of the larval body; it is supported by a notochord and contains a nerve cord. Gravity and light-sensitive 

sensory vesicles along the dorsal surface of the larval body orient the animal as it swims. After a period of up 

to a few days, the larva will settle and attach itself to a surface using three anterior adhesive papillae. As the 

larva metamorphoses into an adult, the tail reabsorbs, providing food reserves for the developing animal. 

This species has only been recorded from French Frigate Shoals in the Monument, where it was collected from 

an Autonomous Reef Monitoring Structures (ARMS) installed in 2006 (Godwin et al., 2008; Figure 8.9). Due to 

the short larval duration of tunicates, this species was likely transported to French Frigate Shoals by some anthropogenic means from a source location in the southeastern portion of the archipelago. Therefore this record 

represents recruitment to the ARMS from an undocumented established population at French Frigate Shoals. 

Figure 8.8. General locations of the Caribbean barnacle (Chthamalus proteus) at Midway Atoll. 

283 
Nonindigenous and Invasive Species

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

284 

The impacts of this species are unknown 

but it has the capacity to become a dominant fouling organism on any man-made 

substrate. 

Styelidae, Solitary Tunicate (Polycarpa aurita) 

This solitary tunicate is pale brown with 

a tough and leathery tunic that is generally encrusted with worm tubes, sponges 

and other fouling organisms. Specimens 

in Hawaii only reach up to 4 cm in length 

but this species attains greater lengths 

(10-12 cm) in other areas of its Indo-Pacific range. This species is also found in 

the western Atlantic (Caribbean and Gulf 

of Mexico). It is established in the southeastern portion of the archipelago as a 

common species in fouling communities 

located within man-made harbors and the shallow and intertidal habitats of natural embayments (Abbott et al., 

1997). 

The larval cycle described under C. 

irene also applies to this species. Therefore, a larval cycle of only a few days 

exists. It was recently recorded from 

French Frigate Shoals from the same 

collections in which C. irene was identi­ fi ed (Godwin et al., 2008). These collections were part of an effort by the Coral 

Reef Ecosystem Division (CRED) of the 

Pacific Islands Fisheries Science Center in Honolulu in 2007. The focus of the 

efforts was to expand a 2000 project, 

which examined fouling organisms associated with derelict fishing gear in the 

NWHI (Godwin, 2000; Figure 8.10) and 

retrieve and quantify the organisms collected by an ARMS deployed in 2006 at 

French Frigate Shoals. As with C. irene, 

anthropogenic transport to French Frigate Shoals is assumed and a scenario of opportunistic recruitment to the ARMS from some established population in the lagoon is likely. 

This species has the capacity to become an aggressive component of a fouling community on man-made surfaces, and the potential for recruitment to natural habitats is always a possibility. Recent incidences of natural 

tunicate populations acting invasively and overgrowing remote coral reef areas demonstrates the potential of 

this group of organisms to cause damage to coral reefs without direct human influence (Littler and Littler, 1995; 

Vargas-Angel et al., 2008) 

Figure 8.9. Documented location of C. irene at French Frigate Shoals. 

Figure 8.10. Documented location of P. aurita at French Frigate Shoals. 
Nonindigenous and Invasive Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Snowfl ake Coral (Carijoa riisei) 

The snowflake coral has not been detected in the NWHI, but is a species of particular concern. It was fi rst spotted in Pearl Harbor in 1972 (DeFelice et al., 2001), and by 1990 had been recorded around all of the MHI. Of 

the 343 nonindigenous marine species that have been introduced to the Hawaiian Islands, the snowfl ake coral 

may be the most successful at proliferation, as demonstrated by its distribution among the MHI, and it may 

exhibit some of the highest invasive potential (Grigg, 2003). It has not been sighted in the NWHI to date, but 

in 2007 a colony was found at Five Fathom Pinnacle (Kahng, per comm.), approximately 200 km from Nihoa 

Island which is the southeastern-most point of the NWHI. 

This species was originally thought to be native to the Caribbean, but recent research has shown it to be more 

likely indigenous to the Indo-Pacific. It is likely that several slightly different species have reached the Hawaiian archipelago (Kahng, 2006). 

The snowflake coral is very light sensitive; it thrives in spots that receive 10–30% ambient light, and avoids 

well-lit habitats. Therefore in shallow water (10–30 m), where light levels are high, it attaches to dark cracks, 

shaded walls or pilings, the underside of ledges and corals, lava tubes and other shaded areas. As it moves 

into deeper water and light levels diminish, it is found on a wider variety of habitats. At depths of 75–110 m, 

it has been found to explode into patches as large as 200 km

2

 (Grigg, 2003). It generally attaches to hard 

substrates such as rocks, corals or anthropogenic structures. It does need to be positioned above the benthic 

layer, and away from stagnant water, as it requires some wave energy to continuously transport the zooplankton that it filters from the water for food (Godwin et al., 2006). 

The snowflake coral reproduces both asexually and sexually. The polyps can split in two, allowing clones to 

spread and cover an entire habitable patch within several years. It can also release gametes into the water 

column, which once fertilized, can survive for up to 90 days (Kahng, 2006) and thus are capable of travelling 

long distances. This species can also spread through hull fouling, although this may not be common. 

At shallow depths, the snowflake coral seems to occupy an unutilized habitat niche in Hawaii (Shluker, 2003). 

However at depth, it has overgrown entire beds of black coral, killing 90% of the coral surveyed in the Maui 

Black Coral Bed in 2001 (Grigg, 2003). Black coral harvesting generates $15 million a year in the state of Hawaiian, and the spread of the snowflake coral represents a serious threat to this industry (Godwin et al., 2006). 

Beyond the economic impacts, it has shown the potential to severely reduce biodiversity by blanketing entire 

areas. 

FISHES 

Three species of nonindigenous fish have been observed in the NWHI, blackline snapper (Lutjanus fulvus), 

blueline snapper (L. kasmira) and Peacock grouper (Cephalopholis argus). All three species were purposefully 

introduced to the MHI between 1955 and 1961 along with eight other species of groupers (Serranidae), snappers (Lujanidae) and emperor breams (Lethrinidae) from Moorea in French Polynesia. All were introduced as 

potential commercial species (Brock, 1960; Randall, 1987). Of the three species, blueline snapper have been 

the most successful in terms of distribution and abundance (Shluker, 2003). 

Blackline Snapper (Lutjanus fulvus or Toau) 

Intentionally introduced in 1956, blackline snapper has spread to all of the MHI, and into the southeastern 

end of the NWHI. It has been spotted at Nihoa and French Frigate Shoals (Shluker, 2003; Figure 8.11). It has 

fairly low abundance, possibly due to its exploitation for food (Shluker, 2003). Blueline snapper (L. kasmira) 

was introduced around the same time, but it has spread much faster than blackline snapper, despite the many 

biological similarities between the two species. Scientists are unsure how to explain the difference in range 

expansion. 

285 
Nonindigenous and Invasive Species

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

286 

Blackline snapper is a reef fi sh, generally found in the lagoons or outer reef 

slopes and usually at depths of 1–40 m, 

but it has been seen as deep as 75 m. It 

has a temperature tolerance of 20–28°C 

and spawns year-round (http://www.lar­

valbase.org), increasing its chances of 

larval dispersal. Ecological impacts are 

unstudied. 

Blueline Snapper 

(Lutjanus kasmira or Taape) 

Blueline snapper has been detected 

throughout the NWHI, including Nihoa, 

Mokumanamana, French Frigate Shoals, 

Maro Reef, Laysan Island and Midway 

Atoll (Friedlander et al., 2005). It likely 

migrated from the MHI where it was intentionally introduced to Oahu in 1955. 

From the initial population of 3,200 individuals brought from French Polynesia, 

the fish has spread throughout the full 

length of the Hawaiian archipelago (Oda 

and Parrish, 1982; Randall et al., 1993; 

Figure 8.12) and is now one of the most 

conspicuous and abundant species in 

the fish community. Friedlander et al. 

(2002) found blueline snapper was the 

second most abundant species by number and biomass over hard substrate in 

Hanalei Bay, Kauai. 

Due to its abundance and the concern 

that blueline snapper might impact native fish, more effort has been spent 

studying its ecology compared to other 

similar nonindigenous species. Blueline 

snapper is generally found in lagoons 

and outer reef slopes at depths from 2-70 m, but it has been seen as deep as 256 m. Friedlander et al. (2002) 

found the species to be abundant over habitats like deep slope, spur and groove and shallow slope, but it was 

also found in lesser quantities in the complex back reef. A more recent report indicated that blueline snapper 

is also common among algal plain habitats (C. Menza, pers. comm.). These low relief habitats dominated by 

algae (macroalgae and crustose coralline algae), may make up a considerable proportion of the deeper benthic habitats in the NWHI where coral are rare. Friedlander et al. (2002) have also shown that blueline snapper 

utilize sand habitats for feeding and the species may undergo an ontogenetic habitat shift. 

The blueline snapper was never accepted into the local diet, and many fishermen believe it out competes native fish for resources and fishing bait. There is little scientific evidence to back this conclusion (but see Schumacher and Parrish, 2005), which leads to disagreement and debate between scientists and fishermen as to 

the effects of the blueline snapper on native species (Shluker, 2003). 

Figure 8.11. Documented distribution of blackline snapper (Lutjanus

fulvus) in the NWHI. 

Figure 8.12. Documented distribution of blueline snapper (Lutjanus kasmira) in the NWHI. Source: Sladek Nowlis and Friedlander, 2004. 
Nonindigenous and Invasive Species 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Peacock Grouper (Cephalopholis argus or Roi) 

The Peacock grouper was introduced 

from French Polynesia in 1956 as a 

food species. Since then, it has spread 

throughout the MHI, and has been seen 

at Nihoa, Mokumanamana and French 

Frigate Shoals in the NWHI (Shluker, 2003; Godwin et al., 2006; Figure 

8.13). 

It is found in lagoons and seaward reef 

habitats, at depths of 1–40 m, although 

it generally prefers depths of 10 m or 

less (Godwin et al., 2006). 

Although originally sought by fishermen, 

its popularity declined after incidences 

of ciguatera poisoning increased and 

is now considered by many fishermen 

as unsafe to eat (Godwin et al., 2006). 

Without fishing pressure, the Peacock 

grouper has grown abundant and could 

impact native reef fishes through predation as well as competition for space and resources. However, there is little scienti

fic research on the effects 

due to Peacock grouper, and thus no conclusive evidence has been gathered. 

MANAGEMENT 

PMNM has taken active steps to mitigate the threats of NIS, including ballast discharge prohibition, hull inspections and cleaning, snorkel/dive gear treatment and luggage inspection of air passengers. Action plans 

consisting of multiple strategies and activities address PMNM priority management needs. One of the PMNM’s 

22 action plans is “to detect, control, eradicate where possible, and prevent the introduction of alien species 

into the Monument”. PMNM has also undertaken research to develop knowledge of baseline conditions and 

detect NIS introductions. Early detection greatly increases the probability of NIS control and possibly eradication (e.g., Pyne, 1999). 

EXISTING DATA GAPS 

The primary data gap for nonindigenous and invasive species in the NWHI is a complete survey of nonindigenous species across habitats. Surveys need to have a greater spatial distribution to have a more complete 

picture of the nonindigenous and invasive species populations. The following are key datasets needed for 

management and future research efforts: 

• Species inventory; 

• Population size; 

• Rate of spread; 

• Spatial distribution; and 

• Habitat requirements and natural history information for established populations to use in habitat suit-

 ability models. 

Figure 8.13. Documented distribution of the Peacock grouper (Cephalopholis argus) in the NWHI. Source: Sladek Nowlis and Friedlander, 2004. 

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288 

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Shoals, Northwestern Hawaiian Islands, with a note on non-indigenous species. Report to the U.S. Fish and Wildlife Service. Bishop Museum, Hawai‘i Biological Survey, Bishop Museum Technical Report No. 23. 

Doty, M. S. 1961. Acanthophora, a possible invader of the marine flora of Hawaii. Pac. Sci. 15(4): 547- 552. 

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Vroom. 2005. The State of the Coral Reef Ecosystems of the Northwestern Hawaiian Islands. Pp. 270-311. In: J. Waddell (ed.), The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2005. NOAA 

Technical Memorandum NOS NCCOS 11. NOAA/NCCOS Center for Coastal Monitoring and Assessment’s Biogeography 

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Friedlander, A.M., J.D. Parrish and R.C. Defelice. 2002. Ecology of the introduced snapper Lutjanus kasmira (Forsskal) 

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Godwin, L.S. 2000. Northwestern Hawaiian Islands derelict fishing net removal project: survey of marine organisms associated with net debris. Report submitted to NOAA-NMFS Coral Reef Ecosystem Investigation. 11 pp. 
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Godwin, L.S. L. Harris, A. Charette and R. Moffitt. 2008. The marine invertebrate species associated with the biofouling of 

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Hawaii. 

Kilar, J.A. and J. McLachlan. 1986. Ecological Studies of the Alga, Acanthophora spicifera (Vahl) Borg. (Ceramiales: Rhodophyta): Vegetative Fragmentation. J. Exp. Mar. Biol. Ecol. 104: 1-21. 

Littler M.M. and D.S. Littler. 1995. A colonial tunicate smothers corals and coralline algae in the Great Astrolabe Reef, Fiji. 

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Oda, D. K. and J.D. Parrish. 1982. Ecology of commercial snappers and groupers introduced to Hawaiian reefs. Pp: 

59–67. In Proceedings of the Fourth International Coral Reef Symposium Vol. 1 (E.D. Gomez, C.E. Birkeland, R.W. 

Buddemeier, R.E. Johannes, J.A., Jr. Marsh, and R.T. Tsuda, eds). Quezon City, Philippines: Marine Sciences Center, 

University of the Philippines. 

Preskitt, L. 2002. Acanthophora spicifera (Vahl) Borgesen 1910. Invasive Marine Algae of Hawaii. University of Hawaii 

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Pyne, R. 1999. The black striped mussel (Mytilopsis sallei) infestation in Darwin: A clean-up strategy. Ecoports Monogr. 

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Randall, J.E., J.L. Earle, T. Hayes, C. Pittman, M. Severns, and R.J.F. Smith. 1993. Eleven new records and validations 

of shore fishes from the Hawaiian Islands. Pac. Sci. 47(3): 222–239. 

Rodgers, K. and E. Cox. 1999. The rate of spread of the introduced Rhodophytes, Kappaphycus alvarezii (Doty), Kap-

paphycus striatum Schmitz and Gracilaria salicornia C. ag. and their present distributions in Kane‘ohe Bay, Oahu, Hawaii. 

Pacific Science, (53)3: 232-241. 

Russell, D.J. 1987. Introductions and establishment of alien marine algae. Bull Mar Sci, 42: 641-642. 

Russell, D.J. 1992. The ecological invasion of Hawaiian reefs by two marine red algae, Acanthophora spicifera (Vahl) 

Boerg and Hypnea musciformis (Wulfen) J. Ag., and their association with two native species, Laurencia nidifica J. Ag. 

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on Hawaiian reefs. Biological Invasions 7: 925-933. 

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Smith, J.E., C.L. Hunter, and C.M. Smith. 2002. Distribution and Reproductive Characteristics of Nonindigenous and Invasive Marine Algae in the Hawaiian Islands. Pacific Science 56 (3):299-315. 

Smith J.E., Hunter C.L., Conklin E.J., R. Most, T. Sauvage, C. Squair, C.M. Smith. 2004. Ecology of the invasive red alga 

Gracilaria salicornia (Rhodophyta) on Oahu, Hawaii. Pac Sci 58: 325–343. 

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Vargas-Angel, B., L.S. Godwin, J. Asher, and R.E. Brainard. 2008. Invasive didemnid tunicate spreading across coral 

reefs at remote Swains Island, American Sāmoa. Coral Reefs (In Press). 

Waddell, J.E. and A.M. Clarke (eds.). 2008. The State of Coral Reef Ecosystems of the United States and Pacifi c Freely 

Associated States: 2008. NOAA Technical Memorandum NOS NCCOS 73. NOAA/NCCOS Center for Coastal Monitoring 

and Assessment’s Biogeography Team. Silver Spring, MD. 569 pp. 

Woo, M.M.L. 2000. Ecological impacts interactions of the introduced red alga, Kappaphycus striatum, in Kaneohe Bay, 

Oahu, Masters Thesis, University of Hawaii at Manoa, Honolulu, Hawaii. 

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Hawaii. Biological Invasions 9: 523-544 

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PERSONAL COMMUNICATIONS 

Abbott, I. The University of Hawaii, HI, USA 

Godwin, S. Papahanaumokuakea Marine National Monument Honolulu, HI, USA 

Kahng, S. Hawaii Pacific University, College of Natural Sciences, Waimanalo, HI, USA 

Menza, C. NOAA Biogeography Branch, Silver Spring, MD, USA 

WEBSITES 

University of Hawaii at Manoa • Botany Department and Bishop Museum. Invasive Marine Algae of Hawaii. 2009

http://hawaii.edu/reefalgae/invasive_algae/index.htm 

German Ministery for Economic Cooperation and Development (BMZ). 2006. http://www.larvalbase.org 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Connectivity and Integrated Ecosystem Studies 

Alan Friedlander1,2, Donald Kobayashi3, Brian Bowen4, Carl Meyers4, Yannis Papastamatiou4, Edward DeMartini3, 

Frank Parrish3, Eric Treml5, Carolyn Currin6, Anna Hilting6, Jonathan Weiss3,7, Chris Kelley8, Robert O’Conner7, Michael 

Parke3

, Randy Clark1, Rob Toonen4 and Lisa Wedding1,9 

INTRODUCTION 

Population connectivity is the exchange of individuals among geographically separated subpopulations. Defining the scale of connectivity among marine populations and determining the factors driving this exchange 

are critical to our understanding of the population dynamics, genetic structure and biogeography of reef fishes 

(Cowen et al., 2006). Although larvae have the potential for long-distance dispersal, evidence is mounting that 

larval dispersal may be limited and marine subpopulations may be more isolated over smaller spatial scales 

than previously thought (Cowen et al., 2007). The rates, scale and spatial structure of successful exchange, or 

connectivity, among local populations of marine organisms drive population replenishment and, therefore, have 

profound implications for population dynamics and genetics of marine organisms, spatially oriented resource 

management (e.g., marine protected areas) and the spread of invasive species. Despite the importance of this 

issue in understanding population dynamics and effectively managing these species or areas (e.g., Crowder 

et al., 2000; Valles et al., 2001), larval connectivity in the Northwestern Hawaiian Islands (NWHI) is relatively 

unknown. The uniquely endemic fish and other marine faunas of the Hawaiian Archipelago (Hourigan and 

Reese, 1987) and the extreme expression of endemism in the NWHI (DeMartini and Friedlander, 2004) make 

such information critically important for the Hawaiian Archipelago and specifically the Papahanaumokuakea 

Marine National Monument (PMNM). 

LARGE-SCALE POPULATION CONNECTIVITY MODELS FROM OCEAN CURRENTS 

For many marine species, population connectivity is determined largely by ocean currents transporting larvae 

and juveniles between distant patches of suitable habitat. To evaluate the patterns in connectivity throughout 

the Hawaiian Archipelago, a spatially explicit biophysical model was used to simulate coral dispersal between 

reefs spanning the archipelago for three different years (a strong El Niño year- 1997, a strong La Niña year1999, and a neutral year- 2001; Treml et al., 2008). Simulated connectivity was summarized seasonally and 

across years. 

This two-dimensional Eulerian advection–diffusion model of coral dispersal incorporates realistic surface current velocity data and estimates of planktonic larval duration (PLD). In this model, the probability of potential 

dispersal to a reef is the product of: 1) the hydrodynamic arrival probability, 2) larval mortality and 3) the settlement probability. The spatially explicit hydrodynamic model and resultant arrival probabilities incorporate reef 

topology, ocean current variability and spawning location. 

Summary of Patterns Across Hawaii with Reference to Spatial Data 

Results indicate that the scale of dispersal is on the order of 50-150 km, which is consistent with recent studies 

in the Caribbean (Cowen et al., 2006). On average, the Main Hawaiian Islands (MHI) appear to be consistently 

connected and well mixed at levels above 1/10,000 per season for hypothetical larvae with a PLD of 60 days 

(Figure 9.1). The northwestern most atolls (Kure, Midway, and Pearl and Hermes) are also constantly and 

strongly connected throughout the dispersal scenarios. The entire Hawaiian archipelago appears completely 

1. NOAA/NOS/NCCOS/CCMA Biogeography Branch

2. The Oceanic Institute 

3. NOAA/NMFS/Pacific Islands Fisheries Science Center, Coral Reef Ecosystem Division

4. Hawaii Institute of Marine Biology

5. World Wildlife Fund Fuller Fellow, School of Integrative Biology, University of Queensland, St. Lucia, QLD Australia

6. NOAA/NOS-Beaufort Lab

7. Joint Institute of Marine and Atmospheric Research

8. Hawaii Undersea Research Lab 

9. University of Hawaii at Manoa 

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292 

Figure 9.1. Dispersal pathways in the Hawaiian Archipelago based on Eulerian advection-diffusion models (adapted from 

Treml et al., 2008). Coral reef habitat is represented by nodes within the graph framework. When larvae from a source 

reef reach a downstream reef site, a dispersal connection is made. This dispersal connection and direction is represented

by an arrow, or ‘edge’ within the graph. The thickness of the arrow reflects the strength of connection. Source: Treml, 

unpublished data; map: L. Wedding. 

connected at similar levels for at least one season out of the years modeled, albeit predominately in a northwesterly direction. For connectivity via rafting and for those organisms that have a longer PLD or higher survival while dispersing, the hydrodynamics around the Hawaiian Islands provide opportunity for dispersal and 

mixing throughout. In addition, long distance larval dispersal from Johnston Atoll to the mid-Hawaii archipelago 

appears to be possible during unique seasons: La Niña, July – September and October – December; neutral 

years, July – September, with the strongest connection in October – December during La Niña years. 

Larval Retention Versus Larval Subsidy 

Metapopulation connectivity in the Hawaiian Archipelago is poorly understood, and this hinders effective management and assessment of living marine resources in the region. Pelagic transport was investigated using 

high-resolution ocean current data and computer simulation (Kobayashi, in review). Adjacent strata in the 

archipelago appeared well connected via simulated pelagic larval transport regardless of larval duration, while 

connectivity of more distant strata appear mediated by larval duration (Figures 9.2-9.8). Retention (defined 

as the return of natal propagules) is contrasted with reception or subsidy (the influx of propagules from other 

sources). These two processes appear to be decoupled based on examination of archipelago-wide simulations. Single-generation and multigeneration effects of connectivity were considered using a simple population 

dynamics model driven by the dispersal kernel probability estimates. The PMNM appears to be largely selfsustaining based on these results, with differential input to certain inhabited islands farther southward in the 

archipelago depending on the pelagic larval duration. 

Retention rate (as a fraction of propagules released) ranged from a low of 0.39% at Lanai, to a high of 17.24% 

for the island of Maui (Figure 9.8). When retention and subsidy were pooled to estimate total settlement per 

unit of habitat, settlement ranged from a low of 6,288 settlers per pixel at Kure Atoll to a high of 149,192 settlers per pixel at Northampton. The high settlement rate at the relatively small Northampton is attributed mostly 

to subsidy. 
Connectivity and Integrated Ecosystem Studies

Figure 9.2. Larval dispersal (45 day PDL) one year after being released from Nihoa Island. Source: Kobayashi, in review; map: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

The biological significance of the PMNM to the entire Hawaiian Archipelago can be considered from the connectivity probabilities and the metapopulation analysis. The equilibrium metapopulation composition predicted 

after many generations can be useful in understanding the importance of adjacent or even nonadjacent geographic strata. For organisms with short larval duration (15 days), a relatively narrow transitional region including Nihoa, Middle Bank, Niihau and Kauai is composed of settlers from both the PMNM and MHI regions. 

Areas farther north and south have negligible crossover. However, at longer PLDs (90 days), nearly all regions 

throughout the MHI have some component of the settlers derived from the PMNM, whereas most of the PMNM 

is self-seeding until approximately Mokumanamana is reached. 

While the effects of Maro and Gardner can be attributed to their relatively large reproductive output in the 

simulations, other large areas do not contribute similarly to the equilibrium composition, which is a model consequence of dispersal kernel probabilities operating over many generations. When the effect of habitat size is 

removed by scaling total retention and reception by habitat pixel counts, this yields evidence of a decoupling of 

retention and reception processes. This implies that there is very little, if any, physical (geographic or oceanographic) relationship between factors which promote effective natal larval retention and factors which promote 

influx of outside larval reception. Settlement and recruitment studies which ignore propagule origins may have 

difficulty in relating observed patterns to oceanographic features for this very reason. Since neither measure 

is a strong proxy for the other, the futility of understanding transport dynamics given the single aggregated 

measure is readily apparent. The need for additional genetics studies and other stock identification markers for 

sourcing of incoming propagules is urgent (e.g., Bernardi et al., 2002; Schultz et al., 2007). 

Clearly since the connectivity measures appear high for adjacent habitats, over evolutionary time the genetic 

connectivity might be more pronounced than inferred here. This could be particularly important at the southern 

boundary of the PMNM, with a protected spawning source able to effectively seed areas to the south over time 

via a “stepping stone” effect, not immediately apparent from examining the pair-wise connectivity values. This 

gradual diffusive process could lead to much more connectivity than that described by a single generation. 

293 
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Figure 9.3. Larval dispersal (45 day PDL) one year after release from Mokumanamana (top) and French Frigate Shoals

(bottom). Source: Kobayashi, in review; maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

294 
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Figure 9.4. Larval dispersal (45 day PDL) one year after release from Gardner Pinnacles (top) and Maro Reef (bottom).

Source: Kobayashi, in review; maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

295 
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Figure 9.5. Larval dispersal (45 day PDL) one year after release from Laysan Island (top) and Lisianski Island (bottom).

Source: Kobayashi, in review; maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

296 
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Figure 9.6. Larval dispersal (45 day PDL) one year after release from Pearl and Hermes Atoll (top) and Midway Atoll (bottom). Source: Kobayashi, in review; maps: L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

297 
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ck

k

c er

k

Figure 9.7. Larval dispersal (45 day PDL) one year after being released from Kure. Source: Kobayashi, in review; map:

L. Wedding. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

298 

Figure 9.8: Larval retention for propagules released at each of 10 islands/atolls. The red bars in each graph indicate the

island or atoll from which the larval propagules were initially released. Source: Kobayashi, unpublished data. 

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Connectivity and Integrated Ecosystem Studies

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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 9.8 (continued): Larval retention for propagules released at each of 10 islands/atolls. The red bars in each graph indicate the island or atoll from which the larval propagules were initially released. Source: Kobayashi, unpublished data. 

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Ne k r

Nihoa

Niihau

Kauai

Oahu 

Molokai

Lanai

Maui

Hawaii

Percent Total Settlers

0 

5 

10 

15 

20 

25 

30 

35 

40 

Kure 

Midway 

Pearl_Hermes 

Lisianski 

Laysan

Maro 

Gardner 

French_Frigate_Shoals 

Nec er

Nihoa

Niihau

Kauai

Oahu 

Molokai

Lanai

Maui 

Hawaii 

0 

5 

10 

15 

20 

25 

30 

35 

Kure 

Midway 

Pearl_Hermes 

Lisianski 

Laysan

Maro 

Gardner 

French_Frigate_Shoals 

Necker 

Nihoa 

Niihau

Kauai 

Oahu 

Molokai 

Lanai

Maui 

Hawaii

Percent Total Settlers

0 

5 

10 

15 

20 

25 

Kure 

Midway 

Pearl_Hermes 

Lisianski 

Laysan

Maro 

Gardner 

French_Frigate_Shoals 

Ne ker 

Nihoa

Niihau

Kauai

Oahu 

Molokai

Lanai

Maui 

Hawaii

Mokumanamana

Mokumanamana 

Mokumanamana 

Mokumanamana

Mokumanamana 

Mokumanamana

299 

Directed Movements of Adult Fishes– Connectivity at the Scale of the Individual 

Acoustic telemetry of giant trevally

(white ulua, Caranx ignobilis; Figure 

9.9) and jobfish (uku, Aprion virescens;

Figure 9.9), large-bodied apex predators on Hawaiian reefs, revealed each

to be site attached and home ranging

(Meyer et al., 2007a,b; Figure 9.10). No 

inter-atoll movements were detected but 

animals were site attached to core activity areas where they exhibited diel habitat shifts and made periodic atoll-wide

excursions up to 29 km. Movements

to seasonal mating aggregations were

identified in the summer during specific 

phases of the moon for each species. 

Figure 9.9. Giant trevally (left) and jobfish (right) are both large, top predators in the NWHI coral reef ecosystem. Photos: J. Zamaow and J. Maragos. 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

300 

Giant Trevally Movement 

A large proportion of giant trevally from 

French Frigate Shoals were caught at 

La Perouse Pinnacle, and these fish 

all showed high detections/day at this 

location, verifying their strong site fidelity to a core area (Figures 9.11). The 

lower detection/day at East and Tern 

Islands also suggests that these locations are on the periphery of the fi sh’s 

home range (none of the fi sh detected 

at East or Tern were tagged at those locations). The large number of fi sh detected at Rapture Reef suggests this 

site provides important habitat for giant 

trevally at French Frigate Shoals, as fish 

tagged throughout the atoll made seasonal excursions to this reef. The arrival 

and departure times of fish were strongly correlated with each other and in turn 

with the lunar cycle. Coupled with anecdotal diver observations, the acoustic 

data indicate that Rapture Reef is likely 

a spawning aggregation site for giant 

trevally at French Frigate Shoals. Giant 

trevally tagged at Rapture Reef were 

detected there year round, suggesting 

that their core home range was located 

within the spawning habitat. These fish 

did not make long seasonal movements, 

as their core ranges were within the 

spawning area. The seasonal spawning 

behavior of giant trevally was characterized by daily runs to the spawning locations during the lunar spawning cycle. 

They did not shift their core home range 

to the spawning location, as they returned to their core range (e.g., La Perouse) after each spawning event. 

At Pearl and Hermes Atoll, the greatest number of detections of tagged giant trevally (for each individual fi sh) occurred at the receiver closest to the location where the fish was originally tagged, providing evidence that they 

show strong site fidelity to core areas (Figure 9.12). Giant trevally were detected at receivers at other parts of 

the atoll, suggesting that these areas were on the periphery of the fish’s home range. These were most likely 

areas visited during the diel habitat shifts exhibited by almost all individuals. Fish tagged at the Main Channel showed greater detections/day at large at the Main Channel receiver, compared to receivers close to fish 

tagged at other parts of the atoll (e.g., northwest corner). The Main Channel is shallow and experiences very 

strong, tidally-driven currents. These strong currents bring animals and materials in and out of the lagoons, 

which appears to make the Main Channel a desirable habitat for apex predators, as suggested by the large 

number of large sharks and teleosts seen at this location. 

Figure 9.10. Trans-atoll movements of giant trevally at French Frigate 

Shoals (top) and Pearl and Hermes (bottom; Meyer et al., 2007a). Circles

indicate locations of VR2 receivers, shaded squares indicate giant trevally

capture sites (numbers within square symbols indicate sites where multiple

individuals were tagged and released). Lines with arrows indicate most direct route between giant trevally release and detection locations. 
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

301Connectivity and Integrated Ecosystem Studies

Only a limited number of giant trevally were tagged at Midway and Kure Atolls, resulting in few detections and 

no evidence of movement (Figures 9.13 and 9.14). Shallow flats appear to be poor habitat for this species, as 

all receivers located in shallow flats at various atolls recorded very few detections. egraL ta syaD/snoitceteD fo rebmuN

575 621 551 619

100.00

80.00

60.00

0.02

0.01

0.00

East Island

575 621 551 619 537 617 525 527 529

100.00

80.00

60.00

40.00

2.00

1.00

0.00

egr

Rapture Reef

aL ta syaD/snoitceteD fo rebmuN

621 551 619 537 617

100.00

80.00

60.00

40.00

20.00

0.00

egr

La Perouse

aL ta syaD/snoitceteD fo rebmuN

Figure 9.11. Number of tag detections/days at large for giant trevally tagged at French Frigate Shoals. Source: Friedlander, unpub. data; maps: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

302Connectivity and Integrated Ecosystem Studies

575

100.00

80.00

60.00

0.20

0.00

egra

Tern

L ta syaD/snoitceteD fo rebmuN

575

100.00

80.00

60.00

2.00

1.00

0.00

egr

Trig

aL ta syaD/noitceteD fo rebmuN

Figure 9.11 (continued). Number of tag detections/days at large for giant trevally tagged at French Frigate Shoals. Source: 

Friedlander, unpub. data; maps: L. Wedding. 

egraL ta syaD/snoitceteD fo rebmuN

521 520 511 574 567

6.00

5.00

4.00

3.00

2.00

1.00

0.00

Main Channel

Figure 9.12. Number of tag detections/days at large for giant trevally tagged at Pearl and Hermes Atoll. Source: Friedlander, unpub. data; maps: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

303Connectivity and Integrated Ecosystem Studies

egraL ta syaD/snoitceteD fo rebmuN

512 576 511 521

6.00

5.00

4.00

3.00

2.00

1.00

0.10

0.05

0.00

NW

521 520 511 574 567 576

6.00

5.00

4.00

3.00

2.00

1.00

0.50

0.40

0.30

0.20

0.10

0.00

egra

SE

L ta syaD/snoitceteD fo rebmuN

567 520 584 576 511 521 512

6.00

5.00

4.00

3.00

2.00

0.10

0.05

0.00

egr

SW

aL ta syaD/snoitceteD fo rebmuN

Figure 9.12 (continued). Number of tag detections/days at large for giant trevally tagged at Pearl and Hermes. Source: 

Friedlander, unpub. data; maps: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

304Connectivity and Integrated Ecosystem Studies

576 584

6.00

5.00

4.00

3.00

2.00

1.00

0.00

egr

West

aL ta syaD/snoitceteD fo rebmuN

Figure 9.12 (continued). Number of tag detections/days at large for giant trevally tagged at Pearl and Hermes Atoll. 

Source: Friedlander, unpub. data; maps: L. Wedding.

egraL ta syaD/snoitceteD fo rebmuN

550 570

6.00

4.00

2.00

0.00

Fish Hole

egraL ta syaD/snoitceteD fo rebmuN

550 570

6.00

4.00

2.00

0.00

Frigate Point

Figure 9.13. Number of tag detections/days at large for giant trevally tagged at Midway Atoll. Source: Friedlander, unpub. 

data; maps: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands egraL ta syaD/snoitceteD fo rebmuN

606

3.00

2.00

1.00

0.02

0.01

0.00

SE Channel

Figure 9.14. Number of tag detections/days at large for giant trevally tagged at Kure Atoll. Source: Friedlander, unpub. 

data; maps: L. Wedding.

egraL ta syaD/snoitceteD fo rebmuN

606

3.00

2.00

1.00

0.10

0.00

West Channel

305Connectivity and Integrated Ecosystem Studies

egraL ta syaD/snoitceteD fo srebmuN

550 570

6.00

4.00

2.00

0.01

0.00

North Flats

Figure 9.13(continued). Number of tag detections/days at large for giant trevally tagged at Midway Atoll. Friedlander, 

unpub. data; maps: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

306Connectivity and Integrated Ecosystem Studies

Jobfish Movement

Movement patterns for jobfish were similar to those observed for giant trevally 

(Figures 9.15). For example, all fish detected at Rapture Reef were tagged at 

Disappearing Island, located close to 

Rapture Reef (Figure 9.16). However, 

there was no evidence that Rapture 

Reef is a spawning location for jobfish. 

Jobfish tagged along the south coast of 

Pearl and Hermes Atoll were detected 

by receivers on both the southwest and 

southeast tips (Figure 9.17). This suggests behavior associated with long, 

daily and tidal excursions.

Overall, jobfish had lower numbers of 

detections/day than giant trevally. This 

may be a function of a key difference in 

their spawning strategy, as well as a tendency for greater diel movement. Unlike 

giant trevally, jobfish perform complete 

seasonal shifts in their home range, occupying separate summer and winter 

core areas. These winter and summer 

locations do not overlap, which is why 

each receiver generally has fewer detections on an annual basis. However, 

jobfish were occasionally detected in 

their winter or summer location during 

the opposing season, suggesting that 

these seasonal core areas are relatively 

close to each other.

egraL ta syaD/snoitceteD fo rebmuN

606

3.00

2.00

1.00

0.04

0.03

0.02

0.01

0.00

West Channel Greg

Figure 9.14 (continued). Number of tag detections/days at large for giant trevally tagged at Kure Atoll. Source: Friedlander, unpub. data; maps: L. Wedding.

Figure 9.15. Trans-atoll movements of jobfish at Pearl and Hermes Reef 

with enlarged views of capture areas (insets) showing VR2 receiver locations (yellow squares), jobfish capture sites (white circles), jobfish transmitter codes (white numbers), most direct routes between jobfish release and 

detection locations (dashed red lines). Source: Meyer et al., 2007b.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

307Connectivity and Integrated Ecosystem Studies

egraL ta syaD/snoitceteD fo rebmuN

536 538 540 542 546

40.00

20.00

8.00

6.00

4.00

2.00

0.00

Rapture Reef

Figure 9.16. Number of tag detections/days at large for jobfish tagged at French Frigate Shoals. Source: Friedlander, 

unpub. data; maps: L. Wedding.

egraL ta syaD/snoitceteD fo rebmuN

559 536

40.00

20.00

0.01

0.00

La Perouse

Jobfish at Kure atoll also show strong site fidelity to core areas, and fish have been detected at one receiver for 

over three years. Again, however, diel and tidal movements result in jobfish moving over a large area, as exemplified by the different detection patterns for individual fish seen in Figures 9.18 and 9.19. These fish make 

complete seasonal shifts in habitat as can be seen by the absence of detections during either the summer or 

winter months. The fact that fish were detected, fish that were absent either during the summer or the winter 

months, suggests that the spawning habitats for this species were located at Kure, and that there is more than 

one spawning location at the atoll.
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308Connectivity and Integrated Ecosystem Studies

egraL ta syaD/snoitceteD fo rebmuN

573

5.00

4.00

3.00

0.01

0.00

NE

egraL ta syaD/snoitceteD fo rebmuN

573

5.00

4.00

3.00

2.00

0.02

0.01

0.00

NW

egraL ta syaD/snoitceteD fo rebmuN

556 566 573 595

5.00

4.00

3.00

2.00

1.00

0.20

0.10

0.00

SE

Figure 9.17. Number of tag detections/days at large for jobfish tagged at Pearl and Hermes Atoll. Source: Friedlander, 

unpub. data; maps: L. Wedding.
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

309Connectivity and Integrated Ecosystem Studies

egraL ta syaD/snoitceteD fo rebmuN

509 556 566 573

5.00

4.00

3.00

2.00

1.00

0.25

0.20

0.15

0.10

0.05

0.00

SW

Figure 9.17 (continued). Number of tag detections/days at large for jobfish tagged at Pearl and Hermes Atoll. Source: 

Friedlander, unpub. data; maps: L. Wedding.

egraL ta syaD/snoitceteD fo rebmuN

573

5.00

4.00

3.00

2.00

1.00

0.01

0.00

West
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

310Connectivity and Integrated Ecosystem Studies

egraL ta syaD/snoitceteD fo rebmuN

602

25.00

20.00

15.00

10.00

0.06

0.04

0.02

0.00

Frigate Point

Figure 9.18. Number of tag detections/days at large for jobfish tagged at Midway Atoll. Source: Friedlander, unpub. data; 

maps: L. Wedding.

egraL ta syaD/snoitceteD fo rebmuN

602

25

20

15

10

5

0

Fish Hole
A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

311Connectivity and Integrated Ecosystem Studies

Inferring Dispersal and Movement by Tracking Introduced Species

Eleven species of shallow-water snappers (F. Lutjanidae) and groupers (F. Serranidae) were purposely introduced to one or more of the main (high) islands of the Hawaiian Archipelago in the late 1950s and early 1960s. 

Of these, three snapper species and one grouper have become established (Randall, 1987). One snapper, 

blueline snapper (Taape or Lutjanus kasmira), and one grouper, Peacock grouper (Roi or Cephalopholis argus), are well-established, and have histories of colonization along the island chain that are reasonably welldocumented. Planktonic stage durations, although unknown for both species, are grossly estimable based on 

congeners elsewhere in the Indo-Pacific. These two species thus represent a unique opportunity to track the 

rate of colonization of introduced species within an oceanic insular (“stepping stone”) environment. 

Blueline snapper, if like several other Indo-Pacific congeners, has a planktonic stage duration approximating 

25-47 days and a settlement size greater than 20-30 mm (Leis, 1987), but there is a great deal of geographic, seasonal, and other environmental variations in stage duration within and among closely related species 

(Leis,1993; Victor, 1993). Given these same caveats, Peacock grouper, if a typical member of its genus in 

the subfamily Epinephelinae, settles at a size of about 18 mm (Leis, 1987) and is likely to have a shorter 

pelagic larval stage than blueline snapper.

A total of about 3,170 blueline snapper were introduced from the Marquesas Islands to Hawaii beginning 

in 1955, including 2,435 released in Kaneohe Bay, Oahu, in 1958 (Oda and Parrish, 1981; Randall, 1987; 

Figure 9.20). The species had colonized the Big Island of Hawaii, 140 nmi downchain of Oahu, by 1960 

(Randall,1987). Blueline snapper had spread upchain to French Frigate Shoals in the NWHI, 490 nmi from egraL ta syaD/snoitceteD fo rebmuN

588 604 607 610

80.00

60.00

40.00

0.20

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0.10

0.05

0.00

West Channel Greg

Figure 9.19. Number of tag detections/days at large for jobfish tagged at Kure Atoll. Source: Friedlander, unpub. data; 

maps: L. Wedding.

egraL ta syaD/snoitceteD fo rebmuN

588 604 607 610

80.00

60.00

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0.25

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0.00

West Channel
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

312 

Oahu, by sometime between 1977 and 

1982 (Okamoto and Kanenaka, 1984). 

The species was sighted another 330 

nmi farther upchain in the NWHI at Laysan Island (820 nmi from Oahu) in June 

1979 (Parrish et al., 1980; Oda and Parrish, 1981). A few individuals were first 

observed at Midway Atoll, 240 nmi farther upchain from Laysan island (1,180 

nmi from Oahu), in May-June 1992; 

the species had not been observed on 

similar surveys conducted at Midway in 

1989 and 1991 (Randall et al., 1993). 

These records suggest rates of dispersal of about 18-70 nmi/year for blueline 

snapper subsequent to its introduction 

to Hawaiian waters. This is consistent 

with estimates of realized mean dispersal distance ranging from 33 to 130 km/ 

year from Shanks et al. (2003). 

The dispersal of Peacock grouper following its introduction to Hawaii is not 

as well documented. However it is clear 

that Peacock grouper has spread less 

extensively than blueline snapper over 

approximately the same time period 

(Figure 9.21). In 1956, a total of 571 

C. argus were introduced from Moorea 

in French Polynesia to Oahu (n=171) 

and to the Kona coast of the Big Island 

(n=400; Randall, 1987). At present, it 

has been documented as far upchain 

as Niihau, 120 nmi from Oahu, where 

it was first observed in November 1978 

(Hobson, 1980). No shallow reef fish 

surveys of the westernmost MHI were 

conducted prior to this time. Peacock 

grouper was absent at French Frigate 

Shoals in 1992 and has been mostly 

absent in annual surveys conducted 

there between 1995 and 2003 (E. DeMartini, unpubl. data). Based on this 

meager data, a dispersal rate of >5 

nmi per year is suggested. Although 

pelagic duration estimates are approximate, Peacock grouper-- the species with a likely shorter-duration pelagic stage-- has spread much more slowly through the Hawaiian Archipelago than blueline snapper. Blueline snapper clearly belongs to the long-distance dispersal group (mode greater than 16 km/ 

year); Peacock grouper probably belongs to this group as well, albeit closer to the lower bound. 

Figure 9.20. Spread of the introduced blueline snapper (Taape, Lutjanus

kasmira) throughout the Hawaiian Islands. Source: Sladek Nowlis and

Friedlander, 2004. 

Figure 9.21. Spread of the introduced Peacock grouper (Roi, Cephalopholis argus) throughout the Hawaiian Islands. Source: Sladek Nowlis and

Friedlander, 2004. 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Genetic Connectivity Studies 

Ongoing research will determine genetic dispersal among islands and atolls of the NWHI, including both 

invertebrates and reef fishes, using molecular genetic markers to resolve populations and evolutionary partitions. Preliminary results indicate large differences among taxa in their degree of connectivity throughout the 

archipelago. Some species appear to move around the archipelago with relative ease and show no significant 

population structure in the NWHI and MHI (e.g., reef fish; Schultz et al., 2007; Craig et al., 2007). Other species 

show modest but significant population structure, including the endemic grouper (Rivera et al., 2004), spinner 

dolphins (Andrews et al., 2006) and two damselfishes (Ramon et al., 2008). 

Opihi, the Hawaiian endemic limpets 

(Cellana exarata; C. sandwicensis, Figure 9.22; and C. talcosa), show striking 

population differentiation between the 

MHI and NWHI (Bird et al., 2007). All 

three species of opihi show significant 

differentiation of populations across 

the Hawaiian Archipelago, but the spatial scales, patterns and magnitudes of 

partitioning differ by almost an order of 

magnitude among species. Preliminary 

data from hermit crabs (Baums et al., in 

prep) indicate variable connectivity in 

this group as well. There is significant 

population differentiation between the 

MHI and NWHI for all three species of 

opihi, and estimates of dispersal (migrants per generation ≤3) are so low that 

recruitment from the NWHI would likely 

have negligible impact on depleted MHI 

populations. Even within the MHI, the 

koele (C. talcosa) exhibits such strong 

population differentiation that if the 

Kauai population were depleted, it could 

not recover within our lifetime (Bird et 

al., 2007). 

Kobayashi (2006) recently used a computer simulation to infer patterns of larval dispersal between Johnston Atoll 

and the Hawaiian Archipelago. Results 

indicate a “northern corridor” which connects Johnston Atoll and the central portion of the NWHI and a “southern corridor” which connects Johnson Atoll to the 

MHI. Sampling was conducted at Johnston Atoll in 2006 to assess connectivity 

between the NWHI and this isolated reef 

habitat. The sea cucumber Holothuria 

atra exhibited low connectivity between 

Oahu and French Frigate Shoals and 

between Oahu and Johnston (Skillings 

et al., in prep; Figure 9.23). In contrast, 

there was no significant difference between samples from French Frigate Shoals and Johnston, supporting 

the northern corridor for dispersal between Johnston and the Hawaiian Archipelago (Figure 9.23). This result 

Figure 9.22. A yellowfoot opihi (Cellana sandwicensis) at Kauai. All Hawaiian Cellana spp. are endemic to the archipelago and exhibit a striking population differentiation between the main and northwestern islands. Photo: 

C.E. Bird. 

313 

Figure 9.23. F-statistics demonstrate population genetic separations for the

sea cucumber Holothuria atra between Oahu (MHI) and French Frigate

Shoals (NWHI), and between the MHI and Johnston, but high connectivity

between Johnston and French Frigate Shoals. Source: Skilling et al., in 

prep. 

FST

=

0 

FST = 0.15 

FST = 0.15 

Oahu 

French Frigate Shoals 

Johnston Atoll 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

314 

supports the hypothesis first advanced by Grigg (1981) and Maragos and Jokiel (1986) that Johnston is a potential gateway that enhances biodiversity in the NWHI. However the alternative hypothesis, that Johnston is 

an outpost of the Hawaiian fauna, remains a viable possibility pending further research. 

Results thus far indicate that population structure across the Hawaiian archipelago does not fit a simple isolation-by-distance model, and generalizations based on average (geostrophic) oceanographic currents may not 

be warranted (Figures 9.24). Closely-related species with similar ecology and reproductive biology (including 

opihi, hermit crabs, and reef fishes) can have dramatically different patterns of connectivity (Bird et al., 2007; 

Rocha et al., 2007). Together, these results mandate that a suite of invertebrates and fish must be surveyed to 

resolve general trends, and to provide connectivity information pertinent to management of the PMNM. 

Figure 9.24. Apparent shared barrier to dispersal in the Hawaiian Archipelago. Consensus of significant genetic partitions

among up to 14 marine species across the Hawaiian Archipelago. Locations of apparent restrictions to dispersal are 

marked with yellow bands, and the number of species that share that break out of the total number of species surveyed

for each location are also given. These results are preliminary, but the shared genetic structure among highly divergent 

species thus far is striking. 

Connectivity considerations are particularly important for Hawaiian endemic species. Conservation of Hawaiian endemic species should take into account the consequences of their restricted distribution, including reduced capacity for recovery following depletion. Recently, scientists at the Hawaii Institute of Marine Biology 

have begun to examine population structure in three species of endemic Hawaiian butterflyfishes: the milletseed butterflyfi sh (Chaetodon miliaris), the bluestripe butterflyfish (C. fremblii) and the pebbled butterflyfi sh (C. 

multicinctus). Thus far, they have collected and sequenced 170 individuals of bluestripe butterflyfi sh (Figure 

9.25), 229 milletseed butterflyfish (Figure 9.26) and have made significant progress in collections of pebbled 

butterflyfi sh (Figure 9.27) throughout the Hawaiian Islands (M.T. Craig et al., pers comm.). These species 

perform distinct roles in the coral reef ecosystem and can provide examples of differential connectivity over 

meso-scale distances. 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 9.25. Haplotype network for the endemic bluestripe butterflyfish. Source: Craig et al., unpub. data. 

315 

Figure 9.26. Haplotype network for of the endemic milletseed butterflyfish. Source: Craig et al., unpub. data. 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

316 

Figure 9.27. Haplotype network for of the endemic pebbled butterflyfish. Source: Craig et al., unpub. data. 

ESSENTIAL FISH HABITAT 

Fisheries-habitat links are an important consideration with respect to forms of spatial management such as 

marine protected areas. The composition of suitable habitat within an area can largely dictate fi sh distribution 

and abundance patterns. The formal concept of essential fish habitat (EFH) was defined with the reauthorization of the U.S. Magnuson-Stevens Fishery Conservation and Management Act in 1996, and refers to habitat 

that is recognized as ecologically important to fisheries resources. Critical fisheries habitats must be identified 

as valued ecosystem components in order to facilitate the formation of ecosystem-based management actions. 

Congress defined EFH as “those waters and substrate necessary to fish for spawning, breeding, feeding, or 

growth to maturity” (16 U.S.C. 1802(10)). The EFH guidelines under 50 CFR 600.10 further interpret the EFH 

definition as follows: Waters include aquatic areas and their associated physical, chemical, and biological 

properties that are used by fish and may include aquatic areas historically used by fish where appropriate; 

substrate includes sediment, hard bottom, structures underlying the waters, and associated biological communities; necessary means the habitat required to support a sustainable fishery and the managed species’ 

contribution to a healthy ecosystem; and “spawning, breeding, feeding, or growth to maturity” covers a species’ 

full life cycle. 

Analysis was conducted for NWHI bottomfish to determine EFH for these important resource species harvested by Hawaiian-based vessels. The bottomfish fishery has targeted about a half-dozen species of deepslope (generally >75-100 fm) eteline snappers (family Lutjanidae) and one endemic species of epinepheline 

grouper (family Serranidae) out of a total of a dozen common Bottomfish Management Unit Species (WPFMC 

2004; Table 9.1). These species typically inhabitat depth ranges from 100 and 400 m and have been found to 

be associated with certain benthic features, such as high-relief hard-bottom slopes (Kelley, et al., 2006; Kelley 

and Ikehara, 2006; Kelley, 2000). 
Connectivity and Integrated Ecosystem Studies

°°

 

 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Table 9.1. Dominant species in NWHI bottomfish catch and research-based essential fish habitat boundaries (depth in

meters). Illustrations by Les Hata from Hawaii Divison of Aquatic Resources. 

LOCAL NAME COMMON NAME SCIENTIFIC NAME DEPTH RANGE (m) 

Ehu Red snapper Etelis carbunculus 100-400 

Gindai Flower snapper Pristipomoides zonatus 100-350 

Hapuupuu Hawaiian grouper Epinephelus quernus 30-300 

Kalekale Von Siebold’s snapper Pristipomoides sieboldii 50-350 

Lehi Reddish snapperfish Apharues rutilans 50-250 

Onaga Scarlet snapper Etelis coruscans 100-400 

Opakapaka Pink snapper Pristipomoides 

filamentosus 

50-300 

The NWHI fishery is divided into two 

management zones (Mau, Hoomalu), 

partly in order to distinguish between 

short- and long-duration fishing trips and 

short-duration trips to the closer (to the 

MHI) Mau and more distant (Hoomalu) 

zones, respectively (Figure 9.28). Between 1996 and 2004, the Mau zone 

bottomfish catch (Figure 9.29) was 

dominated by shallow-water species 

such as jobfish (39%) and thicklipped 

jack (butaguchi, Pseudocaranx dentex, 

14%), with pink snapper (opakapaka, 

Pristipomoides filamentosus, 13%), Hawaiian grouper (hapuupuu, Epinephelus 

quernus, 13%), and red snapper (onaga, Etelis coruscans, 8%). In contrast, 

red snapper and pink snapper accounted for 28% and 25% of the Hoomalu catch, respectively, followed by 

Hawaiian grouper (15%). 

The average annual reported landings of bottomfish in the NWHI between 1984 and 2003 were 336,000 lbs 

(SD ± 235,500; NOAA 2006). Of this, the Mau zone averaged 107,130 (SD ± 53,890) or 32% while the average catch in the Hoomalu zone averaged 228,730 lbs (SD ± 63,030) or 68% (Figure 9.29). In 2003, the gross 

Figure 9.28. Total commercial bottomfish landings from 1996 to 2002. Data

in several cells can not be shown due to confidentiality concerns. Data:

DAR; Ehler, 2004. 

170°W

170°W

25 N25 N

0 

< 10,000 lbs 

10,000 - 25,000 lbs 

25,000 - 50,000 lbs 

> 50,000 lbs 

No Data 

Management Boundary 

EEZ 

Mau Zone 

Hoomalu Zone 

317 
Connectivity and Integrated Ecosystem Studies

Table 9.2. Optimal bottomfish habitat criteria for NWHI. Source: PIBHMC. 

GIS LAYER SOURCE RANGE 

Depth PIBHMC 20 m multibeam data 100-400 m 

Slope Derived from PIBHMC 20 m multibeam data > 20 percent slope 

Backscatter R/V AHI Hard (>120 m) 

Backscatter R/V Kilo Moana Hard (> 1,000 m) 

A Others

13%
 

Onaga
 

8% Uku
 

39%
 

Hapuupuu B 

13% Others Uku 

9% 12% 

Opakapaka Butaguchi

13% Butaguchi 11% 

14% Onaga 

28% 

Opakapaka 

25% 

Hapuupuu 

15% 

Figure 9.29. Average species composition (1996-2004) of bottomfish

catches from the Mau (A) and Hoomalu (B) zones in the NWHI. See text

for scientific and common names. Source: Kawamoto and Gonzales, 

2005. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

318 

reported revenues for the Mau zone

were $611,000 and $674,000 for the

Mau and Hoomalu zones, respectively

(Ehler, 2004). 

In 2003, the number of vessels participating in the two zones remained the

same from the previous year, but there

were substantial changes in the number 

of fishing trips (NOAA, 2006). In 2003,

Mau zone trips decreased by 51% resulting in a 29% drop in landings from

the previous year. The number of trips

in the Hoomalu zone increased by 50% 

in 2003, resulting in a 29% increase in

landings. 

With the initial designation of the NWHI 

Coral Reef Ecosystem Reserve and

now PMNM, fishing activity in the NWHI 

has been on the decline. Proclamation

8031 allows commercial fishing by federally permitted bottomfish fi shery participants that have valid permits until mid-2011 (FR 36443, June 26, 2006). This amounts to a maximum of 

eight permitted bottomfish vessels that fish within the Monument. Significant work was undertaken prior to the 

designation of the Monument in response to previously issued Executive Orders that created the Reserve in 

2000. This fishery operates according to the management regime specified in the Fishery Management Plan 

for Bottomfish and Seamount Groundfish Fisheries in the Western Pacific Region. The management regime 

includes several precautionary measures that minimize potential effects of this fi shery. The bottomfi shery participants do not operate in the presence of the Hawaiian monk seals and the annual harvest limit for the eight 

vessels is 300,000 lbs. 

The criteria used to delineate potential bottomfish habitat in the NWHI was 

based on previous analysis done in the 

MHI (Kelley, 2000; Parke, 2007). Multibeam data sonar provided the GIS layers 

for bottom depth, slope and hardness. 

These factors were used as criteria to 

identify EFH and potential adult habitat for bottomfish (Table 9.2). The depth range found most appropriate for 

this analysis was 100-400 m based on EFH criteria. Areas with slopes greater than 20% were then selected in 

the GIS to further delimit the potential adult habitat areas. Lastly, areas designated as hard bottom based on 

backscatter values were selected for the final potential adult habitat delineation. The range of sonar backscatter values depended upon the instrument used to collect the data. 

EFH and potential adult habitat analysis was completed for French Frigate

Shoals, Kure, Maro, and Pearl and

Hermes because these islands had sufficient multibeam data. These islands

currently do not have complete coverage in the depth range designated for

EFH, so the results of this analysis represent bottomfish EFH and potential

Table 9.3. Area (km2) of EFH based on available multibeam data detailing

depth (100-400 m) within each island. Source: PIBHMC. 

ISLAND AREA EFH (km2) % OF TOTAL MAPPED AREA 

French Frigate Shoals 243.93 23.51 

Kure 138.79 31.19 

Maro 407.97 30.32 

Pearl and Hermes Atoll 54.12 10.98 

Total km2 844.81 24.00 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

adult habitat based on the data available to date. Maps for each island were created for areas that met each of 

the criteria. The areas in these map products that met all three criteria were considered to be “suitable” adult 

bottomfish habitat (Table 9.3; Figure 9.30). 

166°30'W 166°24'W 166°18'W 166°12'W 166°6'W 166°0'W 

French French 

Frigate 

Shoals 

Essential Fish Habitat 

EFH (100-400m)
 

Land
 

Depth (m)
 

0

 -700
 

024 1 Kilometers ± 166°30'W 166°24'W 166°18'W 166°12'W 166°6'W 166°0'W 

Frigate 

Shoals 

28°18'N 28°24'N 28°30'N 25°20'N 25°40'N 23°36'N 23°42'N 23°48'N 23°54'N

25°20'N 25°40'N 28°18'N 28°24'N 28°30'N 23°36'N 23°42'N 23°48'N 23°54'N 

28°18'N 28°24'N 28°30'N 25°20'N 25°40'N

178°30'W 178°24'W 178°18'W 178°12'W 178°30'W 178°24'W 178°18'W 178°12'W 

Kure Kure 

28°18'N 28°24'N 28°30'N 25°20'N 25°40'N 

Potential Adult 

Essential Fish Habitat Bottomfish Habitat

Potential Habitat 

Land 

EFH (100-400m) 

Land 

Depth (m) Depth (m) 

0 0

±
 ± -1000 -700 

036 1.5 

-1-7 00000

036 1.5 Kilometers Kilometers 

178°24'W 178°18'W 178°12'W 178°24'W 178°18'W 178°12'W 

171°W 170°40'W 170°20'W 171°W 170°40'W 170°20'W 

Maro 

Essential Fish Habitat 

Maro 

Potential Adult 

Bottomfish Habitat 

EFH (100-400m) Potential Habitat 

Land Land 

Depth (m) Depth (m) 

0 0

-1000 800 -700 -1000 80-7 0 0

048 2 048 2 ± Kilometers ± ± Kilometers ± 171°W 170°40'W 170°20'W 171°W 170°40'W 170°20'W 

Figure 9.30. Essential fish habitat (yellow) and potential adult bottomfish habitat (red) based on GIS analysis of available

multibeam data. Maps: L. Wedding. 

319 
176°12'W 176°6'W 176°0'W 175°54'W 175°48'W 175°42'W 

Essential Fish Habitat 

EFH (100-400m) 

Land 

Depth (m) 

0

-3000 -700 10- -1000 

036 1.5 ±
 

27°42'N 27°48'N 27°54'N 28°0'N 

27°42'N 27°48'N 27°54'N 28°0'N

Kilometers 

Pearl and 

Hermes 

176°12'W 176°6'W 176°0'W 175°54'W 175°48'W 175°42'W 

176°12'W 176°6'W 176°0'W 175°54'W 175°48'W 175°42'W 

Potential Adult 

Bottomfish Habitat 

Potential Habitat 

Land 

Depth (m) 

0

-30001 -700 -1000 

036 1.5 ±
 

27°42'N 27°48'N 27°54'N 28°0'N

27°42'N 27°48'N 27°54'N 28°0'N 

Kilometers 

Pearl and 

Hermes 

176°12'W 176°6'W 176°0'W 175°54'W 175°48'W 175°42'W 

180° 175°W 170°W 165°W 160°W 155°W N30°

Kure 

N30°

Pearl & Hermes

Midway Maro 

Gardner 

N25°

French Frigate Shoals 

N 25°

Lisianski 

Laysan Nihoa 

Kauai

Mokumanamana Oahu

Maui 

N

Molokai 

N 

20°

20°

Locations of Stable Hawaii Isotope Analysis 

Monument Boundary 

Sampling Locations 

Land

0 2 100 00 N

Kilometers 

N 

15°

±

15°

175°W 170°W 165°W 160°W 155°W

Figure 9.31. Locations for stable isotope analysis from cruises in April, May

and September 2005. Map: L. Wedding.

Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Figure 9.30 (continued). Essential fish habitat (yellow) and potential adult bottomfish habitat (red) based on GIS analysis

of available multibeam data. Maps: L. Wedding 

TROPHIC RELATIONSHIPS: STABLE ISOTOPE COMPOSITION OF PRIMARY PRODUCERS 

AND CONSUMER ORGANISMS 

Analysis of the carbon (C) and nitrogen 

(N) stable isotope composition of primary producers, benthic invertebrates,

bony (teleost) fishes and sharks was

used to assess vertical trophic linkages between primary producers and

consumer organisms in the NWHI, and

horizontal trophic linkages between reef 

and pelagic ecosystems. Samples of

fish, sharks, invertebrates, phytoplankton and benthic algae were obtained

during a May 2005 cruise aboard the

NOAA ship Hiialakai from six locations

in the NWHI (Figure 9.31). Muscle tissue was removed from fish (dissection), 

sharks (plugs from tagged animals), and 

invertebrates (dissection). Animal tissue 

was rinsed in distilled water, dried and

ground prior to stable isotope analysis. Seawater was prefiltered through a 

200 micron mesh to remove zooplankton and retain phytoplankton on ashed

glass fiber filters. Benthic macroalgae were collected by divers, cleaned and rinsed in distilled water, dried and 

ground. Benthic microalgae were collected by divers from surface sediments. Microalgae were separated from 

sediment either by vertical migration through nylon mesh (Currin et al., 2003) or by density centrifugation in 

colloidal silica (Moseman et al., 2004). Algal samples were fumed with concentrated hydrochloric acid to remove carbonates prior to stable isotope analysis. All samples were sent for analysis of 13C and 15N composition 

by mass spectrometry at the University of California-Davis. 

The C and N stable isotope composition of algae is a function of ocean chemistry, photosynthesis and growth 

rates, and the specific nitrogen uptake mechanisms of the algae. Typically, phytoplankton have a C isotopic 

signature distinct from benthic algae, and this distinction can be followed through a food web, as animals are 

usually within 0.5‰ of the 13C value of their food. In contrast, algae differ less in their

15N values, and animals 

320 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

usually have 15N values that are 2.5 to 4 ‰ greater than their food, and so N isotopes provide a means to calculate the number of trophic steps between primary production and a higher level consumer. 

Fish collected from the NWHI were assigned to one of seven trophic groups using diet information in Friedlander and DeMartini (2002) and Parrish and Borland (2004). Invertebrates, which consisted of Hawaiian spiny 

lobster and a single Hawaiian day octopus, were placed in a separate group. All sharks were classifi ed as 

apex predators; see Table 9.4 for list of species collected, trophic group assignments and number of samples 

collected. 

Table 9.4. Trophic group assignments for species collected for stable isotope analysis. Number of samples analyzed (n) 

and common names are also provided. 

TROPHIC GROUP GENUS SPECIES COMMON NAME n 

Herbivores 

Acanthurus olivaceus orangeband surgeonfish 30 

Acanthurus nigrofuscus brown surgeonfish 4 

Acanthurus triostegus convict tang 35 

Acanthurus nigroris bluelined surgeonfish 23 

Stegastes fasciolatus Pacifi c gregory 5 

Zebrasoma flavescens yellow tang 22 

Corallivore Chaetodon lunulatus oval butterflyfish 15 

Zooplanktivores 

Chaetedon milaris milletseed butterflyfish 54 

Dascyllus albisella Hawaiian dascyllus 18 

Myripristis berndti 

Myripristis amaena 

Priacanthus meeki 

big-scale soldierfish 

brick soldierfish 

Hawaiian bigeye 

3 

3 

16 

Invertebrates Octopus cyanea Hawaiian day octopus 1 

Panulirus marginatus spiny lobster 42 

Benthic predators 

Lutjanus kasmira bluestripe snapper 11 

Parupeneus porphyreus whitesaddled goatfish 14 

Parupeneus multifasciatus manybar goatfish 37 

Pareupeneus cyclostomus yellowsaddle goatfish 2 

Bodiandus bilunulatus Hawaiian hogfish/wrasse 15 

Chaetodon fremblii bluestripe butterflyfish 30 

Thalassoma ballieui blacktail wrasse 29 

Pelagic predators Euthynnus affins wavy-backed tuna 5 

Apex predators 

Caranx melampygus blue jack 19 

Caranx ignobilis white jack 36 

Aprion virescens green jobfish 6 

Carcharhinus amblyrhynchos grey reef shark 6 

Carcharhinus galapagensis Galapagos shark 28 

Galeocerdo cuvier tiger shark 8 

Epinephelus quernus Hawaiian grouper 2 

There was a clear separation in the 13C signatures of the primary producers in the NWHI system. Phytoplankton 

(Phyto) had an average 13C value of -23.4‰, consistent with other published values for oceanic phytoplankton. 

Benthic macroalgae (BMA) and microalgae (BMI) were relatively enriched in 13C, with average values of -18.2 

and -9.5 ‰, respectively. There was less separation in the mean 13N values of benthic algae, which ranged 

from 1.1 to 3.4 ‰ (Figure 9.32). 

Fish which were a priori placed in the Herbivore category had lower 15N values than other consumer organisms, 

as expected. However, the offset between the 15N values of algae and several members of the Herbivore group 

was higher than the expected 2 to 4/mil, suggesting that either some of the fish designated as herbivores are in 

fact omnivores, or that the algal N values obtained during the May 2005 cruise were more depleted than algal 

values earlier in the season. This latter point can reasonably explain the observed data, as the isotope composition of fish tissue turns over much more slowly than the isotopic composition of the faster growing algae. 

There was also a significant range in the C values within the Herbivore group, with yellow tang in particular 

321 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

322 

closest to the phytoplankton endmember, and the brown surgeonfi sh closest 

to the benthic microalgal endmember. 

Both yellow tang and brown surgeonfish 

are browsers of macroalgae but isotopic 

differences suggest there may be finer 

scale variations in diet (Jones, 1968). 

Fish designated as Zooplanktivores and 

Corallivores, as well as lobster and octopus, had 15N values of approximately 

8.25‰, consistent with feeding at two 

trophic levels above primary producers 

with an average 15N trophic fractionation 

value of 2‰. The Zooplanktivores had 

the lowest C isotope signature, suggesting a greater contribution of phytoplankton to their food web, although 

a significant portion of benthic production was also utilized by this group. In 

contrast, the Corallivore had a more enriched C isotope signature, consistent 

with a greater contribution of coral and 

benthic algae to its food web. 

Fish designated as Benthic Predators 

exhibited approximately a 3‰ range 

in both C and N isotope signatures. 

Benthic Predators with 15N values >10 

(blacktail wrasse) may be feeding 2.5 

to 3.0 trophic levels above the primary 

producers. The Benthic Predators with 

the most enriched 13C values were the 

whitesaddle goatfish and the Hawaiian 

hogfish, 

The 13C values of fish designated as Pelagic Predators were relatively depleted in 13C, suggesting that phytoplankton did contribute substantially to the food webs supporting these fi sh. The 15N values of Pelagic Predators averaged 9.3‰, which is very similar to the average trophic level of the Benthic Predator group, and 

consistent with an organism feeding two to three levels above the primary producers. 

The 15N values of fish and sharks designated as Apex Predators overlapped with the 15N values of the Pelagic 

Predator (wavy-backed tuna) or Benthic Predator (blacktail wrasse). The exception is the enriched 15N value of 

12.1 for the tiger shark, which puts it nearly a full trophic level above other predators in the NWHI ecosystem. 

This is consistent with marine mammals, sharks, birds and other upper trophic level prey comprising a larger 

portion of the tiger shark diet than that of Galapagos and grey reef sharks (Papastamatiou et al., 2006). The 13C 

values of several of the Apex Predator group were enriched in 13C compared to other predators in the system. 

In particular, it appears that grey reef sharks, Galapagos sharks, giant trevally, and tiger sharks are obtaining 

the bulk of their C from a benthic-based food web. 

The relative contribution of benthic primary production to the food webs supporting bony fish, shark and invertebrate production can be estimated by comparing the stable isotopic composition of these groups with 

values that would be expected from a prescribed food web. In Figure 9.33, the mean isotope values of each 

of the trophic groups described in Table 9.4 are displayed. The black dotted lines in the figure represent the 

Figure 9.32. Dual isotope plot of consumer and producer groups from

NWHI. Each symbol represents the mean ± one standard error of the 15N or 13C value for a species of fish, shark or invertebrate. Species list, number of

samples and trophic group designations are as in Table 9.4; arrows point to 

species referred to in the text. 

-25 -20 -15 -10 -5 

0 

2 

4 

6 

8 

10 

12 

14 

Herbivores 

Zooplanktivores 

Corallivores 

Benthic predators 

Apex predators 

Pelagic predator 

BMA 

BMI 

Phyto 

G15N (‰) 

G13C (‰) 

Tiger shark 

Hawaiian Grouper 

whitesaddled 

goatfish 

brick 

soldierfish 

yellow 

tang 

brown 

surgeonfish 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

expected graphical position of a consumer group feeding at the fi rst Trophic 

Level (1 TL) through the fourth Trophic 

Level (4 TL). The position of these black 

lines is based on the assumption that 

there is a 2 – 4‰ increase in 15N values 

per trophic step, and a 0.5‰ increase 

in 13C values per trophic step, and that 

the food web is based on equal parts 

phytoplankton, benthic microalgae, and 

benthic macroalgae. In terms of trophic 

level of the various groups, the figure 

clearly illustrates the discrepancy between the 15N values of the primary 

producers as measured in May 2005 

and the herbivores that are presumably 

grazing on them. As noted previously, 

this could be due to a short-term decrease in the 15N values of the primary 

producers, and the longer-term average 

value of the primary producers may be 

closer to 3.5 – 4.5‰, which would result in the observed herbivore 15N values. Alternatively, it may be that some 

members of the group designated as 

‘Herbivores’ are in fact. Figure 9.33 also 

clearly illustrates that the groups designated as Zooplanktivores, Corallivores 

and Invertebrates (lobster) are feeding 

a full trophic level above the Herbivores, 

and that the Benthic and Pelagic Predator groups are feeding about one-half 

trophic level above that position. Apex 

Predators (sharks and jacks) are feeding nearly a full trophic level above the 

Invertebrate/Corallivore level, and about 

one-half trophic level above the Benthic 

and Pelagic Predators. As noted previously, and illustrated in Figure 9.32, tiger sharks are an exception and are feeding a full trophic level above the 

Benthic Predator group. The figure also reveals that all groups other than Pelagic Predators, Zooplanktivores 

and Corallivores fall roughly where they would be expected to fall if phytoplankton represented approximately 

33% of the base of their food web, with the remaining portion deriving from equal parts benthic microalgae and 

benthic macroalgae. The position of the exceptions indicate that phytoplankton represent a greater proportion 

of the food web support for Pelagic Predators and Zooplanktivores, and that phytoplankton represent less 

than a third of the food web support for Corallivores. Taken together, these results from analysis of the stable 

isotope composition of primary producers and consumers from the NWHI are remarkably consistent with the 

Ecopath model estimates of the food web supporting fishery production in the NWHI (see next section). Both 

approaches indicate that benthic algae provide the majority of trophic support for apex predators, and that the 

entire system consists of a relatively short (three to four trophic levels above primary production) food chain. 

Figure 9.33. Dual isotope plot of mean isotope values of primary producers

and each of the trophic groups described in Table 9.4. The black dotted 

lines in the figure represent the expected graphical positions of a consumer

group feeding at the first Trophic Level (1 TL) through the fourth Trophic 

Level (4 TL), assuming a food web based on equal parts of each of the

three primary producers (phytoplankton, benthic macroalgae, benthic microalgae). Further details on assumptions are in the text. 

G13C (‰) 

-24 -22 -20 -18 -16 -14 -12 -10 -8 -6 

G15N (‰) 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

Phyto 

BMA 

BMI 

1 TL 

2 TL 

3 TL 

4 TL 

Herbivore 

Corallivore 

Zooplanktivore 

Invertebrate 

Benthic Predator 

Pelagic Predator 

Apex Predator 

Trophic Levels (1 - 4) 

assuming food base 

of 33% Phyto, 33% BMA 

and 33% BMI 

323 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

324 

FOOD WEB MODELS 

The coral reefs of the NWHI represent a 

diverse marine ecosystem that provides 

habitat to a number of organisms (Figure 9.34). In the mid to late 1970s, dozens of scientists participated in a large, 

multi-year field study program at French 

Frigate Shoals to describe and better 

understand this ecosystem (Grigg et al., 

2008). These efforts yielded Ecopath, a 

simulation program designed to model 

the flow of energy throughout the system. Ecopath works by creating a snapshot of the ecosystem and the feeding 

relationships between species within 

that ecosystem. The trophically linked 

components consist of a single species, or a group of species representing ecological levels. For each species 

group, biomass, production/biomass ratio (or total mortality), consumption/biomass ratio and ecotrophic effi ciency are 

measured (Polovina, 1984). Ecosim, a 

new dynamic modeling program based 

on the original Ecopath model, is now 

available at (http://www.ecopath.org). 

Ecopath was first applied to data collected at French Frigate Shoals during 

the late 1970s (Figure 9.35). The ecosystem was divided into 12 species 

groups with sharks, jacks, monk seals, 

sea birds and tuna at the top trophic level, reef fishes at the center, and benthic 

algae, responsible for 90% of the productivity, at the bottom (Polovina, 1984). 

The large reef fishes group was further 

divided into four feeding guilds, resulting in an ecosystem spanning almost 

five trophic levels with sharks, jacks and 

piscivorous reef fish representing the 

top predators (Polovina, 1984). With the 

exception of limited handline fi shing for 

snappers, the NWHI are not fi shed and 

experience relatively few, severe local anthropogenic threats (although sea level rise, acidification, and the 

warming/bleaching and loss of coral habitat will likely become a major human agent of change at basin and 

global scales later in this century). Because the NWHI presently has few severe local threats, the Ecopath 

model provides a picture of an increasingly rare coral reef ecosystem dominated by an abundance of apex 

predators. 

The Ecosim was used to simulate changes in ecosystem dynamics over time in response to top-down or 

bottom-up forcing (Christensen and Walters, 2004) which was modelled by assuming 30 years of high benthic 

primary productivity, followed by 30 years of low benthic primary productivity (Grigg et al., 2008). Significant 

Figure 9.34. The coral reefs of the NWHI are a very diverse and unique

ecosystem, providing habitat for a wide range of marine life. Photo: J. Maragos. 

Figure 9.35. Illustration of the Ecopath Model for the food web at French

Frigate Shoals. The trophic pathway, annual production (P), and mean annual biomass (B; kg/km2

) is given for 12 species groups based on an area

of 1,200 km2. Source: Polovina, 1984. 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

temporal lags, varying by as much as a decade, were observed in the responses of the various trophic guilds 

both under an increase and a decrease in benthic productivity (Grigg et al., 2008). Planktivorous reef fish 

trended downward when benthic productivity was high due to the increase in predatory species (e.g., jacks). 

This was the case even when prey plankton was unchanged. When benthic productivity was changed from 

high to low there was an immediate sharp increase followed by a decline in benthic carnivorous reef fishes. 

The reef fishes quickly increased in abundance in response to higher prey availability, but five years later as 

their predators increased, their abundance declined (Grigg et al., 2008). Even with the more complex Ecosim 

model, it is important to note that ecosystem dynamics are more complicated than the model provides and are 

not always consistent with model forcing. 

In the last 10 years the Ecosim model was revised using updated parameters and a reference biomass based 

on surveys of benthic/demersal fish taxa that exhibited habitat fidelity (Parrish, unpub data). Field surveys were 

spatially stratifi ed by the region’s primary habitat types in order to make the model more accurate (Grigg et al., 

2008). The surveyed fish communities occupied the central portion of the ecosystem food web and were used 

to project a minimum biomass for the lower guilds, as well as a theoretical maximum value for the top level 

transient predators that preyed on the fish (Grigg et al., 2008). Work is now underway to validate the model 

with the best field estimates of population size, body size distributions, and size-specific food and feeding habits for the endangered Hawaiian monk seal, a top level predator in the NWHI. Numbers and body condition of 

the seals have been closely monitored for the last two decades and foraging studies indicate a diet of primarily 

benthic/demersal fish (Goodman-Lowe, 1998; Parrish et al., 2000, 2002 and 2005). Successful validation of 

the model using monk seals will depend on knowing the boundaries of the seal foraging activity and the relative 

composition of the diet (Grigg et al., 2008). Once initial validation efforts are complete, the dynamic simulation 

phase using Ecosim (Figure 9.36) will begin with the goal of forecasting and hindcasting situations to illustrate 

how the system might react to both natural and anthropogenic stressors. 

Biomass/Original Biomass 1.4 

0.9 

0.5 

0.0 

Figure 9.36. Capture of the Ecosim software output for the Ecopath model at French Frigate Shoals. Display shows the

response of ecosystem component to a 50% reduction in benthic algae. 

325 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

326 

EXISTING DATA GAPS 

To understand passive transport, there is a need for basic information on spatial and temporal patterns of water 

movement, quality and characteristics within the NWHI at a range of scales to determine the general patterns 

of passive transport for nutrients and living resources. Building on an understanding of oceanographic processes, specific research needs and opportunities include efforts to: 

• Determine the transport pathways and patterns for the larvae of key organisms; 

• Identify the sources and sinks of larval dispersal for key organisms; 

• Define the sources and patterns of primary productivity resulting from upwelling sites and occurrences 

and nutrient input to the NWHI; and 

• Undertake applied research into the design of protected areas in support of ecosystem resilience 

based on passive transports processes, patterns and pathways. 

Overall there is a need for systematic information on the active transport and movement of biota into, out of 

and within the NWHI. This work can be extended to important applications such as stock identifi cation, population dynamics and species interactions. All of these efforts should be undertaken in a way that contributes to 

the development of models that can predict movement patterns at multiple spatial scales to address questions 

of connectivity, including the linkages between the NWHI and the MHI. 

Specific opportunities include research to improve the understanding of: 

• What are the important species that have regular or episodic, active movements or migrations into and 

out of the NWHI and MHI? 

• What life stages of these species are involved in the active movements? 

• What are the important habitats for different life stages of these species that move among the reefs 

within the NWHI and between the NWHI and MHI? 

• What are the effects of extreme events and anthropogenic stressors on movements and migrations? 

• Which habitats are at risk from climate change and other forces (e.g., sea turtles and their nesting 

beach habitat)? 

As the understanding of most of the species and populations in the NWHI is at the most basic level (e.g., 

identification of species and groups), genetic studies have the capability to enhance the understanding of the 

ecosystem, including distribution, dispersion rates, and connectivity or isolation among plant and animal populations in the NWHI. Specific research opportunities include: 

• Characterizing the genetic structure of key species and populations; 

• Determining genetically distinct subpopulations of flora or fauna between the MHI and the NWHI; 

• Determining the value of selected species in the NWHI for repopulating MHI populations that are over 

exploited or subject to major impacts; 

• Applying genetic techniques to key populations across the stress gradient of the archipelago to detect 

pools of individuals with a genetic makeup that keeps them from being filtered out by the environmental 

stressors; 

• Studying individual species’ response to natural and anthropogenic stress (determining the coral species that are more heat tolerant and can withstand coral bleaching); 

• Identifying key species that may be at risk from the genetic influence of invasive species. Identifying 

pilot taxa to serve as proxies for ecosystem genetic connectivity; and 
Connectivity and Integrated Ecosystem Studies

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

• Because management decision making will be improved by knowledge of many specific factors influencing ecosystem resilience, information is needed on resilience pathways, such as: acclimation to 

stress, adaptation to stress, the role of the environment and the role of the community. Specifi c examples of research opportunities include activities to determine: 

• The key aspects that affect ecosystem stability and resilience (e.g., rates of energy fl ow, oceanographic conditions, nutrient levels and recruitment); 

• The degree to which natural variability in an ecosystem may determine its capacity for resilience; 

• How ecosystem acclimation to change varies among taxa and in relation to survival and the 

ability to effectively reproduce; 

• How genetic makeup enhances the ability of taxa to recover from some kinds of stress; 

• Which environmental conditions, e.g., temperature, flow, geomorphology, have a mitigating influence on survival in a changed environment; 

• The extent to which the reduction or expansion of one or more species or functional groups 

results in top down predation or an increase in bottom up production; 

• How the rebound of an ecosystem depends on maintaining established pathways of energy flow 

which provide the system a stable means of recovery rather than risk a transition to a different 

state of equilibrium; 

• The extent to which reducing fish populations of the ecosystem undermine or realign energy 

flow and trophic stability; and 

• Whether self seeding systems are resilient. 

327 
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A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

328 

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PERSONAL COMMUNICATIONS 

Craig, M.T. Hawaii Institute of Marine Biology, Kaneohe, HI, USA. 

WEBSITES 

University of British Columbia (UBC), Fisheries Centre. http://www.ecopath.org 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Management Concerns and Responsibilities 

Kaylene E. Keller1, Angela D. Anders2, Ann Mooney1, Randall Kosaki1, Malia Chow1 and Mark Monaco3 

INTRODUCTION 

Increasing pressures on the world’s ocean resources in the recent decades has heightened the need for protecting marine resources. Marine Protected Areas (MPA) are an essential tool for achieving marine ecosystem-based management. MPAs in the Pacific, such as Papahanaumokuakea Marine National Monument, the 

Australia’s Great Barrier Reef Marine Park and the Phoenix Islands Protected Area in Kiribati lead the world in 

protecting large-scale marine ecosystems. Each of these MPAs conserves vast contiguous areas of ecosystems ranging from shallow water coral reefs to deep water communities. 

The Papahanaumokuakea Marine National Monument (Monument) is one of the largest and most unique 

MPAs in the world. The Monument contains relatively pristine ecosystems and cultural resources minimally affected by human activities. In seeking to preserve and protect these attributes, Monument managers identified 

the following mission: “Carry out seamless integrated management to ensure ecological integrity and achieve 

strong, long-term protection and perpetuation of the NWHI ecosystems, Native Hawaiian culture, and heritage 

resources for the current and future generations” (Papahanaumokuakea Marine National Monument, 2008). 

Striving to achieve this far-reaching mission creates unique opportunities and challenges for Monument managers. These opportunities include the potential to manage complete ecosystems with few anthropogenic 

inputs and working toward restoring components of the ecosystems that have been modified. Challenges revolve around the remote and vast nature of the Monument, and include threats local to global and internal and 

external to the Monument. This chapter focuses on management of the Monument. This includes: 

• Management structure; 

• Management of protected marine species within the Monument; 

• Management of greatest potential threats to the marine resources across the region; and 

• Management of human activities. 

BACKGROUND 

Management Structure 

On June 15, 2006, President George W. Bush issued Presidential Proclamation 8031 (Proclamation) establishing the NWHI Marine National Monument under the authority of the Antiquities Act of 1906 (16 U.S.C. 431). 

It was subsequently renamed the Papahanaumokuakea Marine National Monument. The Monument includes 

a number of preexisting federal conservation areas: the NWHI Coral Reef Ecosystem Reserve, managed by 

the Department of Commerce through the National Oceanographic and Atmospheric Administration (NOAA) 

Office of National Marine Sanctuaries; Midway Atoll National Wildlife Refuge, Hawaiian Islands National Wildlife Refuge, and Battle of Midway National Memorial, managed by the Department of the Interior through the 

United States Fish and Wildlife Service (USFWS). These areas remain in place within the Monument, subject 

to their applicable laws and regulations in addition to the provisions of the Proclamation. 

The NWHI also include state of Hawaii lands and waters, managed by the Hawaii Department of Land and 

Natural Resources (DLNR) as the NWHI Marine Refuge and the State Seabird Sanctuary at Kure Atoll. These 

areas also remain in place and are subject to their applicable laws and regulations. 

331 

1. NOAA/NOS/ONMS/Papahanaumokuakea Marine National Monument

2. Clancy Environmental Consultants, Inc.

3. NOAA/NOS/NCCOS/CCMA Biogeography Branch 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

332 

The organizational structure for the Monument consists of: 

• Three Co-Trustees-- Department of Commerce, Department of the Interior and the State of Hawaii-- responsible for the management of the Monument. The Co-Trustee agencies have developed a joint management plan that will guide management of the Monument for the next 15 years; 

• A Senior Executive Board composed of a designated senior policy official from each Co-Trustee agency 

that is directly responsible for providing oversight and guidance for management of the Monument; 

• A Monument Management Board composed of representatives from the federal and state agency offices 

that carry out the day-to-day management and coordination of Monument activities; and 

• 

• An Interagency Coordinating Committee representing other state and federal agencies as appropriate to 

assist in the implementation of Monument management activities. 

Management Zones 

Monument regulations define three types of marine zones within the Monument (Figure 10.1): 

1.Special Preservation Areas: These are discrete, biologically important areas of the Monument where resource harvest and almost all forms of discharge are prohibited; 

2.Ecological Reserves: These areas consist of contiguous, diverse habitats that provide natural spawning, nursery, and permanent residence areas. Resource extraction is highly restricted within Ecological 

Reserves; and 

3.Midway Atoll Special Management Area (SMA): Recreational activities in the Monument are restricted to 

the Midway Atoll SMA. 

Zoning not only provides protection to highly sensitive habitats, it also protects the ecological linkages between 

these habitats. Each zone addresses a number of factors including the protection of habitat and foraging areas 

of threatened and endangered species; the inclusion of a representative range of the diverse array of marine 

Figure 10.1. Map of the Papahanaumokuakea Marine National Monument and zones. Map: PMNM. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

habitats, including shallow coral reef environments, as well as deepwater slopes, banks and seamounts; and 

fi nally, the minimization of risks associated with specific activities such as fi shing and recreational activities. As 

of June 2011 all commercial fishing will be prohibited within the Monument. 

In addition to the designation of the Monument management zones, in 2007 the 

Monument was designated “in principle” 

as a Particularly Sensitive Sea Area 

(PSSA) by the International Maritime Organization (IMO), a Specialized Agency 

of the United Nations (Figure 10.2). The 

designation puts into effect internationally recognized measures designed to 

protect marine resources of ecological 

or cultural significance from damage by 

ships while helping keep mariners safe. 

PSSA designation augments domestic 

protective measures by alerting international mariners to exercise extreme 

caution when navigating through the 

area. A U.S. proposal for PSSA designation was submitted in April 2007 for 

consideration at the IMO’s Marine Environment Protection Committee meeting with the final designation made in April 2008. PSSA designation has 

been granted to only 10 marine areas globally, including the marine areas around the Florida Keys, the Great 

Barrier Reef and the Galapagos Islands. The PSSA area is coterminous with the Monument boundary. 

In addition to alerting international mariners to exercise extreme caution when in the area, as part of the PSSA 

designation process, the IMO’s Maritime Safety Committee adopted the U.S proposals for the associated protective measures (APMs) of: (1) the expansion and amendment of the six existing recommendatory Areas to 

be Avoided (ATBAs) in the area, which would enlarge the class of vessels to which they apply and augment the 

geographic scope of these areas, as well as add new ATBAs around Kure and Midway atolls; and (2) the establishment of a ship reporting system for vessels transiting the Monument, which is mandatory for ships 300 

gross tons or greater entering or departing a U.S. port or place and recommendatory for other ships. These 

APMs were implemented in May 2008. 

WORLD HERITAGE NOMINATION 

The unique habitats and ecosystems within the Monument are of great importance to local, regional and global 

marine biodiversity (Figure 10.3). The Monument contains some of the world’s most significant marine and 

terrestrial ecosystems and areas of cultural significance, and is one of the world’s largest protected marine 

areas. It also serves as an example of ongoing geological processes and biological evolution. The volcanic 

rocks, large atolls of sand and coral, and islets surrounded by reefs provide unique habitats for endemic and 

rare species of animals and plants. These features are of universal value from scientific, conservation, cultural 

and aesthetic perspectives. This relatively pristine region contrasts sharply with most insular and marine ecosystems, which are more severely affected by human activities and populations around the world. 

In January 2008, Papahanaumokuakea was selected by the Secretary of the Interior to be included as a candidate for the U.S. Tentative List for nomination as a World Heritage mixed site due to its exceptional natural 

and cultural importance. World Heritage is the designation for places on earth that are of outstanding universal value to humanity and as such, have been inscribed on the World Heritage List to be protected for future 

generations to appreciate and enjoy. In early 2009, the U.S. put forth a full nomination package to the World 

Heritage Centre to have the Monument added to the World Heritage List. The Monument was recommended 

Figure 10.2. PSSA, Areas to be Avoided (ATBA) and Ship Reporting Boundaries around the Papahanaumokuakea Marine National Monument. 

333 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

334 

for consideration as a World Heritage 

Mixed Site. The reasons for listing for 

the Monument for natural values include: 

• The string of islands comprises 

a classic, important and unparalleled example of later stages of 

island and atoll evolution. The archipelago has provided some of 

the most compelling confirmation 

of current theories of global plate 

tectonic movements;
 

• Papahanaumokuakea is a spectacular example of evolution in isolation, which results in enhanced 

speciation and a phenomenally 

high degree of endemism in both 

marine and terrestrial flora and 

fauna. The coral reef ecosystems 

of Papahanaumokuakea also represent on of the worlds’s last apex predator dominated ecosystems, a 

community structure characteristic of coral reefs prior to significant human exploitation; and 

• The region is home to, and a crucial refuge for, many endangered, threatened, and endemic species, including critically endangered marine mammal, bird, and plant species for whom it is the last or only refuge 

anywhere on earth. Papahanaumokuakea is also the largest tropical seabird rookery in the world. 

Remote, uninhabited and relatively pristine in comparison to other marine ecosystems in the world, the Monument has the potential to serve as one of the few reference sights for monitoring and deciphering short-term 

and long-term responses to local, regional, and global environmental and anthropogenic stressors. The Monument is one of the few regions on Earth where monitoring and research activities can be conducted in the 

virtual absence of local human habitation. In comparison, most reef systems in the coastal regions of the 

world are adjacent to human population centers, where vessel traffic, overharvesting, sedimentation, habitat 

destruction, and other human actions have altered the terrestrial and adjacent marine environments. Ongoing 

research, monitoring, habitat restoration and conservation management of the insular and marine ecosystems 

in the NWHI will continue to provide significant insights that will benefit management interventions not only for 

the NWHI, but for insular and marine ecosystems around the world. 

MANAGEMENT OF PROTECTED SPECIES 

The NWHI provides habitat for a wide variety of species including species specifically protected by federal acts 

and state statutes. Three federal acts, as well as multiple state statutes, provide protections for specifi c species in the NWHI. The federal acts are the Endangered Species Act (ESA), the Marine Mammal Protection Act 

(MMPA) and the Migratory Bird Treaty Act (MBTA). The ESA of 1973 provides for the conservation of species 

at risk of extinction throughout all or a significant portion of their range, and the conservation of the ecosystems 

on which they depend. The state of Hawaii has adopted specific criteria for indigenous species to be listed as 

threatened or endangered, as codified in chapter 195D-4, Hawaii Revised Statutes (HRS), as well as chapter 

183D, HRS Wildlife, and chapter 125, Wildlife Sanctuaries, Hawaii Administrative Rules Title 13. The MMPA 

provides protection and conservation of all marine mammals whether or not listed under the ESA. The MBTA is 

a domestic law that implements the United States’ commitment to four international conventions (with Canada, 

Japan, Mexico and Russia) for the protection of shared migratory bird resources. All migratory birds and their 

parts (including eggs, nests and feathers) are fully protected. 

Figure 10.3. The variety of ecosystems within the Monument have been

recognized for their uniqueness and importance to global marine biodiversity. Photos: J. Watt. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

The Monument provides habitat for many protected marine species including the Hawaiian monk seal, five 

cetacean species, five marine turtles and five bird species (Figure 10.4). 

Figure 10.4. The various ecosystems within the Monument are inhabited by of protected species, including marine mammals, marine turtles and seabirds. Photos: J. Watt (right), T. Summers (center) and USFWS (left). 

Hawaiian Monk Seal 

The Hawaiian monk seal (Monachus shauinslandi) is in crisis. The population is in a decline that has lasted 

20 years, and today only about 1,200 monk seals remain. Modeling predicts that the species’ population will 

fall below 1,000 animals by the year 2012. Actions to date have not been sufficient to result in a recovering 

population. Most of the population of Hawaiian monk seals breed and forage inside the Monument boundaries. 

NOAA’s National Marine Fisheries Service (NMFS) is the primary federal agency responsible for the management of the Hawaiian monk seal and has identified the recovery of this species as the number one priority, 

based on the high magnitude of threats, the high recovery potential, and the potential for economic conflicts 

while implementing recovery actions. NMFS recently updated its Hawaiian monk seal recovery plan and has 

detailed several key actions required to address current and potential threats to the recovery and survival of 

this critically endangered species (NMFS, 2007). To advance these efforts, the Monument management board 

is pursuing several key strategies as identified in its management plan in support of monk seal recovery efforts 

(PMNM, 2008). 

Cetaceans 

Sightings and acoustic recordings of baleen whales, as well as toothed whales and dolphins have been documented throughout the Monument. Five species of baleen whales listed as “endangered” under the ESA and 

as “depleted” under the MMPA have been sighted or heard in the Monument area. In addition to these five, the 

endangered sperm whale (Physeter macrocephalus) and at least 18 other non-ESA listed species are found 

in the Monument (see the Marine Protected Species chapter for more information). It has now been documented that humpback whales (Megapera novaeangliae) are calving in the eastern portion of the Monument 

(Johnston et al., 2007). Recovery actions for this listed species are summarized in the final recovery plan for 

the humpback whale (NOAA Fisheries, 1991). Draft recovery plans are available for the fin whale and sperm 

whale (NOAA Fisheries, 2006a, 2006b), and a final plan is available for the recovery of the blue whale (NOAA 

Fisheries, 1998). 

Marine Turtles 

The Hawaiian green turtle (Chelonia mydas), hawksbill (Eretmochelys imbricate), loggerhead (Caretta caretta), and leatherback (Dermochelys coriacea) turtles are known to occur within the Monument boundaries. 

While there are no records of the endangered olive ridley (Lepidochelys olivacea) within Monument waters, 

their wide distribution throughout the tropical Pacific makes it plausible that they also occur there Green and 

loggerhead sea turtles are listed as threatened species; the hawksbill and leatherback turtles are classifi ed as 

endangered species. Recovery plans and five-year reviews jointly published in 2007 are in place for each of 

these species in the Pacific (NOAA Fisheries and USFWS, 1998a; 1998b; 1998c; 1998d; 1998e, 2007). Sea 

turtle population declines have occurred across the Pacific due to nesting habitat loss, fi shery interactions 

and the harvest of eggs and turtles for commercial and subsistence purposes. About 90% of the green turtles 

335 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

336 

in the Hawaiian Islands nest in the NWHI, the majority on a few islets at French Frigate Shoals (Balazs and 

Chaloupka, 2004). Green turtle populations have steadily increased in Hawaiian waters since the species was 

added to the list of threatened species in 1978. 

Seabirds 

Five endangered bird species in the NWHI are protected under the ESA. The only seabird occurring in the 

NWHI listed under the ESA is the Short-tailed Albatross (P. albatrus). The other four ESA listed endangered 

bird species are the Laysan Duck, Laysan Finch, Nihoa Finch and Nihoa Millerbird. 

The Short-tailed Albatross breeds primarily on Torishima, an island owned and administered by Japan. The 

Short-tailed Albatross was first observed at Midway Atoll between 1936 and 1941. Since then, one to three 

individuals have been observed every year in the NWHI, primarily on islands in the northwestern half of the 

Monument. Although short-tailed albatrosses do not currently nest in the NWHI, a small number of adult birds 

conduct breeding displays each year at Midway Atoll. The Short-tailed Albatross Draft Recovery Plan provides 

recommendations for ways in which Monument staff can facilitate recovery of this species (USFWS, 2005). 

The Laysan Albatross (P. immutabilis) and the Black-footed Albatross (P. nigripes) are both considered endangered by International Union for Conservation of Nature (IUCN) and BirdLife International. Both species breed 

in the NWHI and also forage outside of the Monument. A Conservation Action Plan for both Black-footed Albatross and Laysan Albatross (Naughton et al., 2007) has been developed to provide managers with a framework 

for the conservation of both species. In addition to the three albatross species that occur in the Monument, 

another 18 species of seabirds and five species of shorebirds that regularly breed and overwinter, respectively, 

in the NWHI, are fully protected under the MBTA. The Monument Management Plan (MMP) includes activities 

to protect and enhance seabird and shorebird habitat and to minimize impacts of habitat destruction, contaminants and fi sheries interactions 

Management and conservation of migratory species such as cetaceans, marine turtles and seabirds will require coordination with international partners and conservations organizations outside of the Monument. 

MANAGEMENT OF THREATS TO THE ECOSYSTEM 

Anthropogenic activities impact oceans worldwide (Halpern et al., 2008). On a global scale, the highest ranking threats to coral reefs were identified as sedimentation, coastal development, trampling and nutrient inputs 

(Halpern et al., 2007). At a regional scale, these threats vary by location. The remoteness of the Monument as 

well as its limited emergent land results in a different suite of identified ecosystem threats. 

The Monument is affected by past changes to the ecosystem as well as current on-going threats. The emergent land areas and potentially some near shore waters continue to be affected by contaminants left over from 

military use of the islands. During World War II, large scale modifications such as channelization were made to 

the environment which changed the flow of water within the atolls and continues to impact the local ecosystem. 

In addition, marine species that also use emergent land such as seabirds are negatively impacted by invasive 

terrestrial species and other terrestrial based threats such as contaminants. It is important for mangers to be 

able to identify the potential threats and evaluate the impact of the threat to the overall functioning of the ecosystem at a local scale as well as a regional scale. 

In a recent threat analysis of the NWHI region, 24 potential threats were analyzed based on vulnerability factors and order of magnitude of the threat (Selkoe et al., 2008; Table 10.1). The analysis was focused on threats 

to the marine environment across the NWHI region. A systematic and quantitative method was used to collect 

and synthesize expert opinion on the ecological effects of these potential anthropogenic threats to the region. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

The following discussion of threats to the Monument focuses on the top four threats identified across ecozones 

for the region by expert opinion. These threats are: 

1. Climate change 

2. Marine debris/ghost fishing 

3. Alien species 

4. Ship groundings 

Table 10.1. Potential threats analyzed by Selkoe et al., 2008. Source: Selkoe et al., 2008. 

THREAT EXPLANATION 

Alien species Includes only populations that have established, not single sightings 

Anchor damage Includes large anchors in deepwater and small anchors of tender boats 

Aquarium collecting Primarily aquarium trade activities, only one example of legal event to date 

Bottomfishing An ongoing fishery for a suite of deepwater snapper and grouper using hydraulic handlines >100 fathoms depth outside three nautical miles. Boats also troll in transit, impacting pelagic fish and birds 

Coastal engineering The lingering impacts of past dredging, seawalls and pier construction, and ongoing maintenance

activities, primarily at Midway and French Frigate Shoals 

Diver impacts Includes diving for any purpose (but it primarily occurs for research); may cause disturbance to animals, damage to corals, potential for inter-site transfer of micro-organisms 

Ghost fishing A subcategory of marine debris - mostly discarded monofilament and rope nets and some lost lobster

traps that ensnare and drown animals and smother reefs 

Increasing UV radiation Increased ultraviolet radiation from the anthropogenic thinning of the ozone layer 

Indigenous fishing Fishing by native Hawaiians for consumption - this potential activity is likely focused on southeast end

of NWHI 

Chemical contamination The leeching of chemical waste from past and ongoing military activities and habitation, primarily at

Midway and French Frigate Shoals 

Lobster fishing Lobster fisheries were halted in 2000 due to population collapses. Only lingering impacts were considered -- there has been little rebound of lobster to date, potentially impacting lobster predator populations (e.g. monk seals) 

Marine debris All types of man-made materials (including plastics and derelict fishing gear) that may break corals,

entangle animals, are ingested by animals and accumulate on beaches 

Recreation Any recreational activities not covered by fishing and diving, such as boating, water sports, and wildlife

viewing. 

Pelagic fishing Pelagic fishing is banned in NWHI waters but biological connection to the wider Pacific where longlining and net fishing is intense may impact NWHI species which forage in the Pacific, both as bycatch

and because the tuna on which some birds depend for foraging are being depleted 

Research installations Installation of equipment or otherwise modifying benthos, or disturbing animals 

Research wildlife sacrifice Any lethal sampling of organisms for research activities 

Sea level rise Increased sea level from the anthropogenic warming of the planet. May alter habitat availability and

stress populations of depth-dependent species like corals 

Sea temperature rise Increased temperature from the anthropogenic warming of the atmosphere. A suspected cause of 

increases in coral bleaching and coral disease, among other potential effects 

Sea water acidification Decreased sea water pH due to the anthropogenic carbon loading of the atmosphere 

Ship groundings Includes the damage and disturbance from grounding, fuel spill, debris, cyanobacteria inoculation and

debris removal. 

Ship pollution Includes the discharge of bilge water, sewage, spilled fuel, trash and noise and light pollution. Includes 

all types of vessels (fishing, research, shipping, tourist). 

Sport fishing Most relevant to southeast end of chain, the lingering impacts of the abated catch-and-release operation at Midway and Pearl and Hermes, and ongoing trolling during ship transit 

Trampling damage Walking on beaches, intertidal, emergent land and reef flats not associated with diving 

Vessel strikes When a small or large vessel hits benthic communities or large mobile animals while in transit, without

grounding 

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Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

338 

Managers recognize the need to evaluate threats based upon the source and impact of the identifi ed hazard. 

If a threat occurs within the management boundary, managers have more opportunity to successfully mitigate 

the threat. Threats generated outside of the management boundary still require a response, but they are often 

more difficult to prevent. Of the top four identified threats to the Monument, climate change and marine debris 

originate outside the boundaries of the Monument. Alien species establishment and ship groundings are considered locally-based threats that occur within the Monument boundaries. 

Climate change factors are already affecting the NWHI ecosystem and will have a widespread impact. Sealevel rise is already impacting available habitat for species such as the Hawaiian monk seal, green turtle and 

the seabirds. The impact from sea surface temperature (SST) changes will be seen throughout the ecosystem 

including coral bleaching and potential impacts to prey species for seabirds and other predators. Marine debris 

was also identified threat from outside the Monument that will impact many different ecozones. 

Alien species and ship groundings are identified as high local threats because they have a potentially large 

impact on ecosystem function and long recovery times. To date, the threat of alien species may not be highly 

significant in marine areas within the NWHI (i.e., 13 marine alien species currently known to occur within the 

Monument) but the potential impact from an introduction could be widespread. There is always the potential for 

ship groundings but emergency response plans to minimize the impacts of the groundings are under development 

Selkoe et al. (2008) evaluated, eight different ecozones (Table 10.2). A finer-scale threat analysis can occur by 

examining the ecozones and assessing how a threat may impact each specific area. The inner and outer reef 

zones were identified as the most vulnerable. Emergent land was considered vulnerable because of sea level 

rise and the potential loss of habitat. The shallow water ecozones were more vulnerable to extra-boundary 

threats than local threats. Many of these top threats are difficult for local managers to control because they 

arise from activities outside the Monument boundaries, indicating that additional work is needed to preserve 

the NWHI despite its highly protected status. The analysis indicates where interagency cooperation in removing and mitigating threats should be focused (Selkoe et al., 2008) 

Table 10.2. Ecozones evaluated in the threat analysis. Source: Selkoe et al., 2008. 

ECOZONE DESCRIPTION DISTRIBUTION 

Terrestrial Interior land distinct from the littoral zone Kure, Midway, Lisianski, Lysan, Mokumanamana 

and Nihoa 

Rocky Intertidal Solid substrate at intertidal depth composed of basalt rock Gardner Pinnacles, La Perouse Pinnacle (French

Frigate Shoals), Mokumanamana and Nihoa 

Sandy Beach Intertidal beach and adjacent shallows with soft benthos Kure, Midway, Pearl and Hermes, French Frigate 

Shoals, Lisianski, Laysan, and Nihoa 

Algal Beds Primarily Halimeda beds in lagoons and deeper terraces, but

also small stands of endemic seagrass at Midway 

Kure, Midway, Pearl and Hermes,French Frigate 

Shoals, Lisianski, Laysan, Mokumanamana and

Nihoa 

Inner Reef Refers to shallow, mostly protected reef areas (lagoonal, 

back, reticulated or patch reefs) 

Kure, Midway, Pearl and Hermes, Lisianski, Neva 

Shoals, Laysan, Maro, and French Frigate Shoals 

Outer Reef Exposed seaward reefs from the crest down to the slope less

than 30 m depth 

Most NWHI locations where depth is <30 m 

Deep Reef/

Banks 

Deep reef is designated >30 m depth. Banks are sites of high

relief benthos in deep waters with rich fish communities, with 

or without reef builders 

There are approximately 30 deep banks in the

NWHI. Deep reef is usually found adjacent to any

shallow reef area. 

Pelagic Waters The entire water column, from surface to depth, outside of

lagoon and shallow reef environments 

Makes up the majority of NWHI habitat. 

Climate Change 

Sea level rise, changing storm intensity and frequency, sea surface temperature (SST) rise and acidification 

are components of climate change most likely to affect the Monument. Evidence of sea level rise has already 

begun to adversely affect the available terrestrial habitat and models predict that sea level will continue to rise. 

SST is monitored via satellite in addition to using buoys at several locations throughout the NWHI, resulting 

in a long-term temperature time series for Midway Atoll (Jokiel and Brown, 2004). Elevated SST has already 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

impacted corals as indicated by recent coral bleaching events in the Monument (see Coral Bleaching for more 

details). With regards to ocean acidification, the third component of climate change most likely to affect the 

Monument, staff members are in the process of designing experiments to characterize the carbonate chemistry and establish a baseline for the NWHI. 

Sea Level Rise 

Global mean sea levels have risen an estimated 3.1 ± 0.7 mm yr-1 from 1993-2003, an amount higher than any 

other 10-year period since 1950 (IPCC, 2007). However sea level rise varies regionally and in order to understand the effects on the ecosystem it must be monitored at the island and atoll scale. 

One effect of rising sea level in the NWHI is the loss of habitat. Emergent land in the NWHI is estimated at a 

total 14 km2

 and the loss of available emergent land will greatly reduce the available habitat for many species. 

The effect of habitat loss on species that use emergent land features will impact many of the species that are 

already rare and maybe devastating to those populations that depend on these islands for survival. Marine 

species that will be impacted by sea level rise include the Hawaiian monk seal, green turtle and several seabird species. In addition there is the potential for further habitat degradation with the release of contaminants 

contained in landfills and other areas as the islands are eroded or flooded from sea level rise. 

Evidence of sea level rise can be clear- Table 10.3. Sea level rise scenarios modeled for French Frigate Shoals, 

Lisianski Island and Pearl and Hermes Atoll. Source: Baker et al., 2006. ly observed with the submersion of 

Whaleskate Island within French Frigate Shoals in the late 1990s (Baker et 

al., 2006). NOAA Pacific Islands Fisheries Science Center (PIFSC) modeled 

the potential terrestrial habitat loss from 

sea level rise using estimated sea level 

rise values and current elevation data 

collected in the field. The study included 

islands within Pearl and Hermes Atoll, Lisianski Island and French Frigate Shoals. Pearl and Hermes Atoll 

and French Frigate Shoals are both composed of small low lying islets surrounded by a barrier reef, whereas 

Lisianski Island is a single large, low-lying island (Figure 10.5). Six different scenarios using three sea level 

rise values and two different tide conditions were evaluated (Table 10.3). The results of the modeling indicate 

that sea level rise will affect each island group differently. Lisianski Island (the largest and highest island in the 

analysis), could experience the least amount of impact with only a 5% decrease in area using the highest sea 

level rise scenario. In contrast, the highest seal level rise scenario for the islets at Pearl and Hermes Atoll and 

French Frigate shoals range from a 25% loss up to 90% loss (Baker et al., 2006). The estimates produced by 

the model were based on the assumption that the island shape remains constant and the model did not include 

erosion factors. Efforts to develop a monitoring system of the changes in the size of the islands are currently 

underway. 

SCENARIO RISE LEVEL BASE SEA LEVEL 

Scenario 1 - Low 9 cm Mean Low Water (MLW) 

Scenario 2 - Low Spring Tide 

Scenario 3 - Median 48 cm Mean Low Water (MLW) 

Scenario 4 - Median Spring Tide 

Scenario 5 - High 88 cm Mean Low Water (MLW) 

Scenario 6 - High Spring Tide 

Sea turtles are dependent on terrestrial areas for nesting. Islets in French Frigate Shoals support the majority 

of the Hawaiian green turtle breeding population. The loss of habitat and the possibility for nesting areas to 

be flooded during nesting times could have a large impact on the species. In other regions, green turtles have 

demonstrated intra-specific nest destruction once habitat is lost and nest density becomes high (Bustard and 

Tognetti, 1969). This behavior may occur among nesting Hawaiian green sea turtles in the Monument if nesting 

habitat is destroyed. 

Impacts to seabirds will vary depending upon the species. Over 90% of Black-footed and Laysan Albatrosses 

breed in the Monument and the loss of habitat in this area could affect the overall world population. The largest 

breeding populations of these albatross species occur at Midway Atoll and Laysan Island which were not analyzed in the sea level rise study, but habitat loss is expected to be similar to Lisianski Island because they are 

both large islands. The predicted decrease in area would not be large, but the species remain vulnerable as 

the islands represent such a critically important breeding area. Other seabird species may also be potentially 

impacted by the loss of nesting habitat as the result of climate change. 

339 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

340 

Figure 10.5. Current and projected maps of four NWHI at mean low water (MLW) with minimum (9 cm), median (48 cm) 

and maximum (88 cm) predicted sea level rise. The median scenario at spring tide is also shown. (A) Lisianski Island; (B)

East Island, French Frigate Shoals, showing the measured and interpolated points along the waterline and berm used

to create the Triangular Irregular Network (TIN); (C) Trig Island, French Frigate Shoals; (D) Southeast Island, Pearl and 

Hermes Reef. Source: Baker et al., 2006. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Storm Intensity and Frequency 

Global weather patterns appear to be changing and climatologists suggest that the increasing intensity and 

frequency of storms may be related to modern, anthropogenic influences (IPCC, 2001; Nott, 2003; Nott, 2004; 

Nott et al., 2007). Studies into storm trends have shown that while SSTs have been rising, the intensity of the 

storms occurring in this time period has increased (Hoegh-Guldberg, 1999; IPCC, 2001; Hughes, 2003; Webster et al., 2005; IPCC, 2007; NOAA Satellite and Information Service, 2007). While sheer numbers of tropical 

storms have remained relatively constant, the destructiveness of the cyclones has increased over the past 30 

years and hurricanes in the Category 4 and 5 range have nearly doubled since the 1970s (Emanuel, 2005; 

Webster et al., 2005). If climate patterns follow the projections, storms may continue to increase in intensity 

over the coming years. As storm intensity increases, the impacts felt by low-lying islands and atolls could prove 

detrimental to the inhabitants. 

The damage from high intensity storms 

to low lying sand islands was demonstrated in late December 2008 at French 

Frigate Shoals when high levels of erosion occurred at East Island. Using remote cameras available for monitoring 

turtle nesting activity scientists at PIFSC were able to evaluate the damage to 

East Island which included several feet 

of erosion along the northwest side of 

the island (G. Balazs pers. comm; Fig 

10.6). Monitoring will need to be conducted to evaluate the long-term impact 

of the erosion event and to determine if 

accretion will occur to other parts of the 

island. Researchers active in the NWHI 

over the past 30 years have observed 

changes to the size and shape of many 

of the islands (G. Balazs and J. Maragos, pers. comm.). In order to determine if these observed changes are from sea level rise or storm damage a 

monitoring program will need to be developed. 

Sea Surface Temperature Change 

Eleven of the years spanning 1995 to 2006 are ranked among the warmest 12 years of recorded global surface temperature (IPCC, 2007). Temperature change is another component that may impact the Monument’s 

marine ecosystems. The NWHI are monitored as part of the Coral Reef Early Warning System (CREWS). The 

system provides managers and researchers with telemetered meteorological and oceanographic data at precise locations. In the NWHI, NOAA’s PIFSC, Coral Reef Ecosystem Division (CRED) has deployed long-term 

moored observing stations, satellite-tracked drifting buoys, and subsurface instrumented moorings (Table 10.4 

and Figure 10.7) Changes in SSTs will result in changes to available habitat for temperature dependent species and coral bleaching. 

As SSTs change species currently using habitat near the surface may move to lower depths or different latitudes to find the appropriate habitat conditions. This will end up impacting other species dependent on these 

species. For example, seabirds feed on fish and other marine species near the ocean surface. As SST increases, seabird prey species move to deeper, cooler water, decreasing food availability for foraging birds, or 

requiring birds to fly further north in the Pacific to obtain food resources. 

Changes in SST poses a threat to coral reef ecosystems in the form of coral bleaching. Corals are symbiotic 

organisms which secrete a hard, mineral calcium carbonate structure. The symbiosis is between microscopic, 

photosynthetic organisms called zooxanthellae that inhabit the soft tissue of the coral polyp. Zooxanthellae 

provide the pigmentation of the coral and produce energy which is donated to the host and contributes sig341 

Figure 10.6. High levels of erosion on East Island just days after highly

intense storms passed through the area in December 2008. Photo: PIFSC

and G. Balazs. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands
 

Table 10.4. Distribution of long-term oceanography monitoring buoys in the Monument.
 

342 

LOCATION CREWS-ENH1 CREWS-STD2 SST-ARGOS3 ODP4 WTR5 STR6 

Kure -­ X X -­ X X 

Midway -­ -- X X -- X 

Pearl and Hermes -- X -- X X --

Lisianski -­ -­ X -­ X X 

Laysan -­ -­ X -­ -­ X 

Maro Reef -­ X -­ -­ -­ X 

Gardner Pinnacles -­ -­ -­ -­ -­ X 

French Frigate Shoals -­ -­ -­ -­ -­ X 

Mokumanamana -­ -­ -­ -­ -­ --

Nihoa -­ -­ -­ -­ -­ --

1

Coral Reef Early Warning System Enhanced - Moored buoys which provide high resolution SST, barometric pressure, wind speed, 

wind direction, and additionally provide salinity, UV-B, and PAR.

2

Coral Reef Early Warning System Standard - Moored buoys which provide high resolution SST, barometric pressure, wind speed 

and wind direction. Subsets of these data are transmitted daily via satellite telemetry.

3

Moored buoys which provide high resolution SST. Subsets of these data are transmitted daily via satellite telemetry.

4

Subsurface Ocean Data Platform - Subsurface moorings, providing high resolution current profiles, directional wave spectra, and

temperature and salinity.

5

Subsurface moorings providing high resolution wave and tide records, temperature and conductivity.

6

Subsurface moorings providing high resolution temperature. Additionally used on towed platforms for temperature and pressurebased depth. 

nificantly to the ability of a coral to grow 

and reproduce. When a coral is stressed 

by higher than normal temperatures, 

sometimes as little as a 2-3oC increase 

in temperature above their optimal temperature, they expel their zooxanthellae 

into the water column resulting in a loss 

of color (Hoegh-Guldberg, 1999). In this 

bleached, energy depleted state a coral 

is more susceptible to disease infiltration and overgrowth by fast-growing turf 

algae. Anthropogenic activities resulting 

in increased nutrient loads, sedimentation and physical damage at the site can 

make bleaching events worse. 

SST anomalies resulting from regional 

and global-scale climatic phenomena 

are believed to be the cause of bleaching in the NWHI. Mass coral bleaching in 

the NWHI occurred during late summer 

2002 (Aeby et al., 2003; Kenyon and 

Brainard, 2006). This was the first ever recorded bleaching event known to occur in the NWHI. Coral bleaching occurred again at high levels in 2004, and was detected again at low rates in 2006 (Kenyon and Brainard, 

2006). The corals in the NWHI were believed to be less susceptible to bleaching due to the high latitude location. Bleaching was most severe, however at the three northernmost atolls (Pearl and Hermes Atoll, Midway 

Atoll and Kure Atoll), which experience both higher and lower SSTs than other reefs of the NWHI. During the 

bleaching event, greater magnitude and longer durations of temperature anomalies were recorded and attributed to the bleaching events of 2002 (Hoeke et al., 2006). Lisisanski, Laysan and Maro experienced shorter 

and less severe temperature anomalies, resulting in comparatively minor bleaching events. Field investigations conducted in 2004 indicate that bleaching occurrence was highest in shallow back reef and patch reef 

habitats (Kenyon and Brainard, 2006). Researchers from the University of California, Santa Cruz are currently 

modeling circulation patterns at Midway Atoll to determine if anthropogenic changes to the flow and circulation 

patters may exacerbate bleaching events. 

Figure 10.7. Locations of oceanography monitoring buoys in the NWHI.

Map: K. Keller. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

In addition to using field measurements it is possible to detect potential 

coral bleaching events using satellite 

information. NOAA’s Coral Reef Watch 

produces near-real-time alerts from 24 

selected reefs around the globe. Midway Atoll is one of the sites that is monitored. Figure 10.8 contains graphs indicating when Midway Atoll SSTs reached 

levels that are associated with beaching 

events. The graphs show the 2002 and 

2005 SST associated with bleaching 

events were detected by NOAA’s Coral 

Reef Watch prior to being documented 

in the field. 

The development of a bleaching response plan is critical to effective reef 

management. This ensures that when 

a bleaching event occurs, decisive action can be taken as soon as possible 

to mitigate the effects of the bleaching 

event. The NWHI will require a unique 

response plan given that the region is 

largely free from local sources of anthropogenic stressors, so bleaching 

is largely a result of increased SSTs. 

However, managers will work to identify resilient areas based upon the best 

available information from monitoring 

data, research projects, past bleaching events and modelling. A bleaching 

response plan would call for identification of specific groups and actions that 

should take place prior to a bleaching 

event, during the event and follow up 

after SSTs have returned to normal. 

Ocean Acidification 

Coral reef systems maintain a delicate balance between calcifi cation and 

erosional forces. For the reef to grow 

and accrete mass, the corals’ ability to 

calcify must outrun the pressures put 

upon the system, such as bioerosion, 

physical erosion from wave action and 

storms and anthropogenic damage. 

The NWHI are relatively shielded from 

most anthropogenic effects due to their 

remoteness, but they are still subject to 

natural forces. The shallow and deep 

water coral reefs in the NWHI will potentially be impacted by changes in the 

carbonate levels in the ocean. If the reef 

Figure 10.8. Sea surface temperature values recorded at Midway Atoll 

documenting potential conditions for coral bleaching events (2000 - 2008).

Source: NOAA Coral Reef Watch. 

343 
Management Concerns and Responsibilities

Equation 1: The Carbonate Equilibrium 

 Skeletal formation 

CaCO -

3

 + CO2 + H2O  Ca2+ + 2HCO3

Skeletal dissolution

Equation 2: Acidification 

CO2

 + H2O  H2CO3  H+ + HCO3

-  H+ + CO32­

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

344 

structure changes there can be will be an ecosystem wide effect as habitat availability and species ranges 

change. 

Evidence of undersaturation has been reported in the Intermediate Pacific in relatively shallow waters of between 200 m and 1,000 m (Feely et al., 2002). This is of concern to the NWHI deepwater habitat which for 

these purposes will be defi ned as depths greater than 50 m. A number of corals have identified habitat ranging 

from 20-3,000 m (Hourigan et al., 2008). These corals provide structure to the benthos as well as serving as 

habitat for other organisms living in the deep that have yet to be fully explored. Endangered Hawaiian monk 

seals with attached animal borne imaging systems (Crittercams) have been recorded foraging for fi sh that find 

shelter in black coral beds (Parrish and Baco, 2008). However, due to the remoteness of the NWHI follow-up 

deepwater surveys have yet to be conducted, as they require extensive time, planning and budgeting considerations. Deepwater corals are mainly slow-growing species, and the effects of undersaturation may not 

manifest for years after it has occurred. Or, conversely, if the saturation horizon rises to shallow depths, the 

aragonite structure of the deepwater corals may begin to dissolve away into the ocean. 

The degree to which ocean acidification will affect Monument coral reefs is presently under investigation. Plans 

are underway to establish a baseline of the carbonate chemistry of the NWHI. This would be done by utilizing the CTD (conductivity, temperature, depth) sensor scanner onboard R/V Hiialakai and outfitting it with a 

pH sensor. Carbonate chemistry of a water sample can be characterized by taking three measurements; the 

dissolved inorganic carbon, alkalinity and pH. All three of these measurements are planned to be performed 

onboard during regular CTD casts and the seawater samples brought back for further analysis. These types 

of measurements, taken from deepwater habitats and lagoon waters (from small boat platforms) will help the 

Monument to develop an understanding of the current carbonate chemistry of the waters and allow us to monitor future changes. 

Ocean Acidification 

Ocean acidification is the process of seawater becoming less basic and is likely to upset the delicate balance between 

reef calcifi cation and erosion (Hoegh-Guldberg, 1999). The carbonate equilibrium describes the process of calcification in 

marine animals and is illustrated by equation 1 (Kleypas et al., 1999; Royal Society, 2005; Kleypas and Langdon, 2006). 

Acidification, where atmospheric CO2 is absorbed by the surface of the ocean where it forms carbonic acid, is illustrated 

by equation 2;. This acid then dissociates into free hydrogen and bicarbonate ions resulting in increasing amounts of bicarbonate, leaving less carbonate ions available to interact with the abundant calcium ions present in seawater. Calcium 

ions are not thought to be a limiting factor in calcification (Royal Society, 2005). Therefore, when the amount of CO2 in the 

atmosphere increases, the availability of carbonate ions for calcifying organisms (corals, calcareous algae, plankton etc.) 

to incorporate into their skeletons decreases and the carbonate equilibrium shifts facilitating the dissolution of the calcium 

carbonate skeleton (Kleypas et al., 1999; Royal Society, 2005; Kleypas et al., 2006). 

There are two forms of calcium carbonate found in skeletons of CaCO3

 secreting organisms. The first is calcite, which is 

the less soluble form found in crustose coraline algaes, and the other is the aragonite form of calcium carbonate, which is 

utilized by scleractinian corals and other pteropods. There is a critical concentration of carbonate ions in seawater below 

which calcium carbonate will dissolve. The solubility of calcium carbonate is a function of depth and pressure. The critical 

concentration occurs at a depth known as the “saturation horizon”, under which calcium carbonate structures tend to dissolve. Due to increased amounts of CO2 in seawater and the resultant decrease in the carbonate ion concentration (equation 2) the saturation horizon will move ever shallower with increasing releases of anthropogenic CO2

 into the atmosphere. 

This means that the depth at which corals are able to calcify will grow shallower as more CO2 is input into the atmosphere. 

Latitude also plays a role when looking at where saturation boundaries occur. Lower latitudes near the equator tend to 

have saturation states conducive to the solidified structure of corals, while poleward areas are already showing evidence 

of undersaturation at the surface waters. Currently the surface waters of the NWHI still fall within saturation parameters 

(Feely et al., 2002). 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Marine Debris 

A multiagency effort initially launched in 

1996 by the University of Hawaii’s Sea 

Grant College Program began to address the problem of marine debris, a 

problem that was much larger than any 

one agency alone can resolve. An estimated 750 to 1,000 tons of marine debris were on reefs and beaches in the 

NWHI (NOAA PIFSC, unpublished; Figure 10.9). NOAA, in collaboration with 

14 other partners including the U.S. 

Coast Guard (USCG), Schnitzer Steel 

Hawaii Corporation (formerly Hawaii 

Metals Recycling Company), the Hawaii 

Sea Grant College Program, U.S. Navy, 

USFWS, the City and County of Honolulu, the state of Hawaii, The Ocean 

Conservancy, Hawaii Wildlife Fund, 

Matson Navigation Company, and others removed 66 tons of marine debris 

and derelict fishing gear from 1996 to 

2000. In 2001, the multiagency cleanup 

effort was extended, resulting in a corresponding increase of marine debris 

removed from reefs and beaches of the 

NWHI (Table 10.5). The total amount 

of marine debris removed from 1996 to 

2007 was 582 tons. 

The source of much of the marine debris is fishing nets discarded or lost in 

Figure 10.9. Divers cutting away nets from the reef in the NWHI. Photo:

CRED. 

Table 10.5. The total amount of marine debris removed from 1996 to 2007 

was 582 tons. Source: NOAA/PIFSC. 

YEAR TONS REMOVED 

1996 - 2000 Approximately 25 tons per year 

2001 68 

2002 107 

2003 118 

2004 126 

2005 57 

2006 21 

2007 59 

345 

the northeastern Pacific, well outside 

of the Monument boundaries. In order 

to address the source of marine debris 

in the Pacific, Monument managers will 

need to work with international partners 

to look at methods and develop policies 

for reducing marine debris. Even if all 

new input of debris were stopped, existing debris in the ocean would continue 

to accumulate in the NWHI for years to 

come. At a Pacific basin scale, it is suggested that the subtropic convergence 

zone (STCZ) that moves between 25°N 

and 35°N is an area of high ghostnet retention (Figure 10.10). When the STCZ 

moves within range of the NWHI, the 

nets often become entangled on reefs 

and continue to be an entanglement 

hazard for many species. Once the debris reaches the NWHI, the rate of accumulation of nets on reefs varies by island and atoll and within island and atoll 

Figure 10.10. Map illustrating regional current movements and the convergence zone. 
Management Concerns and Responsibilities

Table 10.6. 2007 field season marine debris removal by island and atoll.

Source: 

LOCATION DEBRIS TYPE REMOVED 

(kg) 

REMOVED 

(tons) 

French Frigate Shoals Marine Debris 5,554 6 

Land Debris 1,735 2 

Kure Marine Debris 2,860 3 

Land Debris 1,431 1 

Laysan Marine Debris 0 0 

Land Debris 2,073 2 

Lisianski Marine Debris 0 0 

Land Debris 4,396 4 

Pearl and Hermes Marine Debris 39,250 39 

Land Debris 1,911 2 

Total Marine Debris Weight 47,664 48 

Total Land Debris Weight 11,546 12 

Total Debris Weight 59,210 59 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

(Dameron et al., 2007). A model of potential accumulation rates was developed for the NWHI to help evaluate 

the distribution of marine debris and where efforts should be focused for removal. The results from the model 

can be used by managers to target areas for marine debris clean-up efforts. 

346 

In the 2007 field season Kure Atoll, 

Pearl and Hermes Atoll, Lisianski Island, Laysan Island and French Frigate 

Shoals were targeted for marine debris 

removal (Table 10.6). In addition to the 

marine debris removal efforts, a study 

of the effects of marine debris and marine debris removal on NWHI coral reef 

benthic communities was initiated at 

Midway Atoll in 2008. The study will be 

assessing the long-term effects of removal of nets from reefs as well as the 

effects of nets left in place. Initial survey 

and removal efforts began in August 

2008 and the study will continue into 

2009. The results of the study will help 

managers develop better guidelines for 

marine debris removal and decreasing 

overall impact to the coral reef ecosystems. In addition the results will begin to provide managers with information about recovery rates of the benthic 

communities following debris removal or other anthropogenic disturbance. 

Marine Alien Species 

Monument managers have identified marine invasive species including pathogens as a significant threat and 

are taking action to prevent any additional introductions. Because of the Monument’s vast size, it is difficult 

to carry out surveys to detect marine invasive species. However, based on the few surveys conducted (see 

Nonindigenous and Invasive Species Chapter), there are currently 13 marine invasive species that have been 

identified and documented in the NWHI. Compared to the 343 marine invasive species that have been identified and documented in the Main Hawaiian Islands (MHI), the NWHI have a relatively low abundance of invasive species (Eldredge and Carlton, 2002; Godwin et al., 2006; Godwin, 2008). The potential of additional 

introductions of non-indigenous species in the NWHI could have dramatic consequences to the ecosystem. 

Management tools to reduce the potential introduction and spread of alien species in the Monument are the 

permitting process, enforcement of regulations and development of a monitoring and research program. 

Mandatory hull inspections for all permitted vessels are the primary tool managers can use to reduce the potential of marine alien species introductions. Prior to receiving a Monument permit, any ship that has applied 

for a permit to access the Monument must complete a hull inspection. Another mechanism for potential introductions is by way of ballast water exchange. In response to national concern regarding invasive species, the 

National Invasive Species Act of 1996 was enacted. The Act reauthorized and amended the Nonindigenous 

Aquatic Nuisance Prevention and Control Act of 1990. In addition to the Monument discharge regulations, ballast water exchange in the Monument is regulated by the USCG which codified a national mandatory ballast 

water management program for all vessels equipped with ballast water tanks that enter or operate within U.S. 

waters. These regulations also require vessels to maintain a ballast water management plan that is specifi c for 

that vessel and that assigns responsibility to the master or an appropriate official to understand and execute 

the ballast water management strategy for that vessel. 

There have been several reports written recently on the topic of marine invasive species in the NWHI (Eldredge, 

2005; Godwin et al., 2006; and Godwin, 2008). They provide a number of recommendations for managers to 

deal with invasive species. These reports provided the foundation for the prohibitions on ballast discharge in 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

the Proclamation and the actions outlined in the MMP Alien Species Action Plan. The Alien Species Action Plan 

addresses prevention, monitoring of alien species, and education of Monument users and the public about the 

need to prevent alien species introductions. The following section focuses on how managers can utilize the 

geographic locations of known marine invasive species to shape their actions in three distinct realms: monitoring, permitting and research. 

Monitoring 

The locations of existing alien species populations can provide a foundation for future monitoring efforts. Monitoring of existing infestations and identification of new infestations is a key component to the Alien Species 

Action plan in the MMP. In the past, relatively few marine invasive surveys were conducted and usually only 

once and often opportunistically. The MMP calls for the need to establish a coordinated and systematic effort 

to survey distributions and populations of known alien species at regular intervals. Understanding where existing populations are can help guide managers in the development of monitoring protocols for the detection and 

potential eradication of current populations as well as future infestations. The monitoring program will provide 

important information on the spatial distribution, spread and population sizes of marine alien species within the 

Monument. Currently the existing Rapid Assessment and Monitoring Program monitoring does not specifically 

target alien species, but alien species would be identified during the MMP proposed alien species monitoring 

surveys. 

Permitting 

Knowing the locations of marine invasive species can assist managers in making decisions regarding the issuance of permits in the Monument. An understanding of potential invasive vectors, combined with the knowledge of where marine invasive species reside in the MHI and NWHI will allow managers to take steps to 

minimize those vectors. Steps to minimize the introduction of potential invasive vectors can most effectively be 

implemented through the permitting process. 

Activities authorized under a Monument permit can be structured so that vessels visit the islands in an order 

that minimizes the risk of transporting invasive species. The more pristine sites should be visited first, and the 

most invaded locations last, to minimize the likelihood of organisms being transported from invaded sites to 

pristine areas. This may not always be possible but can be implemented where possible. These recommendations are currently being done on an informal basis through consultations with the applicant, but they could be 

formally incorporated as permit conditions in the fi nal permit. 

Managers can also restrict where vessels anchor or identify a route through the NWHI so as to minimize the 

risk of spreading invasive species through hull fouling or ballast water. To make effective decisions that can be 

justified, managers must have good geographic information on the locations of marine invasive species within 

the Monument. 

Research 

Information about where marine invasive species reside in the Monument is needed to inform managers and 

can serve as a guide on how best to direct management-driven research. Research about the effects of invasive species can be effectively targeted to the locations where known populations of those species do or do not 

exist. Accurate information about the abundance and positions of invasive species can help prioritize research 

based on species or sites. Research should be directed at the more abundant species, or the species in more 

vulnerable sites. In addition, other research that should be undertaken includes factors that cause alien species to become invasive and the interactions between native and alien species. 

Vessel Hazards 

With the exception of a few small boats at Midway Atoll, French Frigate Shoals, Pearl and Hermes and Kure 

Atoll, no vessels have home ports in the NWHI. Therefore, almost all marine traffic in the waters surrounding 

the NWHI is the result of transiting merchant vessels, research ships, fishing vessels, cruise ships, USCG 

ships and recreational vessels which visit infrequently. An estimated 50 vessels pass through the U.S. EEZ 

347 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

348 

surrounding the NWHI each day (Franklin, 2008). Vessels entering shallow waters intentionally or unintentionally have a higher risk of impacting resources. 

Hazards to shipping and other forms of maritime traffic such as shallow submerged reefs and shoals are 

inherent in the NWHI’s 1,931 km of islands and atolls. The region is exposed to open ocean weather and 

sea conditions year-round, punctuated by winter severe storm and wave events. Vessel groundings and the 

release of fuel, cargo and other items pose real threats to the NWHI. A number of factors have contributed to 

vessel groundings and cargo loss over 

the years. These factors include human 

error, lack of appropriate navigational 

practices, inaccurate nautical charts, 

and treacherous conditions due to lowlying islands, atolls, and shallow pinnacles and banks. Periodically, accidental 

loss of cargo overboard causes marine 

debris or hazardous materials to enter 

sensitive shallow-water ecosystems. 

The history of shipwrecks and groundings is as old as the history of ships in 

the NWHI. Many islands and atolls are 

named for ships that went aground. In 

the last 50 years this history has continued, with several vessel groundings 

(Figure 10.11). Most recently the Paradise Queen and Grendel went aground 

at Kure Atoll in 1998 and 2007, respectively, and the Swordman II and Casitas 

went aground at Pearl and Hermes Atoll 

in 2000 and 2005, respectively. 

Unexploded ordnance, debris and modern shipwrecks, such as the fi shing vessels Houei Maru #5, the Paradise Queen II at Kure Atoll or the tanker Mission San Miguel lost at Maro Reef, are not protected as maritime 

heritage resources and represent a more immediate concern as threats to reef ecosystems. Mechanical damage from the initial grounding, subsequent redeposition of wreck material by storm surge, fishing gear damage to reef and reef-associated organisms, and release of fuel or hazardous substances are all issues to be 

considered in protecting the integrity of the environment. Dissolved iron serves as a limiting nutrient in many 

tropical marine areas and tends to fuel cyanobacteria (blue-green algae) or other iron limited species growth 

when the iron begins to dissolve and corrode. This is a problem particularly on atolls and low coral islands 

where basaltic or volcanic rock is absent in the photic zone and natural sources of dissolved iron in seawater 

are minimal. Therefore, any ships left in place would be an iron source that could contribute to potential cyanobacterial blooms. It has been demonstrated that not removing nonhistoric steel vessels will have long-term 

detrimental effects, which in most cases can be worse than any short-term damage to the environment caused 

by the removal action. Vessel traffic can also affect natural resources through direct damage to the reef from 

anchors, waste discharge, light and noise. Monument regulations which prohibit anchoring on or having a vessel anchored on any living or dead coral to prevent anchor damage to reefs. Discharge of waste in the Monument is also regulated by Proclamation and permit requirements. 

The designation of the PSSA and expansion of the ATBA is intended to reduce the potential for large vessel 

groundings within the Monument. In near shore areas, the mandatory requirement for a vessel monitoring system will allow better tracking of permitted vessels as well as provide information for emergency response thus 

reducing any potential impact from vessel grounding. Reducing the response time when groundings do occur 

will also minimize environmental impacts. 

Figure 10.11. Groundings in the NWHI in the last 60 years. Map: K. Keller. 
Management Concerns and Responsibilities

East Island, French Frigate Shoals temporary base 

camps established for Naval ship and aircraft 

exercises 

Midway Naval Air Station established for protection 

of U.S. during World War II 

East Island, French Frigate Shoals Coast Guard 

Long Range Navigation (LORAN) Station built 

Tern Island, French Frigate Shoals Coast Guard 

LORAN Station built 

Tern Island, French Frigate Shoals Pacific Missile 

Range Facility established 

Midway Naval Air Station downgraded to Naval Air 

Facility 

U.S. Navy defeated Imperial Japanese Navy during the 

Battle of Midway 

Tern Island, French Frigate Shoals Naval Air Station 

built 

Tern Island, French Frigate Shoals Naval Air Station 1946 decommissioned 

Green Island, Kure Atoll Coast Guard LORAN 

Station built 

1940 

1942 

1943 

1952 

1960 

1978 

Tern Island, French Frigate Shoals Coast Guard 1979 LORAN Station decommissioned 

1993 

1932-

1940 

1936- Southeast Island, Pearl and Hermes Atoll temporary 

1937 base camps established for Naval ship and aircraft 

exercises 

1961 

Tern Island, French Frigate Shoals Pacific Missile 1963 Range Facility decommissioned

Green Island, Kure Atoll Coast Guard LORAN Station 

decommissioned 

Midway Naval Air Facility decommissioned 

Figure 10.12. History of military presence in the NWHI. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

MANAGEMENT OF HUMAN IMPACTS 

There is a long history of managing impacts from human activities in the NWHI. Beginning in the early 1900s, 

several federal and state agencies, including the Department of Defense, Department of Agriculture, Department of the Interior, the state of Hawaii, and the Department of Commerce were assigned protective responsibilities in the NWHI. Additionally, military defense needs during and after World War II required the construction 

of facilities and the presence of U.S. Navy and U.S. Air Force, and USCG stations on several islands in the 

northwestern archipelago through the end of the 20th century. The following figures (Figures 10.12 and 10.13) 

indicate periods of protective responsibilities of the various federal and state agencies and the time periods in 

which military presence occurred in the NWHI. The following section focuses on the management of human 

activities since the designation of the Monument. 

349 
Management Concerns and Responsibilities

Midway Atoll secured as a U.S. possession by
 

President Theodore Roosevelt.
 

1903 The U.S. Navy was assigned stewardship 

responsibilities for the wildlife and habitat of Midway
 

Atoll.
 

Hawaiian Islands Bird Reservation established by 

President Theodore Roosevelt. 

1909 

U.S. Department of Agriculture was assigned 

stewardship responsibilities for the islets and reefs 

of the Northwestern Hawaiian Islands. 

Hawaiian Islands National Wildlife Refuge established 

by President Franklin D. Roosevelt. 

U.S. Fish and Wildlife Service was assigned 1940 

management responsibilities for the previouslydesignated Hawaiian Islands Bird Reservation as its 

status was changed to a National Wildlife Refuge. 

Midway Atoll National Wildlife Refuge established by 

President Ronald Reagan. 

1988 

U.S. Fish and Wildlife Service was assigned 

stewardship responsibilities for Midway Atoll. 

Kure Atoll designated a State Wildlife Sanctuary. 

State of Hawaii Department of Land and Natural 1993 

Resources was assigned management 

responsibilities for Kure Atoll. 

Midway Atoll administration transferred to U.S. Fish 

and Wildlife Service by President Bill Clinton. 

1996 

USFWS assumed full management responsibilities for 

Midway Atoll after 1993 decommission of Midway 

Naval Air Facility. 

Northwestern Hawaiian Islands Coral Reef Ecosystem 

Reserve established by President Bill Clinton. 

2000 

NOAA’s National Ocean Service was assigned 

stewardship responsibilities for the NWHI Coral Reef 

Ecosystem Reserve. 

Northwestern Hawaiian Islands State Marine Refuge 

established by Governor Linda Lingle. 

2005 State of Hawaii Department of Land and Natural 

Resources was assigned stewardship 

responsibilities for near-shore marine areas of the 

Northwestern Hawaiian Islands. 

PapahƗnaumokuƗkea Marine National Monument 

established by President George W. Bush. 

Department of Commerce through NOAA, Department 

of Interior through USFWS, and State of Hawaii 2006 

through the Department of Land and Natural 

Resources were assigned Co-Trustee and day-to-day 

responsibilities for managing all land and marine 

areas of the Northwestern Hawaiian Islands. 

Figure 10.13. History of Management in the NWHI. 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

350 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

MONUMENT PERMIT APPLICATIONS AND PERMIT ISSUANCE 

Since the designation of the Monument, all activities conducted within the Monument boundaries must meet 

the findings of the Proclamation and obtain a permit from the Monument. The Monument permitting program is 

one of the management tools that the Co-Trustees use to regulate the potential impacts of human activities on 

the Monument resources. Prior to the establishment of the Monument, the separate agencies responsible for 

management of the NWHI had separate permit applications, reviews and issuance processes and their own 

permit reporting requirements. Under Co-Trustee management, activities in the NWHI are prohibited, with limited exception, unless authorized by a Monument permit. Applications for all applicable activities are reviewed 

and permits issued jointly by the three Co-Trustee agencies. 

A joint Monument permit application template and review process were developed and implemented in 2007. 

All applications are reviewed by managers, scientists, other experts within the three Monument Co-Trustee 

agencies and by Native Hawaiian cultural reviewers. In addition, summaries of permit applications are posted 

for public notification, and all applications for activities in State waters must be posted in full for public review 

before they are considered for approval by the State of Hawaii Board of Land and Natural Resources Land 

Board. 

In order for a project to be permitted, it must comply with National Environmental Policy Act requirements 

and all other federal and state required permits and consultations. In addition, any permitted activity must 

meet all of the Findings of the Presidential Proclamation (Proclamation 8031) establishing the Monument. 

Information on Monument permit application procedures is available at http://papahanaumokuakea.gov/resource/permits.html. 

In addition to meeting the findings in the Proclamation, proposed activities to be conducted in the Midway 

Atoll SMA and the other National Wildlife Refuge areas, proposed activities continue to be subject to findings 

of appropriateness (603 FW 1) and compatibility determinations (16 U.S.C. 668dd-668ee and 603 FW 2) by 

USFWS to ensure the activities meet the purposes for establishing the Hawaiian Islands and Midway Atoll 

National Wildlife Refuges and the mission of the National Wildlife Refuge System. 

Findings of Presidential Proclamation 8031 

 The activity can be conducted with adequate safeguards for the resources and ecological integrity of the Monument. 

 The activity will be conducted in a manner compatible with the management direction of the Proclamation, considering the extent to which the conduct of the activity may diminish or enhance Monument resources, qualities, and 

ecological integrity; any indirect, secondary, or cumulative effects of the activity; and the duration of such effects. 

 There is no practicable alternative to conducting the activity within the Monument.

 The end value of the activity outweighs its adverse impacts on Monument resources, qualities, and ecological integrity. 

 The duration of the activity is no longer than necessary to achieve its stated purpose.

 The applicant is qualified to conduct and complete the activity and mitigate any potential impacts resulting from its

conduct. 

 The applicant has adequate financial resources available to conduct and complete the proposed activity and mitigate any potential impacts resulting from its conduct. 

 The methods and procedures proposed by the applicant are appropriate to achieve the proposed activity’s goals in 

relation to their impacts to Monument resources, qualities, and ecological integrity. 

 The applicant’s vessel has been outfitted with a mobile transceiver unit approved by NOAA Office of Law Enforcement and complies with the requirements of Proclamation 8031. 

 There are no other factors that would make the issuance of a permit for the activity inappropriate.

351 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

352 

Types of Permits Issued 

Applicants can apply for Monument permits under the following six permit categories: Research, Conservation 

and Management, Education, Native Hawaiian Practices, Recreation and Special Ocean Use. 

Research 

Research permits are authorized for those activities that enhance the understanding of Monument resources 

and improve resource management decision making. Priority is given to research proposals that help to meet 

the management needs of the Monument Co-Trustee agencies. Examples of types of activities issued under 

a research permit include biological inventories, ecosystem-based research, benthic mapping, habitat characterization, restoration investigations, cultural studies, and terrestrial and marine archaeological research. 

Conservation and Management 

Conservation and Management permits are authorized for those activities that are required for general management of the Monument. This may include activities associated with resource management, such as field 

station operations, marine debris removal, development and maintenance of infrastructure, species and habitat 

restoration, and long-term resource monitoring programs such as monitoring of endangered species, seabird 

populations, and terrestrial native plant communities. Conservation and Management permits also provide a 

mechanism enabling rapid response and follow-up to critical events in the Monument that cannot be anticipated, such as vessel groundings, coral bleaching episodes and invasive species detection. 

Education 

Education permits are authorized for those activities that further the educational value of the Monument. These 

activities may enhance the understanding of ecosystems, improve resource management decision making, 

promote Native Hawaiian knowledge and values, or aid in enforcement and compliance efforts. Priority is given 

to those activities that have clear educational or public outreach benefits and that promote “bringing the place 

to the people, rather than the people to the place.” Examples of past projects issued under an education permit 

include teacher-at-sea programs, distance learning projects, and university classes. 

Native Hawaiian Practices 

Activities conducted under a Native Hawaiian Practice permit must be noncommercial, deemed appropriate 

and necessary by traditional standards, benefit the NWHI and Native Hawaiian community, perpetuate traditional knowledge and restrict the consumption of harvested resources from the Monument. Examples of activities permitted under a Native Hawaiian Practice permit include the entry of vessels for the purpose of applying 

and transferring knowledge of traditional navigation techniques and conducting ceremonies at historic cultural 

sites on Nihoa or Mokumanamana. Permit conditions and protocols for Native Hawaiian Practice permits 

will continue to be developed by the Monument Management Board, including the Office of Hawaiian Affairs 

through consultation with the Native Hawaiian Cultural Working Group and the Native Hawaiian community. 

Recreation 

Recreation permits are limited to the Midway Atoll Special Management Area in the Monument. Recreational 

activities may not be associated with any for-hire operation or involve any extractive use. Examples of recreational activities that may be permitted include snorkeling, SCUBA diving, wildlife viewing and kayaking. 

Special Ocean Use 

Special Ocean Use permits are authorized for those projects related to commercial ocean uses, such as ecotourism or documentary filmmaking, that have a demonstrated net benefit to the Monument. Special Ocean 

Use is defined as any activity or use of the Monument that will generate revenue or profits for one or more of 

the persons associated with the activity or use. Activities that could potentially qualify as another permit type 

but that directly generates revenue or profit for at least one of the persons involved in the activity can only 

be permitted as Special Ocean Use. In addition, Special Ocean Use proposals involving activities outside of 

the Midway Atoll Special Management Area must have demonstrated educational or research purposes that 

directly benefit the conservation and management of the Monument. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Emergencies, Law Enforcement Activities and Armed Forces Actions 

Permits are not required for those activities conducted within the Monument that are necessary to respond 

to emergencies or that are necessary for law enforcement purposes. Activities and exercises of the Armed 

Forces (including those carried out by the USCG) do not require a permit but must be conducted consistent 

with applicable federal laws. All other human presence, including activities conducted by the Co-Trustee agencies, require review and approval through the Monument permitting process. 

Transit Without Interruption Through the Monument 

Uninterrupted passage by vessels through the Monument does not require a permit but vessel operators must 

provide official notice prior to entering and upon departing. Offi cial notification ensures that managers know 

at any given time who is present in the Monument either conducting activities under an authorized permit or 

transiting without interruption 

Additional Federal and State Permits and Consultations Required for Work in the Monument 

In addition to the permit requirements of the Monument, several other federal and state permits and/or consultations are required for many of the activities conducted in the NWHI. For example, all personnel working with 

threatened or endangered species must obtain an endangered species permit. Anyone handling any bird species must obtain one or more permits from the U.S. Fish and Wildlife Service Office of Migratory Bird Management, and all scientists working with marine mammals must obtain one or more permits from the NOAA Fisheries Office of Protected Resources. Consultations may also be required as described under the U.S. ESA or 

Environmental Protection Agency regulations. Finally, although bottomfishing within the Monument boundaries 

will be phased out in 2011, all current bottomfishing operations are required to have valid federal fi shing permits and state commercial marine licenses and fishing vessel registrations to operate within the Monument 

2007 Permitted Activities Conducted Within the Monument 

The first full year in which permits were 

issued by the Monument was 2007. 

Prior to June 2007, the State of Hawaii 

issued separate State permits for the 

Monument. Of a total of 51 permitted 

projects in the Monument in 2007, six 

were issued both Monument and state 

permits. The remaining 45 projects 

were issued a single joint Monument 

permit, issued by all three Co-Trustee 

agencies. Table 10.7 presents information on the number of permits issued, 

by permit type, for activities conducted 

in the Monument in 2007. The numbers 

of newly permitted projects and renewal 

Table 10.7. Numbers of Monument permits granted, by permit type, for activities conducted in 2007. Numbers of projects that were newly-initiated in

2007 and renewal projects (ongoing or long-term projects initiated in previous years) are also listed. 

PERMIT TYPE NUMBER OF 

MONUMENT PER- MITS GRANTED 

NUMBER OF 

NEW NWHI 

PROJECTS 

NUMBER OF 

RENEWAL NWHI 

PROJECTS 

Research 37 16 21 

Conservation and 

Management 

5 0 5 

Education 2 2 0 

Native Hawaiian 

Practices 

1 1 0 

Recreation 1 1 0 

Special Ocean Use 5 5 0 

TOTAL 51 25 26 

projects (i.e., ongoing or long-term projects initiated in previous years) are shown. 

Human activity in the NWHI has been greatly reduced relative to the height of military activity associated with 

World War II. Between 1940 -1945 more than 3,000 people were stationed at Midway Atoll and approximately 

125 were stationed at Tern Island wintin French Frigate Shoals. (Amerson, 1971). The overall level of human 

presence in the Monument in 2007 is indicated in Table 10.8. Eighteen ship cruises and a total of 99 flights 

transported permitted personnel and supplies to and from the Monument. The average number of people 

aboard ship per day throughout the year was 32, and the average number of people on land per day throughout the Monument was 83, for a total average of 115 people in the Monument per day in 2007. The number of 

people on land per day was highest at Midway Atoll, with an average human population of 70. Human presence 

on all other islands and atolls was an order of magnitude lower, with an average of 6.3, 4.2, and 1.5 people on 

land per day at French Frigate Shoals, Laysan Island and Kure Atoll, respectively, and on average, less than 

353 
Management Concerns and Responsibilities

354 

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

one person per day on all other islands

and atolls in the chain. 

The following map (Figure 10.14) indicates locations where permitted activities occurred in the Monument in 2007. 

Many of the permits issued allowed for 

work to be conducted at multiple locations. Thus, for example, a single permit 

may have included work only at French 

Frigate Shoals, or it may have allowed 

for visits to all islands and atolls. In 2007 

the majority of the activities occurred at 

Midway Atoll, Pearl and Hermes Atoll 

and French Frigate Shoals. Midway 

Atoll and French Frigate Shoals have 

relatively easy access and the infrastructure to support activities, including landing strips and facilities to house 

year-round personnel. 

In order to assess cumulative impacts, it 

is important for managers to understand 

the trends and patterns of the different 

types of permitted activities that have 

occurred in the Monument. The following section spatially represents the distribution of activities that took place in 

the Monument by the types of permits 

issued in 2007 

Table 10.8. Number of ship cruises and flights, and average number of

people on land per day in the Monument in 2007. 

TRANSPORTATION 

Number of Ship Cruises 18 

Number of Flights

 French Frigate Shoals 13

 Midway Atoll 86 

VISITATION 

Average Number of People on Land per Day 83

 Nihoa 0.02

 Mokumanamana 0.06

 French Frigate Shoals 6.30

 Laysan 4.20

 Lisianski 0.30

 Pearl and Hermes Atoll 0.80

 Midway Atoll 70.0

 Kure Atoll 1.50 

Average Number of People on Ships per Day 32 

Average Number of People in Monument per Day 115 

Figure 10.14. Locations of all permitted activities within the Monument in

2007. Map: K. Keller. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Research Activities by Location 

Islands and atolls with the highest levels 

of permitted Research activities in 2007 

included French Frigate Shoals, Pearl 

and Hermes Atoll, and Midway Atoll (Figure 10.15). Non-emergent banks and 

reefs, including Twin Banks, St. Rogatien and Brooks Banks, and Maro Reef, 

saw the lowest levels of research activities, while Mokumanamana and Gardner Pinnacles had the fewest number of 

Research activities conducted on emergent lands. Managers can use information on the distribution of past research 

activities to better plan and target future 

research and to ensure that data gaps 

are filled for those areas for which with 

less information is available. 

Conservation and Management 

Activities by Location 

In 2007, U.S. Fish and Wildlife Service 

Conservation and Management activities took place at Nihoa, French Frigate 

Shoals, Laysan, and Pearl and Hermes 

Atoll (within Hawaiian Islands National 

Wildlife Refuge), and at Midway Atoll 

(Midway Atoll National Wildlife Refuge). 

State of Hawaii DLNR activities took 

place at Kure Atoll, and NOAA PIFSCCRED marine debris removal activities 

occurred at French Frigate Shoals, Laysan, Lisianski, Pearl and Hermes Atoll, 

and Kure Atoll (Figure 10.16). 

Figure 10.15. Locations of permitted Research activities in 2007. Several

of the 37 Research permits authorized work at multiple locations within the

Monument; thus, the total number of permits in the figure below adds to

more than 37. Map: K. Keller. 

355 

Figure 10.16. Locations of permitted Conservation and Management activi- ties in 2007. Two of the five Conservation and Management permits autho- rized work at multiple locations within the Monument; thus, the total number

of permits in the figure below adds to more than five. Map: K. Keller. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

356 

Education Activities by Location 

NOAA Monument education activities in 

2007 took place almost entirely aboard 

ship and during 12 shallow-water free 

dives, with land visits made only at Midway Atoll and Kure Atoll. Sites visited, 

where photos and video footage were 

taken, included Nihoa, Gardner Pinnacles, Laysan, Lisianski, Pearl and 

Hermes Atoll, Midway Atoll and Kure 

Atoll. 

DLNR education activities took place 

aboard ship and during 13 shallowwater dives at French Frigate Shoals, 

Pearl and Hermes Atoll, and Midway 

Atoll (Figure 10.17). Photos and video 

footage were taken at each of these 

sites. 

Native Hawaiian Practices Activities by 

Location 

A single Native Hawaiian Practices permit was issued in 2007, to the University 

of Hawaii. Activities conducted under 

this permit included an overnight stay on 

Mokumanamana to conduct traditional 

ceremonies in observance of the summer solstice, and a stop off of the island 

of Nihoa to conduct additional ceremonies aboard ship (Figure 10.18). 

Figure 10.17. Locations of permitted Education activities in 2007. The two

Education permits authorized work at multiple locations within the Monument; thus, the total number of permits in the figure below adds to more

than two. Map: K. Keller. 

Figure 10.18. Locations of permitted native Hawaiian practices and activities in 2007. Map: K. Keller. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

Special Ocean Use Activities by Location 

Five Special Ocean Use permits were 

issued in 2007 occurring at Midway and 

French Frigate Shoals (Figure 10.19). 

Two of these permits were associated 

with the commemoration of the 65th Anniversary of the Battle of Midway and 

involved flight and ship transportation of 

World War II veterans and their families 

to Midway Atoll for the one-day celebration. A third Special Ocean Use permit 

was issued to the British Broadcasting 

Corporation for high-definition fi lming of 

tiger shark predation on albatross fledglings at French Frigate Shoals. The final 

two Special Ocean Use permits were 

issued for two individuals to conduct 

filming and still photography associated 

with NOAA Education and Research activities. Figure 10.19. Locations of permitted Special Ocean Use activities in 2007.

Map: K. Keller. 

357 

PMNM Relative Size and Visitation Rates 

Papahanaumokuakea Marine National 

Monument is the largest protected area 

in the United States, and is larger than 

all of the U.S. National Parks combined. 

It is also larger than almost all other 

protected marine areas in the world, including Great Barrier Reef Marine Park. 

Because of the protections put in place 

by Presidential Proclamation 8031, followed by the permitting system established by the Monument Management 

Board in 2007, the visitation rate to 

the Monument was signifi cantly lower 

in 2007 compared to visitation rates to 

Hanauma Bay Nature Preserve, Yosemite National Park, and even Great Barrier Reef Marine Park (Table 10.9). The following figure (Figure 10.20) 

also illustrates the scale of Papahanaumokuakea Marine National Monument relative to western states on the 

mainland U.S. The Monument is larger than 46 of the 50 states, and if overlain on the west coast would span 

an area from Arizona through Nevada, Oregon, and Washington state. 

Table 10.9. Relative size and visitation rates for Hanauma Bay, Yosemite 

National Park, Great Barrier Reef Marine Park and Papahanaumokuakea

Marine National Monument. 

PROTECTED AREA PER DAY SIZE VISITATION PEOPLE 

RATE PER ACRE 

Hanauma Bay Nature Preserve 100 acres 3,000 people/day 30 

Yosemite National Park 760,000 9,600 people/day 0.01 

acres 

Great Barrier Reef Marine Park 85,100,000 5,423 people/day 0.00006 

acres 

Papahanaumokuakea Marine 89,500,000 115 people/day* 0.000001 

National Monument acres 

*Includes 70 people per day at Midway Atoll. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

358 

Figure 10.20. Size of the Monument relative to states on the west coast of the mainland U.S. Source: D. Turner, PMNM. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

FUTURE DIRECTIONS AND IMPLICATIONS FOR A BIOGEOGRAPHIC ASSESSMENT TO 

SUPPORT HAWAIIAN ARCHIPELAGO SPATIAL MANAGEMENT 

A primary use of implementing a marine biogeographic assessment for the NWHI was to further the understanding of the temporal and spatial coupling between the oceanographic characteristics, pelagic and benthic 

habitats, living marine resources and human uses that collectively comprise the NWHI ecosystem. The biogeographic assessment process is defined in this document’s introduction and illustrated in Figure 10.21. Much 

of the data and information synthesized for this investigation addressed an area (e.g., oceanographic characteristics) much greater than the boundaries of the Monument or the individual atolls that comprise the island 

chain. However, the study area did not encompass the entire Hawaiian Archipelago that would place in context 

the biogeographic results for the NWHI when compared to the Main Hawaiian Islands (MHI). The exception is 

the work that has been done to characterize the shallow-water reef fish assemblages around both the heavily 

fished MHI and the very limited exploited reef fishes of the NWHI. 

Figure 10.21. Generalized biogeographic assessment process developed by CCMA-BB. Source: Kendall and Monaco,

2003. 

The 2,500 km long Hawaiian Archipelago is unified by its geologic origin and geographic isolation. This vast 

area is subject to great spatial gradients in oceanography, erosion and geomorphology. The Hawaiian marine ecosystem has some of the highest marine endemism on the planet, with many species unique to the 

archipelago. Given these broad-scale characteristics, the recently published NOAA Technical Memorandum 

(NOAA, 2008), “Hawaiian Archipelago Marine Ecosystem Research” plan (HAMER), noted that Hawaii could 

359 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

360 

serve as “a large scale archipelagic laboratory for the investigation of biophysical processes, comparing the protected and nearly pristine NWHI to 

the heavily used MHI to improve resources management in Hawaii and in 

comparable marine ecosystems worldwide (NOAA, 2008; Figure 10.22). 

HAMER identified six research themes important to the management of the 

Hawaiian Archipelago. They are: 

• Ecosystem Indicators and Metrics; 

• Native Biodiversity and Invasive Species; 

• Connectivity; 

• Human Interactions; 

• Resilience and Recovery; and 

• Modeling and Forecasting. 

Consistent with HAMER, the draft Papahanaumokuakea Marine National 

Monument Natural Resources Science Plan (NRSP), specifically cited a 

need for archipelagic-wide homogeneity in research planning and execution and adopted nearly identical thematic focus areas: 

• Ecological Processes and Connectivity; 

• Biodiversity and Habitats; 

• Human Impacts; 

• Indicators of Change and Monitoring; and 

• Models and Forecasting. 

Although HAMER is a plan for implementation over a ten year period, and the NRSP spans a shorter, five 

year period. Both plans provide the spatial and institutional framework to conduct research and integrate data 

and information in support of management of the Hawaiian Archipelago as a single, interconnected entity. 

With the recent increase in ecosystem monitoring data (e.g., Hawaii Coral Reef Assessment and Monitoring 

Program [CRAMP], MHI and NWHI Reef Assessment and Monitoring Programs [MHI/NWHI RAMP]), benthic 

habitat mapping (NOAA, 2007), and the assessment of habitats and associated fishes in and outside of marine 

protected areas (Friedlander et al., 2005, 2007), our ability to conduct archipelagic-wide research syntheses 

and biogeographic assessments is greatly enhanced. The biogeographic assessment process and this NWHI 

product directly support these multi-agency visions of HAMER and the PMNM NSRP, and provide a key starting point and many spatial data products that could be incorporated in a recommended MHI or archipelagowide biogeographic assessment. 

Figure 10.22. The Hawaiian Archipelago Marine Ecosystem Research. 
Management Concerns and Responsibilities

A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands 

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PERSONAL COMMUNICATIONS 

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Citations for A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands

Citation for Entire Document

Friedlander, A., K. Keller, L. Wedding, A. Clarke, M. Monaco (eds.). 2009. A Marine 

Biogeographic Assessment of the Northwestern Hawaiian Islands. NOAA Technical 

Memorandum NOS NCCOS 84. Prepared by NCCOS’s Biogeography Branch in cooperation 

with the Office of National Marine Sanctuaries Papahanaumokuakea Marine National 

Monument. Silver Spring, MD. 363 pp. 

Example Citation for an Individual Chapter (example of Oceanographic and Physical Setting 

chapter)

Desch A., T. Wynne, R. Brainard, A. Friedlander, J. Christensen. 2009. Oceanographic and 

Physical Setting. pp. 17-63. In: Friedlander, A., K. Keller, L. Wedding, A. Clarke, M. Monaco 

(eds.). 2009. A Marine Biogeographic Assessment of the Northwestern Hawaiian Islands. NOAA 

Technical Memorandum NOS NCCOS 84. Prepared by NCCOS’s Biogeography Branch in 

cooperation with the Office of National Marine Sanctuaries Papahanaumokuakea Marine 

National Monument. Silver Spring, MD. 363 pp.