ACCESS NUMBER: M13PG00021

STUDY TITLE: Marine Biogeographic Assessment of the Main Hawaiian Islands

REPORT TITLE: Marine Biogeographic Assessment of the Main Hawaiian Islands

CONTRACT NUMBER: M13PG00021

SPONSORING OCS REGION: Pacific

APPLICABLE PLANNING AREA(S): Hawaii

FISCAL YEAR(S) OF PROJECT FUNDING: FY 2013-16

COMPLETION DATE OF REPORT: September 2016

COSTS BY FISCAL YEAR: FY 2013: $200,000; FY 2014: $150,000; FY 2016: $150,000

CUMULATIVE PROJECT COST: $500,000

PROJECT MANAGER(S): Bryan M. Costa and Matthew S. Kendall

AFFILIATION: NOAA National Centers for Coastal Ocean Science, Center for Coastal 

Monitoring and Assessment

ADDRESS: 1305 East West Highway, Silver Spring, MD 20910

PRINCIPAL INVESTIGATOR(S)

*

: Bryan M. Costa and Matthew S. Kendall

KEY WORDS: Main Hawaiian Islands, Hawaii, Maui, KahoAtmospheric conditions, physical 

oceanography, biological oceanography, benthic communities, fishes, sea turtles, marine 

mammals, seabirds

BACKGROUND: The state of Hawai‘i is working to reduce its dependence on fossil fuels by 

developing local renewable energy sources. Most of the State’s potential renewable energy 

resources (notably, wind) are located in federal waters from 3 to 200 nautical miles offshore. 

The Bureau of Ocean Energy Management (BOEM) regulates the leasing, construction and 

operation of most renewable energy projects in federal waters, and is required to evaluate 

potential human, coastal and marine impacts from these projects. BOEM partnered with the 

National Oceanic and Atmospheric Administration’s (NOAA) National Centers for Coastal 

Ocean Science (NCCOS) to gather biogeographic information in support of this evaluation 

around the Main Hawaiian Islands (MHI). This assessment is one component of the larger 

BOEM and State of Hawai‘i process to evaluate renewable energy proposals offshore of the 

MHI.

OBJECTIVES: This biogeographic assessment was designed specifically to inform renewable 

energy decisions by BOEM. Having the most up-to-date and comprehensive information is an 

important part of BOEM’s process to identify and fill critical data gaps, and to assess and 

minimize the potential direct and indirect impacts of renewable energy development on marine 

ecosystems. Products from this assessment also support coastal and ocean planning activities

by other local, state and federal agencies working in the MHI.
ACCESS NUMBER: M13PG00021

DESCRIPTION: Biogeography is the study of spatial and temporal distributions of organisms, 

their associated habitats, and the historical and biological factors that influence their 

distributions. The concept of a “biogeographic assessment” builds on these principles, and 

provides a process to compile and evaluate spatial and temporal data, characterize ecological 

patterns, fill data gaps, as well as measure and map spatial uncertainty in support of 

ecosystem-based management. This process was developed by NCCOS through two decades 

of collaboration with scientists and resource managers. Products from biogeographic 

assessments are developed using Geographic Information Systems (GIS) and statistical 

software packages, and can range from simple distribution maps to complex predictive models.

This biogeographic assessment addresses three main questions: (1) how are select species or 

taxonomic groups distributed spatially and temporally around the MHI?; (2) what environmental 

conditions influence these distributions?; and (3) what significant gaps exist in our knowledge 

about the biogeography of the area? To answer these questions, NOAA NCCOS compiled 

existing, readily-available spatial data and synthesized new products around the MHI, 

describing the physical and biological marine environment, benthic habitats, fishes, sea turtles, 

marine mammals, and seabirds. The assessment focused on federal waters and taxa that were: 

(1) more likely to interact with renewable energy infrastructure, (2) culturally significant, (3) 

legally protected, and/or (4) economically valuable. 

Analyses, were specifically designed for compatibility with BOEM’s regulatory framework of 

1.2x1.2 kilometer (km) aliquots and 4.8x4.8 km lease blocks. Data products range from simple 

animal distribution maps to mathematical models depicting the predicted distributions of 

animals. For some animals, this assessment marks the first time that their space-use patterns 

were mapped or modeled in the MHI, and made available online. Collaborations with a variety of 

federal, state, academic and non-governmental organizations were crucial to this work

including: NOAA’s Pacific Island Fisheries Science Center, NOAA’s Southwest Fisheries 

Science Center, University of Hawai‘i at Mānoa, and the State of Hawai‘i.

SIGNIFICANT CONCLUSIONS: The biogeography of the MHI is shaped by atmospheric and 

oceanographic conditions that operate at different temporal and spatial scales around the 

islands. Marine animals respond to these changing conditions in different ways. Some 

taxonomic groups and species use the same locations year round (e.g., on Penguin Bank or 

offshore of the Kona Coast, Hawaiʻi), while most taxa utilize different geographic areas at 

different times of the year. Understanding these spatial and temporal patterns is critical for 

marine spatial planning efforts, including offshore renewable energy development. This 

assessment also establishes a baseline for assessing potential impacts, a guide for monitoring 

change, a roadmap for prioritizing how to fill data gaps, and a framework for integrating ocean 

research and management efforts moving forward.

STUDY RESULTS:

Environmental Setting: Atmospheric and oceanographic patterns were mapped using satellite 

imagery and oceanographic models. These maps were used to describe the regional 

environment, and to develop models predicting deep-coral, cetacean, and seabird distributions. 

Seasons around the MHI are driven by changes in the North Pacific Subtropical High and the 

Aleutian Low. Winter (November to April) is cooler, rainier, and dominated by the North Pacific 

swell. Summer (May to October) is warmer, less rainy, and dominated by the northeasterly trade 

winds and swell. Mountains and submerged topography change the direction and speed of 

winds and currents. These interactions cause the leeward sides of the island to be warmer and 

drier, and create frequent convergence, mixing, upwelling, fronts and eddies in the channels 
ACCESS NUMBER: M13PG00021

between the islands (e.g., the Kaiwi, Pailolo and ʻAlenuihānā Channels), and on the leeward 

sides of the islands (e.g., Kona Coast, Hawaiʻi). 

Benthic Habitats and Corals: Seafloor habitats were characterized within shallow (<30 m), 

mesophotic (30-150 m), and deep (>150 m) areas using existing maps, in situ survey data and 

spatial models. In shallow areas, rock/boulder habitats were less dominant, hard coral cover 

declined and algal cover increased moving from the southeast to the northwest. Hard coral 

cover was generally higher on leeward sides (e.g., Kona Coast, Hawaiʻi) and more sheltered 

areas (e.g., Kāneʻohe Bay, Oʻahu) around the islands. In mesophotic areas, information was 

limited to the ‘Auʻau Channel. Predicted probabilities of occurrence were highest for three 

genera of hard corals along the western Maui coast. In deep areas, the distribution of observed 

deep-coral presences and predicted suitable habitats varied among 18 taxonomic groups, but 

were often concentrated nearby specific locations, such as Cross Seamount, Makapuʻu Point, 

Makalawena Bank, Lō‘ihi Seamount and the southern edge of Penguin Bank. 

Fishes: The distribution of commercially important bottom fishes (i.e., the deep seven) was 

mapped using fisheries dependent and independent data. Predictive models were developed 

describing the spatial distribution of reef fishes (i.e., species richness and biomass, endemic 

species richness and biomass, and biomass of resource fishes). The bottom fishery is most 

active in the winter months. Datasets identified Southern Penguin Bank, Maui Nui channels, 

west Hawaiʻi, southern Maui, and northern Moloka‘i as important areas. For reef fishes, the 

highest biomass and richness values were in areas least accessible to humans such as the 

Hamakua and Puna districts on Hawaiʻi, northern Moloka‘i, eastern Maui, and western and 

southeastern Oʻahu. Conversely, areas more accessible to humans had overall lower richness 

and biomass values and included the Kona Coast, Hawaiʻi, west Maui and southern Oʻahu. 

Sea Turtles: Basking, nesting, and stranding locations were mapped (in the context of human 

populations, shoreline cliffs, and beaches) for the five species of sea turtles using in situ 

sightings data. Green turtles (Chelonia mydas), the most abundant species, were reported 

basking at 62 locations, with a majority of reports from northwest O‘ahu and west Hawai‘i. Most 

nesting reports are for green turtles with the majority occurring on Kaua‘i and Maui. Hawksbill 

(Eretmochelys imbricata) have key nesting sites on southern Hawai‘i. Stranding reports are 

mostly for green turtles, with many from O‘ahu and parts of Maui. Fibropapillomatosis is the 

major cause along most coastlines. Other common causes include entanglement along 

northeast Kaua‘i and southwest O‘ahu, and illnesses, boat impacts and predation along the 

Kona Coast, Hawai‘i. 

Marine Mammals: The distributions of cetaceans (15 species) were mapped using in situ 

sightings data. Seasonal relative abundance predictions were created for seven of these 

species. Terrestrial and at-sea locations of the endangered Hawaiian monk seal (Neomonachus 

schauinslandi) were also mapped using in situ sightings and telemetry data. For cetaceans, 

species distributions were variable, although some species were sighted or predicted to be 

consistently closer to shore (e.g., Humpback whale, Spinner dolphin, Common bottlenose 

dolphin), while other species were generally located further offshore (e.g., Rough-toothed 

dolphin, Sperm whale). Several species were sighted along the Kona Coast, Hawaiʻi, including 

Cuvier’s beaked whale, Dwarf sperm whale, Pygmy killer whale, Pantropical spotted dolphin, 

and Short-finned pilot whale. Hawaiian monk seals were sighted around each of the MHI, 

although more haul-out sites were identified on the islands to the northwest. Their critical habitat 

includes 0-10 m above the seafloor from 200 m depths to the shoreline, then from the shoreline 

extending 5 m inland. 
ACCESS NUMBER: M13PG00021

Seabirds: The distributions of seabirds (24 species) were mapped using in situ data. 

Seasonal relative density predictions were created for 14 of these species, and maps of 

maximum potential foraging areas were created for seven species. Species distributions were 

variable, although several species were sighted or predicted to be offshore of the Kona Coast, 

Hawaiʻi (e.g., Sooty Tern, Wedge-tailed Shearwater, Juan Fernandez Petrel, Black-winged 

Petrel, and Bulwer’s Petrel). Breeding species were generally located closer to land (e.g., Black 

Noddy, Brown Noddy, and Brown Booby) or occurred more evenly throughout the study area 

(e.g., Sooty Tern and Wedge-tailed Shearwater). Non-breeding/migratory species tended to be 

further offshore with some species being restricted to specific parts of the study area (e.g., Juan 

Fernandez Petrel and Mottled Petrel in the southeast). 

STUDY PRODUCT(S): Products from this project are publicly available. They include: (1) a 

technical report, (2) spatial datasets, (3) online map viewer, (4) web map services. These 

products are available from the project website:

http://coastalscience.noaa.gov/projects/detail?key=163

MAP SHOWING AREA OF STUDY:

 * P.I.’s affiliation may be different than that listed for Project Manager(s).