LOGGERHEAD SEA TURTLE (CARETTA CARETTA)

2009 STATUS REVIEW

UNDER THE U.S. ENDANGERED SPECIES ACT

LOGGERHEAD BIOLOGICAL REVIEW TEAM

Therese A. Conant, Peter H. Dutton, Tomoharu Eguchi, Sheryan P. Epperly, 

Christina C. Fahy, Matthew H. Godfrey, Sandra L. MacPherson, Earl E. Possardt, 

Barbara A. Schroeder, Jeffrey A. Seminoff, Melissa L. Snover, 

Carrie M. Upite, and Blair E. Witherington 

August 2009 

iii

LOGGERHEAD BIOLOGICAL REVIEW TEAM 

Therese A. Conant 

National Marine Fisheries Service 

Office of Protected Resources 

Peter H. Dutton 

National Marine Fisheries Service 

Southwest Fisheries Science Center 

Tomoharu Eguchi 

National Marine Fisheries Service 

Southwest Fisheries Science Center 

Sheryan P. Epperly 

National Marine Fisheries Service 

Southeast Fisheries Science Center 

Christina C. Fahy 

National Marine Fisheries Service 

Southwest Regional Office 

Matthew H. Godfrey 

North Carolina Wildlife Resources Commission 

Sandra L. MacPherson 

U.S. Fish and Wildlife Service 

Earl E. Possardt 

U.S. Fish and Wildlife Service 

Barbara A. Schroeder 

National Marine Fisheries Service 

Office of Protected Resources 

Jeffrey A. Seminoff 

National Marine Fisheries Service 

Southwest Fisheries Science Center 

Melissa L. Snover 

 National Marine Fisheries Service 

Pacific Islands Fisheries Science Center 

Carrie M. Upite 

National Marine Fisheries Service 

Northeast Regional Office 

Blair E. Witherington 

Florida Fish and Wildlife Conservation 

Commission 

Fish and Wildlife Research Institute 
iv

ACKNOWLEDGEMENTS 

The Biological Review Team gratefully acknowledges the key input and assistance of the 

following individuals who served as peer reviewers of this document: Dr. Alan Bolten (Archie 

Carr Center for Sea Turtle Research, University of Florida), Dr. Paolo Casale (MTSG-IUCN 

Italy), Dr. Nancy FitzSimmons (University of Canberra), Dr. Selina Heppell (Oregon State 

University), Dr. Yoshimasa Matsuzawa (Sea Turtle Association of Japan), Dr. Jeffrey Moore 

(Duke University Marine Laboratory), Dr. Ronel Nel (Nelson Mandela Metropolitan University), 

Dr. Kartik Shanker (Indian Institute of Science), and Dr. Manjula Tiwari (National Marine 

Fisheries Service contractor). We also thank the individuals who provided unpublished 

information for use in the document. 

This document should be cited as follows: 

Conant, T.A., P.H. Dutton, T. Eguchi, S.P. Epperly, C.C. Fahy, M.H. Godfrey, S.L. MacPherson, 

E.E. Possardt, B.A. Schroeder, J.A. Seminoff, M.L. Snover, C.M. Upite, and B.E. Witherington. 

2009. Loggerhead sea turtle (Caretta caretta) 2009 status review under the U.S. Endangered 

Species Act. Report of the Loggerhead Biological Review Team to the National Marine 

Fisheries Service, August 2009. 222 pages. 
v

EXECUTIVE SUMMARY

The loggerhead sea turtle (Caretta caretta) was listed as threatened on July 28, 1978. The 

threatened listing was applied to wherever the species occurs. In 2007, the National Marine 

Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (FWS) completed a 5-year 

review for the loggerhead. A 5-year review is an assessment of a listed species to determine 

whether its status has changed since the time of its listing such that it should be delisted or 

classified differently than its current status. The agencies concluded that new information 

available since the completion of the previous 5-year review in 1995 indicated a possible 

separation of populations by ocean basins but that a more in-depth analysis was needed to 

determine the application of the distinct population segment (DPS) policy. Based on the new 

information and the need for further analysis under the DPS policy, NMFS and FWS 

recommended that no change in listing status was warranted. However, they committed to fully 

assemble and analyze all relevant information in accordance with the DPS policy. 

On July 16, 2007, NMFS and FWS received a petition from the Center for Biological Diversity 

and Turtle Island Restoration Network requesting that loggerhead turtles in the North Pacific be 

reclassified as a DPS with endangered status and that critical habitat be designated. On 

November 16, 2007, NMFS and FWS received a petition from the Center for Biological 

Diversity and Oceana requesting that loggerhead turtles in the Northwest Atlantic Ocean be 

reclassified as a DPS with endangered status and that critical habitat be designated. NMFS and 

FWS determined that the July 16, 2007, North Pacific petition and the November 16, 2007, 

Northwest Atlantic petition both presented substantial information that the petitioned actions 

may be warranted. In the published 90-day petition findings, NMFS and FWS committed to 

assess the loggerhead listing status on a global basis, which is consistent with the 

recommendation in the 2007 5-year review. 

NMFS and FWS convened a biological review team (BRT) in February 2008 to review the best 

available scientific information, determine whether DPSs exist, and assess the extinction risk for 

each potential DPS. The BRT organized their evaluation by ocean basin: Pacific Ocean, 

Atlantic Ocean (including the Mediterranean Sea), and Indian Ocean. This approach was 

consistent with the 2007 

5-year review for the loggerhead and was chosen to facilitate data assembly and evaluation. It 

was not meant to preclude identification of DPSs on a broader or finer scale. 

The NMFS and FWS 1996 DPS policy defines a population to be a “distinct population 

segment” if it is both discrete and significant relative to its taxon. The BRT evaluated genetic 

evidence, tagging (flipper and PIT tags) and satellite telemetry data, demographics information, 

oceanographic features, and geographic barriers, and determined that there are at least nine 

discrete population segments for loggerhead sea turtles globally. These discrete population 

segments are markedly separated from each other as a consequence of ecological, behavioral, 

and oceanographic factors, and based on genetic evidence. Therefore, the BRT unanimously 

concluded that two discrete population segments exist in the Pacific Ocean, three in the Indian 

Ocean, and four in the Atlantic Ocean/Mediterranean Sea. 
vi

The BRT then considered whether each of the nine identified discrete population segments is 

significant relative to its taxon. The BRT determined that each of the nine discrete population 

segments were biologically and ecologically significant. They each represent a large portion of 

the species range, sometimes encompassing an entire hemispheric ocean basin. The range of 

each discrete population segment represents a unique ecosystem, influenced by local ecological 

and physical factors. The loss of any single discrete population segment would result in a 

significant gap in the loggerhead’s range. Each discrete population segment is genetically 

unique; the loss of any one discrete population segment would represent a significant loss of 

genetic diversity. Therefore, the BRT concluded that the nine identified population segments are 

both discrete from other conspecific population segments and significant to the species to which 

they belong, Caretta caretta. 

The BRT has identified the following nine loggerhead DPSs distributed globally: 

(1) North Pacific Ocean DPS, 

(2) South Pacific Ocean DPS, 

(3) North Indian Ocean DPS, 

(4) Southeast Indo-Pacific Ocean DPS, 

(5) Southwest Indian Ocean DPS, 

(6) Northwest Atlantic Ocean DPS, 

(7) Northeast Atlantic Ocean DPS, 

(8) Mediterranean Sea DPS, and 

(9) South Atlantic Ocean DPS. 

The BRT next conducted two independent analyses to assess extinction risks of the identified 

DPSs. The first analysis used the diffusion approximation approach based on a time series of 

counts of nesting females or nests to provide a metric, susceptibility to quasi-extinction (SQE). 

SQE is an increasing function of quasi-extinction threshold (QET). The second analysis focused 

on determining the effects of known anthropogenic mortality on each potential DPS with respect 

to the vital rates of the species. This approach focused on how additional mortalities may affect 

the future growth and status of each DPS. 

For three of five DPSs with sufficient data to conduct the SQE analysis (Northwest Atlantic 

Ocean, South Pacific Ocean, and North Pacific Ocean), the threshold of SQE = 0.3 was reached 

at QET < 0.3, indicating high likelihood of quasi-extinction over a wide range of QET values. 

There were not enough data to conduct the SQE analysis for the North Indian Ocean, Southeast 

Indo-Pacific Ocean, Northeast Atlantic Ocean, and Mediterranean Sea DPSs. 

According to the analysis using experts’ opinions in the matrix model framework, all loggerhead 

turtle DPSs have the potential to decline in the future. Although some DPSs are indicating 

increasing trends at nesting beaches (Southwest Indian Ocean and South Atlantic Ocean), 

available information about anthropogenic threats to juveniles and adults in neritic and oceanic 

environments indicate possible unsustainable additional mortalities. According to the threat 

matrix analysis, the potential for future decline is greatest for the North Indian Ocean, Northwest 

Atlantic Ocean, Northeast Atlantic Ocean, Mediterranean Sea, and South Atlantic Ocean DPSs.
vii

TABLE OF CONTENTS 

LOGGERHEAD BIOLOGICAL REVIEW TEAM ................................................................iii 

ACKNOWLEDGEMENTS ........................................................................................................ iv 

EXECUTIVE SUMMARY .......................................................................................................... v 

TABLE OF CONTENTS ........................................................................................................... vii 

LIST OF ACRONYMS AND ABBREVIATIONS .................................................................... 1 

SECTION 1—INTRODUCTION AND BACKGROUND........................................................ 3 

1.1. ESA Overview ................................................................................................................... 3 

1.1.1. Purpose........................................................................................................................... 3 

1.1.2. Definitions...................................................................................................................... 3 

1.1.3. Listing............................................................................................................................. 3 

1.1.4. Distinct Population Segment........................................................................................ 4 

1.2. History of ESA Listing, Status Reviews, and Petitions.................................................. 4 

1.2.1. ESA Listing.................................................................................................................... 4 

1.2.2. ESA 5-year Reviews...................................................................................................... 4 

1.2.3. Petitions.......................................................................................................................... 5 

1.3. Approach to the Status Review........................................................................................ 6 

SECTION 2—SPECIES OVERVIEW ....................................................................................... 7 

2.1. Taxonomy .......................................................................................................................... 7 

2.2. Physical Appearance......................................................................................................... 7 

2.3. Distribution and Habitat.................................................................................................. 8 

2.4. Biological Characteristics............................................................................................... 13 

SECTION 3—DETERMINATION OF DPS ........................................................................... 16 

3.1. Overview of Information Used to Determine DPS....................................................... 16 

3.1.1. Discreteness Determination........................................................................................ 17 

3.1.2. Significance Determination........................................................................................ 30 

3.2. Significant Portion of its Range (SPOIR) Assessment................................................. 35 

SECTION 4—ASSESSMENT OF EXTINCTION RISK....................................................... 36 

4.1. Description of Extinction Risk Assessment Approaches............................................. 36 

4.2. Computation of Susceptibility to Quasi-extinction (SQE).......................................... 36 

4.2.1. Methods........................................................................................................................ 36 

4.2.2. Count Data................................................................................................................... 38 

4.2.2.1. North Pacific Ocean DPS ....................................................................................... 40 

4.2.2.2. South Pacific Ocean DPS........................................................................................ 41 

4.2.2.3. North Indian Ocean DPS........................................................................................ 42 

4.2.2.4. Southeast Indo-Pacific Ocean DPS........................................................................ 42 

4.2.2.5. Southwest Indian Ocean DPS ................................................................................ 42 

4.2.2.6. Northwest Atlantic Ocean DPS.............................................................................. 43 

4.2.2.7. Northeast Atlantic Ocean DPS .............................................................................. 43 

4.2.2.8. Mediterranean Sea DPS ......................................................................................... 43 

4.2.2.9. South Atlantic Ocean DPS ..................................................................................... 43 

4.2.3. Results.......................................................................................................................... 46 

4.3. Threat Matrix Analysis.................................................................................................. 53 

4.3.1. General Modeling Approach ..................................................................................... 53 

4.3.2. Survival Rates and Population Growth Rate for the Base Models........................ 53 
viii

4.3.3. Quantifying Known Threats...................................................................................... 56 

4.3.4. Combining Additional Mortalities and the Base Population Model...................... 58 

4.4. Results.............................................................................................................................. 59 

4.4.1. Results—Base Population Model............................................................................... 59 

4.4.2. Results—Threat Matrix ............................................................................................. 67 

4.4.2.1. North Pacific Ocean DPS ....................................................................................... 68 

4.4.2.2. South Pacific Ocean DPS........................................................................................ 69 

4.4.2.3. North Indian Ocean DPS........................................................................................ 70 

4.4.2.4. Southeast Indo-Pacific Ocean DPS........................................................................ 71 

4.4.2.5. Southwest Indian Ocean DPS ................................................................................ 72 

4.4.2.6. Northwest Atlantic Ocean DPS.............................................................................. 73 

4.4.2.7. Northeast Atlantic Ocean DPS .............................................................................. 74 

4.4.2.8. Mediterranean Sea DPS ......................................................................................... 75 

4.4.2.9. South Atlantic Ocean DPS ..................................................................................... 76 

4.4.3. DPS Status ................................................................................................................... 77 

4.5. Synthesis........................................................................................................................... 83 

4.6. Supplemental Material—Sensitivity Analyses............................................................. 85 

4.6.1. Effects of AFR and CV of AFR on the Base Population Model ............................. 85 

4.6.2. Effects of AFR on the Threat Matrix Analysis ........................................................ 86 

4.6.3. Proportion of Neritic Juvenile Stage Duration ........................................................ 86 

SECTION 5—ANALYSIS OF FACTORS LISTED UNDER ESA SECTION 4(a)(1)...... 100 

5.1. General Description of Threats................................................................................... 100 

5.2. Threats Specific to DPS................................................................................................ 110 

5.2.1. North Pacific Ocean DPS ......................................................................................... 110 

5.2.2. South Pacific Ocean DPS.......................................................................................... 118 

5.2.3. North Indian Ocean DPS.......................................................................................... 122 

5.2.4. Southeast Indo-Pacific Ocean DPS.......................................................................... 124 

5.2.5 Southwest Indian Ocean DPS .................................................................................. 127 

5.2.6. Northwest Atlantic Ocean DPS................................................................................ 129 

5.2.7. Northeast Atlantic Ocean DPS ................................................................................ 138 

5.2.8. Mediterranean Sea DPS ........................................................................................... 145 

5.2.9. South Atlantic Ocean DPS ....................................................................................... 157 

SECTION 6—CONCLUSIONS—SYNTHESIS & INTEGRATION.................................. 161 

6.1. North Pacific Ocean DPS ............................................................................................. 161 

6.2. South Pacific Ocean DPS.............................................................................................. 161 

6.3. North Indian Ocean DPS.............................................................................................. 162 

6.4. Southeast Indo-Pacific Ocean DPS.............................................................................. 162 

6.5. Southwest Indian Ocean DPS ...................................................................................... 163 

6.6. Northwest Atlantic Ocean DPS.................................................................................... 164 

6.7. Northeast Atlantic Ocean DPS .................................................................................... 164 

6.8. Mediterranean Sea DPS ............................................................................................... 165 

6.9. South Atlantic Ocean DPS ........................................................................................... 165 

SECTION 7—REFERENCES................................................................................................. 167 
1

LIST OF ACRONYMS AND ABBREVIATIONS 

The following are standard abbreviations for acronyms and terms found throughout this 

document: 

AFR Age at First Reproduction 

ASEAN Association of South East Asian Nations 

BRT Biological Review Team 

CBD Convention on Biological Diversity 

CCL Curved Carapace Length 

CI Confidence Interval 

CITES Convention on the International Trade in Endangered Species of Wild Fauna and Flora 

CMS Convention on the Conservation of Migratory Species of Wild Animals

COFI FAO Committee on Fisheries 

CPPS Commision Permanente del Pacifico Sur 

CV Coefficient of Variation 

DNA Deoxyribonucleic Acid 

DPS Distinct Population Segment 

ENSO El Niño Southern Oscillation 

ESA Endangered Species Act of 1973, as amended 

FAO Food and Agriculture Organization of the United Nations 

FWS U.S. Fish and Wildlife Service 

GBR Great Barrier Reef 

GCRU Greater Caribbean Recovery Unit 

GIWA Global International Waters Assessment 

IAC Inter-American Convention for the Conservation and Protection of Marine Turtles 

ICCAT International Commission for the Conservation of Atlantic Tunas 

IOSEA Indian Ocean – South-East Asian Marine Turtle Memorandum of Understanding 

IPCC Intergovernmental Panel on Climate Change 

LME Large Marine Ecosystem 

MARPOL International Convention for the Prevention of Pollution from Ships 

MOU Memorandum of Understanding 

MSA U.S. Magnuson-Stevens Fishery Conservation and Management Act 

mtDNA Mitochondrial Deoxyribonucleic Acid 

NBSD Negative Binomial Stage Distribution 

NGMRU Northern Gulf of Mexico Recovery Unit 

NMFS National Marine Fisheries Service 

NPF Northern Australian Prawn Fishery 

NRU Northern Recovery Unit 

PIT Passive Integrated Transponder 

PFRU Peninsular Florida Recovery Unit 

PVA Population Viability Analysis 

QET Quasi-extinction Threshold 

RFMO Regional Fishery Management Organizations 

SCL Straight Carapace Length 

SD Standard Deviation 
2

SEAFO South-East Atlantic Fisheries Organization 

SPAW Protocol Concerning Specially Protected Areas and Wildlife 

SPOIR Significant Portion of its Range 

SPREP South Pacific Regional Environment Programme 

SQE Susceptibility to Quasi-extinction 

STAJ Sea Turtle Association of Japan 

TED Turtle Excluder Device 

UNCLOS United Nations Convention on the Law of the Sea 

UNEP United Nations Environment Programme 
3

SECTION 1—INTRODUCTION AND BACKGROUND 

1.1. ESA Overview 

1.1.1. Purpose 

The purpose of the Endangered Species Act of 1973, as amended (ESA) (16 U.S.C. 1531 et seq.) 

is to provide a means to conserve ecosystems upon which endangered and threatened species 

depend, to provide a program for the conservation of endangered and threatened species, and to 

take appropriate steps to recover endangered and threatened species. The National Marine 

Fisheries Service (NMFS) and U.S. Fish and Wildlife Service (FWS) share responsibility for 

administering the ESA. NMFS and FWS are responsible for determining whether species, 

subspecies, or distinct population segments of vertebrate species are threatened or endangered 

under the ESA. FWS typically has the lead for terrestrial and freshwater species, and NMFS 

typically has the lead for marine, estuarine, and anadromous species. NMFS and FWS share 

jurisdiction for recovering sea turtles – NMFS is responsible for sea turtles in their marine 

environment and FWS is responsible for sea turtles in their terrestrial habitat. 

1.1.2. Definitions 

Species: includes any subspecies of fish or wildlife or plants and any distinct population 

segment of any species of vertebrate fish or wildlife which interbreeds when mature. 

Endangered Species: any species which is in danger of extinction throughout all or a significant 

portion of its range. 

Threatened Species: any species which is likely to become an endangered species within the 

foreseeable future throughout all or a significant portion of its range. 

1.1.3. Listing 

Section 4 of the ESA specifies a process upon which a species may be determined to be listed as 

threatened or endangered with extinction, changed in status, or removed from the list. The 

determination is based solely on the best available scientific and commercial data after reviewing 

the status of the species and taking into account conservation efforts. NMFS and FWS must 

determine whether any species is an endangered species or a threatened species because of any 

of the following factors (section 4(a)(1)(A)-(E)): 

(A) the present or threatened, destruction, modification, or curtailment of its habitat or 

range; 

(B) overutilization for commercial, recreational, scientific, or educational purposes; 

(C) disease or predation; 

(D) the inadequacy of existing regulatory mechanisms; and 

(E) other natural or manmade factors affecting its continued existence. 

NMFS and FWS can begin the review for listing determinations, or any interested person may 

petition for a listing determination under section 553(e) of U.S.C. title 5. 
4

1.1.4. Distinct Population Segment 

In 1996, NMFS and FWS published a policy to define the phrase “distinct population segment” 

(DPS) (FWS and NMFS 1996, 61 FR 4722). The policy defines a population to be a DPS if it is 

both discrete and significant relative to its taxon. A population may be considered discrete if it 

satisfies either one of the following conditions: 

a. It is markedly separated from other populations of the same taxon as a consequence 

of physical, physiological, ecological, or behavioral factors. Quantitative measures of 

genetic or morphological discontinuity may provide evidence of this separation. 

b. It is delimited by international governmental boundaries within which differences in 

control of exploitation, management of habitat, conservation status, or regulatory 

mechanisms exist that are significant in light of section 4(a)(1)(D) of the ESA. 

If a population segment is considered discrete, NMFS and/or FWS must then consider whether 

the discrete segment is significant relative to its taxon. Criteria that can be used to determine 

whether the discrete population segment is significant include, but are not limited to, the 

following: 

a. Persistence of the discrete population segment in an ecological setting unusual or 

unique for the taxon, 

b. Evidence that loss of the discrete population segment would result in a significant gap 

in the range of the taxon, 

c. Evidence that the discrete population segment represents the only surviving natural 

occurrence of a taxon that may be more abundant elsewhere as an introduced 

population outside its historic range, or 

d. Evidence that the discrete population segment differs markedly from other 

populations of the species in its genetic characteristics. 

1.2. History of ESA Listing, Status Reviews, and Petitions 

1.2.1. ESA Listing 

The loggerhead sea turtle (Caretta caretta) was listed as threatened on July 28, 1978 (FWS and 

NMFS 1978, 43 FR 32800). The threatened listing was applied to wherever the species occurs. 

The major factors contributing to its status included human encroachment and associated 

activities on nesting beaches; commercial harvest of eggs, subadults, and adults; predation; lack 

of comprehensive and consistent protective regulations; and incidental take in fisheries. Critical 

habitat has not been designated for the loggerhead sea turtle. 

1.2.2. ESA 5-year Reviews 

Under the ESA, FWS and NMFS are required to conduct a review of listed species under their 

jurisdiction at least once every 5 years. A 5-year review is an assessment of a listed species to 

determine whether its status has changed since the time of its listing such that it should be 

delisted or classified differently than its current status. The purpose of a 5-year review is to 

ensure that a listed species has the appropriate level of protection under the ESA. 
5

NMFS conducted the first 5-year review for the loggerhead in 1985 (Mager 1985). Data on 

population trends were limited and were based largely on the number of nests and nesting 

females. Of 52 nesting populations examined throughout the Atlantic, Pacific, and Indian 

Oceans, 33 were thought to be declining, 18 were unknown, and only one – the southeast U.S. 

Atlantic – was thought to be increasing. Although commercial harvest of eggs had decreased 

and the U.S. had implemented protective regulations, many threats continued both domestically 

and abroad. NMFS determined that, since the 1978 listing, information was insufficient to assess 

whether a listing change was warranted. 

FWS also conducted a 5-year review for the loggerhead in 1991 (FWS 1991, 56 FR 56882). In 

this review, the status of many species was simultaneously evaluated with no in-depth 

assessment of the section 4(a)(1) factors as they pertained to the individual species. The notice 

stated that FWS was seeking any new or additional information reflecting the necessity of a 

change in the status of the species under review. The notice indicated that if significant data 

were available warranting a change in a species’ classification, FWS would propose a rule to 

modify the species’ status. No change in the loggerhead threatened listing classification was 

recommended following this 5-year review. 

In 1995, NMFS and FWS conducted a joint 5-year review (Plotkin 1995). New information on 

population structure indicated the nesting assemblage along the southeast U.S. coast may consist 

of two separate populations – Florida and those nesting in Georgia and northward. Nesting in 

Georgia, South Carolina, and North Carolina was declining. The Florida nesting population was 

stable, but it was determined that human presence in areas of heavy nesting could impact the 

population in the future. Although no change in the loggerhead’s listing classification was 

recommended, a need for further study of U.S. loggerhead population structure was identified. 

The 5-year review further stated that should additional research confirm the existence of two 

separate nesting populations, and if the decline of the northern nesting population continued, 

careful consideration should be given to reclassification during the next 5-year review. 

The last 5-year review was completed in 2007 (NMFS and FWS 2007). Many technological 

advances and a diversity of research occurred since the 1995 review. Molecular markers (i.e., 

mitochondrial DNA and microsatellites) helped define the genetic structuring within and among 

ocean basins, both at the nesting beaches and at foraging grounds. New information existed on 

demographic parameters such as age at first reproduction and survival rates and the biology of 

loggerheads, especially away from the nesting beach. These data indicated a possible separation 

of populations by ocean basins; however, a more in-depth analysis was needed to determine the 

application of the DPS policy. Based on the new information and the need for further analysis 

under the DPS policy, NMFS and FWS recommended that no change in listing status was 

warranted. They committed to fully assemble and analyze all relevant information in accordance 

with the DPS policy. 

1.2.3. Petitions 

Past Petitions

In 2002, NMFS and FWS received a petition to reclassify the Northern (northeast Florida 

through North Carolina) and Florida Panhandle subpopulations as DPSs, change their status to 
6

endangered, and designate critical habitat. NMFS found that the petition presented substantial 

scientific and commercial information indicating that the petitioned reclassification may be 

warranted (a “positive 90-day finding”) (NMFS and FWS 2002, 67 FR 38459). Based on further 

analysis of the best available data, NMFS and FWS found that although there was some degree 

of discreteness between the nesting assemblages, the separation was not highly rigid and did not 

qualify as DPSs (a “12-month determination of not warranted”) (FWS and NMFS 2003, 68 FR 

53947). Therefore, the species’ listing status was not changed. 

Current Petitions 

On July 16, 2007, NMFS and FWS received a petition from the Center for Biological Diversity 

and Turtle Island Restoration Network requesting that loggerhead turtles in the North Pacific be 

reclassified as a DPS with endangered status and that critical habitat be designated. On 

November 16, 2007, NMFS and FWS received a petition from the Center for Biological 

Diversity and Oceana requesting that loggerhead turtles in the Northwest Atlantic Ocean be 

reclassified as a DPS with endangered status and that critical habitat be designated. 

NMFS and FWS determined that the July 16, 2007, North Pacific petition and the November 16, 

2007, Northwest Atlantic petition both presented substantial information that the petitioned 

actions may be warranted (NMFS 2007b, 72 FR 64585; NMFS 2008b, 73 FR 12941). In the 

published 90-day petition findings, NMFS and FWS committed to assess the loggerhead listing 

status on a global basis, which is consistent with the recommendation in the 2007 5-year review 

(see Section 1.2.2.). 

1.3. Approach to the Status Review 

NMFS and FWS convened a biological review team (BRT) in February 2008 to review the best 

available scientific information, determine whether DPSs exist, and assess the extinction risk for 

each potential DPS. The BRT organized their evaluation by ocean basin: Pacific Ocean, 

Atlantic Ocean (including the Mediterranean Sea), and Indian Ocean. This approach was 

consistent with the 2007 5-year review for the loggerhead and was chosen to facilitate data 

assembly and evaluation. It was not meant to preclude identification of DPSs on a broader or 

finer scale. The BRT primarily reviewed genetic, tagging (flipper and PIT tags), and satellite 

telemetry datasets and examined oceanographic features and geographic barriers to determine 

discreteness and significance (Section 3). The BRT conducted two independent analyses to 

assess extinction risks of potential DPSs (Section 4). The first analysis used the diffusion 

approximation approach based on a time series of counts of nesting females or nests to provide a 

metric, susceptibility to quasi-extinction. The second analysis focused on determining the effects 

of known anthropogenic mortality on each potential DPS with respect to the vital rates of the 

species. This approach focused on how additional mortalities may affect the future growth and 

status of potential DPSs.
7

SECTION 2—SPECIES OVERVIEW 

2.1. Taxonomy 

Kingdom: Animalia 

Phylum: Chordata 

Class: Reptilia 

Order: Testudines 

Family: Cheloniidae 

Genus: Caretta

Species: caretta

Common name: Loggerhead sea turtle 

The loggerhead was first described by Linnaeus in 1758 and named Testudo caretta. Over the 

next two centuries more than 35 names were applied to the species (Dodd 1988), but there is now 

agreement on Caretta caretta as the valid name. While Deraniyagala described an Indo-Pacific 

form as C. gigas in 1933, he revised that view in 1939 to hold that gigas was a subspecies of C.

caretta (Deraniyagala 1933, 1939). The genus has been regarded as monotypic since that time. 

The subspecific designation of gigas has likewise been challenged persuasively (Brongersma 

1961, Pritchard 1979). Thorough synonymies and taxonomic reviews of this form are given 

most recently by Pritchard and Trebbau (1984) and Dodd (1988). Subspecies assignments are 

not supported based on genetic evidence (Bowen 2003) or other diagnostic characters (Dodd 

1998). 

2.2. Physical Appearance 

The carapace of adult and juvenile loggerheads is reddish-brown. The dorsal and lateral head 

scales and the dorsal scales of the flippers are also reddish-brown, but with light to medium 

yellow margins. The unscaled areas of the integument (neck, shoulders, limb bases, inguinal 

area) are dull brown dorsally and light to medium yellow laterally and ventrally. The plastron is 

medium to light yellow, and the thick, bony carapace is covered by non-overlapping scutes that 

meet along seam lines. There usually are 11 or 12 pairs of marginal scutes, five pairs of costals, 

five vertebrals, and a nuchal (precentral) scute that is in contact with the first pair of costal 

scutes. The plastron is composed of paired gular, humeral, pectoral, abdominal, femoral, and 

anal scutes and connected to the carapace by three pairs of poreless inframarginal scutes. 

Hatchlings vary from light to dark brown to dark gray dorsally and lack the reddish-brown 

coloration of adults and juveniles. Flippers are dark gray to brown above with distinct white 

margins. The ventral coloration of the plastron and other areas of the integument are generally 

yellowish to tan. The carapace has three keels and the plastron has two keels. At emergence, 

hatchlings average 45 mm in SCL and weigh approximately 20 g (Dodd 1988). 
8

2.3. Distribution and Habitat 

The loggerhead occurs throughout the temperate and tropical regions of the Atlantic, Pacific, and 

Indian Oceans (Dodd 1988). However, the majority of loggerhead nesting is at the western rims 

of the Atlantic and Indian Oceans. The most recent reviews show that only two loggerhead 

nesting aggregations have greater than 10,000 females nesting per year: Peninsular Florida, 

United States and Masirah Island, Oman (Baldwin et al. 2003, Ehrhart et al. 2003, Kamezaki et 

al. 2003, Limpus and Limpus 2003b, Margaritoulis et al. 2003). Nesting aggregations with 

1,000 to 9,999 females nesting annually are Georgia through North Carolina (U.S.), Quintana 

Roo and Yucatán (Mexico), Brazil, Cape Verde Islands (Cape Verde), Western Australia 

(Australia), and Japan. Smaller nesting aggregations with 100 to 999 nesting females annually 

occur in the Northern Gulf of Mexico (U.S.), Dry Tortugas (U.S.), Cay Sal Bank (The Bahamas), 

Tongaland (South Africa), Mozambique, Arabian Sea Coast (Oman), Halaniyat Islands (Oman), 

Cyprus, Peloponnesus (Greece), Zakynthos (Greece), Crete (Greece), Turkey, and Queensland 

(Australia). In contrast to determining population size on nesting beaches, determining 

population size in the marine environment has been very localized (Bjorndal and Bolten 2000). 

At present, there are no data on population size in the oceanic habitat. Detailed information on 

distribution and habitat by ocean basin follows. 

Pacific Ocean

Loggerheads can be found throughout tropical to temperate waters in the Pacific; however, their 

breeding grounds include a restricted number of sites in the North Pacific and South Pacific. 

Within the North Pacific, loggerhead nesting has been documented only in Japan (Kamezaki et 

al. 2003), although low level nesting may occur outside of Japan in areas surrounding the South 

China Sea (Chan et al. 2007). In the South Pacific, nesting beaches are restricted to eastern 

Australia and New Caledonia and, to a much lesser extent, Vanuatu and Tokelau (Limpus and 

Limpus 2003b). 

Important loggerhead nesting locations in Japan include Yakushima Island, and Miyazaki, 

Minabe, and Atsumi beaches on the mainland. Approximately 40% of all loggerhead nesting in 

Japan occurs at three primary nesting beaches on Yakushima Island (Kamezaki et al. 2003). 

Based on tag-recapture studies, the East China Sea has been identified as the major habitat for 

post-nesting adult females (Iwamoto et al. 1985, Kamezaki et al. 1997, Balazs 2006), while 

satellite tracking of juvenile loggerheads indicates the Kuroshio Extension Bifurcation Region to 

be an important pelagic foraging area for juveniles (Polovina et al. 2006). Other important 

juvenile foraging areas have been identified off the coast of Baja California Sur, Mexico (Pitman 

1990, Peckham and Nichols 2006). 

Nesting occurs along the mainland of Australia from South Stradbroke Island to Bustard Head, 

and on the islands of the Capricorn Bunker Group and Swain Reefs, and on Bushy Island 

(Limpus and Limpus 2003b, Limpus 2009). Within this area, five rookeries account for 70% of 

nests in eastern Australia: (1) Mon Repos, (2) Wreck Rock, (3) mainland and Wreck Island, (4) 

Erskine Island, and (5) Tryon Island (Limpus and Reimer 1994). Nesting females tagged on the 

coast of eastern Australia have been recorded foraging in New Caledonia; Queensland, New 

South Wales, and Northern Territory, Australia; Solomon Islands; Papua New Guinea; and 
9

Indonesia (Limpus and Limpus 2003b). Foraging Pacific loggerheads originating from nesting 

beaches in Australia are known to migrate to Chile and Peru (Alfaro-Shigueto et al. 2004, 2008a; 

Donoso and Dutton 2006; Boyle et al. 2009). 

Although nesting in the South Pacific is concentrated in eastern Australia, nesting has also been 

reported in New Caledonia, Vanuatu, and Tokelau (Limpus and Limpus 2003b). Nesting may 

occur in other areas of the South Pacific, but it remains unsubstantiated. In New Caledonia, the 

most substantial loggerhead nesting has been reported on peripheral small coral cays offshore 

from the main island of Île des Pins (Beloff personal communication cited in Limpus and 

Limpus 2003b). The population in the Île des Pins area has been estimated at 10-100 females 

nesting annually (Limpus and Limpus 2003b). Based on aerial surveys of New Caledonia 

nesting beaches conducted between December 2006 and January 2008, it was estimated that the 

nesting female population for this nesting season was approximately 200 individuals (World 

Wildlife Fund 2008). In Vanuatu, low density nesting was reported at Malekula in 1993 (Atuary 

1994 cited in Limpus and Limpus 2003b); however, the status of loggerhead nesting is uncertain 

because most of Vanuatu has been poorly surveyed. In 1981, nesting was reported in Tokelau, a 

territory of New Zealand that comprises three coral atolls in the South Pacific, but is believed to 

be uncommon (Balazs 1983). 

Indian Ocean 

In the Southwest Indian Ocean, loggerhead nesting occurs on the southeastern coast of Africa, 

from the Paradise Islands in Mozambique southward to St. Lucia in South Africa, and on the 

south and southwestern coasts of Madagascar (Baldwin et al. 2003). Foraging habitats are only 

known for post-nesting females from Tongaland, South Africa; tagging data show these 

loggerheads migrating eastward to Madagascar, northward to Mozambique, Tanzania, and 

Kenya, and southward to Cape Agulhas at the southernmost point of Africa and into the Atlantic 

Ocean (Baldwin et al. 2003, Luschi et al. 2006). 

In the North Indian Ocean, Oman hosts the vast majority of loggerhead nesting. The majority of 

the nesting in Oman occurs on Masirah Island, on the Al Halaniyat Islands, and on mainland 

beaches south of Masirah Island all the way to the Oman-Yemen border (IUCN - The World 

Conservation Union 1989a, 1989b; Salm 1991; Salm and Salm 1991). In addition, nesting 

probably occurs on the mainland of Yemen on the Arabian Sea coast, and nesting has been 

confirmed on Socotra, an island off the coast of Yemen (Pilcher and Saad 2000). Limited 

information exists on the foraging habitats of North Indian Ocean loggerheads; however, 

foraging individuals have been reported off the southern coastline of Oman (Salm et al. 1993). 

Satellite telemetry studies conducted in Oman have revealed new information about post-nesting 

migrations of loggerheads nesting on Masirah Island (Environment Society of Oman and 

Ministry of Environment and Climate Change, Oman, unpublished data). Results reveal 

extensive use of the waters off the Arabian Peninsula, with the majority of telemetered turtles (15 

of 20) traveling southwest, following the shoreline of southern Oman and Yemen, and circling 

well offshore in nearby oceanic waters. A minority traveled north as far as the western Persian 

(Arabian) Gulf (3 of 20) or followed the shoreline of southern Oman and Yemen as far west as 

the Gulf of Aden and the Bab-el-Mandab (2 of 20). These preliminary data suggest that postnesting migrations and adult female foraging areas may be centered within the region 
10

(Environment Society of Oman and Ministry of Environment and Climate Change, Oman, 

unpublished data). 

The only verified nesting beaches for loggerheads on the Indian subcontinent are found in Sri 

Lanka. A small number of nesting females use the beaches of Sri Lanka every year 

(Deraniyagala 1939, Kar and Bhaskar 1982, Dodd 1988); however, there are no records 

indicating that Sri Lanka has ever been a major nesting area for loggerheads (Kapurusinghe 

2006). No confirmed nesting occurs on the mainland of India despite historical papers 

suggesting loggerhead sightings on mainland beaches (Tripathy 2005, Kapurusinghe 2006). This 

discrepancy may be attributed to inaccurate identification of nesting species, as loggerheads are 

sometimes confused with olive ridleys in the Indian Ocean (Tripathy 2005). In addition, the 

Gulf of Mannar provides foraging habitat for juveniles and post-nesting adults (Tripathy 2005, 

Kapurusinghe 2006). Although loggerheads have been reported nesting in low numbers in 

Myanmar, these data may not be reliable because of misidentification of species (Thorbjarnarson 

et al. 2000). 

In the East Indian Ocean, western Australia hosts all known loggerhead nesting (Dodd 1988). 

Nesting distributions in western Australia span from the Shark Bay World Heritage Area 

northward through the Ningaloo Marine Park coast to the North West Cape and to the nearby 

Muiron Islands (Baldwin et al. 2003). Nesting individuals from Dirk Hartog Island have been 

recorded foraging within Shark Bay and Exmouth Gulf, while other adults range much farther 

(Baldwin et al. 2003). 

Atlantic Ocean

In the Northwest Atlantic, the majority of loggerhead nesting is concentrated along the coasts of 

the United States from southern Virginia through Alabama. Additional nesting beaches are 

found along the northern and western Gulf of Mexico, eastern Yucatán Peninsula, at Cay Sal 

Bank in the eastern Bahamas (Addison and Morford 1996, Addison 1997), on the southwestern 

coast of Cuba (F. Moncada-Gavilán, personal communication, cited in Ehrhart et al. 2003), and 

along the coasts of Central America, Colombia, Venezuela, and the eastern Caribbean Islands. 

In the Southwest Atlantic, loggerheads nest in significant numbers only in Brazil. In the eastern 

Atlantic, the largest nesting population of loggerheads is in the Cape Verde Islands (L.F. LópezJurado, personal communication, cited in Ehrhart et al. 2003), and some nesting occurs along the 

West African coast (Fretey 2001). 

As post-hatchlings, Northwest Atlantic loggerheads hatched on U.S. beaches migrate offshore 

and become associated with Sargassum habitats, driftlines, and other convergence zones (Carr 

1986, Witherington 2002). These Northwest Atlantic oceanic juveniles use the North Atlantic 

gyre and enter Northeast Atlantic waters (Carr 1987); they are also found in the Mediterranean 

Sea (Carreras et al. 2006, Eckert et al. 2008). In these areas, they overlap with animals 

originating from the Northeast Atlantic and the Mediterranean Sea (Laurent et al. 1993, 1998; 

Bolten et al. 1998; LaCasella et al. 2005; Carreras et al. 2006, Monzón-Argüello et al. 2006; 

Revelles et al. 2007; Eckert et al. 2008). The oceanic juvenile stage in the North Atlantic has 

been primarily studied in the waters around the Azores and Madeira (Bolten 2003). In Azorean 

waters, satellite telemetry data and flipper tag returns suggest a long period of residency (Bolten 

2003), whereas turtles appear to be moving through Madeiran waters (Dellinger and Freitas 
11

2000). Preliminary genetic analyses indicate that juvenile and subadult loggerheads found in 

Moroccan waters are of western Atlantic origin (M. Tiwari, NMFS, and A. Bolten, University of 

Florida, unpublished data). Other concentrations of oceanic juveniles exist in the Atlantic (e.g., 

in the region of the Grand Banks off Newfoundland). Genetic information indicates the Grand 

Banks off Newfoundland are foraging grounds for a mixture of loggerheads from all the North 

Atlantic rookeries (LaCasella et al. 2005, Bowen et al. 2005), and a large size range is 

represented (Watson et al. 2004, 2005). 

After departing the oceanic zone, neritic juvenile loggerheads in the Northwest Atlantic inhabit 

continental shelf waters from Cape Cod Bay, Massachusetts, south through Florida, The 

Bahamas, Cuba, and the Gulf of Mexico (neritic refers to the inshore marine environment from 

the surface to the sea floor where water depths do not exceed 200 meters). In the U.S., estuarine 

waters, including areas such as Long Island Sound, Chesapeake Bay, Pamlico and Core Sounds, 

Mosquito and Indian River Lagoons, Biscayne Bay, Florida Bay, and numerous embayments 

fringing the Gulf of Mexico, comprise important inshore habitat. Along the Atlantic and Gulf of 

Mexico shoreline, essentially all shelf waters are inhabited by loggerheads. 

Habitat preferences of Northwest Atlantic non-nesting adult loggerheads in the neritic zone differ 

from the juvenile stage in that relatively enclosed, shallow water estuarine habitats with limited 

ocean access are less frequently used. Areas such as Pamlico Sound and the Indian River 

Lagoon in the U.S., regularly used by juveniles, are only rarely frequented by adult loggerheads. 

In comparison, estuarine areas with more open ocean access, such as Chesapeake Bay in the U.S. 

mid-Atlantic, are also regularly used by juveniles, as well as by adults primarily during warmer 

seasons. Shallow water habitats with large expanses of open ocean access, such as Florida Bay, 

provide year-round resident foraging areas for significant numbers of male and female adult 

loggerheads. Offshore, adults primarily inhabit continental shelf waters, from New York south 

through Florida, The Bahamas, Cuba, and the Gulf of Mexico. Seasonal use of mid-Atlantic 

shelf waters, especially offshore New Jersey, Delaware, and Virginia during summer months, 

and offshore shelf waters, such as Onslow Bay (off the North Carolina coast), during winter 

months has been documented (Hawkes et al. 2007a; Georgia Department of Natural Resources, 

unpublished data; South Carolina Department of Natural Resources, unpublished data). Shelf 

waters along the west Florida coast, The Bahamas, Cuba, and the Yucatán Peninsula have been 

identified, using satellite telemetry, as important resident areas for adult female loggerheads that 

nest in Florida (Foley et al. 2008; M. Lamont, Florida Cooperative Fish and Wildlife Research 

Unit, personal communication, 2009; M. Nicholas, National Park Service, personal 

communication, 2009). The southern edge of the Grand Bahama Bank is important habitat for 

loggerheads nesting on the Cay Sal Bank in The Bahamas, but nesting females are also resident 

in the bights of Eleuthera, Long Island, and Ragged Islands as well as Florida Bay in the U.S., 

and the north coast of Cuba (A. Bolten and K. Bjorndal, University of Florida, unpublished data). 

Moncada et al. (2009) report the recapture in Cuban waters of five adult female loggerheads 

originally flipper tagged in Quintana Roo, Mexico, indicating that Cuban shelf waters likely also 

provide foraging habitat for adult females that nest in Mexico. 

In the Northeast Atlantic, satellite telemetry studies of post-nesting females from Cape Verde 

identified two distinct dispersal patterns; larger individuals migrated to benthic foraging areas off 

the northwest Africa coast and smaller individuals foraged primarily oceanically off the 
12

northwest Africa coast (Hawkes et al. 2006). Monzon-Arguello et al. (2009) conducted a mixed 

stock analysis of juvenile loggerheads sampled from foraging areas in the Canary Islands, 

Madeira, Azores, and Andalusia and concluded that while juveniles from the Cape Verde 

population were distributed among these four sites, a large proportion of Cape Verde juveniles 

appear to inhabit as yet unidentified foraging areas. 

In the South Atlantic, relatively little is known about the at-sea behavior of loggerheads 

originating from nesting beaches in Brazil. Recaptures of tagged juveniles and nesting females 

have shown movement of animals up and down the coast of South America (Almeida et al. 2000, 

Marcovaldi et al. 2000, Laporta and Lopez 2003, Almeida et al. 2007). Juvenile loggerheads, 

presumably of Brazilian origin, have also been captured on the high seas of the South Atlantic 

(Kotas et al. 2004, Pinedo and Polacheck 2004) and off the coast of Atlantic Africa (Bal et al. 

2007, Petersen 2005, Petersen et al. 2007) suggesting that loggerheads of the South Atlantic may 

undertake transoceanic developmental migrations (Bolten et al. 1998, Peckham et al. 2007). 

Mediterranean Sea

Loggerhead turtles are widely distributed in the Mediterranean Sea. However, nesting is almost 

entirely confined to the eastern Mediterranean basin, with the main nesting concentrations in 

Cyprus, Greece, and Turkey (Margaritoulis et al. 2003). Preliminary surveys in Libya suggested 

nesting activity comparable to Greece and Turkey, although a better quantification is needed 

(Laurent et al. 1999). Minimal to moderate nesting also occurs in other countries throughout the 

Mediterranean including Egypt, Israel, Italy (southern coasts and islands), Lebanon, Syria, and 

Tunisia (Margaritoulis et al. 2003). Recently, isolated nesting events have been recorded in the 

western Mediterranean basin, namely in Spain, Corsica (France), and in the Tyrrhenian Sea 

(Italy) (Bentivegna et al. 2005, Delaugerre and Cesarini 2004, Tomás et al. 2002).

In Cyprus, nesting occurs mainly on beaches of the western coast and Chrysochou Bay 

(Demetropoulos and Hadjichristophorou 1989), as well as along the northern coast (Broderick 

and Godley 1996). Nesting occurs along the western and southern coasts of Greece and on the 

island of Crete, with the vast majority of nesting occurring on the island of Zakynthos 

(Margaritoulis 1987, 1998, 2005; Margaritoulis et al. 1995, 2003). Seventeen important 

loggerhead nesting sites have been identified on Turkey’s beaches (Margaritoulis et al. 2003). 

Nesting activity in Libya is spread throughout the entire coast, but may be less dense in western 

areas (Laurent et al. 1999). 

Important neritic marine habitats have been suggested for the large continental shelves of: (1) 

Tunisia-Libya, (2) northern Adriatic Sea, (3) Egypt, and (4) Spain (Margaritoulis 1988, Argano 

et al. 1992, Laurent and Lescure 1994, Lazar et al. 2000, Gomez de Segura et al. 2006, 

Broderick et al. 2007, Casale et al. 2007b, Nada and Casale 2008). At least the first three 

constitute shallow benthic habitats for adults (including post-nesting females). Some other 

neritic foraging areas include Amvrakikos Bay in western Greece, Lakonikos Bay in southern 

Greece, and southern Turkey. Oceanic foraging areas for small juveniles have been identified in 

the south Adriatic Sea (Casale et al. 2005b), Ionian Sea (Deflorio et al. 2005), Sicily Strait 

(Casale et al. 2007b), and western Mediterranean (Spain) (e.g., Caminas et al. 2006). In 

addition, tagged juveniles have been recorded crossing the Mediterranean from the eastern to the 
13

western basin and vice versa, as well as in the Eastern Atlantic (Argano et al. 1992, Casale et al. 

2007b). 

Reproductive migrations have been confirmed by flipper tagging and satellite telemetry. Female 

loggerheads, after nesting in Greece, migrate primarily to the Gulf of Gabès and the northern 

Adriatic (Margaritoulis 1988, Margaritoulis et al. 2003, Lazar et al. 2004, Zbinden et al. 2008). 

Loggerheads nesting in Cyprus migrate to Egypt and Libya, exhibiting fidelity in following the 

same migration route during subsequent nesting seasons (Broderick et al. 2007). In addition, 

directed movements of juvenile loggerheads have been confirmed through flipper tagging 

(Argano et al. 1992, Casale et al. 2007b) and satellite tracking (Rees and Margaritoulis 2009). 

2.4. Biological Characteristics

Loggerheads nest on ocean beaches and occasionally on estuarine shorelines. Although specific 

characteristics vary between rookeries, loggerhead nesting beaches tend to be wide, sandy 

beaches backed by low dunes and fronted by a flat, sandy approach from the water (Miller et al. 

2003). Nests are typically laid between the high tide line and the dune front (Routa 1968, 

Witherington 1986, Hailman and Elowson 1992). 

Sea turtle eggs require a high-humidity substrate that allows for sufficient gas exchange and 

temperatures conducive to egg development (Miller 1997, Miller et al. 2003). Mean clutch size 

varies greatly between populations, but on average is approximately 100-130 eggs per clutch 

(Dodd 1988). Loggerhead nests incubate for variable periods of time. The length of the 

incubation period is inversely related to nest temperature, such that between 26o

C and 32oC, a 

change of 1o

C adds or subtracts approximately 5 days (Mrosovsky 1980). The warmer the sand 

surrounding the egg chamber, the faster the embryos develop (Mrosovsky and Yntema 1980). 

Sand temperatures prevailing during the middle third of the incubation period also determine the 

sex of hatchlings (Mrosovsky and Yntema 1980). Incubation temperatures near the upper end of 

the tolerable range produce only female hatchlings while incubation temperatures near the lower 

end of the tolerable range produce only male hatchlings. The pivotal temperature (i.e., the 

incubation temperature that produces equal numbers of males and females) in loggerheads is 

approximately 29o

C (Limpus et al. 1983, Mrosovsky 1988, Marcovaldi et al. 1997). Moisture 

conditions in the nest influence incubation period, hatching success, and hatchling size 

(McGehee 1990, Carthy et al. 2003). 

Loggerhead hatchlings pip and escape from their eggs over a 1- to 3-day interval and move 

upward and out of the nest over a 2- to 4-day interval (Christens 1990). The time from pipping 

to emergence ranges from 4 to 7 days with an average of 4.1 days (Godfrey and Mrosovsky 

1997). Hatchlings emerge from their nests en masse almost exclusively at night, and presumably 

using decreasing sand temperature as a cue (Hendrickson 1958, Mrosovsky 1968, Witherington 

et al. 1990). Moran et al. (1999) concluded that a lowering of sand temperatures below a critical 

threshold, which most typically occurs after nightfall, is the most probable trigger for hatchling 

emergence from a nest. After an initial emergence, there may be secondary emergences on 

subsequent nights (Carr and Ogren 1960, Witherington 1986, Ernest and Martin 1993, Houghton 

and Hays 2001). 
14

Hatchlings use a progression of orientation cues to guide their movement from the nest to the 

marine environments where they spend their early years (Lohmann and Lohmann 2003). 

Hatchlings first use light cues to find the ocean. On naturally lighted beaches without artificial 

lighting, ambient light from the open sky creates a relatively bright horizon compared to the dark 

silhouette of the dune and vegetation landward of the nest. This contrast guides the hatchlings to 

the ocean (Daniel and Smith 1947, Limpus 1971, Salmon et al. 1992, Witherington 1997, 

Witherington and Martin 1996, Stewart and Wyneken 2004). 

Immediately after hatchlings emerge from the nest, they begin a period of frenzied activity. 

During this active period, hatchlings move from their nest to the surf, swim, and are swept 

through the surf zone (Carr and Ogren 1960; Carr 1962, 1982; Wyneken and Salmon 1992; 

Witherington 1995). Orientation cues used by hatchlings as they crawl, swim through the surf, 

and migrate offshore are discussed in detail by Lohmann and Lohmann (2003). 

Neonate loggerheads that have migrated away from land differ from swim frenzy stage 

hatchlings in that they are largely inactive and only exhibit infrequent low-energy swimming, 

and they have begun to feed, no longer relying on their retained yolk (Witherington 2002). As 

post-hatchlings, loggerheads are pelagic and are best known from neritic waters along the 

continental shelf. This neritic post-hatchling stage is weeks or months long (Witherington 2002) 

and may be a transition to the oceanic stage that loggerheads enter as they grow and are carried 

within ocean currents (Bolten 2003). 

In the northwest Atlantic, post-hatchling loggerheads inhabit areas where surface waters 

converge to form local downwellings (Witherington 2002). These areas are characterized by 

linear accumulations of floating material, especially Sargassum, and are common between the 

Gulf Stream and the southeast U.S. coast, and between the Loop Current and the Florida coast in 

the Gulf of Mexico. Post-hatchlings within this habitat are observed to be low-energy float-andwait foragers that feed on a wide variety of floating items (Witherington 2002). Witherington 

(2002) found that small animals commonly associated with the Sargassum community, such as 

hydroids and copepods, were most commonly found in esophageal lavage samples. Posthatchling loggerheads from southeast U.S. nesting beaches may linger for months in waters just 

off the nesting beach or become transported by ocean currents within the Gulf of Mexico and 

North Atlantic. 

The oceanic juvenile stage begins when loggerheads first enter the oceanic zone (Bolten 2003). 

Juvenile loggerheads originating from nesting beaches in the Northwest Atlantic, West Indian, 

and West Pacific Oceans appear to use oceanic developmental habitats and move with the 

predominant ocean gyres for several years before returning to their neritic foraging and nesting 

habitats (Bolten 2003, Bowen et al. 1995, Hughes 1974a, Musick and Limpus 1997, Pitman 

1990, Zug et al. 1995). However, the actual duration of the oceanic juvenile stage varies with 

loggerheads leaving the oceanic zone over a wide size range (Bjorndal et al. 2000). In the 

Atlantic, Bjorndal and colleagues (Bjorndal et al. 2000, 2003a) estimated the duration of the 

oceanic juvenile stage to be between 7 and 11.5 years, with juveniles recruiting to neritic habitats 

in the western Atlantic over a size range of 46-64 cm curved carapace length (CCL) (Bolten et 

al. 1993, Turtle Expert Working Group 2009). However Snover (2002) suggests a much longer 

oceanic juvenile stage duration with a range of 9-24 years and a mean 14.8 years over similar 
15

size classes. However, in Japan and Australia, juvenile loggerheads do not disperse to neritic 

habitats until larger than around 60 cm SCL (Y. Matsuzawa and Sea Turtle Association of Japan, 

unpublished data) and 70 cm CCL or larger (Limpus et al. 1994), respectively, while in the 

Mediterranean they do so at around 25 cm CCL (Casale et al. 2008a). 

The neritic juvenile stage begins when loggerheads exit the oceanic zone and enter the neritic 

zone (Bolten 2003). After migrating to the neritic zone, juvenile loggerheads continue maturing 

until they reach adulthood. Some juveniles may periodically move between the neritic and 

oceanic zones (Witzell 2002, Bolten 2003, Morreale and Standora 2005, McClellan and Read 

2007, Mansfield 2006, Eckert et al. 2008). The neritic zone also provides important foraging 

habitat, inter-nesting habitat, and migratory habitat for adult loggerheads. Some adults may also 

periodically move between the neritic and oceanic zones (Harrison and Bjorndal 2006). See 

Schroeder et al. (2003) and Limpus and Limpus (2003a) for reviews of this life stage for the 

Atlantic and Pacific, respectively. 

The duration of the adult stage can be reasonably estimated for females from tag return data at 

nesting beaches. For the Northwest Atlantic nesting assemblages, data from Little Cumberland 

Island, Georgia, show reproductive longevity, and hence duration of adult female stage, as long 

as 25 years (Dahlen et al. 2000). This is likely an underestimate of the average reproductive life 

span given tag loss and incomplete surveys of nesting beaches at night. Comparable data for 

adult males do not exist. 

Based on stable isotope analyses and satellite telemetry, Hatase et al. (2002a) demonstrated that 

some adult female loggerheads nesting in Japan inhabit oceanic habitats rather than neritic 

habitats. Satellite tagged adult loggerheads in western Africa have also been demonstrated to use 

oceanic foraging areas (Hawkes et al. 2006). Preliminary results from stable isotope analyses 

suggest that some loggerheads nesting in Florida also may inhabit oceanic habitats (Reich et al. 

2007). In both Japan and Florida, the females inhabiting oceanic habitats were significantly 

smaller than those in neritic habitats. The extent to which adult loggerheads occupy oceanic 

habitats needs to be evaluated, and effects on survival probabilities and reproductive output 

should be assessed. 

In both the oceanic and neritic zones, loggerheads are primarily carnivorous, although they do 

consume some plant matter as well (see Bjorndal 1997 and Dodd 1988 for reviews). 

Loggerheads are able to exist on a wide variety of food items with ontogenetic and regional 

differences in diet. Loggerhead diets have been described from just a few coastal regions, and 

very little information is available about differences or similarities in diet at various life stages. 

Very little is known of the diet of oceanic juveniles. 
16

SECTION 3—DETERMINATION OF DPS 

3.1. Overview of Information Used to Determine DPS 

The BRT considered a vast array of information in assessing whether there are any loggerhead 

population segments that satisfy the Distinct Population Segment criteria of being both discrete 

and significant. 

First, the BRT discussed whether there were any loggerhead population segments that were 

discrete. As noted previously, joint NMFS/FWS policy defines a population to be a DPS if it is 

both discrete and significant relative to the taxon to which it belongs (FWS and NMFS 1996, 61 

FR 4722). Under the policy, a population may be considered discrete if it satisfies either one of 

the following conditions: (1) it is markedly separated from other populations of the same taxon 

as a consequence of physical, physiological, ecological, or behavioral factors; or (2) it is 

delimited by international governmental boundaries within which differences in control of 

exploitation, management of habitat, conservation status, or regulatory mechanisms exist that are 

significant in light of Section 4(a)(1)(D) of the ESA. 

Data relevant to the discreteness question include physical, physiological, ecological, behavioral, 

and genetic data. Upon looking at the global loggerhead population, the physical separation of 

ocean basins by continents was first considered. The result was an evaluation of the data for 

each ocean basin (Pacific Ocean, Atlantic Ocean, and Indian Ocean). This was not to preclude 

any larger or smaller DPS delineation, but to aid in data organization and assessment. The BRT 

then evaluated genetic information by ocean basin. The genetic data consisted of results from 

studies using maternally inherited mitochondrial DNA (mtDNA) and biparentally inherited 

nuclear DNA microsatellite markers. Next, tagging data (both flipper and PIT tags) and 

telemetry data were reviewed. Additional information, such as potential differences in 

morphology, was also evaluated. Finally, the BRT considered whether the available information 

on loggerhead population segments was bounded by any oceanographic features (e.g., current 

systems) or geographic features (e.g., land masses). 

In accordance with the DPS policy, the BRT also reviewed whether the population segments 

identified in the discreteness analysis were significant. If a population segment is considered 

discrete, its biological and ecological significance must then be considered. NMFS/FWS must 

consider available scientific evidence of the discrete segment’s importance to the taxon to which 

it belongs. Data relevant to the significance question include the morphological, ecological, 

behavioral, and genetic data, as described above. The BRT considered the following factors, 

listed in the DPS policy, in determining whether the discrete population segments were 

significant: 

a) persistence of the discrete segment in an ecological setting unusual or unique for the 

taxon; 

b) evidence that loss of the discrete segment would result in a significant gap in the range of 

the taxon; 

c) evidence that the discrete segment represents the only surviving natural occurrence of a 

taxon that may be more abundant elsewhere as an introduced population outside its 

historical range; and 
17

d) evidence that the discrete segment differs markedly from other populations of the species 

in its genetic characteristics. 

A discrete population segment needs to satisfy only one of these criteria to be considered 

significant. The NMFS/FWS policy also allows for consideration of other factors if they are 

appropriate to the biology or ecology of the species. As will be described in subsequent sections, 

the BRT evaluated the information and considered items (a), (b) and (d), as noted above, to be 

most applicable to loggerheads. 

3.1.1. Discreteness Determination 

The loggerhead sea turtle (Caretta caretta) is present in all tropical and temperate ocean basins, 

and has a life history that involves nesting on coastal beaches and foraging in neritic and oceanic 

habitats, as well as long-distance migrations between and within these areas. As with other 

globally distributed marine species, today’s global loggerhead population has been shaped by a 

sequence of isolation events created by tectonic and oceanographic shifts over geologic time 

scales, the result of which is population substructuring in many areas (Bowen et al. 1994, Bowen 

2003). Globally, loggerhead turtles comprise a mosaic of populations, each with unique nesting 

sites and in many cases possessing disparate demographic features (e.g., mean body size, age at 

first reproduction) (Dodd 1988). However, despite these differences, loggerheads from different 

populations often mix in common foraging grounds (Bolten and Witherington 2003), thus 

creating unique challenges when attempting to delineate distinct population segments for 

management or listing purposes. 

Examining the phylogeography of loggerheads across their global distribution through mtDNA 

sequence diversity, Bowen et al. (1994) found it to be similar to green turtles (Chelonia mydas), 

with a separation of loggerheads in the Atlantic-Mediterranean basins from those in the IndoPacific basins since the Pleistocene period. The divergence between these two primary lineages 

corresponds to approximately three million years, based on a molecular clock for control region 

sequences assessed originally for green turtles (2% per million years; Dutton et al. 1996, 

Encalada et al. 1996). Geography and climate appear to have shaped the evolution of these two 

matriarchal lineages with the onset of glacial cycles, the appearance of the Panama Ithsmus 

creating a land barrier between the Atlantic and eastern Pacific, and upwelling of cold water off 

southern Africa creating an oceanographic barrier between the Atlantic and Indian Ocean 

(Bowen 2003). Recent warm temperatures during interglacial periods allowed bi-directional 

invasion by the temperate-adapted loggerheads into the respective basins (Bowen et al. 1994; 

J.S. Reece, Washington University, personal communication, 2008). Today, it appears that 

loggerheads within a basin are effectively isolated from populations in the other basin, but some 

dispersal from the Tongaland rookery in the Indian Ocean into feeding and developmental 

habitat in the South Atlantic is possible via the Agulhas current (G.R. Hughes, unpublished data, 

cited in Bowen et al. 1994). In the Pacific, extensive mtDNA studies show that the northern 

loggerhead populations are isolated from the southern Pacific populations, and that juveniles 

from these distinct genetic populations do not disperse across the equator (Hatase et al. 2002a; 

Dutton 2007, unpublished data). 
18

Mitochondrial DNA data indicate that regional turtle rookeries within an ocean basin have been 

strongly isolated from one another over ecological timescales (Bowen et al. 1994, Bowen and 

Karl 2007). These same data indicate strong female natal homing and suggest that each regional 

nesting population is an independent demographic unit (Bowen and Karl 2007). It is difficult to 

determine the precise boundaries of these demographically independent populations in regions, 

such as the eastern U.S. coast, where rookeries are close to each other and range along large 

areas of a continental coastline. There appears to be varying levels of connectivity between 

proximate rookeries facilitated by imprecise natal homing and male mediated gene flow (Pearce 

2001, Bowen 2003, Bowen et al. 2005). Regional genetic populations often are characterized by 

allelic frequency differences rather than fixed genetic differences. There is concern that current 

analytical tools are unable to identify discrete or demographically independent populations based 

on genetic data when the allelic frequency differences are slight, and there is a need for new 

approaches to identifying the appropriate units to conserve (Taylor and Dizon 1999). For 

example, incorporating a metapopulation approach to regional population structure analysis may 

be informative for future work addressing connectivity and discreteness of marine turtle 

populations (Crooks and Sanjayan 2006, Kritzer and Sale 2006, Dutton et al. 2007). 

Through the evaluation of genetic data, tagging data, telemetry, and demography, the BRT 

determined that there are at least nine discrete population segments for loggerhead sea turtles 

globally. These discrete population segments are markedly separated from each other as a 

consequence of ecological, behavioral, and oceanographic factors, and given the genetic 

evidence, the BRT has unanimously concluded that each regional population identified is 

discrete from other populations of loggerheads. Information considered by the BRT in its 

delineation of discrete population segments is presented below by ocean basin. 

Pacific Ocean 

Perhaps the most distinct and easily recognized of all loggerhead populations is that from the 

North Pacific Ocean. The primary nesting areas for this population are found along the southern 

Japanese coastline and Ryukyu Archipelago (Kamezaki et al. 2003). Loggerhead turtles 

hatching on Japanese beaches undertake extensive developmental migrations utilizing the 

Kuroshio and North Pacific Currents (Balazs 2006, Kobayashi et al. 2008), and some turtles 

reach the vicinity of Baja California in the eastern Pacific (Uchida and Teruya 1988, Bowen et 

al. 1995, Peckham et al. 2007). After spending years foraging in the central and eastern Pacific, 

loggerheads return to their natal beaches for reproduction (Resendiz et al. 1998, Nichols et al. 

2000) and remain in the western Pacific for the remainder of their life cycle (Iwamoto et al. 

1985, Kamezaki et al. 1997, Sakamoto et al. 1997, Hatase et al. 2002c). 

Despite the long-distance developmental movements of loggerheads in the North Pacific, current 

scientific evidence, based on genetic analysis, flipper tag recoveries, and satellite telemetry, 

indicates that individuals originating from Japan remain in the North Pacific for their entire life 

cycle, never crossing the equator or mixing with individuals from the South Pacific (Hatase et al. 

2002a; Dutton 2007, unpublished data; LeRoux and Dutton 2006). Indeed, this apparent 

complete separation of two adjacent populations is unique and most likely results from: (1) the 

presence of two distinct Northern and Southern Gyre (current flow) systems in the Pacific 

(Briggs 1974), (2) near-passive movements of post-hatchlings in these gyres that initially move 

them farther away from areas of potential mixing among the two populations along the equator, 
19

and (3) the nest-site fidelity of adult turtles that prevents turtles from returning to non-natal 

nesting areas. 

Pacific loggerheads are further partitioned evolutionarily from other loggerheads throughout the 

world based on additional analyses of mtDNA. The haplotypes from both North and South 

Pacific loggerheads are distinguished by a minimum genetic distance (d) equal to 0.017 from 

other conspecifics, which indicates isolation of approximately one million years (Bowen 2003). 

Within the Pacific, Bowen et al. (1995) used mtDNA to identify two genetically distinct nesting 

populations in the Pacific – a northern hemisphere population nesting in Japan and a southern 

hemisphere population nesting primarily in Australia. This study also suggested that some 

loggerheads sampled as bycatch in the North Pacific might be from the Australian nesting 

population (Bowen et al. 1995). However, more extensive mtDNA rookery data from Japan 

(Hatase et al. 2002a) taken together with preliminary results from microsatellite (nuclear) 

analysis confirms that loggerheads inhabiting the North Pacific actually originate from nesting 

beaches in Japan (P. Dutton, NMFS, unpublished data). LeRoux et al. (2008) report additional 

genetic variation in North Pacific loggerheads based on analyses using new mtDNA primers 

designed to target longer mtDNA sequences, and suggest finer scale population structure in 

North Pacific loggerheads may be present. 

Although these studies indicate genetic distinctness between loggerheads nesting in Japan versus 

those nesting in Australia, Bowen et al. (1995) did identify individuals with the common 

Australian haplotype at foraging areas in the North Pacific, based on a few individuals sampled 

as bycatch in the North Pacific. More recently, Hatase et al. (2002a) detected this common 

haplotype at very low frequency at Japanese nesting beaches. However, the presence of the 

common Australian haplotype does not preclude the genetic distinctiveness of Japanese and 

Australian nesting populations, and is likely the result of rare gene flow events occurring over 

geologic time scales. 

The distinct status of loggerheads in the North Pacific is further supported by the results from 

flipper tagging in the North Pacific. Flipper tagging of loggerheads has been widespread 

throughout this region, occurring on adults nesting in Japan and incidentally bycaught in the 

coastal pound net fishery (Y. Matsuzawa, Sea Turtle Association of Japan, personal 

communication, 2006), juveniles reared and released in Japan (Uchida and Teruya 1988, Hatase 

et al. 2002a), juveniles foraging near Baja California, Mexico (Nichols 2003, Seminoff et al. 

2004), and loggerheads captured in and tagged from commercial fisheries platforms in the North 

Pacific high seas (NMFS, unpublished data). To date, there have been at least three transPacific 

tag recoveries showing east-west and west-east movements (Uchida and Teruya 1988; Resendiz 

et al. 1998; W.J. Nichols, Ocean Conservancy, and H. Peckham, Pro Peninsula, unpublished 

data) and several recoveries of adults in the western Pacific (Iwamoto et al.1985, Kamezaki et al. 

1997). However, despite the more than 30,000 marked individuals, not a single tag recovery has 

been reported outside the North Pacific. 

A lack of movements by loggerheads south across the equator has also been supported by 

extensive satellite telemetry. As with flipper tagging, satellite telemetry has been a tool used 

widely in the North Pacific, with satellite transmitters being placed on adult turtles departing 
20

nesting beaches (Sakamoto et al. 1997; Japan Fisheries Resource Conservation Association 

1999; Hatase et al. 2002b, 2002c), on adults and sub-adults bycaught in pound nets off the coast 

of Japan (Sea Turtle Association of Japan, unpublished data), on headstarted juveniles released 

in Japan (Balazs 2006), on juvenile, subadult and adult turtles bycaught in the eastern and central 

North Pacific (e.g., Kobayashi et al. 2008), and on juvenile and subadult turtles foraging in the 

eastern Pacific (Nichols 2003; Peckham et al. 2007; J. Seminoff, NMFS, unpublished data). Of 

the nearly 200 transmitters deployed on loggerheads in the North Pacific, none have moved 

south of the equator. These studies have demonstrated the strong association loggerheads show 

with oceanographic mesoscale features such as the Transition Zone Chlorophyll Front or the 

Kuroshio Current Bifurcation Region (Polovina et al. 2000, 2001, 2004, 2006; Etnoyer et al. 

2006; Kobayashi et al. 2008). Kobayashi et al. (2008) demonstrated that loggerheads strongly 

track these zones even as they shift in location, thus suggesting that strong habitat specificity 

during the oceanic stage also contributes to the lack of mixing. Telemetry studies in foraging 

areas of the eastern Pacific, near Baja California, Mexico (Nichols 2003; Peckham et al. 2007; 

H. Peckham, Pro Peninsula, unpublished data) and Peru (J. Mangel, Pro Delphinus, unpublished 

data) similarly show a complete lack of long distance north or south movements. 

The North Pacific population of loggerheads appears to occupy an ecological setting distinct 

from other loggerheads, including those of the South Pacific population. In general, this is the 

only population of loggerheads to be found north of the equator in the Pacific Ocean, foraging in 

the eastern Pacific as far south as Baja California Sur, Mexico (Seminoff et al. 2004, Peckham et 

al. 2007) and in the western Pacific as far south as the Philippines (Limpus 2009) and the mouth 

of Mekong River, Vietnam (Sadoyama et al. 1996). Pelagic juveniles have been found to spend 

much of their time foraging in the central and eastern North Pacific Ocean. The Kuroshio 

Extension Current, lying west of the international date line, serves as the dominant physical and 

biological habitat in the North Pacific and contains high productivity, likely due to unique 

features such as eddies and meanders that concentrate prey and allow food webs to develop. 

Juvenile loggerheads originating from nesting beaches in Japan were found to exhibit high site 

fidelity to an area referred to as the Kuroshio Extension Bifurcation Region, an area with 

extensive meanders and mesoscale eddies (Polovina et al. 2006). Juveniles also were found to 

correlate strongly with areas of surface chlorophyll a levels in an area known as the Transition 

Zone Chlorophyll Front, an area concentrating surface prey for loggerheads (Polovina et al. 

2001, Parker et al. 2005, Kobayashi et al. 2008). Another area found ecologically unique to the 

North Pacific population of loggerheads, likely because of the high density of pelagic red crabs 

(Pleuronocodes planipes), is located off the Pacific coast of the Baja California Peninsula, 

Mexico, where researchers have documented a foraging area for juveniles based on aerial 

surveys and satellite telemetry (Seminoff et al. 2006, Peckham et al. 2007). Tag returns show 

post-nesting females migrating into the East China Sea off South Korea, China, and the 

Philippines, and the nearby coastal waters of Japan (Iwamoto et al. 1985; Kamezaki et al. 1997, 

2003). Clearly, the North Pacific population of loggerheads is uniquely adapted to the ecological 

setting of the North Pacific Ocean and throughout its long life history serves as an important part 

of the ecosystem it inhabits. 

Loggerheads inhabiting the North Pacific Ocean are derived from Japanese beaches, with the 

possible exception of rare waifs over evolutionary time scales. Furthermore, nesting colonies of 

Japanese loggerheads are found to be genetically distinct based on mtDNA analyses, and when 
21

compared to much larger and more genetically diverse loggerhead populations in the Atlantic 

and Mediterranean, Pacific loggerheads have likely experienced critical bottlenecks (in Hatase et 

al. 2002a), underscoring the importance of management and protection in retaining this genetic 

population. 

In the South Pacific Ocean, loggerhead turtles nest primarily in Queensland, Australia, and, to a 

lesser extent, New Caledonia and Vanuatu (Limpus and Limpus 2003b, Limpus et al. 2006, 

Limpus 2009). Loggerheads from these rookeries undertake an oceanic developmental 

migration, traveling to habitats in the central and southeastern Pacific Ocean where they may 

reside for several years prior to returning to the western Pacific for reproduction. Loggerheads in 

this early life history stage differ markedly from those originating from western Australia 

beaches in that they undertake long west-to-east migrations, likely using specific areas of the 

pelagic environment of the South Pacific Ocean. An unknown portion of these loggerheads 

forage off Chile and Peru, and preliminary genetic information from foraging areas in the 

southeastern Pacific confirms that the haplotype frequencies among immature turtles in these 

areas closely match those found at nesting beaches in eastern Australia (Alfaro-Shigueto et al. 

2004; Donoso and Dutton 2006, 2007; Boyle et al. 2009). Large immature and adult 

loggerheads generally remain in the western South Pacific, inhabiting neritic and oceanic 

foraging sites during non-nesting periods (Limpus et al. 1994, Limpus 2009). 

Loggerheads from Australia and New Caledonia apparently do not travel north of the equator. 

Flipper tag recoveries from nesting females have been found throughout the western Pacific, 

including sites north of Australia, the Torres Straight, and the Gulf of Carpentaria (Limpus 

2009). Of approximately 1,000 (adult and immature; male and female) loggerheads that have 

been tagged in eastern Australian feeding areas, only two have been recorded migrating to breed 

outside of Australia; both traveled to New Caledonia (Limpus 2009). Flipper tagging programs 

in Peru and Chile tagged approximately 500 loggerheads from 1999-2006, none of which have 

been reported from outside of the southeastern Pacific (Alfaro-Shigueto et al. 2008a; S. Kelez, 

Duke University Marine Laboratory, unpublished data; M. Donoso, ONG Pacifico Laud - Chile, 

unpublished data). Limited satellite telemetry data (12 tags) in the area show a similar trend (J. 

Mangel, Pro Delphinus, unpublished data). 

The spatial separation between the North Pacific and South Pacific loggerhead populations has 

contributed to substantial differences in the genetic profiles of the nesting populations in these 

two regions. Whereas the dominant mtDNA haplotypes among loggerheads nesting in Japan are 

CCP2 and CCP3 (equivalent to B and C respectively in Bowen et al. 1995 and Hatase et al. 

2002a; Leroux et al. 2008; P. Dutton, NMFS, unpublished data), loggerheads nesting in eastern 

Australia have a third haplotype (CCP1, previously A) which is dominant (98% of nesting 

females) (Bowen et al. 1994, FitzSimmons et al. 1996, Boyle et al. 2009). Further, preliminary 

genetic analysis using microsatellite markers (nuclear DNA) indicates genetic distinctiveness 

between nesting populations in the North versus South Pacific (P. Dutton, NMFS, personal 

communication, 2008). 

The separateness between nesting populations in eastern and western Australia is less clear, 

although these too are considered to be genetically distinct from one another (Limpus 2009). For 

example, mtDNA haplotype CCP1, which is the overwhelmingly dominant haplotype among 
22

eastern Australia nesting females (98%), is also found in western Australia, although at much 

lower frequency (33%) (FitzSimmons et al. 1996, 2003). The remaining haplotype for both 

regions was the CCP5 haplotype. Further, FitzSimmons (University of Canberra, unpublished 

data) found significant differences in nuclear DNA microsatellite loci from females nesting in 

these two regions. Estimates of gene flow between eastern and western Australian populations 

was an order of magnitude less than gene flow within regions. Although some level of malemediated gene flow may occur within ecological time frames, presumably during mixing at 

foraging areas near the Torres Straight and in the Gulf of Carpentaria, the result may also 

indicate homoplasy within the genetic markers in the two regions leading to a false impression of 

similarity. Male-mediated gene flow between eastern and western Australia, therefore, may be 

insignificant, which, when considered in light of the substantial disparity in mtDNA haplotype 

frequencies between these two regions, provides further evidence of population separation 

between these two regions. 

At present, there is no indication from genetic studies that the loggerhead turtles nesting in 

eastern Australia are distinct from those nesting in New Caledonia. Of 27 turtles sequenced from 

New Caledonia, 93% carried the CCP1 haplotype and the remaining had the CCP5 haplotype; 

similar to eastern Australia (Boyle et al. 2009). There remains a need to analyze these 

populations using nuclear DNA microsatellites. 

The South Pacific population of loggerheads occupies an ecological setting distinct from other 

loggerheads, including the North Pacific population. Much less is known regarding the 

ecosystem upon which oceanic juveniles and oceanic adults depend. Sea surface temperature 

and chlorophyll frontal zones in the South Pacific have been shown to dramatically impact the 

movements of green turtles, Chelonia mydas (Seminoff et al. 2008) and leatherback turtles, 

Dermochelys coriacea (Shillinger et al. 2008), and it is likely that loggerheads similarly benefit 

from interactions with these mesoscale oceanographic features. 

Loggerheads in the South Pacific are substantially impacted by periodic environmental 

perturbations such as the El Niño Southern Oscillation (ENSO). This 3- to 6-year cycle within 

the coupled ocean-atmosphere system of the tropical Pacific brings increased surface water 

temperatures and lower primary productivity, both of which have profound biological 

consequences (Chavez et al. 1999). Loggerheads are presumably adversely impacted by the 

lower food availability that often results from ENSO events, although data on this subject are 

lacking. Although ENSO may last for only short periods and thus not have a long-term effect on 

loggerheads in the region, recent studies by Chaloupka et al. (2008) suggest that long-term 

increases in sea surface temperature within the South Pacific may influence the ability of the 

Australian nesting population to recover from historic population declines. 

Loggerheads originating from nesting beaches in the western South Pacific are the only 

population of loggerheads to be found south of the equator in the Pacific Ocean. As posthatchlings, they are generally swept south by the East Australian Current (Limpus et al. 1994), 

spend a large portion of time foraging in the oceanic South Pacific Ocean, and a fraction migrate 

to the southeastern Pacific Ocean off the coasts of Peru and Chile as juveniles (Alfaro-Shigueto 

et al. 2004, Donoso et al. 2000, Boyle et al. 2009). As large immatures and adults, these 

loggerheads’ foraging range encompasses the eastern Arafura Sea, Gulf of Carpentaria, Torres 
23

Strait, Gulf of Papua, Coral Sea, and western Tasman Sea to southern New South Wales 

including the Great Barrier Reef, Hervey Bay, and Moreton Bay. The outer extent of this range 

includes the coastal waters off eastern Indonesia northeastern Papua New Guinea, northeastern 

Solomon Islands, and New Caledonia (in Limpus 2009). 

All loggerheads inhabiting the South Pacific Ocean are derived from beaches in eastern Australia 

and a lesser known number of beaches in southern New Caledonia, Vanuatu, and Tokelau 

(Limpus and Limpus 2003b, Limpus 2009). Furthermore, nesting colonies of the South Pacific 

population of loggerheads are found to be genetically distinct from loggerheads in the North 

Pacific and Indian Ocean. 

Given the information presented above, the BRT has unanimously concluded that two discrete 

population segments exist in the Pacific Ocean as a consequence of ecological, behavioral, and 

oceanographic factors, and based on genetic evidence: (1) North Pacific Ocean and (2) South 

Pacific Ocean. 

Indian Ocean 

Loggerhead sea turtles in the Indian Ocean have a life history that involves nesting on coastal 

beaches, foraging in neritic and oceanic habitats, and long-distance migrations between and 

within these areas. The distribution of loggerheads in the Indian Ocean is limited by the Asian 

landmass to waters south of 30o

N latitude. In comparison to potential loggerhead distributions in 

southern waters of the Atlantic and Pacific, Indian Ocean distributions east and west are not 

restricted by landmasses south of approximately 38oS latitude. 

Historical accounts of loggerhead turtles in the Indian Ocean were given by Smith (1849), who 

described the species in South Africa, and Deraniyagala (1933, 1939) who described Indian 

Ocean loggerheads within the subspecies C. c. gigas. Hughes (1974a) argued that there was little 

justification for this separation. This work by Deraniyagala provided evidence for the significant 

historical distribution of loggerheads around Sri Lanka. 

Loggerhead nesting in the Southwest Indian Ocean includes the southeastern coast of Africa 

from the Paradise Islands in Mozambique southward to St. Lucia in South Africa, and on the 

south and southwestern coasts of Madagascar (Baldwin et al. 2003). Foraging habitats are only 

known for the Tongaland, South Africa adult female loggerheads. Returns of flipper tags 

describe a range that extends eastward to Madagascar, northward to Mozambique, Tanzania, and 

Kenya, and southward to Cape Agulhas at the southernmost point of Africa (Baldwin et al. 

2003). Four post-nesting loggerheads satellite tracked by Luschi et al. (2006) migrated 

northward, hugging the Mozambique coast and remained in shallow shelf waters off 

Mozambique for more than 2 months. Only one post-nesting female from the Southwest Indian 

Ocean population (South Africa) has been documented migrating north of the equator (to 

southern Somalia) (Hughes and Bartholomew 1996). 

 

In the North Indian Ocean, Oman hosts the vast majority of loggerhead nests. The largest 

nesting assemblage is at Masirah Island, Oman, in the northern tropics at 21o

N (Baldwin et al. 

2003). Other key assemblages occur on the Al Halaniyat Islands, and on mainland beaches south 

of Masirah Island to the Oman-Yemen border (IUCN - The World Conservation Union 1989a, 
24

1989b; Salm 1991; Salm and Salm 1991). In addition, nesting probably occurs on the mainland 

of Yemen on the Arabian Sea coast, and nesting has been confirmed on Socotra, an island off the 

coast of Yemen (Pilcher and Saad 2000). Baldwin et al. (2003) list other major nesting 

assemblages (> approximately 400 nesting females/year) at Oman’s Arabian Sea Coast (17-20o

S) 

and Al Halaniyat Islands, Oman (17o

S). 

Outside of Oman, loggerhead nesting is rare in the North Indian Ocean. The only verified 

nesting beaches for loggerheads on the Indian subcontinent are found in Sri Lanka (Deraniyagala 

1939, Kar and Bhaskar 1982, Dodd 1988, Kapurusinghe 2006). Reports of regular loggerhead 

nesting on the Indian mainland are likely to be from misidentifications of olive ridleys 

(Lepidochelys olivacea) (Tripathy 2005, Kapurusinghe 2006). Although loggerheads have been 

reported nesting in low numbers in Myanmar, these data may not be reliable because of 

misidentification of species (Thorbjarnarson et al. 2000). 

Limited information exists on foraging locations of North Indian Ocean loggerheads. Foraging 

individuals have been reported off the southern coastline of Oman (Salm et al. 1993) and in the 

Gulf of Mannar, between Sri Lanka and India (Tripathy 2005, Kapurusinghe 2006). Satellite 

telemetry studies conducted in Oman have revealed new information on post-nesting migrations 

of loggerheads nesting on Masirah Island (Environment Society of Oman and Ministry of 

Environment and Climate Change, Oman, unpublished data). Results reveal extensive use of the 

waters off the Arabian Peninsula, with the majority of telemetered turtles (15 of 20) traveling 

southwest, following the shoreline of southern Oman and Yemen, and circling well offshore in 

nearby oceanic waters. A minority traveled north as far as the western Persian (Arabian) Gulf (3 

of 20) or followed the shoreline of southern Oman and Yemen as far west as the Gulf of Aden 

and the Bab-el-Mandab (2 of 20). These preliminary data suggest that post-nesting migrations 

and adult female foraging areas may be centered within the region (Environment Society of 

Oman and Ministry of Environment and Climate Change, Oman, unpublished data). 

No tag returns or satellite tracks indicated that loggerheads nesting in Oman traveled south of the 

equator. 

In the East Indian Ocean, western Australia hosts all known loggerhead nesting (Dodd 1988). 

Nesting distributions in western Australia span from the Shark Bay World Heritage Area 

northward through the Ningaloo Marine Park coast to the North West Cape and to the nearby 

Muiron Islands (Baldwin et al. 2003). Nesting individuals from Dirk Hartog Island have been 

recorded foraging within Shark Bay and Exmouth Gulf, while other adults range into the Gulf of 

Carpentaria (Baldwin et al. 2003). At the eastern extent of this apparent range, there is possible 

overlap with loggerheads that nest on Australia’s Pacific coast (Limpus 2009). However, despite 

extensive tagging at principal nesting beaches on Australia’s Indian Ocean and Pacific coasts, no 

exchange of females between nesting beaches has been observed (Limpus 2009). 

The available genetic information relates to connectivity and broad evolutionary relationships 

between ocean basins. There is a lack of genetic information on population structure among 

rookeries within the Indian Ocean. Bowen et al. (1994) described mtDNA sequence diversity 

among eight loggerhead nesting assemblages and found one of two principal branches in the 

Indo-Pacific basins. Using additional published and unpublished data, Bowen (2003) estimated 

divergence between these two lineages to be approximately three million years. Bowen points 
25

out evidence for more recent colonizations (12,000-250,000 years ago) between the Indian 

Ocean and the Atlantic-Mediterranean. For example, the sole mtDNA haplotype (among eight 

samples) observed by Bowen et al. (1994) at Masirah Island, Oman, is known from the Atlantic 

and suggests some exchange between oceans some 250,000 years ago. The other principal 

Indian Ocean haplotype reported by Bowen et al. (1994) was seen in all loggerheads sampled 

(n=15) from Natal, South Africa. Encalada et al. (1998) reported that this haplotype was 

common throughout the North Atlantic and Mediterranean, thus suggesting a similar exchange 

between Atlantic and Indian oceans as recently as 12,000 years ago (Bowen et al. 1994). Bowen 

(2003) speculated that Indian-Atlantic Ocean exchanges took place via the temperate waters 

south of South Africa and became rare as the ocean shifted to cold temperate conditions in this 

region. 

In estimates of loggerhead gene flow in and out of the Indian Ocean, J.S. Reece (Washington 

University, personal communication, 2008) factored 100 samples from Masirah Island, 249 from 

Atlantic rookeries (from Encalada et al. 1998), and 311 from Pacific rookeries (from Hatase et 

al. 2002a and Bowen et al. 1995). Reece used lineage coalescence methods to estimate that gene 

flow, expressed as number of effective migrants, or exchanges of breeding females between 

Indian Ocean rookeries and those from the Atlantic or Pacific occurred at the rate of less than 0.1 

migrant per generation. Reece estimated gene flow based on coalescence of combined mtDNA 

and nuclear DNA data to be approximately 0.5 migrants per generation. These unpublished 

results, while somewhat theoretical, may indicate that there is restricted gene flow into and out of 

the Indian Ocean. The low level of gene flow most likely reflects the historical connectivity over 

geological timescales, rather than any contemporary migration, and is consistent with Bowen’s 

hypothesis that exchange occurred most recently over 12,000-3,000,000 years ago, and has been 

restricted over recent ecological timescales. 

The discrete status of three loggerhead groups in the Indian Ocean is primarily supported by 

observations of tag returns and satellite telemetry. The limited genetic information currently 

available based on mtDNA sequences does not allow for a comprehensive analysis of genetic 

population structure analysis for Indian Ocean rookeries, although Bowen et al. 1994 indicate the 

Oman and South African rookeries are genetically distinct, and once sequencing studies are 

completed for these rookeries, it is likely that they will also be distinct from the rookeries in 

western Australia. Based on multiple lines of evidence, discrete status is supported for the North 

Indian Ocean, Southwest Indian Ocean, and Southeast Indo-Pacific Ocean. Although there is not 

a sufficiently clear picture of gene flow between these regions, we propose that significant 

vicariant barriers exist between these three Indian Ocean groups that would prevent migration of 

individuals on a time scale relative to management and conservation efforts. These vicariant 

barriers are the oceanographic phenomena associated with Indian Ocean equatorial waters, and 

the large expanse between continents in the South Indian Ocean without suitable benthic 

foraging habitat. 

Given the information presented above, the BRT has unanimously concluded that three discrete 

population segments exist in the Indian Ocean as a consequence of ecological, behavioral, and 

oceanographic factors, and given the genetic evidence: (1) North Indian Ocean, (2) Southwest 

Indian Ocean, and (3) Southeast Indo-Pacific Ocean. 
26

Atlantic Ocean and Mediterranean Sea 

Within the Atlantic Ocean, loss and re-colonization of nesting beaches over evolutionary time 

scales has been determined by climate, natal homing, and rare dispersal events (Encalada et al. 

1998, Bowen and Karl 2007). At times, temperate beaches were too cool to incubate eggs and 

nesting could have continued only on tropical beaches. Thus, the contemporary distribution of 

nesting is the product of colonization events from the tropical refugia during the last 12,000 

years. Apparently, turtles from the Northwest Atlantic colonized the Mediterranean and at least 

two matrilines were involved (Schroth et al. 1996); these rookeries became isolated from the 

Atlantic populations in the last 10,000 years (Encalada et al. 1998). A similar colonization event 

appears to have populated the Northeast Atlantic (C. Monzón-Argüello, Instituto Canario de 

Ciencias Marinas - Spain, personal communication, 2008). 

Nesting in the western South Atlantic occurs primarily along the mainland coast of Brazil from 

Sergipe south to Rio de Janeiro, with peak concentrations in northern Bahia, Espírito Santo, and 

northern Rio de Janeiro (Marcovaldi and Chaloupka 2007). In the eastern South Atlantic, diffuse 

nesting may occur along the mainland coast of Africa (Fretey 2001), with more than 200 

loggerhead nests reported for Rio Longa beach in central Angola in 2005 (Brian 2007). 

However, other researchers have been unable to confirm nesting by loggerheads in the last 

decade anywhere along the south Atlantic coast of Africa, including Angola (Fretey 2001, Weir 

et al. 2007). There is the possibility that reports of nesting loggerheads from Angola and 

Namibia (Márquez M. 1990, Brian 2007) may have arisen from misidentified olive ridley turtles 

(Brongersma 1982, Fretey 2001). At the current time, it is not possible to confirm that regular, if 

any, nesting of loggerheads occurs along the Atlantic coast of Africa, south of the equator. 

Genetic surveys of loggerheads have revealed that the Brazilian rookeries have a unique mtDNA 

haplotype (Encalada et al. 1998, Pearce 2001). The Brazilian mtDNA haplotype, relative to 

North Atlantic haplotypes, indicates isolation of South Atlantic loggerheads from North Atlantic 

loggerheads on a scale of 0.25-0.5 million years ago, and microsatellite DNA results show 

divergence on the same time scale (Bowen 2003). Brazil’s unique haplotype has been found 

only in low numbers in foraging populations of juvenile loggerheads of the North Atlantic (Bass 

et al. 2004). Other lines of evidence support a deep division between loggerheads from the 

South Atlantic and from the North Atlantic, including: (1) a nesting season in Brazil that peaks 

in the austral summer around December/January (Marcovaldi and Laurent 1996), as opposed to 

the May-August nesting season in the southeast U.S. in the northern hemisphere (Witherington et 

al. 2009); and (2) no observations of tagged loggerheads moving across the equator in the 

Atlantic, except a single case of a captive-reared animal that was released as a juvenile from 

Espírito Santo and was recaptured 3 years later in the Azores (Bolten et al. 1990). Post-nesting 

females from Espírito Santo moved either north or south along the coast, but remained between 

10°S and 30°S (Projeto TAMAR, unpublished data). 

Relatively little is known about the at-sea behavior of loggerheads originating from nesting 

beaches in Brazil. Recaptures of tagged juveniles and nesting females have shown movement of 

animals up and down the coast of South America (Almeida et al. 2000, Marcovaldi et al. 2000, 

Laporta and Lopez 2003, Almeida et al. 2007). Juvenile loggerheads, presumably of Brazilian 

origin, have also been captured on the high seas of the South Atlantic (Kotas et al. 2004, Pinedo 

and Polacheck 2004) and off the coast of Atlantic Africa (Petersen 2005, Petersen et al. 2007, 
27

Weir et al. 2007) suggesting that, like their North Pacific and Northwest Atlantic counterparts, 

loggerheads of the South Atlantic may undertake transoceanic developmental migrations (Bolten 

et al. 1998, Peckham et al. 2007). There is also the possibility that some loggerhead individuals 

from the Southwest Indian Ocean population segment are swept around the Cape of Good Hope 

by the Benguela Current (Baldwin et al. 2003), into the Southwest Atlantic Ocean, where they 

overlap with loggerheads from the South Atlantic Ocean population segment. 

The mean size of reproductive female loggerheads in Brazil is 92.9 cm SCL, which is 

comparable to the size of nesters in the Northwest Atlantic, but larger than nesters of the 

Northeast Atlantic and Mediterranean (Tiwari and Bjorndal 2000, Margaritoulis et al. 2003, 

Varo Cruz et al. 2007). Egg size and mass of Brazilian loggerheads are smaller than those from 

the Northwest Atlantic, but larger than those of the Mediterranean (Tiwari and Bjorndal 2000). 

Within the Northwest Atlantic, the majority of nesting activity occurs from April through 

September, with a peak in June and July (Williams-Walls et al. 1983, Dodd 1988, Weishampel et 

al. 2006). Nesting occurs within the Northwest Atlantic along the coasts of North America, 

Central America, northern South America, the Antilles, and The Bahamas, but is concentrated in 

the southeastern U.S. and on the Yucatán Peninsula in Mexico (Sternberg 1981, Ehrhart 1989, 

Ehrhart et al. 2003, NMFS and FWS 2008). Many nesting beaches within the Northwest 

Atlantic have yet to be sampled for genetic analysis. Five recovery units (subpopulations) have 

been identified based on genetic differences and a combination of geographic distribution of 

nesting densities and geographic separation. These recovery units are: Northern Recovery Unit 

(Florida/Georgia border through southern Virginia), Peninsular Florida Recovery Unit 

(Florida/Georgia border through Pinellas County, Florida), Northern Gulf of Mexico Recovery 

Unit (Franklin County, Florida, through Texas), Greater Caribbean Recovery Unit (Mexico 

through French Guiana, The Bahamas, Lesser Antilles, and Greater Antilles), and Dry Tortugas 

Recovery Unit (islands located west of Key West, Florida) (NMFS and FWS 2008). There is 

limited exchange of nesting females among these recovery units (Encalada et al. 1998, Foote et 

al. 2000, J. Richardson personal communication cited in NMFS 2001, Hawkes et al. 2005). 

Based on the number of haplotypes, the highest level of loggerhead mtDNA genetic diversity in 

the Atlantic has been observed in females of the Greater Caribbean Recovery Unit that nest at 

Quintana Roo, Mexico (Encalada et al. 1999, Nielsen et al. in press). However, genetic diversity 

should be evaluated further using haplotype and nucleotide diversity calculated similarly for each 

recovery unit. Genetic data are not available for all the nesting assemblages in the region, 

including a key nesting assemblage in Cuba. New genetic markers have recently been 

developed, including primers that produce additional mtDNA sequence data (Abreu-Grobois et 

al. 2006, LeRoux et al. 2008), and an array of microsatellite markers (Shamblin et al. 2008) that 

will enable finer resolution of population boundaries. 

Loggerheads in the Northwest Atlantic display complex population structure based on life 

history stages. Based on mtDNA, oceanic juveniles show no structure, neritic juveniles show 

moderate structure, and nesting colonies show strong structure (Bowen et al. 2005); however, a 

recent study suggests some structure may exist among oceanic juveniles, at least in the Northeast 

Atlantic oceanic foraging grounds (Monzón-Argüello et al. 2009), and is related to the latitudinal 

distributions of the Northwest Atlantic rookeries. In contrast, a survey using microsatellite 

(nuclear) markers showed no significant population structure among nesting populations (Bowen 
28

et al. 2005), indicating that while females exhibit strong philopatry, males may provide an 

avenue of gene flow between nesting colonies in this region. However, the power to detect 

structure with the nuclear markers used in this study may have been limited due to the few 

markers used and small sample sizes. Additional work with larger sample sizes and better 

nuclear markers is underway (B. Shamblin, University of Georgia, personal communication, 

2008). Nevertheless, Bowen et al. (2005) argued that male-mediated gene flow within the 

Northwest Atlantic does not detract from the classification of breeding areas as independent 

populations (e.g., recovery units) because the production of progeny depends on female nesting 

success. All Northwest Atlantic recovery units are reproductively isolated from populations 

within the Northeast Atlantic, South Atlantic, and Mediterranean Sea. 

As oceanic juveniles, loggerheads from the Northwest Atlantic use the North Atlantic gyre and 

often are associated with Sargassum communities (Carr 1987); they also are found in the 

Mediterranean Sea. In these areas, they overlap with animals originating from the Northeast 

Atlantic and the Mediterranean Sea (Laurent et al. 1993, 1998; Bolten et al. 1998; Bowen et al. 

2005; LaCasella et al. 2005; Carreras et al. 2006, Monzón-Argüello et al. 2006; Revelles et al. 

2007). In the western Mediterranean, they tend to be associated with the waters off the northern 

African coast and the northeastern Balearic archipelago, areas generally not inhabited by turtles 

of Mediterranean origin (Carreras et al. 2006, Revelles et al. 2007, Eckert et al. 2008). As 

larger, neritic juveniles, they show more structure and tend to inhabit areas closer to their natal 

origins (Bowen et al. 2004), but some do move to and from oceanic foraging grounds throughout 

this life stage (Mansfield 2006, McClellan and Read 2007), and some continue to use the 

Mediterranean Sea (Casale et al. 2008b, Eckert et al. 2008). Adult populations are highly 

structured with no overlap in distribution among adult loggerheads from the Northwest Atlantic, 

Northeast Atlantic, South Atlantic, and Mediterranean. Carapace epibionts suggest the adult 

females of different subpopulations use different foraging habitats (Caine 1986). In the 

Northwest Atlantic, based on satellite telemetry studies and flipper tag returns, non-nesting adult 

females from the Northern Recovery Unit reside primarily off the east coast of the U.S.; 

movement into the Bahamas or the Gulf of Mexico is rare (Bell and Richardson 1978, Williams 

and Frick 2001, Mansfield 2006, Turtle Expert Working Group 2009). Adult females of the 

Peninsular Florida Recovery Unit are distributed throughout eastern Florida, the Bahamas, 

Greater Antilles, Cuba, the Yucatán Peninsula, and the Gulf of Mexico, as well as along the 

Atlantic seaboard of the U.S. (Meylan 1982, Meylan et al. 1983, Foley et al. 2008; Turtle Expert 

Working Group 2009). Adult females from the Northern Gulf of Mexico Recovery Unit 

remained in the Gulf of Mexico, including off the Yucatán Peninsula, based on satellite telemetry 

and flipper tag returns (Foley et al. 2008; Turtle Expert Working Group 2009; M. Lamont, 

Florida Cooperative Fish and Wildlife Research Unit, personal communication, 2009; M. 

Nicholas, National Park Service, personal communication, 2009). 

Nesting in the Northeast Atlantic is concentrated in the Cape Verde Archipelago, with some 

nesting occurring on most of the islands, and the highest concentration on the beaches of Boa 

Vista Island (López-Jurado et al. 2000, Varo Cruz et al. 2007, Loureiro 2008). On mainland 

Africa, there is minor nesting on the coasts of Mauritania to Senegal (Brongersma 1982, Arvy et 

al. 2000, Fretey 2001). Earlier reports of loggerhead nesting in Morocco (Pasteur and Bons 

1960) have not been confirmed in recent years (Tiwari et al. 2001). Nesting has not been 

reported from Macaronesia (Azores, Madeira Archipelago, The Selvagens Islands, and the 
29

Canary Islands), other than in the Cape Verde Archipelago (Brongersma 1982). In Cape Verde, 

nesting begins in mid June and extends into October (Cejudo et al. 2000), which is somewhat 

later than when nesting occurs in the Northwest Atlantic. 

Based on an analysis of mtDNA of 196 nesting females from Boa Vista Island, the Cape Verde 

nesting assemblage is genetically distinct from other studied rookeries (C. Monzón-Argüello, 

Instituto Canario de Ciencias Marinas - Spain, personal communication, 2008; Monzón-Argüello 

et al. 2009). The results also indicate that despite the close proximity of the Mediterranean, the 

Boa Vista rookery is most closely related to the rookeries of the Northwest Atlantic. 

The distribution of juveniles from the Northeast Atlantic is largely unknown but they have been 

found on the oceanic foraging grounds of the North Atlantic (A. Bolten, University of Florida, 

personal communication, 2008, based on Bolten et al. 1998 and LaCasella et al. 2005; MonzónArgüello et al. 2009; M. Tiwari, NMFS, and A. Bolten, University of Florida, unpublished data) 

and in the western and central Mediterranean (A. Bolten, University of Florida, personal 

communication, 2008, based on Carreras et al. 2006), along with small juveniles from the 

Northwest Atlantic. Loggerheads of both juvenile and adult size also have been reported 

captured incidental to fishing operations off the coasts of Europe and Africa and have been 

reported stranded and in the markets (Maigret 1983; Tiwari et al. 2001; Benhardouze 2004; 

Benhardouze et al. 2004; Duguy et al. 2004, 2005; Witt et al. 2007). The size of nesting females 

in the Northeast Atlantic is comparable to those in the Mediterranean (average 72-80 cm SCL; 

Margaritoulis et al. 2003) and smaller than those in the Northwest Atlantic or the South Atlantic; 

91% of the nesting turtles are < 86.5 cm CCL (Hawkes et al. 2006) and nesting females average 

77.1 cm SCL (Cejudo et al. 2000). Post-nesting females demonstrated two behaviors, depending 

on size (Hawkes et al. 2006). The larger turtles (>93 cm) foraged in coastal waters along 

northwest Africa and the smaller animals (<87 cm) foraged oceanically, mostly between Cape 

Verde and the African shelf from Mauritania to Guinea Bissau. Loureiro (2008) only observed 

the smaller size class of reproductive female loggerheads nesting on Santiago Island, Cape 

Verde. 

Nesting occurs throughout the central and eastern Mediterranean on the shores of Italy, Greece, 

Cyprus, Turkey, Syria, Lebanon, Israel, the Sinai, Egypt, Libya, and Tunisia (Sternberg 1981, 

Margaritoulis et al. 2003, SWOT 2007). Sporadic nesting also has been reported in the western 

Mediterranean on Corsica (Delaugerre and Cesarini 2004), southwestern Italy (Bentivegna et al. 

2005), and on the Spanish Mediterranean coast (Tomás et al. 2003, 2008). Nesting in the 

Mediterranean is concentrated between June and early August (Margaritoulis et al. 2003). 

Within the Mediterranean, a recent study of mitochondrial and nuclear DNA in nesting 

assemblages from Greece to Israel indicated genetic structuring, philopatry by both females and 

males, and limited gene flow between assemblages (Carreras et al. 2007). Genetic 

differentiation based on mtDNA indicated that there are at least four independent nesting 

subpopulations within the Mediterranean and usually they are characterized by a single 

haplotype: (1) mainland Greece and the adjoining Ionian Islands, (2) eastern Turkey, (3) Israel, 

and (4) Cyprus. There is no evidence of adult female exchange among these four subpopulations 

(Carreras et al. 2006). In studies of the foraging grounds in the western and central 

Mediterranean, seven of the 17 distinct haplotypes detected had not yet been described, 
30

indicating that nesting beach data to describe the natal origins of juveniles exploiting the western 

Mediterranean Sea are incomplete (Carreras et al. 2006, Casale et al. 2008b). Gene flow among 

the Mediterranean rookeries estimated from nuclear DNA was significantly higher than that 

calculated from mtDNA, consistent with the scenario of female philopatry maintaining isolation 

between rookeries, offset by male-mediated gene flow. Nevertheless, the nuclear data show 

there was a higher degree of substructuring among Mediterranean rookeries compared to those in 

the Northwest Atlantic (Bowen et al. 2005; Carreras et al. 2007). 

Small oceanic juveniles from the Mediterranean Sea use the eastern basin (defined as inclusive 

of the central Mediterranean, Ionian, Adriatic, and Aegean Seas) and the western basin (defined 

as inclusive of the Tyrrhenian Sea) along the European coast (Laurent et al. 1998, Margaritoulis 

et al. 2003, Carreras et al. 2006, Revelles et al. 2007). Larger juveniles also use the eastern 

Atlantic and the eastern Mediterranean, especially the Tunisia-Libya shelf and the Adriatic Sea 

(Laurent et al. 1993, Margaritoulis et al. 2003, Monzón-Argüllo et al. 2006, Revelles et al. 

2007). Adults appear to forage closer to the nesting beaches in the eastern basin; most tag 

recoveries from females nesting in Greece have occurred in the Adriatic Sea and off Tunisia 

(Margaritoulis et al. 2003, Lazar et al. 2004). 

Straight carapace lengths of loggerheads nesting in the Mediterranean were significantly smaller 

than the lengths of loggerheads nesting in the Northwest Atlantic and the South Atlantic, and 

within the Mediterranean showed some variability among subpopulations. Carapace lengths 

ranged from 58 to 95 cm SCL (Margaritoulis et al. 2003). Greece’s loggerheads averaged 77-80 

cm SCL (Tiwari and Bjorndal 2000, Margaritoulis et al. 2003), whereas Turkey’s loggerheads 

averaged 72-73 cm SCL (Margaritoulis et al. 2003). The Greece turtles also produced larger 

clutches (relative to body size) than those produced by Florida or Brazil nesters (Tiwari and 

Bjorndal 2000). The authors suggested that sea turtles in the Mediterranean encounter 

environmental conditions significantly different from those experienced by populations 

elsewhere in the Atlantic Ocean basin. 

Given the information presented above, the BRT has unanimously concluded that four discrete 

population segments exist in the Atlantic Ocean/Mediterranean Sea as a consequence of 

ecological, behavioral, and oceanographic factors, and based on genetic evidence: (1) Northwest 

Atlantic Ocean, (2) Northeast Atlantic Ocean, (3) South Atlantic Ocean, and (4) Mediterranean 

Sea. These population segments are genetically distinct (Bowen et al. 1994; Encalada et al. 

1998; Pearce 2001; Carerras et al. 2007; C. Monzón-Argüello, Instituto Canario de Ciencias 

Marinas - Spain, personal communication, 2008; Monzon-Arguello et al. 2009) and, although 

they may comingle on oceanic foraging grounds as juveniles, adults apparently are isolated from 

each other; they also differ demographically. 

3.1.2. Significance Determination 

In Section 3.1.1., the BRT identified nine discrete population segments. As described below by 

ocean basin, each of the nine discrete population segments is biologically and ecologically 

significant. They each represent a large portion of the species range, sometimes encompassing 

an entire hemispheric ocean basin. The range of each discrete population segment represents a 

unique ecosystem, influenced by local ecological and physical factors. The loss of any single 
31

discrete population segment would result in a significant gap in the loggerhead’s range. Each 

discrete population segment is genetically unique, often identified by unique mtDNA haplotypes, 

and the BRT believes that these unique haplotypes could represent adaptive differences; the loss 

of any one discrete population segment would represent a significant loss of genetic diversity. 

Therefore, the BRT concludes that these nine population segments are both discrete from other 

conspecific population segments and significant to the species to which they belong, Caretta 

caretta. 

The geographic delineations given below for each discrete population segment were determined 

primarily based on nesting beach locations, genetic evidence, oceanographic features, thermal 

tolerance, fishery bycatch data, and information on loggerhead distribution and migrations from 

satellite telemetry and flipper tagging studies. With rare exception, adults from discrete 

population segments remain within the delineated boundaries. In some cases, juveniles from two 

or more discrete population segments may mix on foraging areas and therefore, their distribution 

and migrations may extend beyond the geographic boundaries delineated below for each discrete 

population segment (e.g., juveniles from the Northwest Atlantic Ocean, Northeast Atlantic 

Ocean, and Mediterranean Sea discrete population segments share foraging habitat in the western 

Mediterranean Sea). 

Pacific Ocean 

The BRT considers 60oN latitude and the equator as the north-south boundaries of the North 

Pacific population segment based on oceanographic features, loggerhead sightings, thermal 

tolerance, fishery bycatch data, and information on loggerhead distribution from satellite 

telemetry and flipper tagging studies. The loss of the North Pacific population segment would 

result in a significant gap in the range of the taxon. There is no evidence or reason to believe 

that female loggerheads from South Pacific nesting beaches would repopulate the North Pacific 

nesting beaches should those nesting assemblages be lost. Tagging studies show that the vast 

majority of nesting females return to the same nesting area. As summarized by Hatase et al. 

(2002a), of 2,219 tagged nesting females from Japan, only five females relocated their nesting 

sites. In addition, flipper tag and satellite telemetry research, as described in detail in Section 

3.1.1., shows no evidence of north-south movement of loggerheads across the equator. The BRT 

concludes that the North Pacific population segment is both discrete from other conspecific 

population segments and significant to the taxon to which it belongs, and therefore, it satisfies 

the DPS policy criteria. 

The BRT considers the equator and 60oS latitude as the north-south boundaries and 67o

W 

longitude and 139oE longitude as the east-west boundaries of the South Pacific population 

segment based on oceanographic features, loggerhead sightings, thermal tolerance, fishery 

bycatch data, and information on loggerhead distribution from satellite telemetry and flipper 

tagging studies. The loss of the South Pacific population segment would result in a significant 

gap in the range of the taxon. The South Pacific population is the only population of loggerheads 

found south of the equator in the Pacific Ocean and there is no evidence or reason to believe that 

female loggerheads from North Pacific nesting beaches would repopulate the South Pacific 

nesting beaches should those nesting assemblages be lost. In addition, flipper tag and satellite 

telemetry research, as described in detail in Section 3.1.1., shows no evidence of north-south 

movement of loggerheads across the equator. We also do not expect that recolonization from 
32

Indian Ocean loggerheads would occur in eastern Australia within ecological time frames. 

Despite evidence of foraging in the Gulf of Carpentaria by adult loggerheads from the nesting 

populations in eastern Australia (South Pacific population segment) and western Australia 

(Southeast Indo-Pacific Ocean population segment), the nesting females from these two regions 

are considered to be genetically distinct from one another (Limpus 2009). In addition to a 

substantial disparity in mtDNA haplotype frequencies between these two populations, 

FitzSimmons (University of Canberra, unpublished data) found significant differences in nuclear 

DNA microsatellite loci between females nesting in these two regions, indicating separation 

between the South Pacific Ocean and the Southeast Indo-Pacific Ocean population segments. 

Long term studies show a high degree of site fidelity by adult females in the South Pacific, with 

most females returning to the same beach within a nesting season and in successive nesting 

seasons (Limpus 1985, 2009; Limpus et al. 1994). This has been documented as characteristic of 

loggerheads from various rookeries throughout the world (Schroeder et al. 2003). The BRT 

concludes that the South Pacific population segment is both discrete from other conspecific 

population segments and significant to the taxon to which it belongs, and therefore, it satisfies 

the DPS policy criteria. 

Indian Ocean 

The BRT considers 30o

N latitude and the equator as the north-south boundary of the North 

Indian Ocean population segment based on oceanographic features, loggerhead sightings, 

thermal tolerance, fishery bycatch data, and information on loggerhead distribution from satellite 

telemetry and flipper tagging studies. The loss of the North Indian Ocean population segment 

would result in a significant gap in the range of the taxon. Genetic studies have shown that adult 

populations are highly structured with no overlap in distribution among adult loggerheads in the 

North Indian Ocean, Southwest Indian Ocean, and Southeast Indo-Pacific. There is no evidence 

or reason to believe that female loggerheads from the Southwest Indian Ocean or Southeast IndoPacific would repopulate the North Indian Ocean nesting beaches should those populations be 

lost. The BRT concludes that the North Indian Ocean population segment is both discrete from 

other conspecific population segments and significant to the taxon to which it belongs, and 

therefore, it satisfies the DPS policy criteria. 

The BRT considers the equator and 60oS latitude as the north-south boundaries and 20oE 

longitude at Cape Agulhas on the southern tip of Africa and 80oE longitude as the east-west 

boundaries of the Southwest Indian Ocean population segment based on oceanographic features, 

thermal tolerance, fishery bycatch data, and information on loggerhead distribution from satellite 

telemetry and flipper tagging studies. The loss of the Southwest Indian Ocean population 

segment would result in a significant gap in the range of the taxon. Genetic studies have shown 

that adult populations are highly structured in the North Indian Ocean, Southwest Indian Ocean, 

and Southeast Indo-Pacific. Only one post-nesting female from the Southwest Indian Ocean 

population (South Africa) has been documented migrating north of the equator (to southern 

Somalia) (Hughes and Bartholomew 1996). There is no evidence or reason to believe that 

female loggerheads from the North Indian Ocean or Southeast Indo-Pacific would repopulate the 

Southwest Indian Ocean nesting beaches should those populations be lost. There is also no 

evidence of movement of adult Southwest Indian Ocean loggerheads west of 20oE longitude at 

Cape Agulhas, the southernmost point on the African continent or east of 80oE longitude within 

the Indian Ocean. The BRT concludes that the Southwest Indian Ocean population segment is 
33

both discrete from other conspecific population segments and significant to the taxon to which it 

belongs, and therefore, it satisfies the DPS policy criteria. 

The BRT considers the equator and 60oS latitude as the north-south boundaries and 139oE 

longitude and 80oE longitude as the east-west boundaries of the Southeast Indo-Pacific Ocean 

population segment based on oceanographic features, thermal tolerance, fishery bycatch data, 

and information on loggerhead distribution from satellite telemetry and flipper tagging studies. 

The loss of the Southeast Indo-Pacific Ocean population segment would result in a significant 

gap in the range of the taxon. Genetic studies have shown that adult populations are highly 

structured with no overlap in distribution among adult loggerheads in the North Indian Ocean, 

Southwest Indian Ocean, and Southeast Indo-Pacific. There is no evidence or reason to believe 

that female loggerheads from the North Indian Ocean or Southwest Indian Ocean would 

repopulate the Southeast Indo-Pacific nesting beaches should those populations be lost. There is 

also no evidence of movement of adult Southeast Indo-Pacific Ocean loggerheads west of 80oE 

longitude within the Indian Ocean. Despite evidence of foraging in the Gulf of Carpentaria by 

adult loggerheads from the nesting populations in eastern Australia (South Pacific population 

segment) and western Australia (Southeast Indo-Pacific Ocean population segment), the nesting 

females from these two regions are considered to be genetically distinct from one another 

(Limpus 2009). In addition to a substantial disparity in mtDNA haplotype frequencies between 

these two regions, FitzSimmons (University of Canberra, unpublished data) found significant 

differences in nuclear DNA microsatellite loci from females nesting in these two regions, 

indicating separation between the South Pacific population segment and the Southeast IndoPacific Ocean population segment. The BRT concludes that the Southeast Indo-Pacific Ocean 

population segment is both discrete from other conspecific population segments and significant 

to the taxon to which it belongs, and therefore, it satisfies the DPS policy criteria. 

Atlantic Ocean and Mediterranean Sea 

The BRT considers 60o

N latitude and the equator as the north-south boundaries and 40oW 

longitude as the east boundary of the Northwest Atlantic Ocean population segment based on 

oceanographic features, loggerhead sightings, thermal tolerance, fishery bycatch data, and 

information on loggerhead distribution from satellite telemetry and flipper tagging studies. The 

loss of the Northwest Atlantic population segment would result in a significant gap in the range 

of the taxon. Genetic studies have shown that adult populations are highly structured with no 

overlap in distribution among adult loggerheads from the Northwest Atlantic, Northeast Atlantic, 

South Atlantic, and Mediterranean. There is no evidence or reason to believe that female 

loggerheads from the Northeast Atlantic, Mediterranean Sea, or South Atlantic nesting beaches 

would repopulate the Northwest Atlantic nesting beaches should these populations be lost. Data 

from satellite telemetry studies and flipper tag returns show that the vast majority of nesting 

females from the Northwest Atlantic return to the same nesting area; they reveal no evidence of 

movement of adults south of the equator or east of 40oW longitude. The BRT concludes that the 

Northwest Atlantic population segment is both discrete from other conspecific population 

segments and significant to the taxon to which it belongs, and therefore, it satisfies the DPS 

policy criteria. 

The BRT considers 60o

N latitude and the equator as the north-south boundaries and 40oW 

longitude as the west boundary of the Northeast Atlantic Ocean population segment. The BRT 
34

considers the boundary between the Northeast Atlantic Ocean and Mediterranean Sea population 

segments as 5o 36’W longitude (Strait of Gibraltar). These boundaries are based on 

oceanographic features, loggerhead sightings, thermal tolerance, fishery bycatch data, and 

information on loggerhead distribution from satellite telemetry and flipper tagging studies. 

The loss of the Northeast Atlantic population segment would result in a significant gap in the 

range of the taxon. Genetic studies have shown that adult populations are highly structured with 

no overlap in distribution among adult loggerheads from the Northwest Atlantic, Northeast 

Atlantic, South Atlantic, and Mediterranean. There is no evidence or reason to believe that 

female loggerheads from the Northwest Atlantic, Mediterranean Sea, or South Atlantic nesting 

beaches would repopulate the Northeast Atlantic nesting beaches should these populations be 

lost. There is also no evidence of movement of Northeast Atlantic adults west of 40oW longitude 

or east of the Strait of Gibraltar (5o 36’W longitude). The BRT concludes that the Northeast 

Atlantic population segment is both discrete from other conspecific population segments and 

significant to the taxon to which it belongs, and therefore, it satisfies the DPS policy criteria. 

The BRT considers the Mediterranean Sea west to 5o 36’W longitude (Strait of Gibraltar) as the 

boundary of the Mediterranean Sea population segment based on oceanographic features, 

loggerhead sightings, thermal tolerance, fishery bycatch data, and information on loggerhead 

distribution from satellite telemetry and flipper tagging studies. The loss of the Mediterranean 

Sea population segment would result in a significant gap in the range of the taxon. Genetic 

studies show that adult populations are highly structured with no overlap in distribution among 

adult loggerheads from the Northwest Atlantic, Northeast Atlantic, South Atlantic, and 

Mediterranean. There is no evidence or reason to believe that female loggerheads from the 

Northwest Atlantic, Northeast Atlantic, or South Atlantic nesting beaches would repopulate the 

Mediterranean Sea nesting beaches should these populations be lost. As previously described, 

adults from the Mediterranean Sea population segment appear to forage closer to the nesting 

beaches in the eastern basin, and most flipper tag recoveries from females nesting in Greece have 

occurred in the Adriatic Sea and off Tunisia (Margaritoulis et al. 2003, Lazar et al. 2004). There 

is no evidence of movement of adult Mediterranean Sea loggerheads west of the Strait of 

Gibraltar (5o 36’W longitude). The BRT concludes that the Mediterranean Sea population 

segment is both discrete from other conspecific population segments and significant to the taxon 

to which it belongs, and therefore, it satisfies the DPS policy criteria. 

The BRT considers the equator and 60o

S latitude as the north-south boundaries and 20oE 

longitude at Cape Agulhas on the southern tip of Africa and 67oW longitude as the east-west 

boundaries of the South Atlantic Ocean population segment based on oceanographic features, 

loggerhead sightings, thermal tolerance, fishery bycatch data, and information on loggerhead 

distribution from satellite telemetry and flipper tagging studies. The loss of the South Atlantic 

population segment would result in a significant gap in the range of the taxon. Genetic studies 

show that adult populations are highly structured with no overlap in distribution among adult 

loggerheads from the Northwest Atlantic, Northeast Atlantic, South Atlantic, and Mediterranean. 

There is no evidence or reason to believe that female loggerheads from the Northwest Atlantic, 

Northeast Atlantic, or Mediterranean Sea nesting beaches would repopulate the South Atlantic 

nesting beaches should these populations be lost. The BRT concludes that the South Atlantic 

population segment is both discrete from other conspecific population segments and significant 

to the taxon to which it belongs, and therefore, it satisfies the DPS policy criteria. 
35

In summary, the BRT has identified nine loggerhead DPSs distributed globally: (1) North 

Pacific Ocean DPS, (2) South Pacific Ocean DPS, (3) North Indian Ocean DPS, (4) Southeast 

Indo-Pacific Ocean DPS, (5) Southwest Indian Ocean DPS, (6) Northwest Atlantic Ocean DPS, 

(7) Northeast Atlantic Ocean DPS, (8) Mediterranean Sea DPS, and (9) South Atlantic Ocean 

DPS. 

3.2. Significant Portion of its Range (SPOIR) Assessment 

The BRT determined that the range of each DPS contributes meaningfully to the conservation of 

the DPS and that populations that may contribute more or less to the conservation of each DPS 

throughout a portion of its range cannot be identified due to the highly migratory nature of the 

listed entity. 

The loggerhead sea turtle is highly migratory and crosses multiple domestic and international 

geopolitical boundaries. Depending on the life stage, they may occur in oceanic waters or along 

the continental shelf of landmasses, or transit back and forth between oceanic and neritic 

habitats. Protection and management of both the terrestrial and marine environments is essential 

to recovering the listed entity. Management measures implemented by any State, foreign nation, 

or political subdivision likely would only affect individual sea turtles during certain stages and 

seasons of the life cycle. Management measures implemented by any State, foreign nation, or 

political subdivision may also affect individuals from multiple DPSs because juveniles from 

disparate DPSs can overlap on foraging grounds or migratory corridors (e.g., Northwest Atlantic, 

Northeast Atlantic, and Mediterranean Sea DPSs). The “significant” term in SPOIR refers to the 

contribution of the population(s) in a portion of the range to the conservation of the listable entity 

being considered. The BRT was unable to subdivide the geographic range of loggerhead 

populations below the DPS level in which threats and conservation efforts specific to any portion 

of its range can be identified and analyzed for listing status without disregarding the impacts of 

these threats and conservation efforts to the listed entity throughout all of its range. 
36

SECTION 4—ASSESSMENT OF EXTINCTION RISK 

4.1. Description of Extinction Risk Assessment Approaches 

To assess extinction risks of loggerhead DPSs, we conducted two independent analyses. The 

first analysis used the diffusion approximation approach based on time series of counts of nesting 

females (Lande and Orzack 1988, Dennis et al. 1991, Holmes 2001, Snover and Heppell 2009). 

This analysis provided a metric (susceptibility to quasi-extinction or SQE) to determine if the 

probability of a population’s risk of quasi-extinction is high enough to warrant a particular status 

listing (Snover and Heppell 2009). This approach is based on stochastic projections of observed 

trends and variability in the numbers of mature females at various nesting beaches. The second 

approach used a deterministic stage-based population model that focused on determining the 

effects of known anthropogenic mortalities on each DPS with respect to the vital rates of the 

species. Anthropogenic mortalities were added to natural mortalities and possible ranges of 

population growth rates were computed as another metric of population health. Because this 

approach is based on matrix models, we call it a threat matrix analysis. This approach focused 

on how additional mortalities may affect the future growth and recovery of a loggerhead turtle 

DPS. The first approach (SQE) was solely based on the available time-series data on the 

numbers of nests at nesting beaches, whereas the second approach (threat matrix analysis) was 

based on the known biology of the species and anthropogenic mortalities independent of 

observed nesting beach data. 

4.2. Computation of Susceptibility to Quasi-extinction (SQE) 

4.2.1. Methods 

Estimates of quasi-extinction risk are known to have high degrees of uncertainty due to the 

stochastic nature of populations and their environments and the error involved in data collection 

and subsequent parameter estimation (Holmes et al. 2007). However, there are ongoing needs 

for management to classify populations in terms of their status when only limited data, often with 

high observation error rates, are available. To address this need, Snover and Heppell (2009) 

presented a quasi-extinction risk index called susceptibility to quasi-extinction (SQE) that can be 

used to classify sea turtle nesting populations based on relative risks using only nesting beach 

census data. This index integrates parameter uncertainty and stochasticity in extinction risk 

forecasting while allowing managers to balance the risk of making Type I (considering a 

population to be not at risk when it is) and Type II (considering a population to be at risk when it 

is not) errors when making decisions. While they showed that the method is robust in assessing 

actual risk (in terms of a binary metric of “at risk” or “not at risk”) using population simulations, 

they clarify that SQE values are not indicative of a true probability of quasi-extinction because 

they assume constant distributions of trend and variance over long time frames (three 

generations) and ignore density dependence. Rather, the index serves as a tool for classifying 

populations by relative status. 

The technique involves standard methods of diffusion approximation (Lande and Orzack 1988, 

Dennis et al. 1991). These methods are based on a density-independent exponential model in a 

randomly varying environment: 
37

 ) exp( 1 = μ + ε + NN tt , (1) 

where ) ,0(~ 2 N σε , N is the population size, and t is time (Dennis et al. 1991, Holmes 2001). 

Assuming that the lognormal distribution can be used to compute the probability that the 

population will be of a certain size, two parameters estimated by this method are μ , the 

arithmetic mean of the log population growth rate, and 2 σ , the variance of the log population 

growth rate, which accounts for sources of variability, including environmental and demographic 

stochasticity, and observation error (Holmes 2001, Morris and Doak 2002 - Chapter 5). These 

parameters were estimated using the regression analysis, whereas the confidence intervals were 

estimated using the method of Dennis et al. (1991) and Morris and Doak (2002). While not as 

statistically robust as the methods presented by Holmes (2001), the methods of Dennis et al. 

(1991) and Morris and Doak (2002) are simpler and more tractable for managers. For the 

lengths of time series typically available for sea turtle populations (i.e., <20 years), Snover and 

Heppell (2009) demonstrated that both methods performed equally well in determining SQE. 

These estimated parameters were used to make inferences on total population growth rates and 

quasi-extinction probability. 

The data available for this analysis were time series of annual counts of nests or nesting females. 

When the data were in units of nests per yr, we converted these numbers to estimates of nesting 

females (see Section 4.2.2 for details). For each nesting beach or region, we followed the 

recommendations in Snover and Heppell (2009), and used a running-sum of 3 yr. This data 

smoothing provides a more accurate reflection of population change by reducing year-to-year 

fluctuations in the number of nests that affect our translation of the number of nests to the 

number of adult females and actual population processes. Current adult female population size, 

n0, was estimated as the sum of the last 3 yr of data. We used the parametric bootstrap estimation 

procedure from Morris and Doak (2002) to compute the μ and σ

2

 distributions required to 

calculate susceptibility to quasi-extinction (SQE) and a wide range of quasi-extinction thresholds 

(QETs). We used a range from 2.5 to 97.5% of the current abundance of nesting females as 

potential QETs. Because loggerhead turtles are likely to mature at > 30 yr (Snover 2002), we 

used the time period of 100 yr to compute QETs, which is consistent with the IUCN criteria (3 

generations or 100 years, whichever is shorter). To incorporate the uncertainty of parameter 

estimates in determining SQE, we used 95% confidence limits of μˆ and 2 σˆ , using the 

parametric bootstrapping method of Morris and Doak (2002). 

The following steps were used to obtain SQEs: 

1. μi and 2 σ i were drawn randomly and independently from respective distributions, { μi

~ , 

~2 σ i }. 

2. Each pair { μi

~ , ~2 σ i } was used to compute the probability of reaching a QET within the 

next 100 years. 

3. Steps 1 and 2 were repeated 5000 times (i = 1, ..., 5000) to create a distribution of 

probabilities of reaching the QET. 

4. The SQE metric for the QET is the proportion of the probabilities that are >0.9 (cut-off 

probability). 
38

5. Steps 1 through 4 were repeated for a range of QETs between 2.5% and 97.5% of the 

current abundance of nesting females. 

Using simulations, Snover and Heppell (2009) demonstrated that SQE values greater than 0.4 

indicated a population has >0.9 probability of quasi-extinction. At this critical value (SQE = 

0.40), Type I and Type II errors are minimized simultaneously at approximately 10%. Reducing 

the critical value to 0.3 lessens the ‘Type I’ error rate but increases the ‘Type II’ error rate 

(Snover and Heppell 2009). The choice of 0.9 as the cut-off probability was arbitrary and values 

other than 0.9 could be used. However, new critical values other than 0.4 needed to be 

established for different values of the cut-off probability. Qualitatively, the results would not 

differ if a value other than 0.9 was used (Snover and Heppell 2009). In this assessment, we used 

the cut-off probability of 0.9 as in Snover and Heppell (2009) and a critical value for the SQE of 

0.30, which reduced the ‘Type I’ error (a DPS is considered to be not at risk when in fact it is). 

SQE values greater than 0.30, therefore, indicate the DPS is at risk. 

4.2.2. Count Data 

The following datasets were used for the computations of SQEs. Ideally, the SQE analysis is 

conducted on the numbers of nesting females over time, which represent the temporal change in 

the number of reproductive females. The statistic, however, is difficult to determine because of 

the required effort to mark and identify individual turtles. Consequently, data are often collected 

for the number of nests per nesting season. To estimate the number of females from the 

observed number of nests, we use the average number of nests per female per nesting season for 

that region. Because the average is treated as a constant over time for each DPS (Table 1) and 

SQE is calculated as probability of a proportional reduction in population size, the SQE analysis 

is unaffected by the choice of unit (i.e., the number of females or nests). In the following, we use 

the number of females as the unit of analysis. Snover and Heppell (2009) suggest that time 

series at least 15 years in length are needed for diffusion approximation analysis, which limits 

the populations that have adequate data for applying this approach. We did include one 

additional nesting recovery unit in the Northwest Atlantic Ocean DPS, the Northern Gulf of 

Mexico Recovery Unit, with only 12 years of data in order to characterize as much of that region 

as possible. Results from that recovery unit should be interpreted with caution, although the 

general trends observed are consistent with region as a whole. 
39

Table 1. Life history parameters used for the nine DPSs. Juvenile survival rates (oceanic and 

neritic) were computed by using the negative binomial stage duration model and fixing survival 

rates of adults and the first year and fecundity. See text for details. Also please consult the excel 

file posted on the NMFS Office of Protected Resources website 

[http://www.nmfs.noaa.gov/pr/species/statusreviews.htm] to access information used in 

identifying the life history parameters. 

 North 

Pacific 

South 

Pacific 

Indian* NW 

Atlantic 

NE 

Atlantic 

Med South 

Atlantic 

Fecundity 

Remigration interval 

(yrs) 

2.7 3.8 3 3 3 2.6 3

Clutch freq. (yr-1) 3 3.4 5 5 5 2 5

Clutch size 112 127 101-118 115 85 95 123

Sex ratio (% female) 50 50 50 50 50 50 50

Emergence success 0.61 0.71 0.54 0.54 0.319 0.67 0.67

 

Habitat use 

Juveniles 

Prop. neritic 0.14 0.50 0.655 0.655 0.655 0.50 0.655

Yrs oceanic 27.0 14.5 10 10 14.5 14.5 10

Yrs neritic 2.0 14.5 19 19 14.5 14.5 19

Mean AFR (yrs) 30 30 30 30 30 30 30

SD AFR 5 5 5 5 5 5 5

 

Adults 

Prop. neritic 

(non-nesting) 

0.82 0.85 0.58 0.95 0.30 0.66 0.95

Prop. neritic 

(nesting) 

0.82 0.85 0.73 0.95 0.30 0.66 0.95

 

Survival rates 

Aquatic hatchlings 0.400 0.400 0.400 0.400 0.400 0.400 0.400

Oceanic juvenile 

λ0 = 1.05 

λ0 = 1.10 

0.858 

0.914 

0.828

0.894

0.796

0.877

0.794

0.875

0.858 

0.933 

0.856 

0.933 

0.787

0.863

Neritic juvenile 

λ0 = 1.05 

λ0 = 1.10 

0.928 

0.955 

0.911

0.949

0.895

0.933

0.893

0.932

0.922 

0.956 

0.921 

0.954 

0.883

0.923

Oceanic adult 0.950 0.950 0.950 0.950 0.950 0.950 0.950

Neritic adult 0.950 0.950 0.950 0.950 0.950 0.950 0.950

*All parameters are identical for three DPSs in the Indian Ocean.
40

4.2.2.1. North Pacific Ocean DPS 

All loggerhead nesting in the North Pacific occurs in Japan. Nesting data for this region are from 

two sources, the Sea Turtle Association of Japan (STAJ; unpublished data provided to the 

Western Pacific Fisheries Management Council) and Kamezaki et al. (2002). Data from the 

STAJ represent total counts for Japan from 1998-2007. Snover (2008) combined these datasets 

to achieve a time series from Japan from 1990-2007 (Figure 1). Due to the nature of the STAJ 

data, the data from Japan are represented by a single time series, rather than by nesting beaches. 

Figure 1. Change in the number of nesting females at nesting beaches for the North Pacific 

Ocean DPS. The number of nesting females was computed from the observed number of nests 

divided by the mean clutch frequency (3 yr-1; Table 1). 
41

4.2.2.2. South Pacific Ocean DPS 

We used nesting census data for index beaches in eastern Australia (Limpus 2009; Figure 2). 

These include mainland beaches, Wreck Rock beaches, Great Barrier Reef (GBR) Coral Cays, 

and Wreck and Tyron Islands. Each beach was analyzed separately. 

Figure 2. The change in the numbers of nesting females at four nesting beaches for the South 

Pacific Ocean DPS. 
42

4.2.2.3. North Indian Ocean DPS 

No adequate time series of nesting beach data was available for this DPS. 

4.2.2.4. Southeast Indo-Pacific Ocean DPS 

No adequate time series of nesting beach data was available for this DPS. 

4.2.2.5. Southwest Indian Ocean DPS 

Count data for the Southwest Indian Ocean DPS were obtained from Baldwin et al. (2003; 

Figure 3). 

Figure 3. Change in the number of nesting females for the Southwest Indian Ocean DPS. 
43

4.2.2.6. Northwest Atlantic Ocean DPS 

The Recovery Plan for the Northwest Atlantic Population of the Loggerhead Sea Turtle (NMFS 

and FWS 2008) recognized five recovery units (subpopulations) of loggerhead turtles within the 

Northwest Atlantic: 

1. Northern Recovery Unit (southern VA through FL/GA border) 

2. Peninsular Florida Recovery Unit (FL/GA border through Pinellas County, FL) 

3. Dry Tortugas Recovery Unit (islands located west of Key West, FL) 

4. Northern Gulf of Mexico Recovery Unit (Franklin County, FL, through TX) 

5. Greater Caribbean Recovery Unit (Mexico through French Guiana, The Bahamas, Lesser 

Antilles, and Greater Antilles) 

Of these recovery units, four have adequate time series data for applying this analysis (Figure 4). 

Data for the Northern Recovery Unit and the Peninsular Florida Recovery Unit comprise sums of 

numerous individual beaches. For the Northern Gulf of Mexico Recovery Unit data, we used a 

time series from the Florida Panhandle. We used nesting beach data from the Yucatan Peninsula 

(J. Zurita, personal communication, 2008) to represent the Greater Caribbean Recovery Unit. 

4.2.2.7. Northeast Atlantic Ocean DPS 

Although nesting data are available for the Cape Verde Archipelago, the time series is not long 

enough for the diffusion approximation analysis. 

4.2.2.8. Mediterranean Sea DPS 

Representative nesting beach data were not available for this DPS. Although nesting data are 

available for Greece and Turkey, the BRT does not think these data are sufficiently 

representative of the entire region given the potential differences in trends among nesting areas. 

4.2.2.9. South Atlantic Ocean DPS 

Data for the South Atlantic Ocean DPS were obtained from Marcovaldi and Chaloupka (2007; 

Figure 5). 
44

Figure 4. Changes in the numbers of nesting females at nesting beaches for the Northwest 

Atlantic Ocean DPS. The number of nesting females was computed from the observed number 

of nests divided by the mean clutch frequency (5 yr-1; Table 1). NRU = Northern Recovery Unit, 

PFRU = Peninsular Florida Recovery Unit, NGMRU = Northern Gulf of Mexico Recovery Unit, 

and GCRU = Greater Caribbean Recovery Unit. 
45

Figure 5. Change in the number of nesting females at nesting beaches for the South Atlantic 

Ocean DPS. The number of nesting females was computed from the observed number of nests 

divided by the mean clutch frequency (5 yr-1; Table 1). 
46

4.2.3. Results 

The metric (susceptibility to quasi-extinction or SQE) is an increasing function of quasiextinction threshold (QET). Unless a DPS is increasing, the likelihood of the population 

reaching some level of QET, as measured in the proportion of current abundance, increases with 

QET. For example, if 95% of the current abundance is used as the QET, the likelihood of a 

declining population reaching the QET is high. For severely declining populations, the QET 

needs to be set very low to reach the defined SQE value of 0.3. Only the Southwest Indian 

Ocean and South Atlantic Ocean DPSs indicated increasing trends (μ > 0; Table 2). Large 

variability in the count data resulted in wide confidence intervals; all but three confidence 

intervals included zero (Table 2). 

For the North Pacific Ocean DPS, SQE = 0.3 was reached at approximately 3% of the current 

female abundance, indicating the high likelihood of quasi-extinction for almost all levels of QET 

(Figure 6). This was caused by the recent decline of nesting females at the majority of nesting 

beaches in Japan (Snover 2008). 

All monitored nesting beaches for the South Pacific Ocean DPS indicated high likelihood of 

SQE (Figure 7). As it was expected from observed counts (Figure 2), nesting beaches on 

Mainland Australia indicated a better chance of persisting than other sites (Figure 7). For Wreck 

Rock, Great Barrier Reef (GBR), and Wreck and Tyron nesting beaches, quasi-extinction was 

certain for all values of QET. 

For the recovery units with sufficient data within the Northwest Atlantic Ocean DPS, the 

likelihood of quasi-extinction was highest for the Northern Gulf of Mexico Recovery Unit 

(NGMRU), where SQE was greater than 0.3 for all values of QET (Figure 8). For the other three 

recovery units, SQE = 0.3 was reached at QET < 0.3 (Figure 8). 

Two DPSs indicated low likelihoods of SQE; the Southwest Indian Ocean (data from South 

Africa) and South Atlantic Ocean DPSs (Figures 9 and 10). Because of the observed increases in 

the nesting females in both time series (Baldwin et al. 2003, Figure 3; Marcovaldi and 

Chaloupka 2007, Figure 5), the likelihood of quasi-extinctions are negligible for these DPSs 

using the SQE analysis. 
47

Table 2. Results of the diffusion approximation analysis for each nesting beach or region. The 

parameter μ is the arithmetic mean of the log population growth rate, and 2 σ is the variance of the 

log population growth rate. CI is confidence interval. PFRU = Peninsular Florida Recovery 

Unit, NRU = Northern Recovery Unit, NGMRU = Northern Gulf of Mexico Recovery Unit, and 

GCRU = Greater Caribbean Recovery Unit. 

DPS μ 95% CI μ σ

2

 95% CI σ

2

North Pacific 

All Japan 

South Pacific 

 -0.032 [-0.111, 0.046] 0.020 [0.011, 0.048] 

Mainland Australia -0.013 [-0.047, 0.021] 0.009 [0.006, 0.016] 

Wreck Rock, 

Australia 

-0.038 [-0.107, 0.032] 0.023 [0.014, 0.048] 

Great Barrier Reef, 

Australia 

-0.050 [-0.116, 0.017] 0.026 [0.016, 0.049] 

Wreck and Tyron 

Islands, Australia 

-0.075 [-0.150, -0.001] 0.030 [0.018, 0.058] 

 

Southwest Indian 0.029 [0.003, 0.054] 0.005 [0.004, 0.009] 

Northwest Atlantic 

 

PFRU -0.026 [-0.065, 0.013] 0.005 [0.003, 0.013] 

NRU -0.012 [-0.079, 0.055] 0.021 [0.012, 0.043] 

NGMRU -0.049 [-0.121, 0.022] 0.009 [0.004, 0.029] 

GCRU -0.012 [-0.068, 0.043] 0.010 [0.006, 0.025] 

South Atlantic 

Bahia and Espirito 

Santa, Brazil 

0.046 [0.023, 0.068] 0.001 [0.001, 0.004] 
48

Figure 6. Susceptibility to quasi-extinction (SQE) as a function of quasi-extinction threshold 

(QET) for the North Pacific Ocean DPS. QET is defined as the proportion of the current female 

abundance. The dotted line indicates SQE = 0.3, which was adapted as the threshold for the 

analysis. 
49

Figure 7. Susceptibility to quasi-extinction (SQE) as a function of quasi-extinction threshold 

(QET) for the South Pacific Ocean DPS. QET is defined as the proportion of the current female 

abundance. Dotted lines indicate SQE = 0.3, which was adapted as the threshold for the analysis. 
50

Figure 8. Susceptibility to quasi-extinction (SQE) as a function of quasi-extinction threshold 

(QET) for the Northwest Atlantic Ocean DPS. QET is defined as the proportion of the current 

female abundance. Dotted lines indicate SQE = 0.3, which was adapted as the threshold for the 

analysis. NRU = Northern Recovery Unit, PFRU = Peninsular Florida Recovery Unit, NGMRU 

= Northern Gulf of Mexico Recovery Unit, and GCRU = Greater Caribbean Recovery Unit. 
51

Figure 9. Susceptibility to quasi-extinction (SQE) as a function of quasi-extinction threshold 

(QET) for the Southwest Indian Ocean DPS. Data are for South Africa nesting beaches. QET is 

defined as the proportion of the current female abundance. Dotted lines indicate SQE = 0.3, 

which was adapted as the threshold for the analysis. 
52

Figure 10. Susceptibility to quasi-extinction (SQE) as a function of quasi-extinction threshold 

(QET) for the South Atlantic Ocean DPS. QET is defined as the proportion of the current female 

abundance. The dotted line indicates SQE = 0.3, which was adapted as the threshold for the 

analysis. 
53

4.3. Threat Matrix Analysis 

4.3.1. General Modeling Approach 

The second approach to our risk analysis was based on a metric that indicates whether or not 

known threats may be sufficient to keep a DPS from recovering. Using as much information on 

the biology of loggerhead turtles as possible, a discrete-time stage-structured population model 

was constructed for each DPS. First, the model was parameterized to represent the maximum 

plausible vital rates and population growth rate, which may be attained for a recovering DPS 

(base population model hereafter). We did not incorporate demographic and environmental 

stochasticities in the base matrix. Known anthropogenic threats to each life stage of a DPS, 

measured as additional annual mortality, were quantified using available data and experts’ 

opinions, where the stage-specific additional annual mortality was summarized in a matrix 

format (threat matrix). The base population model and threat matrix then were multiplied to 

determine effects of the additional mortalities on the base population model. We use the 

dominant eigenvalue (λ) of the product of the two matrices as an index of DPS status, where λ >1 

indicates a healthy population, whereas λ <1 indicates possible decline of the population in the 

future. Because the base matrix of a DPS was developed on hypothesized dominant eigenvalues, 

the actual value of λ should not be considered as the population growth rate of a DPS. We also 

provide the proportion of λ > 1. This proportion increases as the additional mortalities decrease. 

Briefly, the risk analysis for each DPS consisted of four stages. First, a base population model 

was constructed. Second, anthropogenic threats were quantified. Third, effects of the threats 

were calculated via the dominant eigenvalue of a linear time-invariant model. Finally, a range of 

dominant eigenvalues was determined according to the ranges of threat levels. Details of each 

step are described in the following sections. Note that this analysis is similar to a demographic 

population viability analysis (PVA). However, we did not consider environmental or 

demographic stochasticity, density dependence, autocorrelations in vital rates, or sampling 

variations. Consequently, this analysis should not be considered as a complete PVA. The two 

metrics (the dominant eigenvalue and the proportion of λ > 1) are indices of potential population 

decline of a DPS, considering the existing information about the biology of the species and 

experts’ opinions on known anthropogenic threats to the DPS. The analysis does not provide 

estimates for the likelihood or probability of extinction. 

4.3.2. Survival Rates and Population Growth Rate for the Base Models 

Using knowledge of life history of loggerhead turtles and following the previous work of others 

(Crouse et al. 1987, Crowder et al. 1994, Heppell et al. 2003), we constructed a stage-based 

population model for each DPS. The model consisted of four stages; first year, oceanic 

juveniles, neritic juveniles, and adults. The durations of juvenile stages were modeled using the 

negative binomial stage distribution model (NBSD model; Caswell 2001, pp. 164-165). 

The NBSD model does not rely on the assumption of stable age distribution within a stage to 

compute the transition probability, as other methods would. Detailed descriptions are available 

in Caswell (2001). Briefly, for a series of k identical pseudo-stages within a juvenile stage, we 

assign the transition probability (p) of moving from one pseudo-stage to the next pseudo-stage. 
54

Because the total time required to step through all k pseudo-stages is equal to the time required 

for the k

th success in a series of identical Bernoulli trials with probability p, the total time (T) can 

be computed with a negative binomial distribution: 

( ) k kt

pp k

t

tT − − ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

−

− == 1

1

1

Pr( ) , (1) 

where ≥ kt , , k t = ,2,1 L , and 1 0 < p < . The mean (E[T]) and variance (var[T]) of this 

distribution are: 

p

k [ and (2) TE ] =

2

)1( ]var[

p

pk T − = . (3) 

These equations can be solved for p and k by rearranging the above expressions: 

][]var[

][

TET

TE

p

+ = and (4) 

( )

][]var[

][ 2

TET

TE k

+ = . (5) 

Survival rates and transition probabilities among pseudo-stages are assumed identical. 

Therefore, each element of a pseudo-stage is multiplied by the stage specific survival rate. In 

other words, the k diagonal elements for a juvenile stage are (1-p)φ, whereas the sub-diagonal 

elements are pφ, where φ is the stage specific survival rate. For the same mean stage duration, a 

larger variance implies fewer pseudo stages (k) with smaller p, and vice versa. This method 

allowed us to construct projection matrices without assuming the stable age distribution within 

each juvenile stage or a fixed stage duration, while acknowledging the insufficient data to 

construct age-based models with variable growth rates. 

The NBSD model requires the mean and variance of durations of stages. The age at first 

reproduction (AFR), however, has not been estimated directly for loggerhead turtles. 

Skeletochronological studies have indicated that loggerhead turtles in the western Atlantic may 

reach their first reproduction at approximately 30 years (Snover 2002). The experts of the team 

agreed on a standard deviation for the AFR of 5 years. Assuming a negative binomial 

distribution with a mean 30 years and a standard deviation of 5 years, 95% of AFRs are between 

21 years and 41 years. These values were deemed reasonable by the experts. For computing the 

mean and variance for each stage of juveniles, i.e., oceanic and neritic, we used the same 

coefficient of variation (CV = 5/30 = 0.17). For example, if juveniles of a DPS spend 15 years in 

oceanic and 14 years in neritic habitat, standard deviations for these stages are 2.6 and 2.4, 

respectively. We conducted a sensitivity analysis to evaluate the effects of these parameters on 

our conclusions. 
55

The stage-based model requires estimates for stage-specific fertility, mean and variance of 

durations of juvenile stages, and survival rates. Information from various sources provided data 

for fertility and hatching success of eggs (Table 1). The post-breeding census model was used 

for computing the fertility. 

The DPS-specific matrices (A) have the following basic format: 

⎥

⎥

⎥

⎥

⎥

⎥

⎥

⎥

⎥

⎦

⎤

⎢

⎢

⎢

⎢

⎢

⎢

⎢

⎢

⎢

⎣

⎡

−

−

−

A

A

p

p

p

p

p

p

ffp

φφ

φ

φ

φ

φ

φ φ

φφ

22

22

22

22

11

0 11

22

0

0 0)1(

0 0

00 0)1(

0

0)1( 00

000 0

LMMM

MMM O

MM O M

O MM

MMMLO

ML

L

, 

where φ is survival rate, p is transition probability, f is the fertility (i.e., the number of female 

hatchlings that emerge per adult female), and subscripts indicate the first year (0), oceanic 

juveniles (1), neritic juveniles, (2), and adults (A). The numbers of sub-stages for juveniles vary 

according to the NBSD model described previously. 

For survival rates, the vast majority of information comes from studies at nesting beaches, where 

hatching success (egg survival) is evaluated routinely. However, the incubation period consists 

of only approximately 6.5 weeks of the first year (Miller et al. 2003). Consequently, the total 

survival rate during the first year of their life is still unavailable. In the past, 0.4 was used for the 

Kemp’s ridley turtle (Lepidochelys kempii), based on a model fit to the observed numbers of 

nests and hatchling production for that species (Heppell et al. 2005). Because of the 

morphological and behavioral similarities between the two species during the first year, we use 

the same survival rate for loggerhead turtles. Adult survival rates have been estimated for some 

loggerhead DPSs. Studies have indicated that the survival rates of adult loggerhead turtles are 

generally greater than 0.8/yr (0.81; Frazer 1983, 0.88; Chaloupka and Limpus 2002, 0.85; 

Hedges 2007). These estimates, however, likely include anthropogenic mortalities. 

Consequently, the available estimates are negatively biased as the natural survival rate. 

Similarly for juveniles, available estimates for juvenile survival rates include anthropogenic 

mortality rates (Bjorndal et al. 2003b, Braun-McNeill et al. 2007b, Sasso and Epperly 2007). 

The relationship between possible ranges of juvenile survival rates and maximum population 

growth rates was evaluated graphically. The asymptotic population growth rate of a stage-based 

matrix model is a function of fertility, survival rates, and transition probabilities. Consequently, 

the relationship among the average juvenile survival rates, first year survival rates, and dominant 

eigenvalues can be plotted. Similar approaches have been used to evaluate the relationships 

among juvenile survival rates, adult survival rates, fecundity, and average age at sexual maturity 

for the Blanding’s turtle (Emydoidea blandingii; Congdon et al. 1993). We considered adult 

survival rates from 0.80 to 0.99 per year, juvenile survival rates from 0.70 to 0.95 per year, and 

the first year survival from 0.01 to 0.50 per year. To constrain the parameter space, we made an 
56

assumption that the average juvenile survival rate was less than the average adult survival rate. 

Examinations of relationships among these parameters allowed us to find the plausible maximum 

population growth rate (λ). 

To compute the juvenile survival rates, a numerical minimization method was used. By fixing 

the dominant eigenvalue (λ0), the first year survival rate, adult survival rate, and fertility, the 

following equation was solved for two juvenile survival rates with the constraint that the oceanic 

juvenile survival rate (φ1) is less than the neritic juvenile survival rate (φ2): 

)(),( f λφφ 021 −= eig A , 

where eig() is the characteristic equation to find the dominant eigenvalue of a matrix A and | | is 

the absolute value. The general form of the matrix A was shown previously. 

In this analysis, several life history parameters were determined from experts’ knowledge or 

based on estimates from small sample sizes (SD of AFR, AFR, proportion of time spent in 

particular habitat). To determine how these parameters would affect the result of the analysis, 

sensitivity analyses were conducted. Results of these sensitivity analyses are provided as 

supplemental material (Section 4.6). 

4.3.3. Quantifying Known Threats 

We quantified experts’ knowledge about the existing anthropogenic threats on loggerhead turtles, 

which subsequently were combined with the projection model described in the previous section 

(see Tables 3-11 in Sections 4.4.2.1.-4.4.2.9. for the results of the experts’ threats assessments; 

also consult the excel file posted on the NMFS Office of Protected Resources website 

[http://www.nmfs.noaa.gov/pr/species/statusreviews.htm] to access information used to derive 

the estimated threats levels). Because the levels of the existing anthropogenic threats differ 

among habitats (e.g., high seas vs. coastal oceanic shelf), juveniles and adults were further 

separated into neritic and oceanic stages. Threats, therefore, were determined for the following 

six stages: (1) eggs/hatchlings, (2) neritic juveniles, (3) oceanic juveniles, (4) neritic adults, (5) 

oceanic adults, and (6) nesting females. For each of the following four factors, experts were 

asked to categorize known threats for each stage in high, medium, low, or very low, according to 

the level of additional annual mortality (m), where high = 0.20 < m ≤ 0.25, medium = 0.10 < m ≤

0.20, low = 0.01 < m ≤ 0.10, and very low = 0≤ m ≤ 0.01. The four factors are: 

• The present or threatened, destruction, modification, or curtailment of its habitat or range 

(habitat). 

• Overutilization for commercial, recreational, scientific, or educational purposes 

(overuse). 

• Disease or predation. 

• Other natural or manmade factors affecting its continued existence (other). 

The estimated threat levels were based on the best information available. Justifications and 

references for each threat are provided in Section 4.4.2. and in the online threats matrix 

spreadsheets. 
57

These four factors corresponded to four of the five factors in section 4(a)(1) of the ESA. 

Another factor (inadequacy of existing regulatory mechanisms) was excluded from this analysis 

because the effects of the factor were not considered to be reducing the survival rates of 

loggerhead turtles directly. 

For two DPSs (South Pacific and North Pacific), experts were not able to distinguish 

anthropogenic mortalities from the natural mortalities. In other words, the provided mortalities 

included natural and anthropogenic mortalities. Consequently, anthropogenic mortalities were 

computed using the assumed base matrix model for each DPS, which was described in the 

previous section. Let mn = annual natural mortality, ma = annual anthropogenic mortality, and m

= annual total mortality. In the discrete time scale, the total mortality is: 

 ) 1)(1(1 m = − − a − mm n . (6) 

Consequently, the annual anthropogenic mortality can be computed from the total and natural 

mortalities: 

1

1 1 −

− +=

n

a m

m

m (7) 

To use these threat levels in calculations, we used the range limits of mortality values. For 

example, when the effect of a factor to a stage is categorized as ‘Low,’ 0.01 and 0.10 were used 

in the calculations as the lower and upper limits, respectively. To compute the total mortality, 

mortalities from four factors were summed, which bounded the upper limit of “High” at 0.25 so 

that the sum would not exceed one. The use of lower and upper limits provided the best and 

worst case scenarios. The best case scenario was given by the sum of lower limits, whereas the 

upper limits were used to compute the worst case scenario. 

For the three adult stages, threats for three habitats (neritic, oceanic, and nesting) were pooled to 

conform to the projection model. Because adult loggerhead turtles may use multiple habitats 

within a year, where they are exposed to different threats, we computed the total annual 

anthropogenic mortality rate from a threat table using the following two equations. During a 

nesting year, the total anthropogenic mortality of nesting females is: 

 ) 1()1()1(1 , ,

,

lterrestria

adult

oceanic T

adult

neritic T

madult nesting madult m m nestingN nestingO −−= − − . (8) 

where madult,nesting = annual anthropogenic mortality rate for adult females during the nesting year, 

h

madult = annual adult anthropogenic mortality in the habitat h from a threat table, where h is 

either oceanic, neritic, or nesting, and TN,j, and TO,j are the average durations in years adult 

loggerhead turtles spend their time annually in neritic and oceanic habitats in years, respectively, 

and j is either nesting or non-nesting. The total anthropogenic mortality rate during a nonnesting year is: 

nonN nesting oceanic T nonO nesting

adult

neritic T

m nonadult nesting madult m − −

− −−= − , ,, )1()1(1 , (9) 
58

Finally, with an estimated mean remigration interval (R), we calculated the average annual 

anthropogenic mortality rate of adults by: 

( ) ( ) )1(

, , 11 1 + −−= − − Radult nesting

R

madult m nonadult nesting m . (10) 

Using the pre-defined mortality thresholds for each level of threats (very low, low, medium, and 

high), the total anthropogenic mortalities were computed for each of six stages. Although these 

thresholds may not represent the actual mortalities and may overestimate the anthropogenic 

mortalities, comparisons of mortalities among life stages within a DPS, as well as comparisons 

of mortalities among DPSs of a life stage, were conducted to provide relative severity of 

anthropogenic mortalities among life stages. Finally, to evaluate the effects of these additional 

anthropogenic mortalities on a DPS, these additional mortality rates were combined with the 

base matrix model and annual mortality rates for all stage classes computed. 

4.3.4. Combining Additional Mortalities and the Base Population Model 

Anthropogenic mortalities, quantified by the methods described in the previous section, were 

combined with the base population model (A) from the first section via the “harvest” model 

described in Caswell (2001; Chapter 18). In the harvest model, the proportion of each stage 

group that survives the harvest is used to construct a “harvest matrix.” Because many of these 

anthropogenic threats to loggerhead turtle DPSs are not considered as harvest for human 

consumptions, we call them “threat survival matrices.” A threat survival matrix and the base 

population model for each DPS are multiplied together to construct a projection model with 

anthropogenic mortalities (Caswell 2001). 

A threat survival matrix is a diagonal matrix: S = diag(s1, ..., sc), where si is the proportion of 

stage i surviving the threats (si = 1 – μi) and c is the number of stages. We assume a linear 

model: 

 ) n t + = SAn()1( t , (11) 

where t indicates time and n is a vector of stage-specific abundances (Caswell 2001). The 

dominant eigenvalue of SA (λ) is the asymptotic growth rate of the population with additional 

anthropogenic mortalities. Using the ranges of anthropogenic mortalities for each threat matrix, 

we computed the best (λB) and worst (λW) case scenarios of the dominant eigenvalues for each 

DPS, using the lower and upper limits of threat levels, respectively. 

Finally, we provide the proportion of λ > 1.0 in percent (Pλ), which is computed by Pλ = 100×(λB

– 1.0)/( λB - λW), when λB > 1.0, and Pλ = 0.0, when λB ≤ 1.0. This metric (Pλ) is a function of 

several components; the assumed maximum population growth rate, assumed life history 

parameters, thresholds of threat levels, and state of knowledge about precision of the existing 

threats. Assumed life history parameters and the maximum population growth rate define how 

much additional mortalities can be tolerated before the dominant eigenvalue becomes < 1.0. 

Assumed natural survival rates of various life stages can affect the computed proportion; stages 

with high natural survival rates and low reproductive values can tolerate greater additional 
59

mortalities than those with low natural survival rates and high reproductive values. Changes in 

threshold values of threat matrices also can change the results. If the thresholds for each threat 

level were decreased, e.g., 0.01 to 0.05 for low, rather than from 0.01 to 0.10 and so forth for 

other levels, the difference between λB and λW would decrease and the proportion would increase. 

Decreasing the uncertainty in additional mortalities would also decrease the difference (and 

increase the proportion). Consequently, Pλ can be considered as an index of the future 

population health, where it ranges from 0 to 100, conditional on the specific assumptions. The 

management goal for each DPS is to maximize Pλ, which may be attained by reducing additional 

mortalities and increasing the precisions of estimated life history parameters and additional 

mortalities. 

To determine how a “very low” level of threats may affect the computations of the population 

growth rate, an analysis was conducted with all threat categories set to “very low.” This analysis 

provided the baseline with which the other results can be compared. Because experts’ opinions 

on mortalities were provided either with natural mortality (South Pacific and North Pacific) or 

without natural mortality, the effect of this difference also was determined with analysis using 

this hypothetical threat matrix. 

4.4. Results 

4.4.1. Results—Base Population Model 

For plausible ranges of adult survival rates (0.80-0.99/yr), first year survival rates (0.01-0.50/yr), 

and juvenile survival rates (0.70-0.95/yr), the maximum population growth rates appeared to be 

less than 10%/yr for all DPSs. We found many combinations of the parameters to be unlikely 

because of the necessarily high average juvenile survival rates (Figures 11-17). 

Except for the Mediterranean Sea DPS (Figure 16), differences among DPSs were negligible. 

This exception was due to the differences in fertility parameters, where the Mediterranean Sea 

DPS had low average eggs per clutch (95 eggs per clutch) and low number of clutches per 

female (2, Table 1). 

Parameters that defined habitat use were similar among all DPSs, except the North Pacific Ocean 

DPS (Table 1). For the North Pacific Ocean DPS, the proportion of time juveniles spend in the 

neritic habitat (off the coast of Baja Peninsula, Mexico, and in coastal areas of the western 

Pacific) was less (14%) than for other DPSs (50-65.5%). The difference for this DPS comes 

from the experts’ opinions that a large proportion of the juvenile loggerhead turtles of this DPS 

remain in the pelagic habitat. Further, those juveniles along the coast of Baja Peninsula are 

thought to remain in the area for many years. 

As expected, the sensitivity analysis indicated the change in the mean AFR can affect the 

relationship among the survival rates and asymptotic population growth rates (Supplemental 

Figures S1-S7). For the same value of CV, older age at first reproduction resulted in higher 

average survival rates of juveniles and adults to sustain an asymptotic population growth rate. 

Effects of CVs were less than those of the mean AFR. For the following analyses, we use the 

mean AFR = 30 and CV = 0.17 (or SD of AFR = 5 years). 
60

Figure 11. Relationships among adult survival rate, juvenile survival rate, first year survival rate, 

and the dominant eigenvalue for the North Pacific Ocean DPS. Contour lines indicate the 

dominant eigenvalues, whereas the diagonal lines indicate equal annual survival rates between 

juveniles and adults. Dashed horizontal lines indicate the assumed adult survival rate for the 

base matrix model. The mean age at first reproduction was assumed at 30 and its standard 

deviation 5. 
61

Figure 12. Relationships among adult survival rate, juvenile survival rate, first year survival rate, 

and the dominant eigenvalue for the South Pacific Ocean DPS. Contour lines indicate the 

dominant eigenvalues, whereas the diagonal lines indicate equal annual survival rates between 

juveniles and adults. Dashed horizontal lines indicate the assumed adult survival rate for the 

base matrix model. The mean age at first reproduction was assumed at 30 and its standard 

deviation 5. 
62

Figure 13. Relationships among adult survival rate, juvenile survival rate, first year 

survival rate, and the dominant eigenvalue for the North Indian Ocean, Southeast Indo-Pacific 

Ocean, and Southwest Indian Ocean DPSs. Contour lines indicate the dominant eigenvalues, 

whereas the diagonal lines indicate equal annual survival rates between juveniles and adults. 

Dashed horizontal lines indicate the assumed adult survival rate for the base matrix model. The 

mean age at first reproduction was assumed at 30 and its standard deviation 5. 
63

Figure 14. Relationships among adult survival rate, juvenile survival rate, first year survival rate, 

and the dominant eigenvalue for the Northwest Atlantic Ocean DPS. Contour lines indicate the 

dominant eigenvalues, whereas the diagonal lines indicate equal annual survival rates between 

juveniles and adults. Dashed horizontal lines indicate the assumed adult survival rate for the 

base matrix model. The mean age at first reproduction was assumed at 30 and its standard 

deviation 5. 
64

Figure 15. Relationships among adult survival rate, juvenile survival rate, total first year 

survival rate, and the dominant eigenvalue for the Northeast Atlantic Ocean DPS. Contour lines 

indicate the dominant eigenvalues, whereas the diagonal lines indicate equal annual survival 

rates between juveniles and adults. Dashed horizontal lines indicate the assumed adult survival 

rate for the base matrix model. The mean age at first reproduction was assumed at 30 and its 

standard deviation 5. 
65

Figure 16. Relationships among adult survival rate, juvenile survival rate, first year survival rate, 

and the dominant eigenvalue for the Mediterranean Sea DPS. Contour lines indicate the 

dominant eigenvalues, whereas the diagonal lines indicate equal annual survival rates between 

juveniles and adults. Dashed horizontal lines indicate the assumed adult survival rate for the 

base matrix model. The mean age at first reproduction was assumed at 30 and its standard 

deviation 5. 
66

Figure 17. Relationships among adult survival rate, juvenile survival rate, first year survival rate, 

and the dominant eigenvalue for the South Atlantic Ocean DPS. Contour lines indicate the 

dominant eigenvalues, whereas the diagonal lines indicate equal annual survival rates between 

juveniles and adults. Dashed horizontal lines indicate the assumed adult survival rate for the 

base matrix model. The mean age at first reproduction was assumed at 30 and its standard 

deviation 5. 
67

4.4.2. Results—Threat Matrix 

This analysis indicated potential overestimations by the experts of anthropogenic mortalities 

(Tables 3-11). The threat matrices indicated that many DPSs might be in critical condition with 

high mortalities for all stages. One reviewer suggested using a different set of mortality 

thresholds for building the threat matrices. The suggested change, however, was arbitrary and 

expresses a false sense of certainty, although our matrices may provide a false sense of urgency. 

Because our threat levels were determined from available information on anthropogenic 

mortalities and abundance of loggerhead turtles, we retained the thresholds. The potential 

implications of the differences in opinions will be discussed later. In the following nine 

subsections, we provide threat levels for six life stages of each DPS based on available 

information and experts’ opinions. We also provide evidence for each threat. Further, using the 

threshold values presented previously, we provide numerical values as sums of all threats for 

each life stage under the four categories. 
68

4.4.2.1. North Pacific Ocean DPS 

For the North Pacific Ocean DPS, the greatest anthropogenic threats exist for the neritic 

juveniles and neritic adults, where the coastal fisheries in Baja California, Mexico, and Japan kill 

significant number of turtles (Table 3) (Kamezaki et al. 2003, Peckham et al. 2007). A large 

number of loggerhead turtles (~1,000 annually) die in Baja bottom-set gillnet/longline fisheries 

(Koch et al. 2006, Peckham et al. 2007, Peckham et al. 2008). Fishery bycatch also is present in 

West Pacific neritic foraging areas (Cheng and Chen 1997). Recent investigations show a major 

threat off coastal Japan due to pound net fisheries (T. Ishihara, Sea Turtle Association of Japan, 

personal communication, 2007). Coastal development, such as the building of seawalls, erosion 

control structures, beachfront lighting, vehicular and pedestrian traffic, sand extraction, beach 

pollution, removal of native vegetation, and planting of non-native vegetation, has resulted in 

reduction of available habitat for the eggs and hatchlings of this DPS (Suganuma 2002, 

Kamezaki et al. 2003, Kudo et al. 2003). Beach debris also contributes to deaths of hatchlings 

and nesting adults (H. Peckham, ProPeninsula, personal communication, 2009). Although no 

quantitative studies have been conducted, low hatching success has been documented at 

important nesting beaches in recent years. Threat levels for this DPS include anthropogenic and 

natural mortalities. 

Table 3. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the North Pacific Ocean DPS. Threat levels were estimated by life stages and habitats, 

and were grouped into four categories based on four of the five factors in section 4(a)(1) of the 

ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from this 

analysis because the effects of the factor were not considered to be reducing the survival rates 

directly. The column with “Best” indicates the total mortality using the lowest threshold values 

for all factors, whereas the column with “Worst” indicates the total mortality using the highest 

threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings M VL L M 0.21 0.51 

Neritic juveniles L L L M 0.13 0.50 

Oceanic juveniles VL L VL L 0.02 0.22 

Neritic adults L L VL M 0.12 0.41 

Oceanic adults VL VL L L 0.02 0.22 

Nesting females VL VL VL VL 0.00 0.04 
69

4.4.2.2. South Pacific Ocean DPS 

For the South Pacific Ocean DPS, the greatest threats come from bycatch in the oceanic 

environment for juveniles and adults (Table 4). Threats from numerous fisheries have been 

reported (Limpus and Reimer 1994; Poiner and Harris 1996; Robins et al. 2002a, b; Kelez et al. 

2003; Alfaro-Shigueto et al. 2006; Donoso and Dutton 2006; Alfaro-Shigueto et al. 2008b; 

Limpus 2009). At nesting beaches, an average of 40 adult females are taken annually in 

aboriginal harvest (Limpus 2009). Threat levels for this DPS include anthropogenic and natural 

mortalities. 

Table 4. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the South Pacific Ocean DPS. Threat levels were estimated by life stages and habitats, 

and were grouped into four categories based on four of the five factors in section 4(a)(1) of the 

ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from this 

analysis because the effects of the factor were not considered to be reducing the survival rates 

directly. The column with “Best” indicates the total mortality using the lowest threshold values 

for all factors, whereas the column with “Worst” indicates the total mortality using the highest 

threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings L L L L 0.04 0.40 

Neritic juveniles L L L L 0.04 0.40 

Oceanic juveniles VL VL VL M 0.10 0.23 

Neritic adults L L L L 0.04 0.40 

Oceanic adults VL VL L M 0.11 0.32 

Nesting females VL M VL VL 0.10 0.23 
70

4.4.2.3. North Indian Ocean DPS 

Threat levels for the North Indian Ocean DPS were “very low” to “low” for all factors except for 

the fourth factor (“other”) in the neritic environment (Table 5). The relatively high mortalities in 

the neritic environment result from fishery bycatch. Consistent low threats across all factors for 

eggs and hatchlings may affect a significant portion of this stage. These threats include coastal 

development and light pollution, beach habitat degradation from overgrazing and beach driving, 

and bycatch from coastal fisheries. 

Table 5. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the North Indian Ocean DPS. Threat levels were estimated by life stages and habitats, 

and were grouped into four categories based on four of the five factors in section 4(a)(1) of the 

ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from this 

analysis because the effects of the factor were not considered to be reducing the survival rates 

directly. The column with “Best” indicates the total mortality using the lowest threshold values 

for all factors, whereas the column with “Worst” indicates the total mortality using the highest 

threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings L L L L 0.04 0.40 

Neritic juveniles L VL/L L M 0.12 0.41 

Oceanic juveniles VL VL VL L 0.01 0.13 

Neritic adults L VL/L L M 0.12 0.41 

Oceanic adults VL VL VL L 0.01 0.13 

Nesting females L VL VL L 0.02 0.22 
71

4.4.2.4. Southeast Indo-Pacific Ocean DPS 

Anthropogenic effects are very low to low at all life stages for the Southeast Indo-Pacific Ocean 

DPS (Table 6). Cumulatively, however, a large proportion of eggs and hatchlings (~30%) may 

be affected by human activities.

Table 6. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the Southeast Indo-Pacific Ocean DPS. Threat levels were estimated by life stages and 

habitats, and were grouped into four categories based on four of the five factors in section 4(a)(1) 

of the ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from 

this analysis because the effects of the factor were not considered to be reducing the survival 

rates directly. The column with “Best” indicates the total mortality using the lowest threshold 

values for all factors, whereas the column with “Worst” indicates the total mortality using the 

highest threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings VL/L VL L L 0.02 0.31 

Neritic juveniles L VL VL L 0.02 0.22 

Oceanic juveniles VL VL VL L 0.01 0.13 

Neritic adults L VL VL L 0.02 0.22 

Oceanic adults VL VL VL L 0.01 0.13 

Nesting females VL VL VL VL 0.00 0.04 
72

4.4.2.5. Southwest Indian Ocean DPS 

For the Southwest Indian Ocean DPS, wide ranges of total mortalities were found for 

eggs/hatchlings, neritic juveniles, and neritic adults (Table 7). These wide ranges result from 

conservative estimation based on limited information on anthropogenic mortalities. 

Table 7. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the Southwest Indian Ocean DPS. Threat levels were estimated by life stages and 

habitats, and were grouped into four categories based on four of the five factors in section 4(a)(1) 

of the ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from 

this analysis because the effects of the factor were not considered to be reducing the survival 

rates directly. The column with “Best” indicates the total mortality using the lowest threshold 

values for all factors, whereas the column with “Worst” indicates the total mortality using the 

highest threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings VL/L L L L 0.03 0.40 

Neritic juveniles L VL/L VL L/M 0.02 0.40 

Oceanic juveniles VL VL VL L 0.01 0.13 

Neritic adults L VL/L VL L/M 0.02 0.41 

Oceanic adults VL VL VL L 0.01 0.13 

Nesting females VL VL VL VL 0.00 0.04 
73

4.4.2.6. Northwest Atlantic Ocean DPS 

High cumulative threat levels were estimated for neritic and oceanic juveniles and neritic and 

oceanic adults (Table 8). These mortalities primarily result from fishery bycatch. Significant 

mortality occurs in longline fisheries, bottom and mid-water trawl fisheries, dredge fisheries, 

gillnet fisheries, and pot/trap fisheries. Although total mortality from all fisheries has not been 

estimated, the combined mortalities are likely significant. Entanglement in marine debris is an 

additional threat. Further, boat strikes are another growing anthropogenic source of mortality in 

neritic waters (NMFS, unpublished data; Florida Fish and Wildlife Conservation Commission, 

unpublished data). 

Table 8. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the Northwest Atlantic Ocean DPS. Threat levels were estimated by life stages and 

habitats, and were grouped into four categories based on four of the five factors in section 4(a)(1) 

of the ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from 

this analysis because the effects of the factor were not considered to be reducing the survival 

rates directly. The column with “Best” indicates the total mortality using the lowest threshold 

values for all factors, whereas the column with “Worst” indicates the total mortality using the 

highest threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings L VL L L 0.03 0.31 

Neritic juveniles L L L M 0.13 0.50 

Oceanic juveniles VL VL VL M/H 0.10 0.28 

Neritic adults L L L M 0.13 0.50 

Oceanic adults VL VL VL M/H 0.10 0.28 

Nesting females VL VL VL VL 0.00 0.04 
74

4.4.2.7. Northeast Atlantic Ocean DPS 

For the Northeast Atlantic Ocean DPS, relatively high threats are reported for terrestrial, neritic, 

and oceanic habitats (Table 9). The largest source of anthropogenic mortality is deliberate 

hunting of nesting females. Other threats include harvest of eggs and hatchlings, incidental 

capture, particularly in fisheries, propeller and boat strikes, exposure to hydrocarbons, marine 

debris ingestion, and bioaccumulation of metals (see Section 5.2.7.). Sand mining has impacted 

the terrestrial habitats in some areas and changes in trophic structure likely have occurred in both 

the neritic and oceanic environments of the region. Shifts in ocean currents, and ecosystem 

shifts in prey distribution and abundance, could occur with climate change. 

Table 9. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the Northeast Atlantic Ocean DPS. Threat levels were estimated by life stages and 

habitats, and were grouped into four categories based on four of the five factors in section 4(a)(1) 

of the ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from 

this analysis because the effects of the factor were not considered to be reducing the survival 

rates directly. The column with “Best” indicates the total mortality using the lowest threshold 

values for all factors, whereas the column with “Worst” indicates the total mortality using the 

highest threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings L L VL L 0.03 0.31 

Neritic juveniles L L VL M 0.12 0.41 

Oceanic juveniles VL VL VL M/H 0.10 0.28 

Neritic adults L L VL M 0.12 0.41 

Oceanic adults VL VL VL M/H 0.10 0.28 

Nesting females VL H VL L 0.21 0.37 
75

4.4.2.8. Mediterranean Sea DPS 

Fishery bycatch was determined to be the greatest threat for the Mediterranean Sea DPS (Table 

10). For neritic and oceanic juveniles and adults, these threats were considered to be “medium” 

or “high.” Bycatch of juveniles and adults in trawl, pelagic and bottom longline, set net (gillnet 

and trammel nets), and driftnet fisheries is considered significant (Laurent 1991, Argano et al. 

1992, Di Natale 1995, Lazar and Tvrtkovic 1995, Laurent et al. 1996, Camiñas 1997, Gerosa and 

Casale 1999, Silvani et al. 1999, Lazar et al. 2000, Laurent et al. 2001, Camiñas 2004, Carreras 

et al. 2004, Casale et al. 2004, Tudela et al. 2005, Casale et al. 2007a, Jribi et al. 2007, Casale 

2008). See Section 5.2.8.5. for capture levels/citations. Other notable concerns are 

pollution/debris and vessel collisions. The other significant threat comes from habitat 

destruction that affects eggs and hatchlings at nesting beaches. 

Table 10. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the Mediterranean Sea DPS. Threat levels were estimated by life stages and habitats, 

and were grouped into four categories based on four of the five factors in section 4(a)(1) of the 

ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from this 

analysis because the effects of the factor were not considered to be reducing the survival rates 

directly. The column with “Best” indicates the total mortality using the lowest threshold values 

for all factors, whereas the column with “Worst” indicates the total mortality using the highest 

threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings M L L L 0.13 0.50 

Neritic juveniles L L VL M/H 0.12 0.46 

Oceanic juveniles VL L VL M/H 0.11 0.37 

Neritic adults L L L M/H 0.13 0.55 

Oceanic adults VL L VL M/H 0.11 0.37 

Nesting females VL L VL VL 0.01 0.13 
76

4.4.2.9. South Atlantic Ocean DPS 

Significant anthropogenic threats exist for juvenile stages of the South Atlantic Ocean DPS 

(Table 11). For these stages, the most significant factor is fishing bycatch, where coastal and 

oceanic fishery operations interact with loggerheads in the area (Bugoni et al. 2008). Further, 

bycatch in longline fisheries appear to have significant effects on juvenile loggerhead turtles in 

the high seas (Pinedo and Polacheck 2004, Kotas et al. 2004). 

Table 11. Estimated levels and quantification of anthropogenic threats affecting loggerhead 

turtles in the South Atlantic Ocean DPS. Threat levels were estimated by life stages and habitats, 

and were grouped into four categories based on four of the five factors in section 4(a)(1) of the 

ESA. Another factor (inadequacy of existing regulatory mechanisms) was excluded from this 

analysis because the effects of the factor were not considered to be reducing the survival rates 

directly. The column with “Best” indicates the total mortality using the lowest threshold values 

for all factors, whereas the column with “Worst” indicates the total mortality using the highest 

threshold value for all factors. 

Habitat Overuse Disease/ 

Predation Other Best Worst 

Eggs/hatchlings L L VL L 0.03 0.31 

Neritic juveniles L VL L M 0.12 0.41 

Oceanic juveniles VL VL L H 0.21 0.37 

Neritic adults L VL L L 0.03 0.31 

Oceanic adults VL VL L L 0.02 0.22 

Nesting females VL VL VL VL 0.00 0.04 
77

Although the experts were asked to provide qualitative threat levels (very low, low, medium, or 

high) based on threshold values for each level (see Section 4.3.3 for details), it was sometimes a 

difficult task to assign an anthropogenic mortality level to a particular stage class when few or no 

quantitative data existed. Because precise estimates of anthropogenic mortalities do not exist, 

we used the precautionary principle for characterizing the threat level based on best available 

information and/or expert opinion. 

Even though threats were expressed in a qualitative manner, every entry was derived from 

available data and experts’ knowledge. The compilation of known threats for all DPSs provided 

an opportunity to evaluate the potential negative impacts of these threats on each DPS in the 

future. Regardless of the threshold values for each threat level (per suggestion of a reviewer), 

comparisons among life stages within a DPS, as well as comparisons of a life stage among DPSs, 

are meaningful. For example, the North Pacific Ocean and Mediterranean Sea DPSs were shown 

to have high anthropogenic mortalities for the eggs and hatchling stage, relative to other DPSs. 

Within the North Pacific Ocean DPS, for another example, neritic habitats (along the west coast 

of Baja California, Mexico, and the nearshore waters of Japan) indicated greater anthropogenic 

mortalities than other life stages. Finally, the indices of DPS health (λ and Pλ) also provided 

metrics that combined the status and uncertainty of threats levels for each DPS. Interpretations 

of these indices in terms of the DPS status are explained in the following section. 

4.4.3. DPS Status 

The analysis with a hypothetical threat matrix with all threat categories set to “very low” 

indicated the obvious effects of combining anthropogenic and natural mortalities in a threat 

matrix. For those threat matrices of DPSs that included natural mortalities (North Pacific and 

South Pacific), computed anthropogenic mortalities were necessarily less than the assumed 

thresholds. Consequently, ranges of possible λ values for those DPSs were less than those DPSs 

that included only anthropogenic mortalities in their threat matrices (Figures 18 and 19). Even 

when all threat levels were set at “very low,” Pλ was not 100% for the DPSs that included only 

anthropogenic mortalities in the threat matrices and the assumed maximum population growth 

rate was 5% annum (Figure 18). “Very low,” therefore, may not have been an appropriate term 

for this category. As it was stated in the method section, management decisions should focus on 

maximizing Pλ. 
78

Figure 18. Ranges of dominant eigenvalues for nine DPSs when anthropogenic mortalities were 

considered to be “very low” for all factors and the maximum natural population growth rates 

were assumed to be 5% per year (λ0 = 1.05). The mean age at first reproduction (AFR) was 

assumed to be 30 years and its standard deviation (SD) 5. The values above the dotted line 

indicates the proportion of the bars that are above λ = 1.0 (Pλ) 
79

Figure 19. Ranges of dominant eigenvalues for nine DPSs when anthropogenic mortalities were 

considered to be “very low” for all factors and the maximum natural population growth rates 

were assumed to be 10% per year (λ0 = 1.10). The mean age at first reproduction (AFR) was 

assumed to be 30 years and its standard deviation (SD) 5. The values above the dotted line 

indicates the proportion of the bars that are above λ = 1.0 (Pλ). 
80

For computing Pλ, the BRT did not consider functional forms of threat levels. In other words, all 

values between the best and worst case scenarios were considered equally likely. This 

assumption was fundamental for computing the proportion of λ > 1.0. With more information on 

threat levels, it may be possible to assign particular distributions to these threat levels, thereby 

increasing the precision and accuracy of Pλ. 

Among the nine DPSs in this analysis, an index of future population health (Pλ = the proportion 

of λ > 1.0) was 0 for North Indian Ocean, Northwest Atlantic Ocean, Northeast Atlantic Ocean, 

Mediterranean Sea, and South Atlantic Ocean DPSs, when the maximum population growth rate 

was assumed to be 5% per year (Figure 20). Even if the maximum population growth rate was 

10% per year, Pλ for the Northwest Atlantic Ocean, Northeast Atlantic Ocean, Mediterranean 

Sea, and South Atlantic Ocean DPSs was zero (Figure 21). When the maximum population 

growth rate was assumed to be 5% per year (Figure 20), Pλ ranged from 0.0% to 16.9% (North 

Pacific Ocean DPS). The large value for the North Pacific Ocean DPS is caused by precise 

estimates of threats for the DPS, where the length of the bar is less than for the other DPSs. For 

those DPSs that had Pλ = 0 when the maximum population growth rate was assumed to be 5% 

per year, only the North Indian Ocean DPS resulted in Pλ > 0 when the maximum population 

growth rate was assumed to be 10% per year. Pλ ranged from 0.0% to 40.4% (Southeast IndoPacific Ocean DPS), when the maximum population growth rate was assumed to be 10% per 

year (Figure 21). According to Pλ, all DPSs are faced with a potential decline in the future due to 

the existing additional mortalities, relative to the assumed natural survival rates and fertility. 
81

Figure 20. Ranges of dominant eigenvalues for nine DPSs with anthropogenic mortalities that 

were provided by the experts. For this figure, the maximum population growth rates for all DPSs 

were assumed to be 5% per year (λ0 = 1.05). The mean age at first reproduction (AFR) was 

assumed to be 30 years and its standard deviation (SD) 5. The values above the dotted line 

indicates the proportion of the bars that are above λ = 1.0 (Pλ). 
82

Figure 21. Ranges of dominant eigenvalues for nine DPSs with anthropogenic mortalities that 

were provided by the experts. For this figure, the maximum population growth rates for all DPSs 

were assumed to be 10% per year (λ0 = 1.10). The mean age at first reproduction (AFR) was 

assumed to be 30 years and its standard deviation (SD) 5. The values above the dotted line 

indicates the proportion of the bars that are above λ = 1.0 (Pλ). 
83

4.5. Synthesis 

For three of five DPSs with sufficient data to conduct the SQE analysis (Northwest Atlantic 

Ocean, South Pacific Ocean, and North Pacific Ocean), the threshold of SQE = 0.3 was reached 

at QET < 0.3, indicating high likelihood of quasi-extinction over a wide range of QET values. 

Similarly, the threat matrix analysis indicated that all other DPSs have the potential for a severe 

decline in the future (Figures 20 and 21). There were not enough data to conduct the SQE 

analysis for the Northeast Atlantic Ocean, Mediterranean Sea, North Indian Ocean, and 

Southeast Indo-Pacific Ocean DPSs. 

It should be noted that the SQE analysis is based on nesting beach trend data. Trends at nesting 

beaches are often used to assess the status of marine turtle populations, because nesting beach 

studies are usually more easily implemented than in-water studies and, in many cases, have been 

ongoing for many years. However, because of the protracted age to maturity in marine turtles, 

mortality that is acting on younger life stages will not yet be reflected in nest or nesting female 

trends, and may take many years to be detected at the nesting beach. Conversely, mortality 

acting on older life stages, including adults, will be reflected more rapidly in nest or nesting 

female trends at nesting beaches. The SQE approach does not incorporate different mortalities 

among life stages. The threat matrix approach was used to determine effects of known 

anthropogenic mortalities on each DPS. 

According to the threat matrix analysis, using experts’ opinions in the matrix model framework, 

all loggerhead turtle DPSs have the potential to decline in the future. Although some DPSs are 

indicating increasing trends at nesting beaches (Southwest Indian Ocean and South Atlantic 

Ocean), available information about anthropogenic threats to juveniles and adults in neritic and 

oceanic environments indicate possible unsustainable additional mortalities (Figures 20 and 21). 

According to the threat matrix analysis, the potential for future decline is greatest for the North 

Indian Ocean, Northwest Atlantic Ocean, Northeast Atlantic Ocean, Mediterranean Sea, and 

South Atlantic Ocean DPSs. We emphasize, however, that these indices were used to measure 

the negative effects of known anthropogenic mortalities on the overall health of each DPS and 

not to estimate the actual population growth rates of these DPSs. 

Our approach to the risk analysis presented several important points. First, the lack of precise 

estimates of age at first reproduction hindered precise assessment of the status of any DPS. 

Within the range of possible ages at first reproduction of the species, however, some DPSs could 

decline rapidly regardless of the exact age at first reproduction because of high anthropogenic 

mortality. 

Second, the lack of precise estimates of anthropogenic mortalities resulted in a wide range of 

possible status. For the best case scenario, a DPS may be healthy, whereas the same DPS may 

be considered as declining rapidly for the worst case scenario (Figures 20 and 21). The precise 

prognosis of each DPS relies on obtaining precise estimate of anthropogenic mortality and vital 

rates. 

Third, the assessment of a population without the information on natural and anthropogenic 

mortalities is difficult. Because of the longevity of the species, loggerhead turtles require high 
84

survival rates throughout their life to maintain a population. Anthropogenic mortality on the 

species occurs at every stage of their life, where the exact magnitude of the mortality is often 

unknown. As described in this document, the upper end of natural mortality can be computed 

from available information. In the future, as more comprehensive and precise information on 

anthropogenic threats is gathered and available, improvements in model outcomes will result. 

Nesting beach count data for the North Pacific Ocean DPS have indicated a decline of 

loggerhead turtle nesting in the last 20 years (Figure 1). The SQE approach reflected the 

observed decline (Figure 6). However, in the threat matrix analysis, the range of λ values 

contains 1.0, indicating the large uncertainty about the future of the DPS. As stated elsewhere, 

fishery bycatch along the coast of the Baja Peninsula and the nearshore waters of Japan are the 

main known sources of mortalities (Table 3). Mortalities in the high-seas, where a large number 

of juvenile loggerhead turtles reside (Kobayashi et al. 2008), from fishery bycatch are still 

unknown. 

The SQE approach indicated that, based on nest count data for the past three decades, the South 

Pacific Ocean DPS is at risk and thus likely to decline in the foreseeable future. These results 

were based on recently published nesting census data for loggerhead turtles at index beaches in 

eastern Australia (Limpus 2009). The threat matrix approach provided uncertain results: in the 

case of the lowest anthropogenic threats, the South Pacific Ocean DPS may recover, but in the 

worst-case scenario, the DPS may substantially decline in the foreseeable future. These results 

are largely driven by the ongoing threats to juvenile and adult loggerheads from fishery bycatch 

that occur throughout the South Pacific Ocean and the uncertainty in estimated mortalities (Table 

4). 

For the North Indian Ocean DPS, there were no nesting beach data available to conduct the SQE 

analysis. The threat matrix analysis indicated a decline of the DPS in the foreseeable future, 

primarily as a result of fishery bycatch in neritic habitats. Cumulatively, substantial threats may 

exist for eggs/hatchlings (Table 5). Because of the lack of precise estimates of bycatch, 

however, the range of possible λ values was large (Figures 20 and 21). 

Similar to the North Indian Ocean DPS, no nesting beach data were available for the Southeast 

Indo-Pacific Ocean DPS. The level of anthropogenic mortalities is low for the Southeast IndoPacific Ocean DPS, based on the best available information, resulting in relatively large Pλ

values and a narrow range (Figures 20 and 21). The greatest threats for the Southeast IndoPacific Ocean DPS exist for the first year of the life stages (eggs and hatchlings; Table 6). For 

the Southwest Indian Ocean DPS, the SQE approach, based on a 37-year time series of nesting 

female counts at Tongaland, South Africa (1963-1999), indicated this segment of the population, 

while small, has increased, and the likelihood of quasi-extinction is negligible. The threat matrix 

approach, on the other hand, provided a wide range of results: in the best case scenario, the DPS 

would grow slowly, whereas in the worst case scenario, the DPS would decline in the 

foreseeable future. The results of the threat matrix approach were driven by uncertainty in 

anthropogenic mortalities in the neritic environment and the eggs/hatchling stage (Table 7, 

Figures 20 and 21). 
85

The SQE analysis indicated differences in SQEs among recovery units within the Northwest 

Atlantic Ocean DPS (Figure 8). Although the Northern Gulf of Mexico Recovery Unit indicated 

the worst result among the four recovery units under consideration (Figure 8), the length of the 

time series was shortest (12 data points; Figure 4). Other recovery units, however, appeared to 

show similar declining trends, which were also indicated through the SQE approach. The threat 

matrix analysis indicated a likely decline of the DPS in the foreseeable future. The greatest 

threats to the DPS result from cumulative fishery bycatch in neritic and oceanic habitats (Table 

8). 

The high likelihood of the predicted decline of the Northeast Atlantic Ocean DPS from the threat 

matrix analysis is largely driven by the ongoing harvest of nesting females, low hatchling and 

emergence success, and mortality of juveniles and adults from fishery bycatch throughout the 

Northeast Atlantic Ocean (Table 9). The threat matrix analysis indicated a consistently 

pessimistic future for the DPS (Figures 20 and 21). 

Nesting beach data for the Mediterranean Sea DPS were not available to conduct the SQE 

analysis. The threat matrix analysis indicated the DPS is likely to decline in the foreseeable 

future (Figures 20 and 21). The primary threats are fishery bycatch in neritic and oceanic 

habitats (Table 10). 

The two approaches for determining risks to the South Atlantic Ocean DPS provided different, 

although not incompatible, results. The SQE approach indicated that, based on nest count data 

for the past two decades, the population was unlikely to decline in the foreseeable future (Figure 

10). These results were based on recently published nesting beach trend analyses by Marcovaldi 

and Chaloupka (2007) and this QET analysis was consistent with their conclusions. However, 

the SQE approach was based on past performance of the DPS, specifically only nesting beach 

data, and did not address ongoing or future threats to segments of the DPS that might not have 

been nor might not yet be reflected by nest count data. The threat matrix approach indicated that 

the South Atlantic Ocean DPS is likely to decline in the foreseeable future (Figures 20 and 21). 

These results were largely driven by the ongoing mortality threats to juveniles from fishery 

bycatch that occurs throughout the South Atlantic Ocean (Table 11). Although conservation 

efforts by national and international groups in the South Atlantic are currently working toward 

mitigating bycatch in the South Atlantic, it is unlikely that this source of mortality can be greatly 

reduced in the near future, largely due to inadequate funding and knowledge gaps that together 

inhibit implementation of large-scale management actions (Domingo et al. 2006). 

4.6. Supplemental Material—Sensitivity Analyses 

Because our threat matrix analysis was based on a deterministic model, and a few life history 

parameter values were determined from little empirical data, we conducted sensitivity analyses 

to evaluate the effects of these life history parameters on the results of the threat matrix analysis. 

4.6.1. Effects of AFR and CV of AFR on the Base Population Model 

Figures S1-S7 indicate relationships among AFR, CV of AFR, average adult survival rates, 

average juvenile survival rates, and the dominant eigenvalues. Effects of AFR on the dominant 
86

eigenvalues were greater than those of CV of AFR (differences are greater among columns than 

rows in Figures S1-S7). Differences among DPSs were small as was expected from the small 

differences in vital rates among the DPSs. 

For a deterministic age or stage based matrix model, the asymptotic population growth rate (or 

the dominant eigenvalue) is a function of survival rates, transition probabilities, and fertility. 

Consequently, for reasonable ranges of survival rates, the upper bound of the dominant 

eigenvalue can be found. Fertility parameters of the base matrices were obtained from averages 

(clutch size, remigration intervals, and nests per female). Consequently, if we were to construct 

a stochastic demographic model, our base matrix would be treated as the average matrix. The 

dominant eigenvalue of the average matrix is greater than or equal to the average dominant 

eigenvalue from stochastic matrices (Jensen’s inequality). Consequently, the dominant 

eigenvalue from our matrix, based on the average life history parameters used in this analysis, 

may be considered as the maximum possible. 

4.6.2. Effects of AFR on the Threat Matrix Analysis 

Figures S8-S11 indicate changes in results of the threat matrix analysis due to the assumed AFR. 

For S8 and S9, AFR was assumed to be 25 years, whereas the CV of AFR was fixed at 15%. 

Because of the small difference caused by CV of AFR from the previous analysis, results of the 

sensitivity analysis for CV of AFR are not shown. Greater proportions of dominant eigenvalues 

are above 1 as the AFR decreases. 

4.6.3. Proportion of Neritic Juvenile Stage Duration 

To incorporate different levels of anthropogenic mortalities between neritic and oceanic 

environment in the threat matrix analysis, the matrix model required the durations of neritic and 

oceanic juvenile stages. Because these estimates are based on a combination of published data, 

extrapolations, and experts’ opinions, and because empirical data were not available for several 

DPSs, we used the Northwest Atlantic Ocean DPS (19 years in neritic habitat) as a proxy for five 

DPSs (Table 1). To determine the sensitivity of the default value to the results, the threat matrix 

analysis was conducted while the proportion of time juveniles spend in neritic habitat was 

changed from 10% to 90%. 

Lower bounds of the dominant eigenvalues decreased as juveniles spent more time in the neritic 

habitat (Figures S12-S13). This result was caused by the higher anthropogenic mortalities in 

neritic habitats for all DPSs than in oceanic habitats. The upper bounds of the dominant 

eigenvalues did not change as much as the lower bound, except the South Atlantic Ocean DPS. 
87

Figure S1. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

North Pacific Ocean DPS. Contour lines indicate the dominant eigenvalues, whereas the 

diagonal lines indicate equal survival rates between juveniles and adults. Dashed horizontal lines 

indicate the assumed adult survival rate for the base matrix model. The oceanic survival rate 

during the first year was fixed at 0.4/year. 
88

Figure S2. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

South Pacific Ocean DPS. Contour lines indicate the dominant eigenvalues, whereas the 

diagonal lines indicate equal survival rates between juveniles and adults. Dashed horizontal lines 

indicate the assumed adult survival rate for the base matrix model. The oceanic survival rate 

during the first year was fixed at 0.4/year. 
89

Figure S3. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

North Indian Ocean, Southeast Indo-Pacific Ocean, and Southwest Indian Ocean DPSs. Contour 

lines indicate the dominant eigenvalues, whereas the diagonal lines indicate equal survival rates 

between juveniles and adults. Dashed horizontal lines indicate the assumed adult survival rate 

for the base matrix model. The oceanic survival rate during the first year was fixed at 0.4/year. 
90

Figure S4. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

Northwest Atlantic Ocean DPS. Contour lines indicate the dominant eigenvalues, whereas the 

diagonal lines indicate equal survival rates between juveniles and adults. Dashed horizontal lines 

indicate the assumed adult survival rate for the base matrix model. The oceanic survival rate 

during the first year was fixed at 0.4/year. 
91

Figure S5. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

Northeast Atlantic Ocean DPS. Contour lines indicate the dominant eigenvalues, whereas the 

diagonal lines indicate equal survival rates between juveniles and adults. Dashed horizontal lines 

indicate the assumed adult survival rate for the base matrix model. The oceanic survival rate 

during the first year was fixed at 0.4/year. 
92

Figure S6. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

Mediterranean Sea DPS. Contour lines indicate the dominant eigenvalues, whereas the diagonal 

lines indicate equal survival rates between juveniles and adults. Dashed horizontal lines indicate 

the assumed adult survival rate for the base matrix model. The oceanic survival rate during the 

first year was fixed at 0.4/year. 
93

Figure S7. Relationships among adult survival rate, juvenile survival rate, age at first 

reproduction (AFR), coefficient of variation (CV) of AFR, and the dominant eigenvalue for the 

South Atlantic Ocean DPS. Contour lines indicate the dominant eigenvalues, whereas the 

diagonal lines indicate equal survival rates between juveniles and adults. Dashed horizontal lines 

indicate the assumed adult survival rate for the base matrix model. The oceanic survival rate 

during the first year was fixed at 0.4/year. 
94

Figure S8. Ranges of dominant eigenvalues for nine DPSs with anthropogenic mortalities when 

the maximum population growth rates are assumed to be 5% per year. The mean age at first 

reproduction was assumed to be 25 years and its standard deviation 3.75 (CV=15%). The values 

above the dotted line indicates the proportion of the bars that are above λ = 1.0. 
95

Figure S9. Ranges of dominant eigenvalues for nine DPSs with anthropogenic mortalities when 

the maximum population growth rates are assumed to be 10% per year. The mean age at first 

reproduction was assumed to be 25 years and its standard deviation 3.75 (CV = 15%). The 

values above the dotted line indicates the proportion of the bars that are above λ = 1.0. 
96

Figure S10. Ranges of dominant eigenvalues for nine DPSs with anthropogenic mortalities when 

the maximum population growth rates are assumed to be 5% per year. The mean age at first 

reproduction was assumed to be 35 years and its standard deviation 5.25 (CV = 15%). The 

values above the dotted line indicates the proportion of the bars that are above λ = 1.0. 
97

Figure S11. Ranges of dominant eigenvalues for nine DPSs with anthropogenic mortalities when 

the maximum population growth rates are assumed to be 10% per year. The mean age at first 

reproduction was assumed to be 35 years and its standard deviation 5.25 (CV = 15%). The 

values above the dotted line indicates the proportion of the bars that are above λ = 1.0. 
98

Figure S12. Effects of the changes in the proportion of time juveniles spend in neritic habitat on 

results of the threat matrix analysis. For each DPS, vertical lines indicate the range of the 

dominant eigenvalues for the best and worst threat scenarios. Each vertical line is for a 

proportion of neritic juvenile stage, where the proportion is from 10% to 90% with 10% 

increments (from left to right). Empty boxes are based on the values in Table 1. The mean age 

at first reproduction was assumed to be 30 years and its standard deviation 5 (CV=17%). The 

asymptotic population growth rate was assumed to be 5% per year. 
99

Figure S13. Effects of the proportion of time juveniles spend in neritic habitat on results of the 

risk analysis. For each DPS, vertical lines indicate the range of the dominant eigenvalues for the 

best and worst threat scenarios. Each vertical line is for a proportion of neritic juvenile stage, 

where the proportion is from 10% to 90% with 10% increments (from left to right). Empty 

boxes are based on the values in Table 1. The mean age at first reproduction was assumed to be 

30 years and its standard deviation 5 (CV=17%). The asymptotic population growth rate was 

assumed to be 10% per year. 
100

SECTION 5—ANALYSIS OF FACTORS LISTED UNDER ESA 

SECTION 4(a)(1) 

Under Section 4(a)(1) of the ESA, NMFS and FWS are required to determine whether any 

species is an endangered or threatened species because of any of the following factors. These 

factors are: 

(A) the present or threatened destruction, modification, or curtailment of its habitat or 

range; 

(B) overutilization for commercial, recreational, scientific, or educational purposes; 

(C) disease or predation; 

(D) the inadequacy of existing regulatory mechanisms; or 

(E) other natural or manmade factors affecting its continued existence. 

The following is an analysis of these factors as they relate to the current status of the nine 

loggerhead DPSs: 

1. North Pacific Ocean 

2. South Pacific Ocean 

3. North Indian Ocean 

4. Southeast Indo-Pacific Ocean 

5. Southwest Indian Ocean 

6. Northwest Atlantic Ocean 

7. Northeast Atlantic Ocean 

8. Mediterranean Sea 

9. South Atlantic Ocean 

In Section 5.1., a general description of the threats that occur for all DPSs is presented under the 

relevant section 4(a)(1) factor to avoid duplication. In Section 5.2, threats that are specific to a 

particular DPS are presented by DPS under each section 4(a)(1) factor. 

5.1. General Description of Threats 

5.1.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

Destruction and modification of loggerhead nesting habitats are occurring worldwide throughout 

the species range. The main anthropogenic threats impacting loggerhead nesting habitat include 

coastal development/construction, placement of erosion control structures and other barriers to 

nesting, beachfront lighting, vehicular and pedestrian traffic, sand extraction, beach erosion, 

beach sand placement, beach pollution, removal of native vegetation, and planting of non-native 

vegetation (Baldwin 1992; NMFS and FWS 1998, 2008; Margaritoulis et al. 2003). 

Worldwide, development near coastal areas continues and is a major problem as more and more 

people are moving to or visiting coastal areas. Coastal development may include, but is not 

limited to, the construction of roads, highways, public infrastructure, hotels, condominiums, 

houses, harbors, nearshore shoreline stabilization structures (e.g., groins, jetties, breakwaters), 
101

and seawalls and other forms of coastal armoring. All of these various forms of coastal 

construction alter nesting habitat to one degree or another, typically making it less suitable for 

nesting females, egg incubation, and hatchling emergence. This development can also lead to 

deleterious effects of animals at-sea through increased fishing activity near important foraging 

areas (Peckham et al. 2007), along migratory corridors, and coastally, near the nesting beaches 

(e.g., Kamezaki et al. 2003). 

Erosion of nesting beaches can occur as a result of coastal development when native dune 

vegetation, which enhances beach stability and acts as an integral buffer zone between land and 

sea, is degraded or destroyed. This in turn often leaves insufficient nesting opportunities above 

the high tide line, and nests may be washed out. In contrast, the planting or invasion of less 

stabilizing, non-native plants can lead to increased erosion and degradation of suitable nesting 

habitat (Schmelz and Mezich 1988). In addition, taller plants and structures can increase shading 

and alter the natural sex ratios of hatchlings (Mrosovsky et al. 1995). Non-native vegetation also 

may form impenetrable root mats that can prevent proper nest cavity excavation, as well as trap 

hatchlings attempting to emerge from nests. 

Beach nourishment also affects the incubation environment and nest success. Although the 

placement of sand on beaches may provide a greater quantity of nesting habitat, the quality of 

that habitat may be less suitable than pre-existing natural beaches. Constructed beaches tend to 

differ from natural beaches in several important ways. They are typically wider, flatter, more 

compact, and the sediments are more moist than those on natural beaches (Nelson et al. 1987, 

Ackerman et al. 1991, Ernest and Martin 1999). On severely eroded sections of beach, where 

little or no suitable nesting habitat previously existed, sand placement can result in increased 

nesting (Ernest and Martin 1999). However, on most beaches, nesting success typically declines 

for the first year or two following construction, even though more nesting habitat is available for 

turtles (Trindell et al. 1998, Ernest and Martin 1999, Herren 1999). Reduced nesting success on 

constructed beaches has been attributed to increased sand compaction, escarpment formation, 

and changes in beach profile (Nelson et al. 1987, Crain et al. 1995, Lutcavage et al. 1997, 

Steinitz et al. 1998, Ernest and Martin 1999, Rumbold et al. 2001). Compaction can inhibit nest 

construction or increase the amount of time it takes for turtles to construct nests, while 

escarpments often cause female turtles to return to the ocean without nesting or to deposit their 

nests seaward of the escarpment where they are more susceptible to frequent and prolonged tidal 

inundation. In short, sub-optimal nesting habitat may cause decreased nesting success, place an 

increased energy burden on nesting females, result in abnormal nest construction (Carthy 1996), 

and reduce the survivorship of eggs and hatchlings. In addition, sand used to nourish beaches 

may have a different composition than the original beach; thus introducing lighter or darker sand, 

consequently affecting the relative nest temperatures (Ackerman 1997, Milton et al. 1997). 

Crain et al. (1995) provides a review of the potential effects of beach nourishment on sea turtles. 

Groins and jetties, shore-perpendicular structures designed to trap sand that would otherwise be 

transported by longshore currents, interfere with nesting turtle access to the beach, result in a 

change in beach profile and width (e.g., downdrift erosion, loss of sandy berms, and escarpment 

formation) (Komar 1983, Pilkey et al. 1984, National Research Council 1987), trap hatchlings, 

and concentrate predatory fishes, resulting in hatchling predation. 
102

The construction of beachfront armoring (i.e., rigid structures placed parallel to the shoreline on 

the upper beach to prevent both landward retreat of the shoreline and inundation or loss of 

upland property by flooding and wave action) includes bulkheads, seawalls, soil retaining walls, 

rock revetments, sandbags, and geotextile tubes. These structures can greatly impact nesting 

opportunities and hatching success of loggerhead turtles. Mosier (1998) reported that fewer 

loggerheads made nesting attempts on beaches fronted by seawalls than on adjacent beaches 

where armoring structures were absent. Mosier (1998) and Mosier and Witherington (2002) 

found that when turtles did emerge in the presence of armoring structures, more returned to the 

water without nesting than those on non-armored beaches. Additionally, Mosier (1998) found 

that turtles on armored sections of beach tended to wander greater distances than those that 

emerged on adjacent natural beaches. Armoring structures can effectively eliminate a turtle’s 

access to upper regions of the beach/dune system. Consequently, nests on armored beaches were 

generally found at lower elevations than those on non-walled beaches. Nests laid at lower 

elevations are subject to a greater risk of repeated tidal inundation and erosion, which can 

potentially alter thermal regimes, and thus sex ratios (Mrosovsky and Provancha 1992, 

Mrosovsky 1994, Ackerman 1997). The demand for both nourishment and the placement of 

hardened structures on the beach as management options for beach erosion are likely to increase 

in the future in the face of projected sea level rise and more intense storm activity associated 

with global climate change. 

Developments, such as roadways, high rise hotels, and condominiums, also contribute to habitat 

degradation by increasing noise and light pollution. Studies have shown that light pollution 

disorients hatchlings, causing them to move inland away from the ocean (Witherington 1997). 

Hatchlings unable to find the ocean, or delayed in reaching it, incur high mortality from 

dehydration, exhaustion, or predation (Ehrhart and Witherington 1987, Witherington and Martin 

1996). Hatchlings lured into lighted parking lots or toward streetlights are often crushed by 

passing vehicles (Witherington and Martin 1996). In addition, light pollution deters nesting 

females from emerging onto the beach to nest (Witherington 1992). 

Burgeoning numbers of visitors to beaches may cause sand compaction and nest trampling 

(Kudo et al. 2003). In addition, the placement of recreational beach equipment (e.g., lounge 

chairs, cabanas, umbrellas, catamarans) degrades the suitability of beaches as nesting habitat by 

hampering or deterring nesting turtles from accessing the upper beach (Sobel 2002; 

Margaritoulis et al. 2007; Florida Fish and Wildlife Conservation Commission, unpublished 

data), thus limiting the potential area for nesting. Debris on nesting beaches is also a threat to 

hatchlings and nesting females. Hatchlings often must navigate through a variety of obstacles 

before reaching the ocean. These include natural and human-made debris. Debris on the beach 

may interfere with a hatchling’s progress toward the ocean. Research has shown that travel 

times of hatchlings from the nest to the water may be extended when traversing areas of heavy 

foot traffic or vehicular ruts (Hosier et al. 1981); the same is true of debris on the beach. 

Hatchlings may be upended and spend both time and energy in righting themselves. Some beach 

debris may have the potential to trap hatchlings and prevent them from successfully reaching the 

ocean. In addition, debris over the tops of nests may impede or prevent hatchling emergence. 

Nesting females also may be impeded by beach debris in their movement up or down the beach, 

and this may influence selection of nest sites. In rarer circumstances, large debris items may 

entrap nesting females. 
103

Operating public vehicles on nesting beaches for recreational purposes or beach access also 

degrades nesting habitat. The ruts left by vehicles in the sand prevent or impede hatchlings from 

reaching the ocean following emergence from the nest (Mann 1977, Hosier et al. 1981, Cox et al. 

1994, Hughes and Caine 1994). Hatchlings impeded by vehicle ruts are at greater risk of death 

from predation, fatigue, desiccation, and being crushed by additional vehicle traffic. Light 

pollution from vehicle lights on the beach after dark may deter females from nesting and 

disorient hatchlings. Sand compaction due to vehicles on the beach may hinder nest construction 

and hatchling emergence from nests. Driving directly above incubating egg clutches can cause 

sand compaction, which may decrease hatching and emerging success and directly kill preemergent hatchlings (Mann 1977). Additionally, vehicle traffic on nesting beaches may 

contribute to erosion, especially during high tides or on narrow beaches where driving is 

concentrated on the high beach and foredune. 

Neritic/Oceanic Zone

Habitat degradation and destruction in the neritic and oceanic zones occur less conspicuously 

than they do in the terrestrial zone. Direct impacts to bottom habitats occur from activities 

including bottom trawl and dredge fishing, channel dredging, and sand extraction. Indirect 

effects can result from both point and non-point source pollution (e.g., upland runoff, direct 

sewage discharge) associated with coastal development. The impacts of climate change may 

also result in trophic level alterations, and therefore may affect loggerhead prey abundance 

and/or distribution. There are currently no data available to quantify impacts from these 

potential trophic level alterations. 

Other fishing methods such as drift and set gillnets, longlines, and pots/traps affect both neritic 

and oceanic zones by not only incidentally capturing loggerheads but also depleting fish 

populations, and thus altering ecosystem dynamics. In many cases, loggerhead foraging areas 

coincide with fishing zones. Selective and usually intense harvest of species in fisheries will 

result in changes in neritic and oceanic ecosystems (e.g., predator-prey interactions, trophic 

dynamics and food webs; see Bjorndal 2003). Seney and Musick (2007) reported changes in 

loggerhead diet resulting from alterations of prey availability in the Chesapeake Bay, Virginia, 

USA, an important foraging habitat. Perhaps the most destructive fishing methods in neritic 

ecosystems are bottom trawling (Auster 1998, Brailovskaya 1998, Engel and Kvitek 1998, 

Kaiser 1998, Pilskaln et al. 1998, Schwinghamer et al. 1998, Watling and Norse 1998) and 

dredging (Murray 2004, 2005, 2007). Benthic habitat alteration by mobile fishing gear, 

especially trawls and dredges, constitutes a globally significant physical disturbance to the 

marine environment and has significant effects on marine biodiversity (Watling and Norse 

1998). The ecological effects of trawling and dredging on the marine environment have been 

likened to the terrestrial ecological effects of clearcutting forests (Watling and Norse 1998). 

Mobile fishing gear has been shown to result in short and long-term changes in benthic 

community composition, including species groups on which loggerheads forage (Gordon et al. 

1998). The National Research Council (1994) found that habitat alteration by fishing activities is 

perhaps the least understood of the important environmental effects of fishing. Comprehensive 

data are lacking to fully understand and quantify these impacts. 

Marine pollution can affect loggerhead habitats in both the neritic and oceanic zones. These 

impacts include contamination from herbicides, pesticides, oil spills, and other chemicals, as well 
104

as impacts on water quality (e.g., increases in water column sediments) resulting from structural 

degradation from excessive boat anchoring, dredging, and marine explosives (Francour et al. 

1999, Lee Long et al. 2000, Margaritoulis et al. 2003, Waycott et al. 2005). 

5.1.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Deliberate hunting of loggerheads for their meat, shells, and eggs is reduced from previous 

exploitation levels, but still exists. The level of harvest varies significantly by region. Despite 

national laws in various countries, in many areas the poaching of eggs and hunting of adults and 

juveniles is still a problem. Details on these threats are described by DPS in Section 5.2. 

5.1.3. Disease or Predation 

The population level effects of diseases in loggerheads are not known. At least two bacterial 

diseases have been described in wild loggerhead populations, including bacterial encephalitis and 

ulcerative stomatitis/obstructive rhinitis/pneumonia (George 1997). There are few reports of 

fungal infections in wild loggerhead populations (Homer et al. 2000). Both bacterial and fungal 

infections are common in captive sea turtles (Herbst and Jacobson 1995, George 1997). 

Viral diseases have not been documented in free-ranging loggerheads, with the possible 

exception of sea turtle fibropapillomatosis, which may have a viral etiology (Herbst and 

Jacobson 1995, George 1997). Fibropapillomatosis is a disease that is characterized by the 

presence of internal and/or external tumors (fibropapillomas). External tumors can interfere with 

swimming, vision, and feeding. Although fibropapillomatosis reaches epidemic proportions in 

some wild green turtle populations, the prevalence of this disease in most loggerhead populations 

is thought to be small. Mortality levels associated with the disease are still unknown. 

A variety of endoparasites, including trematodes, tapeworms, and nematodes have been 

described in loggerheads (Herbst and Jacobson 1995). Heavy infestations of endoparasites may 

cause or contribute to debilitation or mortality in sea turtles. 

Depredation of sea turtle eggs and hatchlings by native and introduced species occurs on a large 

number of nesting beaches, as described by DPS in Section 5.2. Planting of non-native plants 

can have a detrimental effect in the form of roots invading eggs (e.g., tamarisk tree roots 

invading eggs in Zakynthos, Greece) (Margaritoulis et al. 2007). 

Harmful algal blooms, such as a red tide, also impact loggerheads. Karenia brevis, a type of 

microalgae known as a dinoflagellate that produces a toxin, has been known to cause red tides 

(Florida Marine Research Institute 2003). Other types of microorganisms cause different kinds 

of harmful algal blooms in other parts of the world as well (Florida Marine Research Institute 

2003, Gilbert et al. 2005). 

5.1.4. Inadequacy of Existing Regulatory Mechanisms 

Loggerheads are highly migratory, which makes them a shared resource among many nations. 

Therefore, conservation efforts for loggerhead populations in one country may be jeopardized by 
105

activities in another. Many countries lack regulations or have inadequate regulations in place to 

address the impacts of a wide range of anthropogenic activities that directly injure and kill 

loggerheads, disrupt necessary behaviors, and alter terrestrial and marine habitats used by the 

species. In particular, improved regulations of fisheries that incidentally capture loggerheads are 

needed to reduce mortality. Improved fishery observer coverage is also needed to provide more 

basic information on loggerhead bycatch. Government regulations and community programs 

need to be initiated or strengthened to address the impacts of turtle hunting and egg poaching. 

Overall, increased efforts are needed to assist many foreign countries with the enactment and 

enforcement of national regulations to protect loggerheads. 

The conservation and recovery of sea turtles is facilitated by a number of regulatory instruments 

at international, regional, national, and local levels. As a result of these designations and 

agreements, many of the intentional impacts directed at sea turtles have been lessened: harvest 

of eggs and adults has been slowed at several nesting areas through nesting beach conservation 

efforts and an increasing number of community-based initiatives are in place to slow the take of 

turtles in foraging areas. Moreover, there is now a more internationally concerted effort to 

reduce sea turtle interactions and mortality in artisanal and industrial fishing practices. 

Despite these advances, human impacts continue throughout the world. The lack of 

comprehensive and effective monitoring and bycatch reduction efforts in many pelagic and nearshore fisheries operations still allows substantial direct and indirect mortality, and the 

uncontrolled development of coastal and marine habitats threatens to destroy the supporting 

ecosystems of long-lived sea turtles. Although several international agreements provide legal 

protection for sea turtles, additional multi-lateral efforts are needed to ensure they are sufficiently 

implemented and/or strengthened, and key non-signatory parties need to be encouraged to 

accede. 

Considering the worldwide distribution of loggerhead turtles, the majority of legal instruments 

that target or impact sea turtles cover loggerhead turtles. A summary of the main regulatory 

instruments from throughout the world that relate to loggerhead turtle management is provided 

below. Cross-regional regulatory instruments will be highlighted here. If an agreement or act is 

specific to a DPS’s geographic area, that action will be discussed under the appropriate DPS in 

Section 5.2. The pros and cons of many of these were evaluated by Hykle (2002), and a 

summary of his findings is given when appropriate. 

United States Magnuson-Stevens Fishery Conservation and Management Act 

The recently-amended U.S. Magnuson-Stevens Fishery Conservation and Management Act 

(MSA), implemented by NMFS, mandates environmentally responsible fishing practices within 

U.S. fisheries and has provisions that extend to fishing activities in waters beyond U.S. 

jurisdiction. Section 610 calls on the U.S. Secretary of Commerce to identify nations with 

fishing vessels that are engaged or have been engaged in fishing activities in waters beyond any 

national jurisdiction or in areas beyond the Exclusive Economic Zone of the United States. This 

section authorizes NMFS to conduct bilateral consultations with such nations to protect living 

marine resources. If a nation continues to conduct fishing activities that result in bycatch of 

protected living marine resources, they can be certified to the United States Congress. A result 

of this certification could be suspension in the trade of fisheries products. Finally, the Act 
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specifically encourages NMFS to conduct international cooperation and assistance with foreign 

nations that are identified so that bycatch of protected living marine resources can be reduced. 

FAO Technical Consultation on Sea Turtle-Fishery Interactions 

While not a true international instrument for conservation, the Food and Agriculture 

Organization of the United Nations' (FAO) technical consultation on sea turtle-fishery 

interactions was groundbreaking in that it solidified the commitment of this international body to 

reduce sea turtle bycatch in marine fisheries operations. Recommendations from the technical 

consultation were endorsed by the FAO Committee on Fisheries (COFI) and called for the 

immediate implementation by member nations and Regional Fishery Management Organizations 

(RFMOs) of guidelines to reduce sea turtle mortality in fishing operations, developed as part of 

the technical consultation. Compliance with these guidelines is voluntary. 

Convention on the Conservation of Migratory Species of Wild Animals 

This Convention, also known as the Bonn Convention or CMS, is an international treaty that 

focuses on the conservation of migratory species and their habitats. As of March 2008, the 

Convention had 108 member states, including parties from Africa, Central and South America, 

Asia, Europe, and Oceania. While the Convention has successfully brought together about half 

the countries of the world with a direct interest in sea turtles, it has yet to realize its full potential 

(Hykle 2002). Its membership does not include a number of key countries, including Brazil, 

Canada, China, Indonesia, Japan, Mexico, Oman, and the United States. Additional information 

is available at http://www.cms.int. 

Convention on Biological Diversity (CBD) 

The primary objectives of this international treaty are: (1) the conservation of biological 

diversity, (2) the sustainable use of its components, and (3) the fair and equitable sharing of the 

benefits arising out of the utilization of genetic resources. This Convention has been in force 

since 1993 and had 191 Parties as of June 2008. While the Convention provides a framework 

within which broad conservation objectives may be pursued, it does not specifically address sea 

turtle conservation (Hykle 2002). Additional information is available at http://www.cbd.int. 

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) 

Known as CITES, this Convention was designed to regulate international trade in a wide range 

of wild animals and plants. CITES was implemented in 1975 and currently includes 173 Parties. 

Although CITES has been effective at minimizing the international trade of sea turtle products, it 

does not limit legal harvest within countries, nor does it regulate intra-country commerce of sea 

turtle products (Hykle 2002). Additional information is available at http://www.cites.org. 

United Nations Convention on the Law of the Sea (UNCLOS) 

To date, 155 countries, including most mainland countries lining the western Pacific, and the 

European Community have joined in the convention. The United States has signed the treaty, 

but the Senate has not ratified it. Aside from its provisions defining ocean boundaries, the 

convention establishes general obligations for safeguarding the marine environment through 

mandating sustainable fishing practices and protecting freedom of scientific research on the high 

seas. Additional information is available at http://www.un.org/Depts/los/index.htm. 
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United Nations Resolution 44/225 on Large-Scale Pelagic Driftnet Fishing 

In 1989, the United Nations called, in an unanimous resolution, for the elimination of all high 

seas driftnets by 1992. Additional information is available at 

http://www.intfish.net/treaties/ga44_225.htm. 

The International Convention for the Prevention of Pollution from Ships (MARPOL) 

The MARPOL Convention is a combination of two treaties adopted in 1973 and 1978 to prevent 

pollution of the marine environment by ships from operational or accidental causes. The 1973 

treaty covered pollution by oil, chemicals, harmful substances in packaged form, sewage and 

garbage. The 1978 MARPOL Protocol was adopted at a Conference on Tanker Safety and 

Pollution Prevention which included standards for tanker design and operation. The 1978 

Protocol incorporated the 1973 Convention as it had not yet been in force and is known as the 

International Convention for the Prevention of Marine Pollution from Ships, 1973, as modified 

by the Protocol of 1978 relating thereto (MARPOL 73/78). The 1978 Convention went into 

force in 1983 (Annexes I and II). The Convention includes regulations aimed at preventing and 

minimizing accidental and routine operations pollution from ships. Amendments passed since 

have updated the convention. To date there are six Annexes with Annexes I and II being 

mandatory for State Parties and the others being voluntary. 

Annex I Regulations for the Prevention of Pollution by Oil 

Annex II Regulations for the Control of Pollution by Noxious Liquid Substances in Bulk 

Annex III Prevention of Pollution by Harmful Substances Carried by Sea in Packaged Form 

Annex IV Prevention of Pollution by Sewage from Ships 

Annex V Prevention of Pollution by Garbage from Ships 

Annex VI Prevention of Air Pollution from Ships 

The Convention Concerning the Protection of the World Cultural and Natural Heritage (World 

Heritage Convention) 

The World Heritage Convention was signed in 1972 and, as of November 2007, 185 states were 

parties to the Convention. The instrument requires parties to take effective and active measures 

to protect and conserve habitat of threatened species of animals and plants of scientific or 

aesthetic value. The World Heritage Convention currently includes 31 marine sites, including 

important marine turtle habitat such as the Belize Barrier Reef Reserve System, Belize. 

Additional information is available at http://whc.unesco.org/en/conventiontext. 

Ramsar Convention on Wetlands 

The Convention on Wetlands, signed in Ramsar, Iran, in 1971, is an intergovernmental treaty, 

which provides the framework for national action and international cooperation for the 

conservation and wise use of wetlands and their resources. Currently, there are 158 parties to the 

convention, with 1,752 wetland sites, including important marine turtle habitat such as the Turtle 

Beaches and Coral Reefs of Tongaland, South Africa. Additional information is available at 

http://www.ramsar.org. 
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5.1.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

The most significant manmade factor affecting the conservation and recovery of the loggerhead 

is incidental capture in commercial and artisanal fisheries. Incidental capture (bycatch) of 

loggerheads occurs in various fisheries throughout the range of the species. Fishing gear types 

that may affect loggerheads include pelagic and demersal longlines, drift and set nets (e.g., 

gillnets, trammel nets), bottom and mid-water trawling, fishing dredges, pound nets and weirs, 

haul and purse seines, pots and traps, and hook and line gear. While significant progress has 

been made to reduce bycatch in some fisheries in certain parts of the loggerhead’s range, serious 

bycatch problems remain unaddressed. Specific information on bycatch rates or the number of 

takes is presented by DPS in Section 5.2. 

Other Manmade and Natural Impacts 

In addition to fishery bycatch, climate change is another factor that has the potential to greatly 

impact loggerhead turtles. Impacts from global climate change induced by human activities are 

likely to become more apparent in future years (Intergovernmental Panel on Climate Change 

(IPCC) 2007a). The global mean temperature has risen 0.76oC over the last 150 years, and the 

linear trend over the last 50 years is nearly twice that for the last 100 years (IPCC 2007a). There 

is a high confidence, based on substantial new evidence, that observed changes in marine 

systems are associated with rising water temperatures, as well as related changes in ice cover, 

salinity, oxygen levels, and circulation. Ocean acidification resulting from massive amounts of 

carbon dioxide and pollutants released into the air can have major adverse impacts on the 

calcium balance in the oceans and, thus, on sea turtles. Changes to the marine ecosystem due to 

climate change include shifts in ranges and changes in algal, plankton, and fish abundance (IPCC 

2007b), which could affect loggerhead prey distribution and abundance. 

One of the most certain consequences of climate change is rising sea levels (Titus and Narayanan 

1995), which will result in increased erosion rates along nesting beaches. This could particularly 

impact areas with low-lying beaches where sand depth is a limiting factor, as the sea will 

inundate nesting sites and decrease available nesting habitat (Daniels et al. 1993, Fish et al. 

2005, Baker et al. 2006). The loss of habitat as a result of climate change could be accelerated 

due to a combination of other environmental and oceanographic changes such as an increase in 

the frequency of storms and/or changes in prevailing currents, both of which could lead to 

increased beach loss via erosion (Antonelis et al. 2006, Baker et al. 2006). On some 

undeveloped beaches, shoreline migration will have limited effects on the suitability of nesting 

habitat. Bruun (1962) hypothesized that during a sea level rise a typical beach profile will 

maintain its configuration but will be translated landward and upward. However, along 

developed coastlines, and especially in areas where erosion control structures have been 

constructed to limit shoreline movement, rising sea levels will cause severe effects on nesting 

females and their eggs. Erosion control structures can result in the permanent loss of dry nesting 

beach or deter nesting females from reaching suitable nesting sites (National Research Council 

1990). Nesting females may deposit eggs seaward of the erosion control structures potentially 

subjecting them to repeated tidal inundation. 
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Climate change also may affect loggerhead sex ratios. Loggerhead turtles exhibit temperaturedependent sex determination. Rapidly increasing global temperatures may result in warmer 

incubation temperatures and highly female-biased sex ratios (e.g., Glen and Mrosovsky 2004, 

Hawkes et al. 2009). 

Loggerhead sea turtles may be killed or injured from collisions with boat hulls and propellers. 

These interactions are becoming more common. Capture and mortality of loggerheads during 

periodic dredging of sediments from navigational channels also have been documented. Power 

plants have also been found to impinge and/or entrain loggerheads on/in their intake 

screens/structures. 

Marine pollution, including marine debris, oil spills, and bioaccumulative chemicals, is one of 

the main anthropogenic threats to sea turtles (Tomás et al. 2002). Because of their habitat and 

feeding behavior, loggerheads appear to be one of two sea turtle species that ingest more debris 

in all of its life stages (Lutcavage et al. 1997). Direct or indirect disposal of anthropogenic waste 

introduces potentially lethal materials into loggerhead foraging habitats or into convergence 

zones, affecting oceanic juveniles. Loggerheads will ingest plastic pieces, styrofoam pieces, and 

other marine debris. Ingestion occurs when debris is mistaken for or associated with prey items. 

Effects may be lethal or non-lethal, resulting in varying side effects that may increase the 

probability of death (Balazs 1985, Carr 1987, McCauley and Bjorndal 1999, Witherington 2002). 

For example, nutrient dilution occurs when non-nutritive debris displaces food in the gut, which 

then may decrease somatic growth and reproduction (McCauley and Bjorndal 1999). Sea turtles 

at all life stages appear to be highly sensitive to oil spills, perhaps due to certain aspects of their 

biology and behavior, including a lack of avoidance behavior, indiscriminate feeding in 

convergence zones, and large pre-dive inhalations (Milton et al. 2003). Milton et al. (2003) state 

that the oil effects on turtles include increased egg mortality and developmental defects, direct 

mortality due to oiling in hatchlings, juveniles and adults, and impacts to the skin, blood, salt 

glands, and digestive and immune systems. In addition, loggerheads can become entangled in 

marine debris, such as discarded fishing gear or other entangling materials. 

All loggerhead life history stages are vulnerable to the harmful effects of oil through direct 

contact, degradation of food resources, and loss of habitat (Vargo et al. 1986, Minerals 

Management Service 2000). Vargo et al. (1986) reported that sea turtles would be at substantial 

risk if they encountered an oil spill or large amounts of tar in the environment. In a review of 

available information on debris ingestion, Balazs (1985) reported that tar balls were the second 

most prevalent type of debris ingested by sea turtles. Physiological experiments showed that sea 

turtles exposed to petroleum products may suffer inflammatory dermatitis, ventilatory 

disturbance, salt gland dysfunction or failure, red blood cell disturbances, immune response, and 

digestive disorders (Vargo et al. 1986, Lutz and Lutcavage 1989, Lutcavage et al. 1995). 

Operational discharge of produced waters, drill muds, and drill cuttings are routinely discharged 

in marine waters as a result of petroleum production activities (Minerals Management Service 

2000). Loggerheads may bioaccumulate heavy metals found in drill muds resulting in 

debilitation or death. The effects of large-scale oil spills on loggerheads could be locally 

catastrophic. The impacts of offshore lighted oil production platforms on loggerheads are 

unknown. Lighted platforms may attract hatchlings, making them more susceptible to predation 
110

(de Silva 1982). Neritic juveniles and adults may be attracted by high prey concentrations 

around the structures, making them more susceptible to ingestion of petroleum products. 

Natural factors that have the potential to affect loggerhead recovery include the effects of 

aperiodic hurricanes, seasonal typhoons, and catastrophic environmental events such as 

tsunamis. In general, these events are episodic and, although they may affect loggerhead 

hatchling production, the results are generally localized and they rarely result in whole-scale 

losses over multiple nesting seasons. The negative effects of these types of events on low-lying 

and/or developed shorelines may be longer-lasting and a greater threat overall. 

Loggerheads are also susceptible to cold stunning, a phenomenon in which turtles become 

incapacitated as a result of rapidly dropping water temperatures (Witherington and Ehrhart 1989, 

Morreale et al. 1992). As temperatures fall below 8-10o

C, turtles may lose their ability to swim 

and dive, often floating to the surface. It appears to be the rate of cooling that precipitates cold 

stunning rather than the water temperature itself (Milton and Lutz 2003). Sea turtles that 

overwinter in inshore waters are most susceptible to cold stunning, because temperature changes 

are most rapid in shallow water (Witherington and Ehrhart 1989). 

5.2. Threats Specific to DPS 

5.2.1. North Pacific Ocean DPS 

5.2.1.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

As described in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the 

North Pacific result from coastal development and construction, placement of erosion control 

structures and other barriers to nesting, beachfront lighting, vehicular and pedestrian traffic, sand 

extraction, beach erosion, beach sand placement, beach pollution, removal of native vegetation, 

and planting of non-native vegetation (NMFS and FWS 1998). Beaches in Japan where 

loggerheads nest are extensively eroded due to dredging and dams constructed upstream, and are 

obstructed by seawalls as well. Unfortunately, no quantitative studies have been conducted to 

determine the impact to the loggerhead nesting populations (Kamezaki et al. 2003). However, it 

is clear that loggerhead nesting habitat has been impacted by erosion and extensive beach use by 

tourists, both of which have contributed to unusually high mortality of eggs and pre-emergent 

hatchlings at many Japanese rookeries (Matsuzawa 2006). 

Maehama Beach and Inakahama Beach on Yakushima in Kagoshima Prefecture account for 

approximately 30% of loggerhead nesting in Japan (Kamezaki et al. 2003), making Yakushima 

an important area for nesting beach protection. However, the beaches suffer from beach erosion 

and light pollution, especially from passing cars, as well as from tourists encroaching on the 

nesting beaches (Matsuzawa 2006). Burgeoning numbers of visitors to beaches may cause sand 

compaction and nest trampling. Egg and pre-emergent hatchling mortality in Yakushima has 

been shown to be higher in areas where public access is not restricted and is mostly attributed to 

human foot traffic (“stomping”) on nests (Kudo et al. 2003). Fences have been constructed 
111

around areas where the highest densities of nests are laid; however, there are still lower survival 

rates of eggs and pre-emergent hatchlings due to excessive foot traffic (Ohmuta 2006). Recently, 

the Ministry of Environment has supported the local non-governmental organization conducting 

turtle surveys and conservation on Yakushima in establishing guidelines for surveys and 

minimizing impacts by humans encroaching on the nesting beaches. As of the 2009 nesting 

season, humans accessing Inakahama, Maehama, and Yotsuse beaches at night must comply 

with the established rules (Y. Matsuzawa, Sea Turtle Association of Japan, personal 

communication, 2009). 

Loggerhead nesting habitat also has been lost at important rookeries in Miyazaki due in part to 

port construction that involved development of a groin of one kilometer from the coast into the 

sea, a yacht harbor with breakwaters and artificial beach, and an airport, causing erosion of 

beaches on both sides of the construction zone. This once excellent breeding habitat for 

loggerheads is now seriously threatened by erosion (Takeshita 2006). 

Minabe-Senri beach, Wakayama Prefecture is a “submajor” nesting beach (in Kamezaki et al. 

2003), but is one of the most important rookeries on the main island of Japan (Honshu). Based 

on unpublished data, Matsuzawa (2006) reported hatching success of unwashed-out clutches at 

Minabe-Senri beach to be 24% in 1996, 50% in 1997, 53% in 1998, 48% in 1999, 62% in 2000, 

41% in 2001, and 34% in 2002. 

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, marine pollution, and climate 

change. These threats also occur in the North Pacific Ocean. Fishing methods not only 

incidentally capture loggerheads (Section 5.1.5.), but also deplete invertebrate and fish 

populations and thus alter ecosystem dynamics. In many cases loggerhead foraging areas 

coincide with fishing zones. For example, using aerial surveys and satellite telemetry, juvenile 

foraging hotspots have recently been identified off the coast of Baja California, Mexico; these 

hotspots overlap with intensive small-scale fisheries (Peckham and Nichols 2006; Peckham et al. 

2007, 2008). Comprehensive data currently are unavailable to fully understand how intense 

harvesting of fish resources changes neritic and oceanic ecosystems. Climate change also may 

result in future trophic changes, thus impacting loggerhead prey abundance and/or distribution. 

5.2.1.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

In Japan, the use of loggerhead meat for food is not popular except historically in local 

communities such as Kochi and Wakayama prefectures. In addition, egg collection was common 

in the coastal areas during times of hunger and later by those who valued loggerhead eggs as 

revitalizers or aphrodisiacs and acquired them on the black market (in Kamezaki et al. 2003, 

Takeshita 2006). Currently, due in large part to research and conservation efforts throughout the 

country, egg harvesting no longer represents a problem in Japan (Kamezaki et al. 2003, Ohmuta 

2006, Takeshita 2006). Laws were enacted in 1973 to prohibit egg collection on Yakushima, and 

in 1988, the laws were extended to the entire Kagoshima Prefecture, where two of the most 

important loggerhead nesting beaches are protected (Matsuzawa 2006). 
112

Despite national laws, in many other countries where loggerheads are found migrating through or 

foraging, the hunting of adults and juveniles is still a problem, as seen in Baja California Sur, 

Mexico (Koch et al. 2006). Sea turtles have been protected in Mexico since 1990, when a 

federal law decreed the prohibition of the “extraction, capture and pursuit of all species of sea 

turtle in federal waters or from beaches within national territory ... [and a requirement that] ... 

any species of sea turtle incidentally captured during the operations of any commercial fishery 

shall be returned to the sea, independently of its physical state, dead or alive” (in GarciaMartinez and Nichols 2000). Despite the ban, studies have shown that sea turtles continue to be 

caught, both indirectly in fisheries and by a directed harvest of juveniles and subadults. Turtles 

are principally hunted using nets, longlines, and harpoons. While some are killed immediately, 

others are kept alive in pens and transported to market. The market for sea turtles consists of two 

types: the local market (consumed locally) and the export market (sold to restaurants in Mexico 

cities such as Tijuana, Ensenada, and Mexicali, and U.S. cities such as San Diego and Tucson). 

Consumption is highest during holidays such as Easter and Christmas (Wildcoast/Grupo 

Tortuguero de las Californias 2003). 

Based on a combination of analyses of stranding data, beach and sea surveys, tag-recapture 

studies, and extensive interviews, all carried out between June 1994 and January 1999, Nichols 

(2003) conservatively estimated the annual take of sea turtles by various fisheries and through 

direct harvest in the Baja California, Mexico, region. Sea turtle mortality data collected between 

1994 and 1999 indicate that over 90% of sea turtles recorded dead were either green turtles (30% 

of total) or loggerheads (61% of total), and signs of human consumption were evident in over 

half of the specimens. These studies resulted in an estimated 1,950 loggerheads killed annually, 

affecting primarily immature size classes. The primary causes for mortality were the incidental 

take in a variety of fishing gears and direct harvest for consumption and [illegal] trade (Nichols 

2003). 

From April 2000 to July 2003 throughout the Bahia Magdalena region (including local beaches 

and towns), researchers found 1,945 sea turtle carcasses, 44.1% of which were loggerheads. Of 

the sea turtle carcasses found, slaughter for human consumption was the primary cause of death 

for all species (63% for loggerheads). Over 90% of all turtles found were juveniles or subadults 

(Koch et al. 2006). As the population of green turtles has declined in Baja California Sur waters, 

poachers have switched to loggerheads (H. Peckham, Pro Peninsula, personal communication, 

2006). 

5.2.1.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the North Pacific Ocean. As in other nesting locations, egg predation also 

exists in Japan, particularly by raccoon dogs (Nyctereutes procyonoides) and weasels (Mustela 

itatsi); however, quantitative data do not exist to evaluate the impact on loggerhead populations 

(Kamezaki et al. 2003). Loggerheads in the North Pacific Ocean also may be impacted by 

harmful algal blooms. 
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5.2.1.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the North Pacific. The following additional instruments 

also apply to loggerheads found in this area. 

United States Magnuson-Stevens Fishery Conservation and Management Act 

The recently-amended U.S. Magnuson-Stevens Fishery Conservation and Management Act 

(MSA), implemented by NMFS, mandates environmentally responsible fishing practices within 

U.S. fisheries. Section 301 of the MSA establishes National Standards to be addressed in 

management plans. Any regulations promulgated to implement such plans, including 

conservation and management measures, shall, to the extent practicable, (A) minimize bycatch 

and (B) to the extent bycatch cannot be avoided, minimize the mortality of such bycatch. 

Section 301 by itself does not require specific measures. However, mandatory bycatch reduction 

measures can be incorporated into management plans for specific fisheries, as has happened with 

the U.S. pelagic longline fisheries in the Atlantic and Pacific oceans. Section 316 requires the 

establishment of a bycatch reduction engineering program to develop "technological devices and 

other conservation engineering changes designed to minimize bycatch, seabird interactions, 

bycatch mortality, and post-release mortality in Federally managed fisheries." 

Indian Ocean – South-East Asian Marine Turtle Memorandum of Understanding (IOSEA) 

This Memorandum of Understanding (MOU) puts in place a framework through which States of 

the Indian Ocean and South-East Asian region, as well as other concerned States, can work 

together to conserve and replenish depleted marine turtle populations for which they share 

responsibility. This collaboration is achieved through the collective implementation of an 

associated Conservation and Management Plan. Currently, there are 27 signatory states. The 

United States became a signatory in 2001. Numerous accomplishments have been made under 

the auspices of this MOU. For detailed information, visit the IOSEA website at 

http://www.ioseaturtles.org. 

Memorandum of Understanding on ASEAN Sea Turtle Conservation and Protection 

The objectives of this MOU, initiated by the Association of South East Asian Nations (ASEAN), 

are to promote the protection, conservation, replenishing, and recovery of sea turtles and their 

habitats based on the best available scientific evidence, taking into account the environmental, 

socio-economic and cultural characteristics of the Parties. It currently has 10 signatory states in 

the South East Asian Region: Brunei Darussalam, Cambodia, Indonesia, Laos, Malaysia, 

Myanmar, Philippines, Singapore, Thailand, and Vietnam. Additional information is available at 

http://www.aseansec.org/6185.htm. 

Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC) 

This Convention is one of only a handful of international treaties dedicated exclusively to sea 

turtles, setting standards for the conservation of these endangered animals and their habitats with 

a large emphasis on bycatch reduction. It is the only binding multi-national agreement for sea 

turtles and is open to all countries in North, Central, and South America, and the Caribbean. It 

currently has 12 Contracting Parties, with the United States being a signatory in 1999. 

Additional information is available at http://www.iacseaturtle.org. 
114

Convention for the Protection of the Marine Environment and Coastal Area of the South-East 

Pacific (Lima Convention) 

This Convention’s signatories include all countries along the Pacific Rim of South America from 

Panama to Chile. Among other resource management components, this Convention established a 

protocol for the conservation and management of protected marine resources. Stemming from 

this Convention is the Commision Permanente del Pacifico Sur (CPPS) that has developed a 

Marine Turtle Action Plan for the Southeast Pacific that outlines a strategy for protecting and 

recovering marine turtles in this region. 

Convention for the Protection of Natural Resources and Environment of the South Pacific 

Region (Noumea Convention) 

In force since 1990, this Convention includes 19 Parties from throughout the Southwest Pacific 

Ocean: Australia, Cook Islands, Federated States of Micronesia, Fiji, France, Kiribati, Marshall 

Islands, Nauru, New Zealand, Niue, Palau, Papua New Guinea, Samoa, Solomon Islands, Tonga, 

Tuvalu, United Kingdom, United States, and Vanuatu. This Convention is relevant only for the 

Exclusive Economic Zones of Party nations, and does not have jurisdiction in international 

waters. Relevant to marine turtles are the associated Protocol for the Prevention of Pollution of 

the South Pacific Region by Dumping (reduction of marine debris), and the Action Plan for 

Managing the Natural Resources and Environment of the South Pacific Region, which occurs 

under the auspices of the South Pacific Regional Environment Programme (SPREP). Additional 

information is available at 

http://sedac.ciesin.org/entri/texts/natural.resources.south.pacific.1986.html. 

5.2.1.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

Incidental capture in artisanal and commercial fisheries is a significant threat to the survival of 

loggerheads in the North Pacific. Sea turtles may be caught in pelagic and demersal longlines, 

drift and set gillnets, bottom and mid-water trawling, fishing dredges, pound nets and weirs, haul 

and purse seines, pots and traps, and hook and line gear. 

Based on turtle sightings and capture rates reported in a survey of fisheries research and training 

vessels and extrapolated to total longline fleet effort by the Japanese fleet in 1978, Nishemura 

and Nakahigashi (1990) estimated that 21,200 turtles, including greens, leatherbacks, 

loggerheads, olive ridleys, and hawksbills, were captured annually by Japanese tuna longliners in 

the western Pacific and South China Sea, with a reported mortality of approximately 12,300 

turtles per year. Using commercial tuna longline logbooks, research vessel data, and 

questionnaires, Nishemura and Nakahigashi (1990) estimated that for every 10,000 hooks in the 

western Pacific and South China Sea, one turtle is captured, with a mortality rate of 42%. 

Although species-specific information on the bycatch is not available, vessels reported that 36% 

of the sightings of turtles in locations that overlap with these commercial fishing grounds were 

loggerheads. 

Caution should be used in interpreting the results of Nishemura and Nakahigashi (1990), 

including estimates of sea turtle take rate (per number of hooks) and resultant mortality rate, and 
115

estimates of annual take by the fishery, for the following reasons: (1) the data collected were 

based on observations by training and research vessels, logbooks, and a questionnaire (i.e., 

hypothetical), and do not represent actual, substantiated logged or observed catch of sea turtles 

by the fishery; (2) the authors assumed that turtles were distributed homogeneously; and (3) the 

authors used only one year (1978) to estimate total effort and distribution of the Japanese tuna 

longline fleet. Although the data and analyses provided by Nishemura and Nakahigashi (1990) 

are conjectural, longliners fishing in the Pacific have significantly impacted and, with the current 

level of effort, probably will continue to have significant impacts on sea turtle populations. 

Foreign high-seas driftnet fishing in the North Pacific Ocean for squid, tuna, and billfish ended 

with a United Nations moratorium in December 1992. Except for observer data collected in 

1990-1991, there is virtually no information on the incidental take of sea turtle species by the 

driftnet fisheries prior to the moratorium. The high-seas squid driftnet fishery in the North 

Pacific was observed in Japan, Korea, and Taiwan, while the large-mesh fisheries targeting tuna 

and billfish were observed in the Japanese fleet (1990-1991) and the Taiwanese fleet (1990). A 

combination of observer data and fleet effort statistics indicate that 2,986 loggerhead turtles were 

entangled by the combined fleets of Japan, Korea, and Taiwan during June 1990 through May 

1991, when all fleets were monitored. Of these incidental entanglements, an estimated 805 

loggerheads were killed (27% mortality rate) (Wetherall 1997). Data on size composition of the 

turtles caught in the high-seas driftnet fisheries also were collected by observers. The majority 

of loggerheads measured by observers were immature (Wetherall 1997). The cessation of highseas driftnet fishing in 1992 should have reduced the incidental take of marine turtles. However, 

nations involved in driftnet fishing may have shifted to other gear types (e.g., pelagic or demersal 

longlines, coastal gillnets); this shift in gear types could have resulted in either similar or 

increased turtle bycatch and associated mortality. 

These rough mortality estimates for a single fishing season provide only a narrow glimpse of the 

impacts of the driftnet fishery on sea turtles, and a full assessment of impacts would consider the 

turtle mortality generated by the driftnet fleets over their entire range. Unfortunately, 

comprehensive data are lacking, but the observer data do indicate the possible magnitude of 

turtle mortality given the best information available. Wetherall et al. (1993) speculate that the 

actual mortality of sea turtles may have been between 2,500 and 9,000 per year, with most of the 

mortalities being loggerheads taken in the Japanese and Taiwanese large-mesh fisheries. 

While a comprehensive, quantitative assessment of the impacts of the North Pacific driftnet 

fishery on turtles is impossible without a better understanding of turtle population abundance, 

genetic identities, exploitation history, and population dynamics, it is likely that the mortality 

inflicted by the driftnet fisheries in 1990 and in prior years was significant (Wetherall et al. 

1993), and the effects may still be evident in sea turtle populations today. The high mortality of 

juveniles, subadults, and reproductive adults in the high-seas driftnet fishery has probably altered 

the current age structure (especially if certain age groups were more vulnerable to driftnet 

fisheries) and therefore diminished or limited the reproductive potential of affected sea turtle 

populations. 

Extensive ongoing studies regarding loggerhead mortality and bycatch have been administered 

off the coast of Baja California Sur, Mexico. The location and timing of loggerhead strandings 
116

documented in 2003-2005 along a 43-kilometer beach (Playa San Lázaro) indicated bycatch in 

local small-scale fisheries. In order to corroborate this, in 2005, researchers observed two smallscale fleets operating closest to an area identified as a high-use area for loggerheads. One fleet, 

based out of Puerto López Mateos, fished primarily for halibut using bottom set gillnets, soaking 

from 20 to 48 hours. This fleet consisted of up to 75 boats in 2005, and, on a given day, 9 to 40 

vessels fished the deep area (32-45 meter depths). During a two-month period, 11 loggerheads 

were observed taken in 73 gillnet day-trips, with eight of those loggerheads landed dead 

(observed mortality rate – 73%). The other fleet, based in Santa Rosa, fished primarily for 

demersal sharks using bottom-set longlines baited with tuna or mackerel and left to soak for 20 

to 48 hours. In 2005, the fleet numbered only five to six vessels. During the seven daylong 

bottom-set longline trips observed, 26 loggerheads were taken, with 24 of them landed dead 

(observed mortality rate – 92%). Based on these observations, researchers estimated that in 2005 

at least 299 loggerheads died in the bottom-set gillnet fishery and at least 680 loggerheads died 

in the bottom-set longline fishery. This annual bycatch estimate of approximately 1,000 

loggerheads is considered a minimum and is also supported by shoreline mortality surveys and 

informal interviews (Peckham et al. 2007). 

These results suggest that incidental capture at Baja California Sur is one of the most significant 

sources of mortality identified for the North Pacific loggerhead population and underscores the 

importance of reducing bycatch in small-scale fisheries. 

In the U.S. Pacific, longline fisheries targeting swordfish and tuna and drift gillnet fisheries 

targeting swordfish have been identified as the primary fisheries of concern for loggerheads. 

Bycatch of loggerhead turtles in these fisheries has been significantly reduced as a result of timearea closures, required gear modifications, and hard caps imposed on turtle bycatch, with 100% 

observer coverage in certain areas. 

The California/Oregon (CA/OR) drift gillnet fishery targets swordfish and thresher shark off the 

west coast of the United States. The fishery has been observed by NMFS since July 1990, and 

currently averages 20%. From July 1990 to January 2000, the CA/OR drift gillnet fishery was 

observed to incidentally capture 17 loggerheads (12 released alive, 1 injured, and 4 killed). 

Based on a worst-case scenario, NMFS estimated that a maximum of 33 loggerheads in a given 

year could be incidentally taken by the CA/OR drift gillnet fleet. Sea turtle mortality rates for 

hard-shelled species were estimated to be 32% (NMFS 2000). 

In 2000, analyses conducted under the mandates of the ESA showed that the CA/OR drift gillnet 

fishery was taking excessive numbers of sea turtles, such that the fishery “jeopardized the 

continued existence of” loggerheads and leatherbacks. In this case, the consulting agency 

(NMFS) was required to provide a reasonable and prudent alternative to the action (i.e., the 

fishery). In order to reduce the likelihood of interactions with loggerhead sea turtles, NMFS has 

regulations in place to close areas to drift gillnet fishing off southern California during forecasted 

or occurring El Niño events from June 1 through August 31, when loggerheads are likely to 

move into the area from the Pacific coast of Baja California following a preferred prey species, 

pelagic red crabs. 
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Prior to 2000, the Hawaii-based longline fishery targeted highly migratory species north of 

Hawaii using gear largely used by fleets around the world. From 1994-1999, the fishery was 

estimated to take between 369 and 501 loggerheads per year, with between 64 and 88 mortalities 

per year (NMFS 2000). Currently, the Hawaii-based shallow longline fishery targeting 

swordfish is strictly regulated such that an annual take of 17 loggerheads is authorized for the 

fishery, beginning in 2004, when the fishery was re-opened after being closed for several years. 

In 2004 and 2005, the fishing year was completed without reaching the turtle take levels (1 and 

10 loggerheads were captured, respectively, with fleets operating with 100% observer coverage). 

However, in 2006, 17 loggerheads were taken, forcing the fishery to be shut down early. In 

2007, 15 loggerheads were taken by the fishery. Most loggerheads were released alive (NMFSPacific Islands Regional Office, Observer Database Public Website, 2008). 

Recent investigations off the coast of Japan, particularly focused off the main islands of Honshu, 

Shikoku, and Kyushu, have revealed a major threat to the more mature stage classes of 

loggerheads (approximately 70-80 cm SCL) due to pound net fisheries set offshore of the nesting 

beaches and in the coastal foraging areas. While pound nets constitute the third largest fishery in 

terms of metric tons of fish caught in Japan, they account for the majority of loggerhead bycatch 

by Japanese fisheries. Open-type pound nets studied in an area off Shikoku were shown to take 

loggerheads as the most prevalent sea turtle species caught but had lower mortality rates (less 

than 15%), primarily because turtles could reach the surface to breathe. Middle layer and 

bottom-type pound nets in particular have high rates of mortality (nearly 100%), because the nets 

are submerged and sea turtles are unable to reach the surface. Estimates of loggerhead mortality 

in one area studied between April 2006 and September 2007 were on the order of 100 

individuals. While the fishing industry has an interest in changing its gear to open-type, it is 

very expensive, and the support from the Japanese government is limited (T. Ishihara, Sea Turtle 

Association of Japan, personal communication, 2007). Nonetheless, the BRT recognizes that 

coastal pound net fisheries off Japan may pose a significant threat to the North Pacific population 

of loggerheads. 

Quantifying the magnitude of the threat of fisheries in the North Pacific Ocean on loggerhead sea 

turtles is very difficult given the low level of observer coverage or investigations into bycatch 

conducted by countries that have large fishing fleets. Efforts have been made to quantify the 

effect of pelagic longline fishing on loggerheads, and annual estimates of bycatch were on the 

order of over 10,000 sea turtles, with as many as 2,600 individual loggerheads killed annually 

through immediate or delayed mortality as a result of interacting with the gear (Lewison et al. 

2004). 

Other Manmade and Natural Impacts 

Similar to other areas of the world (see Section 5.1.5.), climate change and sea level rise have the 

potential to impact loggerheads in the North Pacific Ocean. For example, Matsuzawa et al.

(2002) found heat-related mortality of pre-emergent hatchlings in Minabe Senri Beach and 

concluded that this population is vulnerable to even small temperature increases resulting from 

global warming because sand temperatures already exceed the optimal thermal range for 

incubation. Recently, Chaloupka et al. (2008) used generalized additive regression modeling 

and autoregressive-prewhitened cross-correlation analysis to consider whether changes in 

regional ocean temperatures affect long-term nesting population dynamics for Pacific 
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loggerheads from primary nesting assemblages in Japan and Australia. Researchers chose four 

nesting sites with a generally long time series to model, two in Japan (Kamouda rookery, 

declining population, and Yakushima rookery, generally increasing in the last 20 years), and two 

nesting sites in Australia (Woongarra rookery, generally declining through early 1990s and 

beginning to recover, and Wreck Island rookery, which is generally declining). Analysis of 51 

years of mean annual sea surface time series around two core foraging areas off Japan and 

eastern Australia, showed a general warming of the oceans in these regions. In general, nesting 

abundance for all four rookeries was inversely related to sea surface temperatures; that is, higher 

sea surface temperatures during the previous year in the core foraging area resulted in lower 

summer season nesting at all rookeries. Given that cooler ocean temperatures are generally 

associated with increased productivity and that female sea turtles generally require at least one 

year to acquire sufficient fat stores for vitellogenesis to occur in the foraging grounds, as well as 

the necessary energy required for migration, any lag in productivity due to warmer temperatures 

has physiological basis. Over the long-term, warming ocean temperatures could therefore lead to 

lower productivity and prey abundance, and thus reduced nesting and recruitment by Pacific 

loggerheads (Chaloupka et al. 2008). 

As described in Section 5.1.5., other anthropogenic impacts, such as boat strikes and ingestion or 

entanglement in marine debris, as well as entrainment in coastal power plants, also apply to 

loggerheads in the North Pacific. 

Natural environmental events, such as cyclones and hurricanes, may affect loggerheads in the 

North Pacific Ocean. Typhoons have also been shown to cause severe beach erosion and 

negatively affect hatching success at many loggerhead nesting beaches in Japan, especially in 

areas already prone to erosion. For example, during the 2004 season, the Japanese archipelago 

suffered a record number of typhoons and many nests were drowned or washed out. Extreme 

sand temperatures at nesting beaches also create highly skewed female sex ratios of hatchlings or 

threaten the health of hatchlings. Without human intervention to protect clutches against some 

of these natural threats, many of these nests would be lost (Matsuzawa 2006). 

5.2.2. South Pacific Ocean DPS 

The following information on threats pertains to all loggerhead turtles that may be found within 

the boundaries of the South Pacific Ocean DPS. Because foraging loggerheads from this DPS 

also are found within the boundaries of the Southeast-Indo Pacific Ocean DPS (specifically in 

the Gulf of Carpentaria west of 142.5oE), the narrative for that region should also be consulted. 

5.2.2.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

As described in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the 

South Pacific result from coastal development and construction, placement of erosion control 

structures and other barriers to nesting, beachfront lighting, vehicular traffic, beach erosion, 

beach pollution, removal of native vegetation, and planting of non-native vegetation (NMFS and 

FWS 1998, Limpus 2009). 
119

Removal or destruction of native dune vegetation, which enhances beach stability and acts as an 

integral buffer zone between land and sea, results in erosion of nesting habitat. Preliminary 

studies on nesting beaches in New Caledonia include local oral histories that attribute the 

decrease in loggerhead nesting to the removal of vegetation for construction purposes and 

subsequent beach erosion (Limpus et al. 2006). 

Beach armoring presents a barrier to nesting in the South Pacific. On the primary nesting beach 

in New Caledonia, a rock wall was constructed to prevent coastal erosion, and sea turtle nesting 

attempts have been unsuccessful. Local residents are seeking authorization to extend the wall 

further down the beach (Limpus et al. 2006). 

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, marine pollution, and climate 

change. These threats also occur in the South Pacific Ocean. Climate change, for instance, may 

result in future trophic changes, thus impacting loggerhead prey abundance and/or distribution. 

5.2.2.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Legislation in Australia outlaws the harvesting of loggerheads by indigenous peoples (Limpus et 

al. 2006). Despite national laws, in many areas the poaching of eggs and hunting of adults and 

juveniles is still a problem, and Limpus (2009) suggests that the harvest rate of loggerheads by 

indigenous hunters, both within Australia and in neighboring countries, is on the order of 40 

turtles per year. Preliminary studies suggest that local harvesting in New Caledonia constitutes 

about 5% of the nesting population (Limpus et al. 2006). Loggerheads also are consumed after 

being captured incidentally in high-seas fisheries of the southeastern Pacific (Alfaro-Shigueto et 

al. 2006), and occasionally may be the product of illegal trade throughout the region. 

5.2.2.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the South Pacific. While the prevalence of fibropapillomatosis in most 

loggerhead populations is thought to be small, an exception is in Moreton Bay, Australia, where 

4.4% of the 320 loggerheads captured exhibited the disease during 1990-1992 (Limpus et al. 

1994). A subsequent study also found a high prevalence of fibropapillomatosis in the area 

(Quackenbush et al. 2000). 

Predation on nests and hatchlings by terrestrial vertebrates is a major problem at loggerhead 

rookeries in the South Pacific. At mainland rookeries in eastern Australia, for example, the 

introduced fox (Vulpes vulpes) has been the most significant predator on loggerhead eggs 

(Limpus 1985, 2009). Although this has been minimized in recent years (to <5%; Limpus 2009), 

researchers believe the earlier egg loss will greatly impact recruitment to this nesting population 

in the early 21st century (Limpus and Reimer 1994). Predation on hatchlings by crabs and 

diurnal birds is also a threat (Limpus 2009). In New Caledonia, feral dogs pose a predation 

threat to nesting loggerheads, and thus far no management has been implemented (Limpus et al. 

2006). 
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5.2.2.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the South Pacific Ocean. The following additional 

instruments also apply to loggerheads found in this area. 

Indian Ocean – South-East Asian Marine Turtle Memorandum of Understanding (IOSEA) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Memorandum of Understanding on ASEAN Sea Turtle Conservation and Protection 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Convention for the Protection of the Marine Environment and Coastal Area of the South-East 

Pacific (Lima Convention) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Convention for the Protection of Natural Resources and Environment of the South Pacific 

Region (Noumea Convention) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

5.2.2.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

Incidental capture in artisanal and commercial fisheries is a significant threat to the survival of 

loggerheads throughout the South Pacific. The primary gear types involved in these interactions 

include longlines, driftnets, set nets, and trawl fisheries. These are employed by both artisanal 

and industrial fleets, and target a wide variety of species including tunas, sharks, sardines, 

swordfish, and mahi mahi (see below). 

In the southwestern Pacific, bottom trawling gear has been a contributing factor to the decline in 

the eastern Australian loggerhead population (Limpus and Reimer 1994). The northern 

Australian prawn fishery (NPF) is made up of both a banana prawn fishery and a tiger prawn 

fishery, and extends from Cape York, Queensland (142oE) to Cape Londonberry, Western 

Australia (127oE). The fishery is one of the most valuable in all of Australia and in 2000 

comprised 121 vessels fishing approximately 16,000 fishing days (Robins et al. 2002a). In 2000, 

the use of turtle excluder devices (TEDs) in the NPF was made mandatory, due in part to several 

factors: (1) objectives of the Draft Australian Recovery Plan for Marine Turtles, (2) requirement 

of the Australian Environment Protection and Biodiversity Conservation Act for Commonwealth 

fisheries to become ecologically sustainable, and (3) the 1996 U.S. import embargo on wildcaught prawns taken in a fishery without adequate turtle bycatch management practices (Robins 

et al. 2002a). Data primarily were collected by volunteer fishers who were trained extensively in 

the collection of scientific data on sea turtles caught as bycatch in their fishery. Prior to the use 

of TEDs in this fishery, the NPF annually took between 5,000 and 6,000 sea turtles as bycatch, 
121

with a mortality rate of an estimated 40% due to drowning, injuries, or being returned to the 

water comatose (Poiner and Harris 1996). Since the mandatory use of TEDs has been in effect, 

the annual bycatch of sea turtles in the NPF has dropped to less than 200 sea turtles per year, 

with a mortality rate of approximately 22% (based on recent years). This lower mortality rate 

also may be based on better sea turtle handling techniques adopted by the fleet. In general, 

loggerheads were the third most common sea turtle taken in this fishery. 

Loggerheads are also taken by longline fisheries operating out of Australia (Limpus 2009). For 

example, Robins et al. (2002b) estimate that approximately 400 turtles are killed annually in 

Australian pelagic longline fishery operations. Of this annual estimate, leatherbacks accounted 

for over 60% of this total, while unidentified hardshelled turtles accounted for the remaining 

species. Therefore, the effect of this longline fishery on loggerheads is unknown. 

Loggerheads also have been the most common turtle species captured in shark control programs 

in Australia (Kidston et al. 1992, Limpus 2009). From 1998-2002, a total of 232 loggerheads 

were captured with 195 taken on drum lines and 37 taken in nets, both with a low level of direct 

mortality (Limpus 2009).

In the southeastern Pacific, significant bycatch has been reported in artisanal gillnet and longline 

shark and mahi mahi fisheries operating out of Peru (Kelez et al. 2003, Alfaro-Shigueto et al. 

2006) and to a lesser extent, Chile (Donoso and Dutton 2006). The fishing industry in Peru is the 

second largest economic activity in the country, and, over the past few years, the longline fishery 

has rapidly increased. Currently, nearly 600 longline vessels fish in the winter and over 1,300 

vessels fish in the summer. During an observer program in 2003/2004, 588 sets were observed 

during 60 trips, and 154 sea turtles were taken as bycatch. Loggerheads were the species most 

often caught (73.4%). Of the loggerheads taken, 68% were entangled and 32% were hooked. Of 

the two fisheries, sea turtle bycatch was highest during the mahi mahi season, with 0.597 

turtles/1,000 hooks, while the shark fishery caught 0.356 turtles/1,000 hooks (Alfaro-Shigueto et 

al. 2008b). A separate study by Kelez et al. (2003) reported that approximately 30% of all 

turtles bycaught in Peru were loggerheads. In many cases, loggerheads are kept on board for 

human consumption; therefore, the mortality rate in this artisanal longline fishery is likely high 

because sea turtles are retained for future consumption or sale. 

Data on loggerhead bycatch in Chile are limited to the industrial swordfish fleet. Since 1990, 

fleet size has ranged from 7 to 23 vessels with a mean of approximately 14 vessels per year. 

These vessels fish up to and over 1,000 nautical miles along the Chilean coast with mechanized 

sets numbering approximately 1,200 hooks (M. Donoso, ONG Pacifico Laud - Chile, personal 

communication, 2007). Loggerhead bycatch is present in Chilean fleets; however, the catch rate 

is substantially lower than that reported for Peru (P. Dutton, NMFS, and M. Donoso, ONG 

Pacifico Laud - Chile, unpublished data). 

Other Manmade and Natural Impacts 

Other threats such as debris ingestion, boat strikes, and port dredging also impact loggerheads in 

the South Pacific, although these threats have been minimized in recent years due to a variety of 

legislative actions (Limpus 2009). Loggerhead mortality resulting from dredging of channels in 

Queensland is a persistent, albeit minor problem. From 1999-2002, the average annual reported 
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mortality was 1.7 turtles per year (range = 1-3) from port dredging operations (Limpus 2009). 

Climate change and sea level rise have the potential to impact loggerheads in the South Pacific 

Ocean, yet the impact of these threats has not been quantified. 

Natural environmental events, such as cyclones or hurricanes, may affect loggerheads in the 

South Pacific Ocean. These types of events may disrupt loggerhead nesting activity, albeit on a 

temporary scale. As described in more detail in Section 5.2.1.5., Chaloupka et al. (2008) 

demonstrated that nesting abundance of loggerheads in Australia was inversely related to sea 

surface temperatures, and suggested that a long term warming trend in the South Pacific may be 

adversely impacting the recovery potential of this population. 

5.2.3. North Indian Ocean DPS 

5.2.3.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

As described in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the 

North Indian Ocean result from coastal development and construction, beachfront lighting, 

vehicular and pedestrian traffic, beach pollution, removal of native vegetation, and planting of 

non-native vegetation (NMFS and FWS 1998). 

The primary loggerhead nesting beaches of this DPS are at Masirah Island, Oman, and are still 

relatively undeveloped but now facing increasing development pressures. Newly paved roads 

closely paralleling most of the Masirah Island coast are bringing newly constructed highway 

lights (E. Possardt, FWS, personal observation, 2008) and greater access to nesting beaches by 

the public. Light pollution from the military installation at Masirah Island also is evident at the 

most densely nested northern end of the island and is a likely cause of hatchling misorientation 

and nesting female disturbance (E. Possardt, FWS, personal observation, 2008). Beach driving 

occurs on most of the major beaches outside the military installation. This vehicular traffic 

creates ruts that obstruct hatchling movements (Mann 1977, Hosier et al. 1981, Cox et al. 1994, 

Baldwin 1992), tramples nests, and destroys vegetation and dune formation processes, which 

exacerbates light pollution effects. Free ranging camels, sheep, and goats overgraze beach 

vegetation, which impedes natural dune formation (E. Possardt, FWS, personal observation, 

2008). Development of a new hotel on a major loggerhead nesting beach at Masirah Island is 

near completion and, although not yet approved, there are plans for a major resort at an important 

loggerhead nesting beach on one of the Halaniyat Islands. Armoring structures common to many 

developed beaches throughout the world are not yet evident on the major loggerhead nesting 

beaches of this DPS. 

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, marine pollution, and climate 

change. These threats also occur in the North Indian Ocean. 
123

Fishing methods not only incidentally capture loggerheads (Section 5.1.5.), but also deplete 

invertebrate and fish populations and thus alter ecosystem dynamics. In many cases loggerhead 

foraging areas coincide with fishing zones. There has been an apparent growth in artisanal and 

commercial fisheries in waters surrounding Masirah Island (Baldwin 1992). Climate change also 

may result in future trophic changes, thus impacting loggerhead prey abundance and/or 

distribution. 

5.2.3.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

The use of loggerhead meat for food in Oman is not legal or popular. However, routine egg 

collection on Masirah Island does occur (Baldwin 1992). The extent of egg collection as 

estimated by Masirah rangers and local residents is approximately 2,000 clutches per year 

(<10%). 

5.2.3.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the North Indian Ocean. Natural egg predation on Oman loggerhead 

nesting beaches undoubtedly occurs, but is not well documented or believed to be significant. 

Predation on hatchlings by Arabian red fox (Vulpes vulpes arabica), ghost crabs (Ocypode 

saratan), night herons (Nycticorax nycticorax), and gulls (Larus spp.) likely occurs. While 

quantitative data do not exist to evaluate these impacts on the North Indian Ocean loggerhead 

population, they are not likely to be significant. 

5.2.3.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the North Indian Ocean. There are two additional 

instruments that apply to loggerheads found in this area. 

Indian Ocean – South-East Asian Marine Turtle Memorandum of Understanding (IOSEA) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Nairobi Convention for the Protection, Management and Development of the Marine and 

Coastal Environment of the Eastern African Region 

The Nairobi Convention was signed in 1985 and came into force in 1996. The Convention 

covers 10 States, including five island States in the Western Indian Ocean. The Contracting 

Parties are Comoros, France (La Reunion), Kenya, Madagascar, Mauritius, Mozambique, 

Seychelles, Somalia, Tanzania and the Republic of South Africa. This instrument “provides a 

mechanism for regional cooperation, coordination and collaborative actions, and enables the 

Contracting Parties to harness resources and expertise from a wide range of stakeholders and 

interest groups towards solving interlinked problems of the coastal and marine environment.” 

Additional information is available at http://www.unep.org/NairobiConvention. 
124

5.2.3.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

The magnitude of the threat of incidental capture of sea turtles in artisanal and commercial 

fisheries in the North Indian Ocean is difficult to assess. A bycatch survey administered off the 

coast of Sri Lanka between September 1999 and November 2000 reported 5,241 total turtle 

entanglements, of which 1,310 were loggerheads, between Kalpitiya and Kirinda (Kapurusinghe 

and Saman 2001, Kapurusinghe and Cooray 2002). Sea turtle bycatch has been reported in 

driftnet and set gillnets, longlines, trawls, and hook and line gear (Kapurusinghe and Saman 

2001, Kapurusinghe and Cooray 2002, Lewison et al. 2004). 

Quantifying the magnitude of the threat of fisheries on loggerheads in the North Indian Ocean is 

difficult given the low level of observer coverage or investigations into bycatch conducted by 

countries that have large fishing fleets. Efforts have been made to quantify the effects of pelagic 

longline fishing on loggerheads globally (Lewison et al. 2004). While there were no turtle 

bycatch data available from the North Indian Ocean to use in their assessment, extrapolations 

that considered bycatch data for the Pacific and Atlantic basins gave a conservative estimate of 

6,000 loggerheads captured in the Indian Ocean in the year 2000. Interviews with rangers at 

Masirah Island reveal that shark gillnets capture many loggerheads off nesting beaches during 

the nesting season. As many as 60 boats are involved in this fishery with up to 6 km of gillnets 

being fished daily from June through October along the Masirah Island coast. Rangers reported 

one example of 17 loggerheads in one net (E. Possardt, FWS, personal communication, 2008). 

Other Manmade and Natural Impacts 

As described in Section 5.1.5., other anthropogenic impacts, such as boat strikes and ingestion or 

entanglement in marine debris, as well as entrainment in coastal power plants, likely apply to 

loggerheads in the North Indian Ocean. Similar to other areas of the world (see Section 5.1.5.), 

climate change and sea level rise have the potential to impact loggerheads in the North Indian 

Ocean. This includes beach erosion and loss from rising sea levels, skewed hatchling sex ratios 

from rising beach incubation temperatures, and abrupt disruption of ocean currents used for 

natural dispersal during the complex life cycle. Climate change impacts could have profound 

long term impacts on nesting populations in the North Indian Ocean, but it is not possible to 

quantify the potential impacts at this point in time. 

Natural environmental events, such as cyclones, tsunamis, and hurricanes, affect loggerheads in 

the North Indian Ocean. For example, during the 2007 season, Oman suffered a rare typhoon. 

In general, however, severe storm events are episodic and, although they may affect loggerhead 

hatchling production, the results are generally localized and they rarely result in whole-scale 

losses over multiple nesting seasons.

5.2.4. Southeast Indo-Pacific Ocean DPS 

The following information on threats pertains to all loggerhead turtles that may be found within 

the boundaries of the Southeast Indo-Pacific Ocean DPS. Because foraging loggerheads from 

this DPS also are found within the boundaries of the South Pacific Ocean DPS, the narrative for 

that region should also be consulted. 
125

5.2.4.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

The primary loggerhead nesting beaches for this DPS occur in Australia on Dirk Hartog Island 

and Murion Islands (Baldwin et al. 2003), which are undeveloped. Dirk Hartog Island is soon to 

become part of the National Park System. 

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, marine pollution, and climate 

change. These threats also occur in the Southeast Indo-Pacific Ocean. Fishing methods not only 

incidentally capture loggerheads (Section 5.1.5.), but also deplete invertebrate and fish 

populations and thus alter ecosystem dynamics. In many cases, loggerhead foraging areas 

coincide with fishing zones. Climate change also may result in future trophic changes, thus 

impacting loggerhead prey abundance and/or distribution. 

5.2.4.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Legislation in Australia outlaws the harvesting of loggerheads by indigenous peoples (Limpus et 

al. 2006). Dirk Hartog Island and Murion Islands are largely uninhabited, and poaching of eggs 

and turtles is likely negligible. 

5.2.4.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the Southeast Indo-Pacific Ocean. On the North West Cape and the 

beaches of the Ningaloo coast of mainland Australia, a long established feral European red fox 

(Vulpes vulpes) population preyed heavily on eggs and is thought to be responsible for the lower 

numbers of nesting turtles on the mainland beaches (Baldwin et al. 2003). The fox populations 

have been eradicated on Dirk Hartog Island and Murion Islands (Baldwin et al. 2003). 

5.2.4.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the Southeast Indo-Pacific Ocean. The following 

additional instrument also applies to loggerheads found in this area. 

Indian Ocean – South-East Asian Marine Turtle Memorandum of Understanding (IOSEA) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

5.2.4.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

The extent of the threat of incidental capture of sea turtles in artisanal and commercial fisheries 

in the Southeast Indo-Pacific Ocean is unknown. Sea turtles are caught in pelagic and demersal 
126

longlines, gillnets, trawls, seines, and pots and traps (Environment Australia 2003). There is 

evidence of significant historic bycatch from prawn fisheries, which may have depleted nesting 

populations long before nesting surveys were initiated in the 1990s (Baldwin et al. 2003). 

Quantifying the magnitude of the threat of fisheries on loggerheads in the Southeast Indo-Pacific 

Ocean is very difficult given the low level of observer coverage or investigations into bycatch 

conducted by countries that have large fishing fleets. Efforts have been made to quantify the 

effects of pelagic longline fishing on loggerheads globally (Lewison et al. 2004). While there 

were no turtle bycatch data available from the Southeast Indo-Pacific Ocean to use in their 

assessment, extrapolations that considered bycatch data for the Pacific and Atlantic basins gave a 

conservative estimate of 6,000 loggerheads captured in the Indian Ocean in the year 2000. 

Loggerheads are known to be taken by Japanese longline fisheries operating off of Western 

Australia (Limpus 2009). The effect of the longline fishery on loggerheads in the Indian Ocean 

is largely unknown (Lewison et al. 2004). 

The northern Australian prawn fishery (NPF) is made up of both a banana prawn fishery and a 

tiger prawn fishery, and extends from Cape York, Queensland (142oE) to Cape Londonberry, 

Western Australia (127oE). The fishery is one of the most valuable in all of Australia and in 

2000 comprised 121 vessels fishing approximately 16,000 fishing days (Robins et al. 2002a). In 

2000, the use of turtle excluder devices in the NPF was made mandatory, due in part to several 

factors: (1) objectives of the Draft Australian Recovery Plan for Marine Turtles, (2) requirement 

of the Australian Environment Protection and Biodiversity Conservation Act for Commonwealth 

fisheries to become ecologically sustainable, and (3) the 1996 U.S. import embargo on wildcaught prawns taken in a fishery without adequate turtle bycatch management practices (Robins 

et al. 2002a). Data primarily were collected by volunteer fishers who were trained extensively in 

the collection of scientific data on sea turtles caught as bycatch in their fishery. Prior to the use 

of TEDs in this fishery, the NPF annually took between 5,000 and 6,000 sea turtles as bycatch, 

with a mortality rate of an estimated 40%, due to drowning, injuries, or being returned to the 

water comatose (Poiner and Harris 1996). Since the mandatory use of TEDs has been in effect, 

the annual bycatch of sea turtles in the NPF has dropped to less than 200 sea turtles per year, 

with a mortality rate of approximately 22% (based on recent years). This lower mortality rate 

also may be based on better sea turtle handling techniques adopted by the fleet. In general, 

loggerheads were the third most common sea turtle taken in this fishery. 

Loggerheads also have been the most common turtle species captured in shark control programs 

in Pacific Australia (Kidston et al. 1992, Limpus 2009); however, the Western Australian 

demersal longline fishery for sharks has no recorded interaction with loggerheads. From 1998-

2002, a total of 232 loggerheads were captured with 195 taken on drum lines and 37 taken in 

nets, both with a low level of direct mortality (Limpus 2009). 

Other Manmade and Natural Impacts 

As described in Section 5.1.5., other anthropogenic impacts, such as boat strikes and ingestion or 

entanglement in marine debris, likely apply to loggerheads in the Southeast Indo-Pacific Ocean. 

Similar to other areas of the world (see Section 5.1.5.), climate change and sea level rise have the 

potential to impact loggerheads in the Southeast Indo-Pacific Ocean. This includes beach 

erosion and loss from rising sea levels, skewed hatchling sex ratios from rising beach incubation 
127

temperatures, and abrupt disruption of ocean currents used for natural dispersal during the 

complex life cycle. Climate change impacts could have profound long term impacts on nesting 

populations in the Southeast Indo-Pacific Ocean, but it is not possible to quantify the potential 

impacts at this point in time. 

Natural environmental events, such as cyclones and hurricanes, may affect loggerheads in the 

Southeast Indo-Pacific Ocean. In general, however, severe storm events are episodic and, 

although they may affect loggerhead hatchling production, the results are generally localized and 

they rarely result in whole-scale losses over multiple nesting seasons.

5.2.5 Southwest Indian Ocean DPS 

5.2.5.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

All nesting beaches within South Africa are within protected areas (Baldwin et al. 2003). In 

Mozambique, nesting beaches in the Maputo Special Reserve (approximately 60 km of nesting 

beach) and in the Paradise Islands are within protected areas (Baldwin et al. 2003, Costa et al. 

2007). There are no protected areas for loggerheads in Madagascar (Baldwin et al. 2003). 

Neritic/Oceanic Zone

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, marine pollution, and climate 

change. These threats also occur in the Southwest Indian Ocean. Fishing methods not only 

incidentally capture loggerheads (Section 5.1.5.), but also deplete invertebrate and fish 

populations and thus alter ecosystem dynamics. In many cases, loggerhead foraging areas 

coincide with fishing zones. Climate change also may result in future trophic changes, thus 

impacting loggerhead prey abundance and/or distribution. 

5.2.5.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

In the Southwest Indian Ocean, on the east coast of Africa, subsistence hunting by local people is 

a continued threat to loggerheads (Baldwin et al. 2003). Illegal hunting of marine turtles and egg 

harvesting remains a threat in Mozambique as well (Louro et al. 2006). 

5.2.5.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the Southwest Indian Ocean. Side striped jackals (Canis adustus) and 

honey badgers (Melivora capensis) are known to depredate nests (Baldwin et al. 2003). 
128

5.2.5.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the Southwest Indian Ocean. The following additional 

instrument also applies to loggerheads found in this area. 

Indian Ocean – South-East Asian Marine Turtle Memorandum of Understanding (IOSEA) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Nairobi Convention for the Protection, Management and Development of the Marine and 

Coastal Environment of the Eastern African Region 

For information about this instrument, see section 5.2.3.4. for the North Indian Ocean DPS. 

5.2.5.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

The full extent of the threat of incidental capture of sea turtles in artisanal and commercial 

fisheries in the Southwest Indian Ocean is unknown. Sea turtles are caught in demersal and 

pelagic longlines, trawls, gillnets, and seines (Petersen 2005; Louro et al. 2006; Petersen et al.

2006, 2009; Costa et al. 2007; Fennessy and Isaksen 2007). There is evidence of significant 

historic bycatch from prawn fisheries, which may have depleted nesting populations long before 

nesting surveys were initiated in the 1990s (Baldwin et al. 2003). 

Quantifying the magnitude of the threat of fisheries on loggerheads in the Southwest Indian 

Ocean is very difficult given the low level of observer coverage or investigations into bycatch 

conducted by countries that have large fishing fleets. Efforts have been made to quantify the 

effects of pelagic longline fishing on loggerheads globally (Lewison et al. 2004). While there 

were no turtle bycatch data available from the Southwest Indian Ocean to use in their 

assessment, extrapolations that considered bycatch data for the Pacific and Atlantic basins gave a 

conservative estimate of 6,000 loggerheads captured in the Indian Ocean in the year 2000. The 

effect of the longline fishery on loggerheads in the Indian Ocean is largely unknown (Lewison et 

al. 2004). 

Other Manmade and Natural Impacts 

As described in Section 5.1.5., other anthropogenic impacts, such as boat strikes and ingestion or 

entanglement in marine debris, likely apply to loggerheads in the Southwest Indian Ocean. 

Similar to other areas of the world (see Section 5.1.5.), climate change and sea level rise have the 

potential to impact loggerheads in the Southwest Indian Ocean. This includes beach erosion and 

loss from rising sea levels, skewed hatchling sex ratios from rising beach incubation 

temperatures, and abrupt disruption of ocean currents used for natural dispersal during the 

complex life cycle. Climate change impacts could have profound long term impacts on nesting 

populations in the Southwest Indian Ocean, but it is not possible to quantify the potential impacts 

at this point in time. 

Natural environmental events, such as cyclones, tsunamis and hurricanes, may affect loggerheads 

in the Southwest Indian Ocean. In general, however, severe storm events are episodic and, 
129

although they may affect loggerhead hatchling production, the results are generally localized and 

they rarely result in whole-scale losses over multiple nesting seasons.

5.2.6. Northwest Atlantic Ocean DPS 

The following information on threats pertains to all loggerhead turtles that may be found in the 

Northwest Atlantic. Because it is likely that oceanic juveniles from this DPS also are found in 

the Northeast Atlantic Ocean and in the Mediterranean Sea, the narratives for those regions 

should also be consulted. 

5.2.6.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

As described in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the 

Northwest Atlantic results from coastal development and construction, placement of erosion 

control structures and other barriers to nesting, placement of nearshore shoreline stabilization 

structures, beachfront lighting, vehicular and pedestrian traffic, beach erosion, beach sand 

placement, removal of native vegetation, and planting of non-native vegetation (NMFS and FWS 

2008). 

In the southeastern U.S., numerous erosion control structures that create barriers to nesting have 

been constructed. The proportion of coastline that is armored is approximately 18% (239 km) in 

Florida (Clark 1992, Schroeder and Mosier 2000, Witherington et al. 2006), 9% (14 km) in 

Georgia (M. Dodd, GDNR, personal communication, 2000), 12% (29 km) in South Carolina (D. 

Griffin, SCDNR, personal communication, 2009), and 3% (9 km) in North Carolina (M. 

Godfrey, North Carolina Wildlife Resources Commission, 2009). These assessments of 

armoring extent do not include structures that are a barrier to sea turtle nesting but that do not fit 

the definition of armoring, such as dune crossovers, cabanas, sand fences, and recreational 

equipment. 

In the Northwest Atlantic, jetties have been placed at many ocean inlets to keep transported sand 

from closing the inlet channel. Witherington et al. (2005) found a significant negative 

relationship between loggerhead nesting density and distance from the nearest of 17 ocean inlets 

on the Atlantic coast of Florida. The effect of inlets in lowering nesting density was observed 

both updrift and downdrift of the inlets, leading researchers to propose that beach instability 

from both erosion and accretion may discourage loggerhead nesting. 

Numerous beaches in the southeastern U.S. are eroding due to both natural (e.g., storms, sea 

level changes, waves, shoreline geology) and anthropogenic (e.g., construction of armoring 

structures, groins, and jetties; coastal development; inlet dredging) factors. Such shoreline 

erosion leads to a loss of nesting habitat for sea turtles. As a result, beach nourishment is a 

frequent activity, and many beaches are on a periodic nourishment schedule. On severely eroded 

sections of beach, where little or no suitable nesting habitat previously existed, beach 

nourishment has been found to result in increased nesting (Ernest and Martin 1999). However, 

on most beaches in the southeastern U.S., nesting success typically declines for the first year or 
130

two following construction, even though more nesting habitat is available for turtles (Trindell et 

al. 1998, Ernest and Martin 1999, Herren 1999). Reduced nesting success on constructed 

beaches has been attributed to increased sand compaction, escarpment formation, and changes in 

beach profile (Nelson et al. 1987, Crain et al. 1995, Lutcavage et al. 1997, Steinitz et al. 1998, 

Ernest and Martin 1999, Rumbold et al. 2001). 

Stormwater and other water source runoff from beachfront parking lots, building rooftops, roads, 

decks, and draining swimming pools adjacent to the beach is frequently discharged directly onto 

Northwest Atlantic beaches and dunes either by sheet flow, through stormwater collection 

system outfalls, or through small diameter pipes. These outfalls create localized erosion 

channels, prevent natural dune establishment, and wash out sea turtle nests (Florida Fish and 

Wildlife Conservation Commission, unpublished data). Contaminants contained in stormwater, 

such as oils, grease, antifreeze, gasoline, metals, pesticides, chlorine, and nutrients, are also 

discharged onto the beach. 

In the U.S., vehicular driving is allowed on certain beaches in northeast Florida (Nassau, Duval, 

St. Johns, and Volusia counties), northwest Florida (Walton and Gulf counties), Georgia 

(Cumberland, Little Cumberland, and Sapelo Islands), North Carolina (Fort Fisher State 

Recreation Area, Carolina Beach, Freeman Park, Onslow Beach, Emerald Isle, Indian 

Beach/Salter Path, Pine Knoll Shores, Atlantic Beach, Cape Lookout National Seashore, Cape 

Hatteras National Seashore, Nag’s Head, Kill Devil Hills, Town of Duck, and Currituck Banks), 

Virginia (Chincoteague NWR and Wallops Island), and Texas (the majority of beaches except 

for a highly developed section of South Padre Island and Padre Island National Seashore, San 

Jose Island, Matagorda Island, and Matagorda Peninsula where driving is not allowed or is 

limited to agency personnel, land owners, and/or researchers). Beach driving has been found to 

reduce the quality of loggerhead nesting habitat in several ways. In the southeastern U.S., 

vehicle ruts on the beach have been found to prevent or impede hatchlings from reaching the 

ocean following emergence from the nest (Mann 1977, Hosier et al. 1981, Cox et al. 1994, 

Hughes and Caine 1994). Sand compaction by vehicles has been found to hinder nest 

construction and hatchling emergence from nests (Mann 1977). Vehicle lights and vehicle 

movement on the beach after dark results in reduced habitat suitability, which can deter females 

from nesting and disorient hatchlings. Additionally, vehicle traffic on nesting beaches 

contributes to erosion, especially during high tides or on narrow beaches where driving is 

concentrated on the high beach and foredune. 

As described in Section 5.1.1., coastal development contributes to habitat degradation by 

increasing light pollution. Reports of hatchling disorientation events in Florida alone describe 

several hundred nests each year and are likely to involve tens of thousands of hatchlings (Nelson 

et al. 2002). However, this number calculated from disorientation reports is likely a vast 

underestimate. Independent of these reports, Witherington et al. (1996) surveyed hatchling 

orientation at nests located at 23 representative beaches in six counties around Florida in 1993 

and 1994 and found that, by county, approximately 10 to 30% of nests showed evidence of 

hatchlings disoriented by lighting. From this survey and from measures of hatchling production 

(Florida Fish and Wildlife Conservation Commission, unpublished data), the number of 

hatchlings disoriented by lighting in Florida is calculated in the range of hundreds of thousands 

per year. 
131

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, oil exploration and development, 

marine pollution, and climate change. These threats also occur in the Northwest Atlantic Ocean. 

Fishing methods not only incidentally capture loggerheads (Section 5.1.5.), but also deplete 

invertebrate and fish populations and thus alter ecosystem dynamics. Although anthropogenic 

disruptions of natural ecological interactions have been difficult to discern, a few studies have 

been focused on the effects of these disruptions on loggerheads. For instance, Youngkin (2001) 

analyzed gut contents from hundreds of loggerheads stranded in Georgia over a 20-year period. 

His findings point to the probability of major effects on loggerhead diet from activities such as 

shrimp trawling and dredging. Lutcavage and Musick (1985) found that horseshoe crabs 

strongly dominated the diet of loggerheads in Chesapeake Bay in 1980-1981. Subsequently, 

fishermen began to harvest horseshoe crabs, primarily for use as bait in the eel and whelk pot 

fisheries, using several gear types. Atlantic coast horseshoe crab landings increased by an order 

of magnitude (0.5 to 6.0 million pounds) between 1980 and 1997, and in 1998 the Atlantic States 

Marine Fisheries Commission implemented a horseshoe crab fishery management plan to curtail 

catches (Atlantic States Marine Fisheries Commission 1998). The decline in horseshoe crab 

availability has apparently caused a diet shift in juvenile loggerheads, from predominantly 

horseshoe crabs in the early to mid-1980s to blue crabs in the late 1980s and early 1990s, to 

mostly finfish in the late 1990s and early 2000s (Seney 2003, Seney and Musick 2007). These 

data suggest that turtles are foraging in greater numbers in or around fishing gears and on 

discarded bycatch (Seney 2003). 

Periodic dredging of sediments from navigational channels is carried out at large ports to provide 

for the passage of large commercial and military vessels. In addition, sand mining (dredging) for 

beach renourishment and construction projects occurs in the Northwest Atlantic along the U.S., 

Mexico, Central American, Colombia, and Venezuela coasts. Although directed studies have not 

been conducted, dredging activities, which occur regularly in the Northwest Atlantic, have the 

potential to destroy or degrade benthic habitats used by loggerheads. Channelization of inshore 

and nearshore habitat and the subsequent disposal of dredged material in the marine environment 

can destroy or disrupt resting or foraging grounds (including grass beds and coral reefs) and may 

affect nesting distribution by altering physical features in the marine environment (Hopkins and 

Murphy 1980). Oil exploration and development on live bottom areas may disrupt foraging 

grounds by smothering benthic organisms with sediments and drilling muds (Coston-Clements 

and Hoss 1983). The effects of benthic habitat alteration on loggerhead prey abundance and 

distribution, and the effects of these potential changes on loggerhead populations, have not been 

determined but are of concern. Climate change also may result in trophic changes, thus 

impacting loggerhead prey abundance and/or distribution. 

5.2.6.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Deliberate hunting of loggerheads for their meat, shells, and eggs is reduced from previous 

exploitation levels, but still exists. In the Caribbean, 13 of 29 (45%) countries/territories allow 

the harvest of loggerheads (NMFS and FWS 2008, see Appendix 3). The loggerhead harvest in 

the Caribbean is generally restricted to the non-nesting season with the exception of St. Kitts and 

Nevis, where turtle harvest is allowed annually from March 1 through September 30, and the 
132

Turks and Caicos Islands, where turtle harvest is allowed year-round. Most countries/territories 

that allow harvest have regulations that favor the harvest of large juveniles and adults, the most 

reproductively valuable members of the population. Exceptions include the Cayman Islands, 

which mandates maximum size limits, and Haiti and Trinidad and Tobago, which have no size 

restrictions. All North, Central, and South American countries in the Northwest Atlantic 

legislate complete protection of loggerheads from harvest in their territorial waters with the 

exception of Guyana. Despite national laws, in many countries the poaching of eggs and hunting 

of adults and juveniles still occurs at varying levels (NMFS and FWS 2008, see Appendix 3). 

5.2.6.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the Northwest Atlantic. Viral diseases have not been documented in freeranging loggerheads, with the possible exception of sea turtle fibropapillomatosis, which may 

have a viral etiology (Herbst and Jacobson 1995, George 1997). Although fibropapillomatosis 

reaches epidemic proportions in some wild green turtle populations, the prevalence of this 

disease in most loggerhead populations is thought to be small. An exception is Florida Bay 

where approximately 9.5% of the loggerheads captured exhibit fibropapilloma-like external 

lesions (B. Schroeder, NMFS, personal communication, 2006). Mortality levels and populationlevel effects associated with the disease are still unknown. Heavy infestations of endoparasites 

may cause or contribute to debilitation or mortality in sea turtles. Trematode eggs and adult 

trematodes were recorded in a variety of tissues including the spinal cord and brain of debilitated 

loggerheads during an epizootic in South Florida, USA, during late 2000 and early 2001. These 

endoparasites were implicated as a possible cause of the epizootic (Jacobson et al. 2006). 

Although many health problems have been described in wild populations through the necropsy 

of stranded turtles, the significance of diseases on the ecology of wild loggerhead populations is 

not known (Herbst and Jacobson 1995). 

Predation of eggs and hatchlings by native and introduced species occurs on almost all nesting 

beaches throughout the Northwest Atlantic. The most common predators at the primary nesting 

beaches in the southeastern United States are ghost crabs (Ocypode quadrata), raccoons 

(Procyon lotor), feral hogs (Sus scrofa), foxes (Urocyon cinereoargenteus and Vulpes vulpes), 

coyotes (Canis latrans), armadillos (Dasypus novemcinctus), and red fire ants (Solenopsis 

invicta) (Stancyk 1982, Dodd 1988). In the absence of well managed nest protection programs, 

predators may take significant numbers of eggs; however, nest protection programs are in place 

at most of the major nesting beaches in the Northwest Atlantic. 

Non-native vegetation has invaded many coastal areas and often outcompetes native plant 

species. Exotic vegetation may form impenetrable root mats that can invade and desiccate eggs, 

as well as trap hatchlings. The Australian pine (Casuarina equisetifolia) is particularly harmful 

to sea turtles. Dense stands have taken over many coastal areas throughout central and south 

Florida. Australian pines cause excessive shading of the beach that would not otherwise occur. 

Studies in Florida suggest that nests laid in shaded areas are subjected to lower incubation 

temperatures, which may alter the natural hatchling sex ratio (Marcus and Maley 1987, Schmelz 

and Mezich 1988, Hanson et al. 1998). Fallen Australian pines limit access to suitable nest sites 

and can entrap nesting females (Austin 1978, Reardon and Mansfield 1997). The shallow root 
133

network of these pines can interfere with nest construction (Schmelz and Mezich 1988). Davis 

and Whiting (1977) reported that nesting activity declined in Everglades National Park where 

dense stands of Australian pine took over native dune vegetation on a remote nesting beach. 

Beach vitex (Vitex rotundifolia) was introduced to the horticulture trade in the mid-1980s and is 

often sold as a “dune stabilizer.” The plant is native to countries in the western Pacific and was 

introduced into the southeastern U.S. in the mid-1980s. Its presence on North Carolina and 

South Carolina beaches have a negative effect on sea turtle nesting as its dense mats interfere 

with sea turtle nesting and hatchling emergence from nests (Brabson 2006). This exotic plant is 

crowding out the native species, such as sea oats and bitter panicum, and can colonize large areas 

in just a few years. Sisal, or century plant, (Agave americana) is native to arid regions of 

Mexico. The plant was widely grown in sandy soils around Florida in order to provide fiber for 

cordage. It has escaped cultivation in Florida and has been purposely planted on dunes. 

Although the effects of sisal on sea turtle nesting are uncertain, thickets with impenetrable sharp 

spines are occasionally found on developed beaches. 

Harmful algal blooms, such as a red tide, also impact loggerheads in the Northwest Atlantic. In 

Florida, USA, the species that causes most red tides is Karenia brevis, a dinoflagellate that 

produces a toxin (Florida Marine Research Institute 2003). During four red tide events along the 

west coast of Florida, sea turtle stranding trends indicated that these events were acting as a 

mortality factor (Redlow et al. 2003). Sea turtles that washed ashore alive during these red tide 

events displayed symptoms that were consistent with acute brevitoxicosis (e.g., uncoordinated 

and lethargic but otherwise robust and healthy in appearance) and completely recovered within 

days of being removed from the area of the red tide. The population level effects of these events 

are not yet known. 

5.2.6.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the Northwest Atlantic Ocean. The following additional 

instruments also apply to loggerheads found in this area. 

United States Magnuson-Stevens Fishery Conservation and Management Act 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Convention for the Protection and Development of the Marine Environment of the Wider 

Caribbean Region 

Also called the Cartagena Convention, this instrument has been in place since 1986 and currently 

has 21 signatory states. Under this Convention, the component that may relate to loggerhead 

turtles is the Protocol Concerning Specially Protected Areas and Wildlife (SPAW) that has been 

in place since 2000. The goals of this protocol are to encourage Parties "to take all appropriate 

measures to protect and preserve rare or fragile ecosystems, as well as the habitat of depleted, 

threatened or endangered species, in the Convention area." All six sea turtle species in the Wider 

Caribbean are listed in Annex II of the protocol, which prohibits (a) the taking, possession or 
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killing (including, to the extent possible, the incidental taking, possession or killing) or 

commercial trade in such species, their eggs, parts or products, and (b) to the extent possible, the 

disturbance of such species, particularly during breeding, incubation, estivation, migration, and 

other periods of biological stress. Hykle (2002) believes that in view of the limited participation 

of Caribbean States in the aforementioned Convention on the Conservation of Migratory Species 

of Wild Animals, the provisions of the SPAW Protocol provide the legal support for domestic 

conservation measures that might otherwise not have been afforded. Additional information is 

available at http://www.cep.unep.org/cartagena-convention. 

Convention for the Protection of the Marine Environment of the North-East Atlantic 

This Convention is included under the Northwest Atlantic Ocean DPS because it is likely that 

oceanic juveniles from this DPS also are found in the Northeast Atlantic Ocean. For information 

about this instrument, see section 5.2.7.4. for the Northeast Atlantic Ocean DPS. 

5.2.6.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

Bycatch of loggerheads in commercial and recreational fisheries in the Northwest Atlantic is a 

significant threat facing the species in this region. A variety of fishing gears that incidentally 

capture loggerhead turtles are employed including gillnets, trawls, hook and line, longlines, 

seines, dredges, pound nets, and various types of pots/traps. Among these, gillnets, longlines, 

and trawl gear contribute to the vast majority of bycatch mortality of loggerheads annually 

throughout their range in the Atlantic Ocean and Gulf of Mexico (Epperly et al. 1995; NMFS 

2002a, 2004, 2007a, 2008a; Lewison et al. 2003, 2004; Richards 2007; NMFS, unpublished 

data). Considerable effort has been expended since the 1980s to document and address fishery 

bycatch, especially in the United States and Mexico. Observer programs have been implemented 

in some fisheries to collect turtle bycatch data, and efforts to reduce bycatch and mortality of 

loggerheads in certain fishing operations have been undertaken and implemented or partially 

implemented. These efforts include developing gear solutions to prevent or reduce captures or to 

allow turtles to escape without harm (e.g., TEDs, circle hooks and bait combinations), 

implementing time and area closures to prevent interactions from occurring (e.g., prohibitions on 

gillnet fishing along the mid-Atlantic coast during the critical time of northward migration of 

loggerheads, implementation of careful release protocols (e.g., requirements for careful release 

of turtles captured in longline fisheries), prohibitions of gillnetting in some U.S. state waters), 

and/or modifying gear (e.g., requirements to reduce mesh size in the leaders of pound nets in 

certain U.S. coastal waters to prevent entanglement). 

The primary bycatch reduction focus in the Northwest Atlantic, since the 1978 ESA listing of the 

loggerhead, has been on bycatch reduction in shrimp trawls. The development of turtle excluder 

devices (TEDs) in the 1970s and the refinement of these devices over the past three decades has 

been a primary focus of loggerhead bycatch reduction efforts. The U.S. has required the use of 

TEDs throughout the year since the mid-1990s, with modifications required and implemented as 

necessary (NMFS 1987, 52 FR 24244; NMFS 1992, 57 FR 57348). Most notably, in 2003, 

NMFS implemented new requirements for TEDs in the shrimp trawl fishery to ensure that large 

loggerheads could escape through TED openings (NMFS 2003, 68 FR 8456). Significant effort 

has been expended to transfer this technology to other shrimping fleets in the Northwest Atlantic; 
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however, not all nations where loggerheads occur require the device be used. Enforcement of 

TED regulations is difficult and compliance is not believed to be complete. Because TEDs are 

not 100% effective, a significant number of loggerheads are estimated to still be killed annually 

in shrimp trawls throughout the Northwest Atlantic. In the U.S. Southeast food shrimp trawl 

fishery, NMFS estimated the annual mortality of loggerheads in the Gulf of Mexico and 

Southeast U.S. Atlantic Ocean as 3,948 individuals (95% CI, 1,221-8,498) (NMFS 2002a). 

Shrimping effort in the Southeast U.S. has reportedly declined, a revised estimate of annual 

loggerhead mortality for the Gulf of Mexico segment of the Southeast food shrimp trawl fishery 

is 647 individuals (NMFS, unpublished data). 

Other trawl fisheries operating in Northwest Atlantic waters that are known to capture sea turtles 

include, but are not limited to, summer flounder, calico scallop, sea scallop, blue crab, whelk, 

cannonball jellyfish, horseshoe crab, and mid-Atlantic directed finfish trawl fisheries and the 

Sargassum fishery. In the U.S., the summer flounder fishery is the only trawl fishery (other than 

the shrimp fishery) with federally mandated TED use (in certain areas). Loggerhead annual 

bycatch estimates in 2004 and 2005 in U.S. mid-Atlantic scallop trawl gear ranged from 81 to 

191 turtles, depending on the estimation methodology used (Murray 2007). Estimated average 

annual bycatch of loggerheads in other mid-Atlantic federally managed bottom otter trawl 

fisheries during 1996-2004 was 616 turtles (Murray 2006). The harvest of Sargassum by 

trawlers can result in incidental capture of post-hatchlings and habitat destruction (Schwartz 

1988, Witherington 2002); this fishery is not currently active. 

Dredge fishing gear is the predominant gear used to harvest sea scallops off the mid- and 

northeastern U.S. Atlantic coast. Sea scallop dredges are composed of a heavy steel frame and 

cutting bar located on the bottom part of the frame and a bag, made of metal rings and mesh 

twine, attached to the frame. The gear is fished along the bottom and weighs from 500-1,000 

pounds (National Research Council 2002). Turtles can be struck and injured or killed by the 

dredge frame and/or captured in the bag where they may drown or be further injured or killed 

when the catch and heavy gear are dumped on the vessel deck. Total estimated bycatch of 

loggerhead turtles in the U.S. sea scallop dredge fishery operating in the mid-Atlantic region 

(New York to North Carolina) from June through November is on the order of several hundred 

turtles per year (Murray 2004, 2005, 2007). The impact of the sea scallop dredge fishery on 

loggerheads in U.S. waters of the Northwest Atlantic remains a serious concern. 

Incidental take of oceanic-stage loggerheads in pelagic longline fisheries has recently received 

significant attention (Balazs and Pooley 1994; Bolten et al. 1994, 2000; Aguilar et al. 1995; 

Laurent et al. 1998; Long and Schroeder 2004; Watson et al. 2005). Large-scale commercial 

longline fisheries operate throughout the pelagic range of the Northwest Atlantic loggerhead, 

including the western Mediterranean. The largest size classes in the oceanic stage are the size 

classes impacted by the swordfish longline fishery in the Azores (Bolten 2003) and on the Grand 

Banks (Watson et al. 2005), and this is likely the case for other nation’s fleets operating in the 

region, including but not limited to, the European Union, United States, Japan, and Taiwan. The 

demographic consequences relative to population recovery of the increased mortality of these 

size classes have been discussed (Crouse et al. 1987; see also Heppell et al. 2003 and Chaloupka 

2003). Estimates derived from data recorded by the international observer program (IOP) 

suggest that thousands of mostly immature loggerheads have been captured in the Canadian 
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pelagic longline fishery in the western North Atlantic since 1999 (Brazner and McMillan 2008). 

NMFS (2004a) estimates that 635 loggerheads (143 lethal) will be taken annually in the U.S. 

pelagic longline fishery. 

Incidental capture of neritic-stage loggerheads in demersal longline fishing gear has also been 

documented. Richards (2007) estimated total annual bycatch of loggerheads in the Southeast 

U.S. Atlantic and U.S. Gulf of Mexico commercial directed shark bottom longline fishery from 

2003-2005 as follows: 2003: 302 – 1,620 (CV 0.45); 2004: 95 – 591 (CV 0.49); 2005: 139-778 

(CV 0.46). NMFS (2009) estimated the total number of captures of hardshell turtles in the U.S. 

Gulf of Mexico reef fish fishery (demersal longline fishery) from July 2006 – December 2008 as 

861 turtles (95% CI 383 – 1934). These estimates are not comprehensive across this gear type 

(i.e., pelagic and demersal longline) throughout the Northwest Atlantic Ocean. Cumulatively, 

the bycatch and mortality of Northwest Atlantic loggerheads in longline fisheries is significant. 

Gillnet fisheries may be the most ubiquitous of fisheries operating in the neritic range of the 

Northwest Atlantic loggerhead. Comprehensive estimates of bycatch in gillnet fisheries do not 

yet exist and, while this precludes a quantitative analysis of their impacts on loggerhead 

populations, the cumulative mortality of loggerheads in gillnet fisheries is likely high. In the 

U.S. mid-Atlantic, the average annual estimated bycatch of loggerheads from 1995 – 2006 was 

350 turtles (CV= 0.20., 95% CI over the 12-year period: 234 to 504) (Murray in press). In the 

U.S., some states (e.g., South Carolina, Georgia, Florida, Louisiana, and Texas) have prohibited 

gillnets in their waters, but there remain active gillnet fisheries in other U.S. states, in U.S. 

federal waters, Mexican waters, Central and South America, and the Northeast Atlantic. 

Pound nets are fixed gear composed of a series of poles driven into the bottom upon which 

netting is suspended. Pound nets basically operate like a trap with the pound constructed of a 

series of funnels leading to a bag that is open at the top, and a long leader of netting that extends 

from shallow to deeper water where the pound is located. In some configurations, the leader is 

suspended from the surface by a series of stringers or vertical lines. Sea turtles incidentally 

captured in the open top pound, which is composed of small mesh webbing, are usually safe 

from injury and may be released easily when the fishermen pull the nets (Mansfield et al. 2002). 

However, sea turtle mortalities have been documented in the leader of certain pound nets. Large 

mesh leaders (greater than 12-inch stretched mesh) may act as a gillnet, entangling sea turtles by 

the head or foreflippers (Bellmund et al. 1987) or may act as a barrier against which turtles may 

be impinged (NMFS, unpublished data). Nets with small mesh leaders (less than 8 inches 

stretched mesh) usually do not present a mortality threat to loggerheads, but some mortalities 

have been reported (Morreale and Standora 1998; Epperly et al. 2000, 2007; Mansfield et al. 

2002). In 2002, the U.S. prohibited, in certain areas within the Chesapeake Bay and at certain 

times, pound net leaders having mesh greater than or equal to 12 inches and leaders with 

stringers (NMFS 2002b, 67 FR 41196). Subsequent regulations have further restricted the use of 

certain pound net leaders in certain geographic areas and established pound net leader gear 

modifications (NMFS 2004b, 69 FR 24997; NMFS 2006, 71 FR 36024). 

Pots/traps are commonly used to target crabs, lobsters, whelk, and reef fishes. These traps vary 

in size and configuration, but all are attached to a surface float by means of a vertical line leading 

to the trap. Entanglement and mortality of loggerheads has been documented in various pot/trap 
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fisheries in the U.S. Atlantic and Gulf of Mexico. Data from the U.S. Sea Turtle Stranding and 

Salvage Network indicate that 82 loggerheads (dead and rescued alive) were documented by the 

stranding network in various pot/trap gear from 1996-2005, of these approximately 30-40% were 

adults and the remainder juveniles (NMFS, unpublished data). Without intervention it is likely 

that the majority of the live, entangled turtles would die. Additionally, documented strandings 

represent only a portion of total interactions and mortality. Recently, a small number of 

loggerhead entanglements also have been recorded in whelk pot bridles in the U.S. Mid-Atlantic 

(Meredith Fagan, Virginia Institute of Marine Science, personal communication, 2008). 

However, no dedicated observer programs exist to provide estimates of take and mortality from 

pot/trap fisheries; therefore, comprehensive estimates of loggerhead interactions with pot/trap 

gear are not available, but the gear is widely used throughout the range of the DPS, and poses a 

continuing threat. 

Other Manmade and Natural Impacts 

Similar to other areas of the world (see Section 5.1.5.), climate change and sea level rise have the 

potential to impact loggerheads in the Northwest Atlantic Ocean. 

Propeller and collision injuries from boats and ships are becoming more common in sea turtles. 

In the U.S. Atlantic, from 1997 to 2005, 14.9% of all stranded loggerheads were documented as 

having sustained some type of propeller or collision injuries (NMFS, unpublished data). The 

incidence of propeller wounds observed in sea turtles stranded in the U.S. has risen from 

approximately 10% in the late 1980s to a record high of 20.5% in 2004 (NMFS, unpublished 

data). In the U.S., propeller wounds are greatest in southeast Florida; during some years, as 

many as 60% of the loggerhead strandings found in these areas had propeller wounds (Florida 

Fish and Wildlife Conservation Commission, unpublished data). As the number of vessels 

increases, in concert with increased coastal development, especially in nearshore waters, 

propeller and vessel collision injuries are also expected to rise. 

Several activities associated with offshore oil and gas production, including oil spills, water 

quality (operational discharge), seismic surveys, explosive platform removal, platform lighting, 

and noise from drillships and production activities, are known to impact loggerheads (National 

Research Council 1996; MMS 2000; Gregg Gitschlag, NMFS, personal communication, 2007; 

Viada et al. 2008). Currently, there are 3,443 federally regulated offshore platforms in the Gulf 

of Mexico dedicated to natural gas and oil production. Additional state-regulated platforms are 

located in state waters (Texas and Louisiana). There are currently no active leases off the 

Atlantic coast. 

Oil spills also threaten loggerheads in the Northwest Atlantic. Two oil spills that occurred near 

loggerhead nesting beaches in Florida were observed to affect eggs, hatchlings, and nesting 

females. Approximately 350,000 gallons of fuel oil spilled in Tampa Bay in August 1993 and 

was carried onto nesting beaches in Pinellas County. Observed mortalities included 31 

hatchlings and 176 oil covered nests; an additional 2,177 eggs and hatchlings were either 

exposed to oil or disturbed by response activities (FDEP et al. 1997). Another spill near the 

beaches of Broward County in August 2000 involved approximately 15,000 gallons of oil and tar 

(NOAA and FDEP 2002). Models estimated that approximately 1,500 to 2,000 hatchlings and 0 

to 1 adults were injured or killed. Annually about 1% of all sea turtle strandings along the U.S. 
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east coast have been associated with oil, but higher rates of 3 to 6% have been observed in South 

Florida and Texas (Teas 1994, Rabalais and Rabalais 1980, Plotkin and Amos 1990). 

In addition to the destruction or degradation of habitat described in Section 5.2.6.1., periodic 

dredging of sediments from navigational channels can also result in incidental mortality of sea 

turtles. Direct injury or mortality of loggerheads by dredges has been well documented in the 

southeastern and mid-Atlantic U.S. (National Research Council 1990). Solutions, including 

modification of dredges and time/area closures, have been successfully implemented to reduce 

mortalities and injuries in the U.S. (NMFS 1991, 1995, 1997; Nelson and Shafer 1996). 

The entrainment and entrapment of loggerheads in saltwater cooling intake systems of coastal 

power plants has been documented in New Jersey, North Carolina, Florida, and Texas (Eggers 

1989; National Research Council 1990; Carolina Power and Light Company 2003; FPL and 

Quantum Resources, Inc. 2005; Progress Energy Florida, Inc. 2003). Average annual incidental 

capture rates for most coastal plants from which captures have been reported amount to several 

turtles per plant per year. One notable exception is the St. Lucie Nuclear Power Plant located on 

Hutchinson Island, Florida. During the first 15 years of operation (1977-1991), an average of 

128 loggerheads per year was captured in the intake canal with a mortality rate of 6.4%. During 

1991-2005, loggerhead captures more than doubled (average of 308 per year), while mortality 

rates decreased to 0.3% per year (FPL and Quantum Resources, Inc. 2005). 

Although not a major source of mortality, cold stunning of loggerheads has been reported at 

several locations in U.S., including Cape Cod Bay, Massachusetts (Still et al. 2000); Long Island 

Sound, New York (Meylan and Sadove 1986, Morreale et al. 1992); the Indian River system, 

Florida (Mendonça and Ehrhart 1982, Witherington and Ehrhart 1989); and Texas inshore waters 

(Hildebrand 1982, Shaver 1990). 

Another natural factor that has the potential to affect recovery of loggerhead turtles is aperiodic 

hurricanes. In general, these events are episodic and, although they may affect loggerhead 

hatchling production, the results are generally localized and they rarely result in whole-scale 

losses over multiple nesting seasons. The negative effects of hurricanes on low-lying and/or 

developed shorelines may be longer-lasting and a greater threat overall. 

Similar to other areas of the world (see Section 5.1.5.), climate change and sea level rise have the 

potential to impact loggerheads in the Northwest Atlantic. This includes beach erosion and loss 

from rising sea levels, repeated inundation of nests, skewed hatchling sex ratios from rising 

beach incubation temperatures, and abrupt disruption of ocean currents used for natural dispersal 

during the complex life cycle. 

5.2.7. Northeast Atlantic Ocean DPS 

The following information on threats pertains to all loggerhead turtles that may be found in the 

Northeast Atlantic. Because it is likely that oceanic juveniles from this DPS also are found in the 

Northwest Atlantic Ocean and in the Mediterranean Sea, the narratives for those regions should 

also be consulted. 
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5.2.7.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

As described in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the 

Northeast Atlantic result from coastal development and construction, placement of erosion 

control structures and other barriers to nesting, beachfront lighting, vehicular and pedestrian 

traffic, sand extraction, beach erosion, and beach pollution (NMFS and FWS 1998, Formia et al. 

2003). 

In the Northeast Atlantic, the only loggerhead nesting of note occurs in the Cape Verde Islands. 

The Cape Verde government’s plans to develop Boa Vista Island, the location of the main 

nesting beaches, could increase the terrestrial threats to loggerheads (van Bogaert 2006). Sand 

extraction on Santiago Island, Cape Verde, may be responsible for the apparent decrease in 

nesting there (Loureiro 2008). Scattered and infrequent nesting occurs in western Africa, where 

much industrialization is located on the coast and population growth rates fluctuate between 

0.8% (Cape Verde) and 3.8% (Côte D’Ivoire) (Abe et al. 2004, Tayaa et al. 2005). Land mines 

on some of the beaches of mainland Africa, within the reported historical range of nesting by 

loggerheads (e.g., the Western Sahara region) would be detrimental to nesters and are an 

impediment to scientific surveys of the region (Tiwari et al. 2001). Tiwari et al. (2001) noted a 

high level of human use of many of the beaches in Morocco – enough that any evidence of 

nesting activity would be quickly erased. Garbage litters many developed beaches (Formia et al. 

2003). Erosion is a problem along the long stretches of high energy ocean shoreline of Africa 

and is further exacerbated by sand mining and harbor building (Formia et al. 2003); crumbling 

buildings claimed by the sea may present obstructions to nesting females. 

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, marine pollution and climate change. These threats also occur in the 

Northeast Atlantic Ocean. Ecosystem alterations have occurred due to the tremendous human 

pressure on the environment in the region. Turtles, including loggerheads, usually are included 

in ecosystem models of the region (see Palomares and Pauly 2004). In the Canary Current Large 

Marine Ecosystem (LME), the area is characterized by the Global International Waters 

Assessment (GIWA) as severely impacted in the area of modification or loss of ecosystems or 

ecotones and health impacts, but these impacts are decreasing (http://www.lme.noaa.gov). The 

Celtic-Biscay Shelf LME is affected by alterations to the seabed, agriculture, and sewage 

(Valdés and Lavin 2002). The Gulf of Guinea has been characterized as severely impacted in the 

area of solid wastes by the GIWA; this and other pollution indicators are increasing 

(http://www.lme.noaa.gov). Marine pollution, such as oil and debris, has been shown to 

negatively impact loggerheads and represent a degradation of the habitat (Orós et al. 2005, 2009; 

Calabuig Miranda and Liria Loza 2007). Climate change also may result in future trophic 

changes, thus impacting loggerhead prey abundance and/or distribution. 

Additionally, fishing is a major source of ecosystem alteration of the neritic and oceanic habitats 

of loggerhead turtles in the region. Fishing effort off the western African coast is increasing and 

record low biomass has been recorded for exploited resources, representing a 13X decline in 
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biomass since 1960 (see Palomares and Pauly 2004). Throughout the North Atlantic, fishery 

landings fell by 90% during the 20th century, foreboding a trophic cascade and a change in foodweb competition (Pauly et al. 1998, Christensen et al. 2003). For a description of the exploited 

marine resources in the region, see Lamboeuf (1997). The Celtic-Biscay Shelf LME, the Iberian 

Coastal Ecosystem LME, the Canary Current LME, and the Guinea Current LME all are severely 

overfished, and effort now is turning to a focus on pelagic fisheries, whereas historically there 

were demersal fisheries. The impacts continue to increase in the Guinea Current LME despite 

efforts throughout the region to reduce fishing pressure (http://www.lme.noaa.gov). 

The threats to bottom habitat for loggerheads previously described in this document include 

modification of the habitat through bottom trawling. Trawling occurs off the European coast and 

the area off Northwest Africa is one of the most intensively trawled areas in the world (Zeeberg 

et al. 2006). Trawling has been banned in the Azores, Madeira, and Canary Islands to protect 

cold-water corals (Lutter 2005). Although illegal, trawling also occurs in the Cape Verde Islands 

(López-Jurado et al. 2003). The use of destructive fishing practices, such as explosives and toxic 

chemicals, has been reported in the Canary Current area, causing serious damage to both the 

resources and the habitat (Tayaa et al. 2005). 

5.2.7.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Deliberate hunting of loggerheads for their meat, shells, and eggs still exists and remains the 

most serious threat facing nesting turtles in the Northeast Atlantic. Historical records indicate 

turtles were harvested throughout Macaronesia (see López-Jurado 2007). Intensive exploitation 

has been cited for the extirpation of the loggerhead nesting colony in the Canary Islands (LópezJurado 2007), and heavy human predation on nesting and foraging animals occurred on Santiago 

Island, Cape Verde, the first in the Archipelago to be settled (Loureiro 2008), as well as on Sal 

and Sao Vicente islands (López-Jurado 2007). Nesting loggerheads and eggs are still harvested 

at Boa Vista, Cape Verde (Cabrera et al. 2000, López-Jurado et al. 2003). In 2007, over 1,100 

(36%) of the nesting turtles were hunted, which is about 15% of the estimated adult female 

population (Marco et al. in press). In 2008, the military protected one of the major nesting 

beaches on Boa Vista where in 2007 55% of the mortality had occurred; with the additional 

protection, only 17% of the turtles on that beach were slaughtered (Roder et al. in press). On Sal 

Island, 11.5% of the emergences on unprotected beaches ended with mortality, whereas mortality 

was 3% of the emergences on protected beaches (Cozens et al. in press). The slaughter of 

nesting turtles is a problem wherever turtles nest in the Cape Verde Islands and may approach 

100% in some places (C. Roder, Turtle Foundation, Münsing, Germany, personal 

communication, 2009; Cozens in press). The meat and eggs are consumed locally as well as 

traded among the archipelago (C. Roder, Turtle Foundation, Münsing, Germany, personal 

communication, 2009). Hatchlings are collected on Sal Island, but this activity appears to be rare 

on other islands of the archipelago (J. Cozens, SOS Tartarugas Cabo Verde, Santa Maria, Sal 

Island, Cape Verde, personal communication, 2009). Additionally, free divers target turtles for 

consumption of meat, often selectively taking large males (López-Jurado et al. 2003). Turtles 

are harvested along the African coast and, in some areas, are considered a significant source of 

food and income due to the poverty of many residents along the African coast (Formia et al. 

2003). Loggerhead carapaces are sold in markets in Morocco and Western Sahara (Fretey 2001, 

Tiwari et al. 2001, Benhardouze et al. 2004). 
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5.2.7.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the Northeast Atlantic Ocean. Spontaneous diseases documented in the 

Northeast Atlantic include pneumonia, hepatitis, meningitis, septicemic processes, and neoplasia 

(Orós et al. 2005). Pneumonia could result from the aspiration of water from forced 

submergence in fishing gear. The authors also reported nephritis, esophagitis, nematode 

infestation, and eye lesions. Fibropapillomatosis does not appear to be an issue in the Northeast 

Atlantic. 

Nest depredation by ghost crabs (Ocypode cursor) occurs in Cape Verde (López-Jurado et al. 

2000). The ghost crabs feed on both eggs and hatchlings. Arvy et al. (2000) reported predation 

of loggerhead eggs in two nests in Mauritania by golden jackals (Canis aureus); a loggerhead 

turtle creating a third nest also had been killed, with meat and eggs eaten, but the predator was 

not identified. 

Loggerheads in the Northeast Atlantic also may be impacted by harmful algal blooms, which 

have been reported infrequently in the Canary Islands and the Iberian Coastal LME (Ramos et al. 

2005, Akin-Oriola et al. 2006, Amorim and Dale 2006, Moita et al. 2006; 

http://www.lme.noaa.gov). 

5.2.7.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the Northeast Atlantic Ocean, although not all nations in 

the region are signatory to them all (e.g., Western Sahara is not signatory to the CMS/Bonn 

Convention). The following additional instruments and regulation also apply to loggerheads 

found in this area.

Convention for the Protection of the Marine Environment of the North-East Atlantic 

Also called the OSPAR Convention, this 1992 instrument combines and updates the 1972 Oslo 

Convention against dumping waste in the marine environment and the 1974 Paris Convention 

addressing marine pollution stemming from land-based sources. The convention is managed by 

the OSPAR Commission, which is comprised of representatives from 15 signatory nations 

(Belgium, Denmark, Finland, France, Germany, Iceland, Ireland, Luxembourg, The Netherlands, 

Norway, Portugal, Spain, Sweden, Switzerland, and United Kingdom), as well as the European 

Commission, representing the European Community. The mission of the OSPAR Convention 

“...is to conserve marine ecosystems and safeguard human health in the North-East Atlantic by 

preventing and eliminating pollution; by protecting the marine environment from the adverse 

effects of human activities; and by contributing to the sustainable use of the seas.” Loggerheads 

are included on the OSPAR List of Threatened and/or Declining Species and Habitats, which is 

used by the OSPAR Commission for setting priorities for work on the conservation and 

protection of marine biodiversity. Additional information is available at http://www.ospar.org. 
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Convention on the Conservation of European Wildlife and Natural Habitats 

Also known as the Bern Convention, the goals of this instrument are to conserve wild flora and 

fauna and their natural habitats, especially those species and habitats whose conservation 

requires the cooperation of several States, and to promote such cooperation. The Convention 

was enacted in 1982 and currently includes 48 European and African States and the European 

Union. Sea turtles are included on the “strictly protected” list. According to Hykle (2002), 

while the Convention's “innovative approach to holding States to account for their 

implementation of the Convention is laudable, and has certainly drawn attention to issues of 

species and habitat protection, its efficacy in relation to particular marine turtle cases that have 

been deliberated for many years is debatable.” Additional information is available at 

http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm. 

African Convention on the Conservation of Nature and Natural Resources (Algiers Convention)

Adopted in September 1968, the contracted states were “to undertake to adopt the measures 

necessary to ensure conservation, utilization and development of soil, water, floral and faunal 

resources in accordance with scientific principles and with due regard to the best interests of the 

people”. It was followed by the 1972 Stockholm Conference on the Human Environment and 

led to the establishment of environmental ministries in African nations and the creation of the 

United Nations Environment Programme (UNEP) headquartered in Nairobi. The Algiers 

Convention recently has undergone revision (not yet in force) and its objectives are to enhance 

environmental protection, foster conservation and sustainable use of natural resources, and 

harmonize and coordinate policies in these fields with a view to achieving ecologically rational, 

economically sound, and socially acceptable development policies and programs. Additional 

information is available at http://www.unep.ch/regionalseas/legal/afr.htm. 

Convention on the Conservation of Migratory Species of Wild Animals, Memorandum of 

Understanding Concerning Conservation Measures for Marine Turtles of the Atlantic Coast of 

Africa (Abidjan Memorandum)

This MOU was concluded under the auspices of the Convention on the Conservation of 

Migratory Species of Wild Animals (CMS) and became effective in 1999. The MOU area 

covers 26 Range States along the Atlantic coast of Africa extending approximately 14,000 km 

from Morocco to South Africa. The goal of this MOU is to improve the conservation status of 

marine turtles along the Atlantic Coast of Africa. It aims at safeguarding six marine turtle 

species – including the loggerhead turtle – that are estimated to have rapidly declined in numbers 

during recent years due to excessive exploitation (both direct and incidental) and the degradation 

of essential habitats. This includes the projection of hatchlings through adults with particular 

attention paid to the impacts of fishery bycatch and the need to include local communities in the 

development and implementation of conservation activities. However, despite this agreement, 

killing of adult turtles and harvesting of eggs remains rampant in many areas along the Atlantic 

African coast. Additional information is available at 

http://www.cms.int/species/africa_turtle/AFRICAturtle_bkgd.htm. 

The Convention for the Co-operation in the Protection and Development of the Marine and 

Coastal Environment of the West and Central African Region (Abidjan Convention)

The Abidjan Convention covers the marine environment, coastal zones, and related inland waters 

from Mauritania to Namibia. The Abidjan Convention countries are Angola, Benin, Cameroon, 
143

Cape Verde, Congo, Cote d'Ivoire, Democratic Republic of Congo, Equatorial Guinea, Gabon, 

Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mauritania, Namibia, Nigeria, Sao Tome and 

Principe, Senegal, Sierra Leone, and Togo. The Abidjan Convention is an agreement for the 

protection and management of the marine and coastal areas that highlights sources of pollution, 

including pollution from ships, dumping, land-based sources, exploration and exploitation of the 

sea-bed, and pollution from or through the atmosphere. The Convention also identifies where 

co-operative environmental management efforts are needed. These areas of concern include 

coastal erosion, specially protected areas, combating pollution in cases of emergency, and 

environmental impact assessment. The Action Plan and the Abidjan Convention were adopted 

by the Governments in 1981; the Convention entered into force in 1984. Western Sahara and 

Morocco are not signatories of the Abidjan Convention. 

Accra Declaration of the Ministerial Committee of the Gulf of Guinea Large Marine Ecosystem 

(GOG-LME)-1998 Abuja Declaration of the Guinea Current Large Marine Ecosystem Project2006 

In 1998, the environmental ministers of Cote d’Ivoire, Ghana, Togo, Benin, Nigeria, and 

Cameroon signed the Accra Declaration to strengthen regional capacity to prevent and correct 

pollution in the LME and prevent and correct degradation of critical habitats. The ministers 

identified the living resources and management problems in the area. The countries decided on a 

detailed survey of industries, defined regional effluent standards, instituted community based 

mangrove restoration activities, and created a campaign for the reduction, recovery, recycling, 

and re-use of industrial wastes. In 2006, the Guinea Current LME Project expanded the project 

scope to 10 neighboring countries (Guinea-Bissau, Guinea, Sierra Leone, Liberia, Sao Tome and 

Principe, Equatorial Guinea, Gabon, Congo Brazzaville, Congo-Kinshasa, and Angola). 

Council Regulation (EC) No. 1239/98 of 8 June 1998 Amending Regulation (EC) No. 894/97 

Laying Down Certain Technical Measures for the Conservation of Fishery Measures (Council of 

the European Union)

This measure banned the use of driftnets by 1 January 2002 for European fleets. Fleets from 

other nations fishing in international waters can still use driftnets. 

5.2.7.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

Loggerhead turtles strand throughout the Northeast Atlantic (Fretey 2001; Tiwari et al. 2001; 

Duguy et al. 2004, 2005; Witt et al. 2007), and there are indications that the turtles become 

entangled in nets and monofilament and swallow hooks in the region (Orós et al. 2005, Calabuig 

Miranda and Liria Loza 2007). On the European coasts, most stranded loggerheads are small 

(mean < 30 cm SCL), but a few are greater than 60 cm SCL (Witt et al. 2007). Similarly, Tiwari 

et al. (2001) and Benhardouze et al. (2004) indicated that the animals they viewed in Morocco 

and Western Sahara were small juveniles and preliminary genetic analyses of stranded turtles 

indicate that they are of western Atlantic origin (M. Tiwari, NMFS, and A. Bolten, University of 

Florida, unpublished data), whereas Fretey (2001) reported that loggerheads captured and 

stranded in Mauritania were both juvenile and adult-sized animals. 
144

Incidental capture of sea turtles in artisanal and commercial fisheries is a threat to the survival of 

loggerheads in the Northeast Atlantic. Sea turtles may be caught in a multitude of gears 

deployed in the region: pelagic and demersal longlines, drift and set gillnets, bottom and midwater trawling, weirs, haul and purse seines, pots and traps, cast nets, and hook and line gear (see 

Pascoe and Gréboval 2003, Bayliff et al. 2005, Tayaa et al. 2005, Dossa et al. 2007). Fishing 

effort off the western African coast has been increasing (see Palomares and Pauly 2004). 

Impacts continue to increase in the Guinea Current LME, but, in contrast, the impacts are 

reported to be decreasing in the Canary Current LME (http://www.lme.noaa.gov). Throughout 

the region, fish stocks are depleted and management authorities are striving to reduce the fishing 

pressure. 

In the Northeast Atlantic, loggerheads, particularly the largest size classes in the oceanic 

environment (most of which are small juveniles), are captured in surface longline fisheries 

targeting swordfish (Ziphias gladius) and tuna (Thunnus spp.) (Ferreira et al. 2001, Bolten 

2003). Bottom longlines in Madeira Island targeting black-scabbard (Aphanopus carbo) capture 

and kill small juvenile loggerhead turtles as the fishing depth does not allow hooked turtles to 

surface (Dellinger and Encarnaçâo 2000, Delgado et al. in press). 

In United Kingdom and Irish waters, loggerhead bycatch is uncommon but has been noted in 

pelagic driftnet fisheries (Pierpoint 2000, Rogan and Mackey 2007). Loggerheads have not been 

captured in pelagic trawls, demersal trawls, or gillnets in United Kingdom and Irish waters 

(Pierpoint 2000), but have been captured in nets off France (Duguy 2004, 2005). 

International fleets of trawl fisheries operate in Mauritania and have been documented to capture 

sea turtles, including loggerheads (Zeeberg et al. 2006). Despite being illegal, trawling occurs in 

the Cape Verde Islands and has the potential to capture and kill loggerhead turtles; one piece of 

abandoned trawl net washed shore with eight live and two dead loggerheads (López-Jurado et al. 

2003). Longlines, seines, and hook and line have been documented to capture loggerheads 35-73 

cm SCL off the northwestern Moroccan coast (Benhardouze 2004). 

Other Manmade and Natural Impacts 

As described in Section 5.1.5., other anthropogenic impacts, such as boat strikes and ingestion or 

entanglement in marine debris, also apply to loggerheads in the Northeast Atlantic. Propeller 

and boat strike injuries have been documented in the Northeast Atlantic (Orós et al. 2005, 

Calabuig Miranda and Liria Loza 2007). Exposure to crude oil is also of concern. Loggerhead 

strandings in the Canary Islands have shown evidence of hydrocarbon exposure as well as 

ingestion of marine debris, such as plastic and monofilament (Orós et al. 2005, Calabuig 

Miranda and Liria Loza 2007), and in the Azores and elsewhere plastic debris is found both on 

the beaches and floating in the waters (Barrerios and Barcelos 2001, Tiwari et al. 2001). 

Pollution from heavy metals is a concern for the seas around the Iberian Peninsula (European 

Environmental Agency 1998) and in the Guinea Current LME (Abe et al. 2004). 

Bioaccumulation of metals in loggerheads has been measured in the Canary Islands and along 

the French Atlantic Coast (Caurant et al. 1999, Torrent et al. 2004). However, the consequences 

of long term exposure to heavy metals are unknown (Torrent et al. 2004). The effects of 

pollution on the ecosystem are addressed in Section 5.2.7.1. 
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Natural environmental events, such as climate change, could impact affect loggerheads in the 

Northeast Atlantic. Similar to other areas of the world (see Section 5.1.5.), climate change and 

sea level rise have the potential to impact loggerheads in the Northeast Atlantic, and the changes 

may be further exacerbated by the burning of fossil fuels and deforestation. These effects range 

from flooding of nesting beaches, shifts in ocean currents, ecosystem shifts in prey distribution 

and abundance, and a shift in the sex ratio of the population if rookeries do not migrate 

concurrently (e.g., northward in the case of global warming) or if nesting phenology does not 

change (see Doody et al. 2006). Tropical and sub-tropical storms occasionally strike the area 

and could have a negative impact on nesting, although such an impact would be of limited 

duration. 

5.2.8. Mediterranean Sea DPS 

The following information on threats pertains to all loggerhead turtles that may be found in the 

Mediterranean Sea. Because it is likely that oceanic juveniles from this DPS also are found in 

the Northeast Atlantic Ocean, the narrative for that region should also be consulted. 

5.2.8.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

In the Mediterranean, some areas known to host nesting activity in the past have been lost to 

turtles (e.g., Malta) or severely degraded (e.g., Israel) (Margaritoulis et al. 2003). As described 

in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the Mediterranean 

result from coastal development and construction, placement of erosion control structures and 

other barriers to nesting, beachfront lighting, vehicular and pedestrian traffic, sand extraction, 

beach erosion, beach sand placement, beach pollution, removal of native vegetation, and planting 

of non-native vegetation (Baldwin 1992, Margaritoulis et al. 2003). These activities may 

directly impact the nesting success of loggerheads and survivability of eggs and hatchlings. 

Nesting in the Mediterranean almost exclusively occurs in the Eastern basin, with the main 

concentrations found in Cyprus, Greece, Turkey, and Libya (Margaritoulis et al. 2003, Laurent et 

al. 1999); therefore, the following threats to the nesting habitat are concentrated in these areas. 

The Mediterranean experiences a large influx of tourists during the summer months, coinciding 

with the nesting season. Margaritoulis et al. (2003) state that extensive urbanization of the 

coastline, largely a result of tourism and recreation, is likely the most serious threat to 

loggerhead nesting areas. The large numbers of tourists that use Mediterranean beaches result in 

an increase in umbrellas, chairs, garbage, and towels, as well as related hotels, restaurants, and 

stationary (e.g., street lights, hotels) and moving (e.g., cars) lighting, all which can impact sea 

turtle nesting success (Demetropoulos 2000). Further, the eastern Mediterranean is exposed to 

high levels of pollution and marine debris, in particular the nesting beaches of Cyprus, Turkey, 

and Egypt (Camiñas 2004). 

Construction and infrastructure development also have the potential to alter nesting beaches and 

subsequently impact nesting success. The construction of new buildings on or near nesting 

beaches has been a problem in Greece and Turkey (Camiñas 2004). The construction of a jetty 
146

and waterworks around Mersin, Turkey, has contributed significantly to the continuous loss of 

adjacent beach (Camiñas 2004). 

Beach erosion and sand extraction also pose a problem for sea turtle nesting sites. The noted 

decline of the nesting population at Rethymno, Island of Crete, Greece, is partly attributed to 

beach erosion caused by construction on the high beach and at sea (e.g., groins) (Margaritoulis et 

al. 2009). A 2001 survey of Lebanese nesting beaches found severe erosion on beaches where 

previous nesting had been reported, and in some cases the beaches had disappeared completely 

(Venizelos et al. 2005). Definitive causes of this erosion were found to be sand extraction, 

offshore sand dredging, and sediment removal from river beds for construction and military 

purposes. Beach erosion also may occur from natural changes, with the same deleterious effects 

to loggerhead nesting. On Patara, Turkey, beach erosion and subsequent inundation by waves 

and shifting sand dunes are responsible for about half of all loggerhead nest losses (Camiñas 

2004). Erosion can further be exacerbated when native dune vegetation, which enhances beach 

stability and acts as an integral buffer zone between land and sea, is degraded or destroyed. This 

in turn often leaves insufficient nesting opportunities above the high tide line, and nests may be 

washed out. In contrast, the planting or invasion of less stabilizing, non-native plants can lead to 

increased erosion and degradation of suitable nesting habitat. Finally, sand extraction has been a 

serious problem on Mediterranean nesting beaches, especially in Turkey (Türkozan and Baran 

1996), Cyprus (Godley et al. 1996, Demetropoulos and Hadjichristophorou 1989), and Israel 

(Levy 2003). 

While the most obvious effect of nesting beach destruction and modification may be to the 

existence of the actual nests, hatchlings are also threatened by habitat alteration. In the 

Mediterranean, disorientation of hatchlings due to artificial lighting has been recorded mainly in 

Greece (Rees 2005, Margaritoulis et al. 2007, Margaritoulis et al. 2009), Turkey (Türkozan and 

Baran 1996), and Lebanon (Newbury et al. 2002). Additionally, vehicle traffic on nesting 

beaches may disrupt the natural beach environment and contribute to erosion, especially during 

high tides or on narrow beaches where driving is concentrated on the high beach and foredune. 

On Zakynthos Island in Greece, Venizelos et al. (2006) reported that vehicles drove along the 

beach and sand dunes throughout the tourist season on East Laganas and Kalamaki beaches, 

leaving deep ruts in the sand, disturbing sea turtles trying to nest, and impacting hatchlings trying 

to reach the sea. 

Neritic/Oceanic Zone 

As described in Section 5.1.1., threats to habitat in the loggerhead neritic and/or oceanic zones 

include fishing practices, channel dredging, sand extraction, marine pollution, and climate 

change. These threats also occur in the Mediterranean. 

Trawling occurs throughout the Mediterranean, most notably in areas off Albania, Algeria, 

Croatia, Egypt, France, Greece, Italy, Libya, Morocco, Slovenia, Spain, Tunisia, and Turkey 

(Gerosa and Casale 1999, Camiñas 2004, Casale 2008). This fishing practice has the potential to 

destroy bottom habitat in these areas. Fishing methods affect neritic zones by not only impacting 

bottom habitat and incidentally capturing loggerheads but also depleting fish populations, and 

thus altering ecosystem dynamics. For example, depleted fish stocks in Zakynthos, Greece, 

likely contributed to predation of adult loggerheads by monk seals (Monachus monachus) 
147

(Margaritoulis et al. 1996). Further, by depleting fish populations, the trophic dynamics will be 

altered, which may then in turn affect the ability of loggerheads to find prey resources. If 

loggerheads are not able to forage on the necessary prey resources, their long term survivability 

may be impacted. Climate change also may result in future trophic changes, thus impacting 

loggerhead prey abundance and/or distribution. 

Marine pollution, including direct contamination and structural habitat degradation, can affect 

loggerhead neritic and oceanic habitat. As the Mediterranean is an enclosed sea, organic and 

inorganic wastes, toxic effluents, and other pollutants rapidly affect the ecosystem (Camiñas 

2004). The Mediterranean has been declared a “special area” by the MARPOL Convention, in 

which deliberate petroleum discharges from vessels are banned, but numerous repeated offenses 

are still thought to occur (Pavlakis et al. 1996). Some estimates of the amount of oil released 

into the region are as high as 1,200,000 metric tons (Alpers 1993). Direct oil spill events also 

occur as happened in Lebanon in 2006 when 10,000 to 15,000 tons of heavy fuel oil spilled into 

the eastern Mediterranean (United Nations Environment Programme 2007). 

Destruction and modification of loggerhead habitat also may occur as a result of other activities. 

For example, underwater explosives have been identified as a key threat to loggerhead habitat in 

internesting areas in the Mediterranean (Margaritoulis et al. 2003). Further, the Mediterranean is 

a site of intense tourist activity, and corresponding boat anchoring also may impact loggerhead 

habitat in the neritic environment. 

5.2.8.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Mediterranean turtle populations were subject to severe exploitation until the mid-1960s 

(Margaritoulis et al. 2003). Deliberate hunting of loggerheads for their meat, shells, and eggs is 

reduced from previous exploitation levels, but still exists. For example, Nada and Casale (2008) 

found that egg collection (for individual consumption) still occurs in Egypt. In some areas of the 

Mediterranean, like on the Greek Island of Zakynthos, nesting beaches are protected 

(Panagopoulou et al. 2008), so egg harvest by humans in those areas is likely negligible. 

Exploitation of juveniles and adults still occurs in some Mediterranean areas. In Tunisia, 

clandestine trade for local consumption is still recorded, despite prohibition of the sale of turtles 

in fish markets in 1989 (Laurent et al. 1996). In Egypt, turtles are sold in fish markets despite 

prohibitive laws; of 71 turtles observed at fish markets in 1995 and 1996, 68% were loggerheads 

(Laurent et al. 1996). Nada (2001) reported 135 turtles (of which 85% were loggerheads) 

slaughtered at the fish market of Alexandria in six months (December 1998-May 1999). Based 

on observed sea turtle slaughters in 1995 and 1996, Laurent et al. (1996) estimated that several 

thousand sea turtles were probably killed each year in Egypt. More recently, a study found that 

the open selling of sea turtles in Egypt generally has been curtailed due to enforcement efforts, 

but a high level of intentional killing for the black market or for direct personal consumption still 

exists (Nada and Casale 2008). Given the high numbers of turtles caught in this area, several 

hundred turtles are currently estimated to be slaughtered each year in Egypt (Nada and Casale 

2008). This estimate likely includes both juvenile and adult loggerheads, as Egyptian fish 

markets have been documented selling different sized sea turtles. While the mean sea turtle size 
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was 65.7 cm CCL (range 38-86.3 cm CCL; n=48), 37.5% of observed loggerhead samples were 

greater than 70 cm CCL (Laurent et al. 1996). 

5.2.8.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the Mediterranean. Endoparasites in loggerheads have been studied in the 

western Mediterranean. While the composition of the gastrointestinal community of sea turtles 

is expected to include digeneans, nematodes, and aspidogastreans, loggerheads in the 

Mediterranean were found to harbor only four digenean species typical of marine turtles (Aznar 

et al. 1998). There have been no records of fibropapillomatosis in the Mediterranean. While 

there is the potential for disease in this area, information on the prevalence of such disease is 

lacking. 

In the Mediterranean Sea, loggerhead hatchlings and eggs are subject to depredation by wild 

canids (i.e., foxes (Vulpes vulpes), golden jackals (Canis aureus)), feral/domestic dogs, and ghost 

crabs (Ocypode cursor) (Margaritoulis et al. 2003). Predators have caused the loss of 48.4% of 

loggerhead clutches at Kyparissia Bay, Greece (Margaritoulis 1988), 70-80% at Dalyan Beach, 

Turkey (Erk'akan 1993), 36% (includes green turtle clutches) in Cyprus (Broderick and Godley 

1996), and 44.8% in Libya (Laurent et al. 1995). A survey of the Syrian coast in 1999 found 

100% nest predation, mostly due to stray dogs and humans (Venizelos et al. 2005). Loggerhead 

eggs are also depredated by insect larvae in Cyprus (McGowan et al. 2001), Turkey (Özdemir et 

al. 2004), and Greece (Lazou and Rees 2006). Ghost crabs have been reported preying on 

loggerhead hatchlings in northern Cyprus and Egypt, suggesting 66% of emerging hatchlings 

succumb to this mortality source (Simms et al. 2002). Predation also has been influenced by 

anthropogenic sources. On Zakynthos, Greece, a landfill site next to loggerhead nesting beaches 

has resulted in an artificially high level of seagulls (Larus spp.), which results in increased 

predation pressure on hatchlings (Panagopoulou et al. 2008). Planting of non-native plants also 

can have a detrimental effect on nests in the form of roots invading eggs (e.g., tamarisk tree 

(Tamarix spp.) roots invading eggs in Zakynthos, Greece; Margaritoulis et al. 2007). 

Predation on adult and juvenile loggerheads has also been documented in the Mediterranean. 

Predation of nesting loggerheads by golden jackals has been recorded in Turkey (Peters et al. 

1994). During a 1995 survey of loggerhead nesting in Libya, two nesting females were found 

killed by carnivores, probably jackals (Laurent et al. 1997). Off the sea turtle nesting beach of 

Zakynthos, Greece, adult loggerheads were found being predated upon by Mediterranean monk 

seals (Monachus monachus). Of the eight predated turtles observed or reported, 62.5% were 

adult males (Margaritoulis et al. 1996). Further, stomach contents were examined from 24 

Mediterranean white sharks (Carcharodon carcharias), and 17% contained remains of marine 

turtles, including two loggerheads, one green, and one unidentifiable turtle (Fergusson et al. 

2000). One of the loggerhead turtles ingested was a juvenile with a carapace length of 

approximately 60 cm (length not reported as either SCL or CCL). Fergusson et al. (2000) report 

that white shark interactions with sea turtles are likely rare east of the Ionian Sea, and while the 

impact of shark predation on turtle populations is unknown, it is probably small compared to 

other sources of mortality. 
149

The Mediterranean is a low-productivity body of water, with high water clarity as a result. 

However, harmful algal blooms do occur in this area (e.g., off Algeria in 2002), and the problem 

is particularly acute in enclosed ocean basins such as the Mediterranean. In the northern Adriatic 

Sea, fish kills have occurred as a result of noxious phytoplankton blooms and anoxic conditions 

(Mediterranean Sea LME). While fish may be more susceptible to these harmful algal blooms, 

loggerheads in the Mediterranean also may be impacted by such noxious or toxic phytoplankton 

to some extent. 

5.2.8.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the Mediterranean Sea. The following additional 

instruments and regulation also apply to loggerheads found in this area. 

Protocol Concerning Specially Protected Areas and Biological Diversity in the Mediterranean 

This Protocol is under the auspices of the Barcelona Convention of 1976 for the Protection of the 

Mediterranean Sea against Pollution (amended in 1995). The Protocol has been in force since 

1999 and includes general provisions to protect sea turtles and their habitats within the 

Mediterranean Sea. The Protocol requires Parties to protect, preserve, and manage threatened or 

endangered species, establish protected areas, and coordinate bilateral or multilateral 

conservation efforts (Hykle 2002). In the framework of the Barcelona Convention, to which all 

Mediterranean countries are parties, the Action Plan for the Conservation of Mediterranean 

Marine Turtles has been in effect since 1989. The main objectives of the Action Plan are to 

enhance the population of marine turtles, protect their critical habitats (including nesting, 

feeding, wintering, and migrating areas), and improve scientific knowledge by research and 

monitoring. In particular, the Action Plan has focused on promulgating education and training 

(especially among fishermen), establishing and improving rescue centers, promoting legislation 

guidelines, and improving research and monitoring of sea turtles (Demetropoulos 2007). 

Unfortunately, little research on or implementation of fishing gear bycatch techniques to reduce 

sea turtle incidental captures has occurred. Additional information is available at 

http://www.rac-spa.org. 

Convention on the Conservation of European Wildlife and Natural Habitats 

For information about this instrument, see section 5.2.7.4. for the Northeast Atlantic Ocean DPS. 

Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and 

Flora (EC Habitats Directive)

The EC Habitats Directive was adopted by the European Community in May 1992, as the means 

by which the Community meets its obligations as a signatory of the Bern Convention. It aims to 

protect approximately 200 habitats and 1,000 animal and plant species listed in the Directive's 

Annexes, of which loggerhead sea turtles are included. The provisions in the Directive require 

Member States to introduce a range of measures including the protection of species listed in the 

Annexes, undertake surveillance of habitats and species, and produce a report every six years on 

the implementation of the Directive. The first complete set of country data was reported in 2007. 

The Directive led to the establishment of a network of Special Areas of Conservation that, 

together with the existing Special Protection Areas classified under the separate EC Birds 
150

Directive, form a network of protected areas known as Natura 2000. Additional information is 

available at http://ec.europa.eu/environment/nature/legislation/habitatsdirective/index_en.htm. 

Council Regulation (EC) No. 1239/98 of 8 June 1998 Amending Regulation (EC) No. 894/97 

Laying Down Certain Technical Measures for the Conservation of Fishery Measures (Council of 

the European Union) 

For information about this instrument, see section 5.2.7.4. for the Northeast Atlantic Ocean DPS. 

Convention for the Protection of the Marine Environment of the North-East Atlantic 

This Convention is included under the Mediterranean Sea DPS because it is likely that oceanic 

juveniles from this DPS also are found in the Northeast Atlantic Ocean. For information about 

this instrument, see section 5.2.7.4. for the Northeast Atlantic Ocean DPS. 

In addition to these international mechanisms, most Mediterranean countries have developed 

legislation to protect sea turtles and/or nesting habitats (Margaritoulis 2007). For example, in 

1999, a National Marine Park was established on Zakynthos in western Greece, with the primary 

aim to provide protection to loggerhead nesting areas (Dimopoulos 2001). However, while 

improved over the last several years, it appears that management and protection at this Park is 

lacking (Robinson et al. 2007, Panagopoulou et al. 2008). In Turkey, five nesting beaches were 

designated Specially Protected Area status, and in Cyprus, two nesting beaches have been 

afforded protection through the Fisheries Regulation, with a maritime zone extending to the 20 

meter isobath (Margaritoulis 2007). In Italy, a reserve to protect nesting on Lampedusa was 

established in 1984 (Margaritoulis et al. 2003). The overall effectiveness of this country specific 

legislation is unknown at this time. 

5.2.8.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

As noted in Section 5.1.5., other anthropogenic and natural factors affecting loggerhead survival 

include incidental bycatch in fisheries, vessel collisions, marine pollution, climate change, and 

cyclonic storm events. Fishing practices alone have been estimated to result in over 150,000 sea 

turtle captures per year, with approximately 50,000 mortalities (Casale 2008). 

The only estimation of loggerhead survival probabilities in the Mediterranean was calculated by 

using capture-mark-recapture techniques from 1981-2003 (Casale et al. 2007c). Of the 3,254 

loggerheads tagged, 134 were recaptured at different sites throughout the Mediterranean. Most 

recaptured animals were juveniles (mean 54.4 cm CCL; range 25-88 cm CCL), but the study did 

not delineate between juvenile life stages. This research estimated a loggerhead annual survival 

probability of 0.73 (95% confidence intervals; 0.67-0.78), recognizing that there are 

methodological limitations of the technique used. Nonetheless, Casale et al. (2007a) stated that 

assuming a natural survivorship no higher than 0.95 and a tag loss rate of 0.1, a range of 0.1-0.2 

appears reasonable for the additional human induced mortality (from all sources). 

Incidental Bycatch in Fishing Gear 

Incidental capture of sea turtles in artisanal and commercial fisheries is a significant threat to the 

survivability of loggerheads in the Mediterranean. Sea turtles may be caught in pelagic and 

demersal longlines, drift gillnets, set gillnets and trammel nets, bottom and mid-water trawls, 
151

seines, dredges, traps/pots, and hook and line gear. In a 2004 FAO Fisheries Report, Camiñas 

(2004) stated that the main fisheries affecting sea turtles in the Mediterranean Sea (at that time) 

were Spanish and Italian longline, North Adriatic Italian, Tunisian, and Turkish trawl, and 

Moroccan and Italian driftnet. Available information on sea turtle bycatch by gear type is 

discussed below. There is growing evidence that artisanal/small vessel fisheries (set gillnet, 

bottom longline, and part of the pelagic longline fishery) may be responsible for a comparable or 

higher number of captures with higher mortality rates than the commercial/large vessel fisheries 

(Casale 2008) as previously suggested by indirect clues (Casale et al. 2005a). 

Mediterranean fish landings have increased steadily since the 1950s, but the FAO 10-year 

capture trend from 1990-1999 shows stable landings (Mediterranean LME, 

http://www.lme.noaa.gov). However, stable fish landings may result from stable fishing effort at 

the same catch rates, or higher fishing effort at lower catch rates. As fish stocks in the 

Mediterranean are being depleted (P. Casale, MTSG-IUCN Italy, personal communication, 

2009), fishing effort in some areas may be increasing to catch the available fish. This trend has 

not yet been verified throughout the Mediterranean, but fishing pressures may be increasing even 

though landings appear stable. 

Longline fisheries

In the Mediterranean, pelagic longline fisheries targeting swordfish (Ziphias gladius) and 

albacore (Thunnus alalunga) may be the primary source of loggerhead bycatch. It appears that 

most of the incidental captures occur in the western and central portions of the area 

(Demetropoulos and Hadjichristophorou 1995). The most severe bycatch in the Mediterranean 

occurs around the Balearic Islands where 1,950-35,000 juveniles are caught annually in the 

surface longline fishery (Mayol and Castelló Mas 1983; Camiñas 1988, 1997; Aguilar et al. 

1995). Specifically, the following regions have reported annual estimates of total turtle bycatch 

from pelagic longlines: Spain – 17,000 to 35,000 turtles (Aguilar et al. 1995, Camiñas et al. 

2003); Italy (Ionian Sea) – 1,084 to 4,447 turtles (Deflorio et al. 2005); Morocco – 3,000 turtles 

(Laurent 1990); Greece – 280 to 3,310 turtles (Panou et al. 1999, Kapantagakis and Lioudakis 

2006); Italy (Lampedusa) – 2,100 turtles (Casale et al. 2007a); Malta – 1,500 to 2,500 turtles 

(Gramentz 1989); South Tunisia (Gulf of Gabès) – 486 turtles (Jribi et al. 2008); and Algeria – 

300 turtles (Laurent 1990). 

For the entire Mediterranean pelagic longline fishery, an extrapolation resulted in a bycatch 

estimate of 60,000 to 80,000 loggerheads in 2000 (Lewison et al. 2004). Further, a more recent 

paper used the best available information to estimate that Spain, Morocco, and Italy have the 

highest level of sea turtle bycatch, with over 10,000 turtle captures per year for each country, and 

Greece, Malta, Libya, and Tunisia each catch 1,000 to 3,000 turtles per year (Casale 2008). 

Available data suggest the annual number of loggerhead sea turtle captures by all Mediterranean 

pelagic longline fisheries may be greater than 50,000 (Casale 2008). Note that these are not 

necessarily individual turtles, as the same sea turtle can be captured more than once. 

Mortality estimates in the pelagic longline fishery at gear retrieval appear to be lower than in 

some other types of gear (e.g., set gillnet). Although limited to observations of direct mortality 

at gear retrieval, Carreras et al. (2004) found mortality to be low (0-7.7%) in the longline fishery 

off the Balearic Islands, and Jribi et al. (2008) reported 0% direct mortality in the southern 
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Tunisia surface longline fishery. These estimates are consistent with those found in other areas; 

direct mortality was estimated at 4.3% in Greece (n=23), 0% in Italy (n=214), and 2.6% in Spain 

(n=676) (Laurent et al. 2001). However, considering injured turtles and those released with 

hooks, the potential for mortality is likely much higher. Based upon observations of hooked 

loggerhead turtles in captivity, Aguilar et al. (1995) estimated 20-30% of animals caught in 

longline gear may eventually die. More recently, Casale et al. (2008c) found, given variations in 

hook position affecting survivability, the mortality rate of turtles caught by pelagic longlines may 

be higher than 30%, which is greater than previously thought (17-42%; Lewison et al. 2004). 

Considering direct and post-release mortality, Casale (2008) used a conservative approach to 

arrive at 40% for the average mortality from Mediterranean pelagic longlines. The result is an 

estimated 20,000 turtles killed per year by pelagic longlines (Casale 2008). 

These incidental capture levels may impact the Mediterranean Sea DPS. Of loggerheads caught 

in the summer pelagic longline fishery from the western and eastern Mediterranean, more than 

half originated from the Mediterranean nesting population (as opposed to all animals in the 

western Mediterranean originating from the Atlantic as previously believed; Laurent et al. 1998). 

In general, most of the turtles captured in the Mediterranean surface longline fisheries are 

juvenile animals (Aguilar et al. 1995, Panou et al. 1999, Camiñas et al. 2003, Casale et al. 

2007a, Jribi et al. 2008), but some adult loggerhead bycatch is also reported. Considering data 

from many Mediterranean areas and research studies, the average size of turtles caught by 

pelagic longlines was 48.9 cm CCL (range 20.5-79.2 cm CCL; n=1868) (Casale 2008). 

Specifically, in the Spanish surface longline fishery, 13% of estimated carapace sizes (n=455) 

ranged from 75.36 to 107 cm CCL, considered to be adult animals (Camiñas et al. 2003), and in 

the Ionian Sea, 15% of a total 157 loggerhead turtles captured in swordfish longlines were adult 

animals (estimated size ≥75 cm) (Panou et al. 1999). 

Bottom longlines are also fished in the Mediterranean, but specific capture rates for loggerheads 

are largely unknown for many areas. The countries with the highest number of documented 

captures (in the thousands per year) are Tunisia, Libya, Greece, Turkey, Egypt, Morocco, and 

Italy (Casale 2008). Available data suggest the annual number of loggerhead sea turtle captures 

(not necessarily individual turtles) by all Mediterranean demersal longliners may be greater than 

35,000 (Casale 2008). 

Mortality from bottom longlines occurs if the hooked animal cannot reach the surface to breathe 

or if the ingested hooks and branch lines result in injuries and post-release mortality. For 

example, in the Gulf of Gabès off Tunisia, the estimated total capture from bottom longlines was 

733 loggerheads, with a direct and potential mortality (assuming all comatose turtles would die) 

of 12.5 to 33%, respectively (Jribi et al. 2008). Given available information and using a 

conservative approach, mortality from bottom longlines may be at least equal to pelagic longline 

mortality (40%; Casale 2008). The result is an estimated 14,000 turtles killed per year in 

Mediterranean bottom longlines (Casale 2008). It is likely that these animals represent mostly 

juvenile, but some adult, loggerheads. Casale (2008) reported an average turtle size of 51.8 cm 

CCL (n=35) in bottom longlines based on available data throughout the Mediterranean. 

Artisanal longline fisheries also have the potential to take sea turtles. A survey of 54 small boat 

(4-10 meter length) artisanal fishermen in Cyprus and Turkey resulted in an estimated minimum 
153

bycatch of over 2,000 turtles per year, with an estimated 10% mortality rate (Godley et al. 

1998a). These small boats fished with a combination of longlines and trammel/gillnets. 

However, note that it is likely that a proportion (perhaps a large proportion) of the turtle bycatch 

estimated in this study are green turtles. 

Set net (gillnet) fisheries

As in other areas, sea turtles have the potential to interact with set nets (gillnets or trammel nets) 

in the Mediterranean. Mediterranean set nets refer to gillnets (a single layer of net) and trammel 

nets, which consist of three layers of net with different mesh size. Casale (2008) estimated that 

the countries with the highest number of loggerhead captures (in the thousands per year) are 

Tunisia, Libya, Greece, Turkey, Cyprus, and Croatia. Italy, Morocco, Egypt, and France likely 

have high capture rates as well. Available information suggests the annual number of 

loggerhead captures by Mediterranean set nets may be greater than 30,000 (Casale 2008). 

Due to the nature of the gear and fishing practices (e.g., relatively long soak times), incidental 

capture in gillnets is among the highest source of direct sea turtle mortality. An evaluation of 

turtles tagged then recaptured in gillnets along the Italian coast found 14 of 19 loggerheads 

(73.7%) to be dead (Argano et al. 1992). Gillnets off France were observed to capture six 

loggerheads with a 50% mortality rate (Laurent 1991). Six loggerheads were recovered in 

gillnets off Croatia between 1993 and 1996; 83% were found dead (Lazar et al. 2000). Off the 

Balearic Islands, 196 sea turtles were estimated to be captured in lobster trammel nets in 2001, 

with a CPUE of 0.17 turtles per vessel (Carreras et al. 2004). Mortality estimates for this 

artisanal lobster trammel net fishery ranged from 78 to 100%. Given this mortality rate and the 

number of turtles reported in lobster trammel nets, Carreras et al. (2004) estimate that a few 

thousand loggerhead turtles are killed annually by lobster trammel nets in the whole western 

Mediterranean. Considering data throughout the entire Mediterranean, as well as a conservative 

approach, Casale (2008) considered mortality by set nets to be 60%, with a resulting estimate of 

16,000 turtles killed per year. Most of these animals are likely juveniles; Casale (2008) 

evaluated available set net catch data throughout the Mediterranean and found an average size of 

45.4 cm CCL (n=74). 

As noted above, artisanal set net fisheries also may capture numerous sea turtles, as observed off 

Cyprus and Turkey (Godley et al. 1998a). 

Driftnet fisheries

Historically, driftnet fishing in the Mediterranean caught large numbers of sea turtles. An 

estimated 16,000 turtles were captured annually in the Ionian Sea driftnet fishery in the 1980s 

(De Metrio and Megalofonou 1988). The United Nations established a worldwide moratorium 

on driftnet fishing effective in 1992, but unregulated driftnetting continued to occur in the 

Mediterranean. For instance, a bycatch estimate of 236 loggerhead turtles was developed for the 

Spanish swordfish driftnet fishery in 1994 (Silvani et al. 1999). While the Spanish fleet curtailed 

activity in 1994, the Moroccan, Turkish, French, and Italian driftnet fleets continued to operate. 

Tudela et al. (2005) presented bycatch rates for driftnet fisheries in the Alboran Sea and off Italy. 

The Moroccan Alboran Sea driftnet fleet bycatch rate ranged from 0.21 to 0.78 loggerheads per 

haul, whereas the Italian driftnet fleet had a lower bycatch rate of 0.046 to 0.057 loggerheads per 

haul (Di Natale 1995, Camiñas 1997, Silvani et al. 1999). The use of driftnets in the 
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Mediterranean continues to be illegal: the General Fisheries Commission for the Mediterranean 

prohibited driftnet fishing in 1997; a total ban on driftnet fishing by the European Union fleet in 

the Mediterranean went into effect in 2002; and the International Commission for the 

Conservation of Atlantic Tunas (ICCAT) banned driftnets in 2003. Nevertheless, there are an 

estimated 600 illegal driftnet vessels operating in the Mediterranean, including fleets based in 

Algeria, France, Italy, Morocco, and Turkey (Environmental Justice Foundation 2007). In 

particular, the Moroccan fleet, operating in the Alboran Sea and Straits of Gibraltar, comprises 

the bulk of Mediterranean driftnetting, and has been found responsible for high bycatch, 

including loggerhead turtles (Environmental Justice Foundation 2007, Aksissou et al. in press). 

Driftnet fishing in the Mediterranean, and accompanying threats to loggerhead turtles, continues 

to occur. 

Trawl fisheries

Sea turtles are known to be incidentally captured in trawls in Albania, Algeria, Croatia, Egypt, 

France, Greece, Italy, Libya, Morocco, Slovenia, Spain, Tunisia, and Turkey (Gerosa and Casale 

1999, Camiñas 2004, Casale 2008). Laurent et al. (1996) estimated that approximately 10,000 to 

15,000 sea turtles (most of which are loggerheads) are captured by bottom trawling in the entire 

Mediterranean. More recently, Casale (2008) compiled available trawl bycatch data throughout 

the Mediterranean and reported that Italy and Tunisia have the highest level of sea turtle bycatch, 

potentially over 20,000 captures per year combined, and Croatia, Greece, Turkey, Egypt, and 

Libya each catch more than 2,000 turtles per year. Further, Spain and Albania may each capture 

a few hundred sea turtles per year (Casale 2008). Available data suggest the annual number of 

sea turtle captures by all Mediterranean trawlers may be greater than 40,000 (Casale 2008). Note 

that these are capture events and not necessarily individual turtles. 

Information from specific study areas of the Mediterranean provides additional insight into 

individual bycatch rates and details of the captures. Casale et al. (2004) estimated that 4,273 

loggerheads per year are caught by the Italian bottom trawl fishery in the western part of the 

northern Adriatic Sea, but as catch rates in the eastern part of the Adriatic Sea are higher than in 

the western, it is likely that actual total catch in the entire North Adriatic Sea is much higher. In 

southern Italy, off Lampedusa, Casale et al. (2007a) estimated an annual total catch of 1,016 for 

the vessels in the study port. However, the catch estimate increased to approximately 4,000 to 

11,000 turtles if trawlers from other ports fishing in the study area were considered. In the Gulf 

of Gabès, Tunisia, 5,458 loggerhead turtles per year were estimated to be captured by the trawl 

fishery (Jribi et al. 2007), while in Croatia, an annual incidental catch of 2,500 turtles was 

previously estimated based on fishermen interviews (Lazar and Tvrtkovic 1995). In Greece, 

total catch (presented as 95% confidence intervals) in 2000 was estimated at 0 to 418 turtles in 

the northern Aegean Sea and at 0 to 448 turtles in the Ionian Sea (Laurent et al. 2001). 

Although juveniles are incidentally captured in trawl gear in many areas of the Mediterranean 

(Casale et al. 2004, 2007a; Jribi et al. 2007), adult turtles are also found. In Egypt, 25% of 

loggerheads captured in bottom trawl gear (n=16) were ≥ 70 cm CCL, and in Tunisia, 26.2% 

(n=62) were of this larger size class (Laurent et al. 1996). Off Lampedusa Island, Italy, the 

average size of turtles caught by bottom trawlers was 51.8 cm CCL (range 22-87 cm CCL; 

n=368), and approximately 10% of the animals measured greater than 75 cm CCL (Casale et al. 

2007a). For all areas of the Mediterranean, Casale (2008) reported that medium to large turtles 

are generally caught by bottom trawl gear (mean 53.9 cm CCL; range 22-87 cm CCL; n=648). 
155

While there is a notable interaction rate in the Mediterranean, it appears that the mortality 

associated with trawling is relatively low. Incidents of mortality have ranged from 3.3% (n=60) 

in Tunisia (Jribi et al. 2007) and 3.3% (n=92) in France (Laurent 1991) to 9.4% (n=32) in Italy 

(Casale et al. 2004). Casale et al. (2004) found that mortality would be higher if all comatose 

turtles were assumed to die. It also should be noted that the mortality rate in trawls depends on 

the duration of the haul, with longer haul durations resulting in higher mortality rates (Henwood 

and Stuntz 1987, Sasso and Epperly 2006). Jribi et al. (2007) stated that the low recorded 

mortality in the Gulf of Gabès is likely due to the short haul durations in this area. Based on 

available information from multiple areas of the Mediterranean, and assuming that comatose 

animals die if released in that condition, the overall average mortality rate for bottom trawlers 

was estimated to be 20% (Casale 2008). This results in at least 7,400 turtles killed per year by 

bottom trawlers in all of the Mediterranean, but the number is likely more than 10,000 (Casale 

2008).

Bottom trawl fisheries are likely impacting the Mediterranean Sea DPS. Although in a previous 

assessment of bottom trawl fisheries sampled from Tunisia, Egypt, and Turkey, all loggerheads 

captured were from the Mediterranean nesting population (as opposed to Atlantic nesting 

animals; Laurent et al. 1998), a recent genetic study with a larger sample size found a minor but 

significant contribution from the Atlantic populations in the turtles foraging in the neritic habitats 

off Tunisia (Casale et al. 2008b). 

Mid-water trawling may have less total impact on sea turtles found in the Mediterranean than 

some other gear types, but interactions still occur. Casale et al. (2004) found that while no 

turtles were caught on observed mid-water trawl trips in the North Adriatic Sea, vessel captains 

reported 13 sea turtles captured from April to September. Considering total fishing effort, these 

reports resulted in a minimum total catch estimate of 161 turtles/year in the Italian mid-water 

trawl fishery. Off Turkey, 71 loggerheads were captured in mid-water trawls from 1995-1996, 

while 43 loggerheads were incidentally taken in bottom trawls (Oruç 2001). In this same study, 

of a total 320 turtles captured in mid-water trawls (loggerheads and greens combined), 95% were 

captured alive and apparently healthy. While the total catch numbers throughout the 

Mediterranean have not been estimated, mid-water trawl fisheries do present a threat to 

loggerhead sea turtles. 

Other gear types

Seine, dredge, trap/pot, and hook and line fisheries operate in Mediterranean waters and may 

affect loggerhead turtles, although incidental captures in these gear types are largely unknown 

(Camiñas 2004). Artisanal fisheries using a variety of gear types also have the potential for sea 

turtle takes, but the effects of most artisanal gear types on sea turtles have not been estimated. 

Other Manmade and Natural Impacts 

Other anthropogenic threats, such as interactions with recreational and commercial vessels, 

marine pollution, and intentional killing, also impact loggerheads found in the Mediterranean. 

Propeller and collision injuries from boats and ships are becoming more common in sea turtles, 

although it is unclear as to whether the events are increasing or just the reporting of the injuries. 

Speedboat impacts are of particular concern in areas of intense tourist activity, such as Greece 

and Turkey. Losses of nesting females from vessel collisions have been documented in 

Zakynthos and Crete in Greece (Camiñas 2004). In the Gulf of Naples, 28.1% of loggerheads 
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recovered from 1993-1996 had injuries attributed to boat strikes (Bentivegna and Paglialonga 

1998). Along the Greece coastline from 1997-1999, boat strikes were reported as a seasonal 

phenomenon in stranded turtles (Kopsida et al. 2002), but numbers were not presented. 

Direct or indirect disposal of anthropogenic debris introduces potentially lethal materials into 

loggerhead foraging habitats. Unattended or discarded nets, floating plastics and bags, and tar 

balls are of particular concern (Camiñas 2004, Margaritoulis 2007). Monofilament netting 

appears to be the most dangerous waste produced by the fishing industry (Camiñas 2004). In the 

Mediterranean, 20 out of 99 loggerhead turtles examined from Maltese fisheries were found 

contaminated with plastic or metal litter and hydrocarbons, with crude oil being the most 

common pollutant (Gramentz 1988). Of 54 juvenile loggerhead turtles incidentally caught by 

fisheries in Spanish Mediterranean waters, 79.6% had debris in their digestive tracts (Tomás et 

al. 2002). In this study, plastics were the most frequent type of marine debris observed (75.9%), 

followed by tar (25.9%). However, an examination of stranded sea turtles in Northern Cyprus 

and Turkey found that only 3 of 98 animals were affected by marine debris (Godley et al. 

1998b). 

Pollutant waste in the marine environment may impact loggerheads, likely more than other sea 

turtle species. Omnivorous loggerheads stranded in Cyprus, Greece, and Scotland had the 

highest organochlorine contaminant concentrations, as compared to green and leatherback turtles 

(Mckenzie et al. 1999). In northern Cyprus, Godley et al. (1999) found heavy metal 

concentrations (mercury, cadmium, and lead) to be higher in loggerheads than green turtles. 

Even so, concentrations of contaminants from sea turtles in Mediterranean waters were found to 

be comparable to other areas, generally with levels lower than concentrations shown to cause 

deleterious effects in other species (Godley et al. 1999, Mckenzie et al. 1999). However, lead 

concentrations in some Mediterranean loggerhead hatchlings were at levels known to cause toxic 

effects in other vertebrate groups (Godley et al. 1999). 

As in other areas of the world, intentional killing or injuring of sea turtles has been reported to 

occur in the Mediterranean. Of 524 strandings in Greece, it appeared that 23% had been 

intentionally killed or injured (Kopsida et al. 2002). While some turtles incidentally captured are 

used for consumption (as noted in Section 5.2.8.2 above), it has been reported that some 

fishermen kill the sea turtles they catch for a variety of other reasons, including non-commercial 

use, hostility, prejudice, recovery of hooks, and ignorance (Laurent et al. 1996, Godley et al. 

1998a, Gerosa and Casale 1999, Casale 2008). 

Natural environmental events also may affect loggerheads in the Mediterranean. Cyclonic 

storms that closely resemble tropical cyclones in satellite images occasionally form over the 

Mediterranean Sea (Emanuel 2005). While hurricanes typically do not occur in the 

Mediterranean, researchers have suggested that climate change could trigger hurricane 

development in this area in the future (Gaertner et al. 2007). Any significant storm event that 

may develop could disrupt loggerhead nesting activity and hatchling production, but the results 

are generally localized and rarely result in whole-scale losses over multiple nesting seasons. 

Similar to other areas of the world (see Section 5.1.5.), climate change and sea level rise have the 

potential to impact loggerheads in the Mediterranean. Over the long term, Mediterranean turtle 
157

populations could be threatened by the alteration of thermal sand characteristics (from global 

warming), resulting in the reduction or cessation of female hatchling production (Camiñas 2004). 

Further, a significant rise in sea level would restrict loggerhead nesting habitat in the eastern 

Mediterranean. 

5.2.9. South Atlantic Ocean DPS 

5.2.9.1. Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or 

Range 

Terrestrial Zone 

As described in Section 5.1.1., destruction and modification of loggerhead nesting habitat in the 

South Atlantic result from coastal development and construction, placement of erosion control 

structures and other barriers to nesting, beachfront lighting, vehicular and pedestrian traffic, sand 

extraction, beach erosion, beach sand placement, beach pollution, removal of native vegetation, 

and planting of non-native vegetation (D'Amato and Marczwski 1993; Marcovaldi and 

Marcovaldi 1999; Naro-Maciel et al. 1999; Marcovaldi et al. 2002, 2005; Marcovaldi 2007). 

The primary nesting areas for loggerheads in the South Atlantic are in the states of Sergipe, 

Bahia, Espírito Santo, and Rio de Janeiro in Brazil (Marcovaldi and Marcovaldi 1999). These 

primary nesting areas are monitored by Projeto TAMAR, the national sea turtle conservation 

program in Brazil. Since 1980, Projeto TAMAR has worked to establish legal protection for 

nesting beaches (Marcovaldi and Marcovaldi 1999). As such, human activities, including sand 

extraction, beach nourishment, seawall construction, beach driving, and artificial lighting, that 

can negatively impact sea turtle nesting habitat, as well as directly impact nesting turtles and 

their eggs and hatchlings during the reproductive season, are restricted by various state and 

federal laws (Marcovaldi and Marcovaldi 1999; Marcovaldi et al. 2002, 2005). Nevertheless, 

tourism development in coastal areas in Brazil is high, and Projeto TAMAR works toward 

raising awareness of turtles and their conservation needs through educational and informational 

activities at their Visitor Centers that are dispersed throughout the nesting areas (Marcovaldi et 

al. 2005). 

In terms of non-native vegetation, the majority of nesting beaches in northern Bahia, where 

loggerhead nesting density is highest in Brazil (Marcovaldi and Chaloupka 2007), have coconut 

plantations dating back to the 17th century backing them (Naro-Maciel et al. 1999). It is 

impossible to assess whether this structured habitat has resulted in long-term changes to the 

loggerhead nesting rookery in northern Bahia. 

Neritic/Oceanic Zone 

As described in Section 5.1.1., human activities that impact bottom habitat in the loggerhead 

neritic and oceanic zones include fishing practices, channel dredging, sand extraction, marine 

pollution, and climate change. These threats also occur in the South Atlantic Ocean (e.g., Ibe 

1996, Silva et al. 1997). General human activities have altered ocean ecosystems, as identified 

by ecosystem models (http://www.lme.noaa.gov). On the western side of the South Atlantic, the 

Brazil Current Large Marine Ecosystem (LME) region is characterized by the Global 

International Waters Assessment (GIWA) as suffering severe impacts in the areas of pollution, 
158

coastal habitat modification, and overexploitation of fish stocks (Marques et al. 2004). The 

Patagonian Shelf LME is moderately affected by pollution, habitat modification, and overfishing 

(Mugetti et al. 2004). On the eastern side of the South Atlantic, the Benguela Current LME has 

been characterized as moderately impacted in the area of overfishing, with future conditions 

expected to worsen by the GIWA (Prochazka et al. 2005). Climate change also may result in 

future trophic changes, thus impacting loggerhead prey abundance and/or distribution. 

5.2.9.2. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes 

Deliberate hunting of loggerheads for their meat, shells, and eggs is reduced from previous 

exploitation levels, but still exists. Limited numbers of eggs are taken for human consumption in 

Brazil, but the relative amount is considered minor when compared to historical rates of egg 

collection (Marcovaldi and Marcovaldi 1999, Marcovaldi et al. 2005, Almeida and Mendes 

2007). Use of sea turtles including loggerheads for medicinal purposes occasionally occurs in 

northeastern Brazil (Alves and Rosa 2006). Use of bycaught loggerheads for subsistence and 

medicinal purposes is likely to occur in southern Atlantic Africa, based on information from 

central West Africa (Fretey 2001, Fretey et al. 2007). 

5.2.9.3. Disease or Predation 

The potential effects of diseases and endoparasites, as described in Section 5.1.3., also exist for 

loggerheads found in the South Atlantic Ocean. There have been five confirmed cases of 

fibropapillomatosis in loggerheads in Brazil (Baptistotte 2007). There is no indication that this 

disease poses a major threat for this species in the eastern South Atlantic (Formia et al. 2007). 

Eggs and nests in Brazil experience depredation, primarily by foxes (Marcovaldi and Laurent 

1996). Nests laid by loggerheads in the southern Atlantic African coastline, if any, likely 

experience similar predation pressures to those on nests of other species laid in the same area 

(e.g., jackals depredate green turtle nests in Angola; Weir et al. 2007). 

Loggerheads in the South Atlantic also may be impacted by harmful algal blooms (Gilbert et al. 

2005). 

5.2.9.4. Inadequacy of Existing Regulatory Mechanisms 

Unless identified to a specific geographic area, the regulatory mechanisms described in Section 

5.1.4. also apply to sea turtles found in the South Atlantic Ocean. The following additional 

instruments also apply to loggerheads found in this area. 

Convention on the Conservation of Migratory Species of Wild Animals, Memorandum of 

Understanding Concerning Conservation Measures for Marine Turtles of the Atlantic Coast of 

Africa (Abidjan Memorandum)

For information about this instrument, see section 5.2.7.4. for the Northeast Atlantic Ocean DPS. 
159

The Convention for the Co-operation in the Protection and Development of the Marine and 

Coastal Environment of the West and Central African Region (Abidjan Convention)

For information about this instrument, see section 5.2.7.4. for the Northeast Atlantic Ocean DPS. 

South-East Atlantic Fisheries Organization (SEAFO) 

SEAFO manages fisheries activities in the Southeast Atlantic high seas area, excluding tunas and 

billfish. SEAFO adopted Resolution 01/06, “to Reduce Sea Turtle Mortality in Fishing 

Operations,” in 2006. The Resolution requires Members to: (1) implement the FAO Guidelines; 

and (2) establish on-board observer programs to collect information on sea turtle interactions in 

SEAFO-managed fisheries. This Resolution is not legally binding. Additional information is 

available at http://www.seafo.org. 

Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC) 

For information about this instrument, see section 5.2.1.4. for the North Pacific Ocean DPS. 

Nairobi Convention for the Protection, Management and Development of the Marine and 

Coastal Environment of the Eastern African Region 

For information about this instrument, see section 5.2.3.4. for the North Indian Ocean DPS. 

5.2.9.5. Other Natural or Manmade Factors Affecting Its Continued Existence 

Incidental Bycatch in Fishing Gear 

Incidental capture of sea turtles in artisanal and commercial fisheries is a significant threat to the 

survivability of loggerheads in the South Atlantic. Sea turtles may be caught in pelagic and 

demersal longlines, drift and set gillnets, bottom and mid-water trawling, fishing dredges, pound 

nets and weirs, haul and purse seines, pots and traps, and hook and line gear. In the western 

South Atlantic, there are various efforts aimed at mitigating bycatch of sea turtles in various 

fisheries. In Brazil, there is the National Action Plan to Reduce Incidental Capture of Sea 

Turtles in Fisheries, coordinated by Projeto TAMAR (Marcovaldi et al. 2006). This action plan 

focuses on both artisanal and commercial fisheries, and collects data directly from fishers as well 

as on-board observers. Although loggerheads have been observed as bycatch in all fishing gear 

and methods identified above, Marcovaldi et al. (2006) have identified longlining as the major 

source of incidental capture of loggerhead turtles. Reports of loggerhead bycatch by pelagic 

longlines come mostly from the southern portion of the Brazilian Exclusive Economic Zone, 

between 20o

S and 35oS. Bugoni et al. (2008) reported a loggerhead bycatch rate of 0.52 juvenile 

turtles/1000 hooks by surface longlines targeting dolphinfish. Pinedo et al. (2004) reported 

seasonal variation in bycatch of juvenile loggerheads (and other sea turtle species) by pelagic 

longlines in the same region of Brazil, with the highest rates (1.85 turtles/1000 hooks) in the 

austral spring. Kotas et al. (2004) reported the highest rates of loggerhead bycatch (>10 

turtles/1000 hooks) by pelagic longlines in the austral summer/fall months. A study based on 

several years found that the highest rate of loggerhead bycatch in pelagic longlines off of 

Uruguay and Brazil was in the late austral summer month of February: 2.72 turtles/1000 hooks 

(López-Medilaharsu et al. 2007). Sales et al. (2004) reported a loggerhead bycatch rate of 

0.87/1000 hooks near the Rio Grande Elevação do Rio Grande, about 600 nm off the coast of 

southern Brazil. In Uruguayan waters, the primary fisheries with loggerhead bycatch are bottom 

trawlers and longlines (Domingo et al. 2006). Domingo et al. (2008) reported bycatch rates of 
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loggerheads of 0.9-1.3/1000 hooks by longline deployed south of 30°S. In waters off Argentina, 

bottom trawlers also catch some loggerheads (Domingo et al. 2006). 

In the eastern South Atlantic, sea turtle bycatch in fisheries has been documented from Gabon to 

South Africa (Fretey 2001). Limited data are available on bycatch of loggerheads in coastal 

fisheries, although loggerheads are known (or strongly suspected) to occur in coastal waters from 

Gabon to South Africa (Fretey 2001, Bal et al. 2007, Weir et al. 2007). Coastal fisheries 

implicated in bycatch of loggerheads and other turtles include gillnets, beach seines, and trawlers 

(Bal et al. 2007). 

In the high seas, longlines are used by fishing boats targeting tuna and swordfish in the eastern 

South Atlantic. A recent study by Honig et al. (2008) estimates 7,600-120,000 sea turtles are 

incidentally captured by commercial longlines fishing in the Benguela Current LME; 60% of 

these are loggerheads. Petersen et al. 2007, 2009) report that the rate of loggerhead bycatch in 

South African longliners was around 0.02 turtles/1000 hooks, largely in the Benguela Current 

LME. In the middle of the South Atlantic, loggerhead bycatch by longlines was reported to be 

low, relative to other regions in the Atlantic (Mejuto et al 2008). 

Other Manmade and Natural Impacts 

As described in Section 5.1.5., other anthropogenic impacts, such as boat strikes and ingestion or 

entanglement in marine debris, also apply to loggerheads in the South Atlantic. Bugoni et al. 

(2001) have suggested the ingestion of plastic and oil may contribute to loggerhead mortality on 

the southern coast of Brazil. Plastic marine debris in the eastern South Atlantic also may pose a 

problem for loggerheads and other sea turtles (Ryan 1996). Similar to other areas of the world 

(see Section 5.1.5.), climate change and sea level rise have the potential to impact loggerheads in 

the South Atlantic. 

Oil reserve exploration and extraction activities also may pose a threat for sea turtles in the South 

Atlantic. Seismic surveys in Brazil and Angola have recorded sea turtle occurrences near the 

seismic work (Gurjão et al. 2005, Weir et al. 2007). While no sea turtle takes were directly 

observed on these surveys, increased equipment and presence in the water that is associated with 

these activities also increases the likelihood of sea turtle interactions (Weir et al. 2007). 

Natural environmental events may affect loggerheads in the South Atlantic. However, while a 

rare hurricane hit Brazil in March 2004, typically hurricanes do not occur in the South Atlantic 

(McTaggart-Cowan et al. 2006). This is generally due to higher windspeeds aloft, preventing the 

storms from gaining height and therefore strength.
161

SECTION 6—CONCLUSIONS—SYNTHESIS & INTEGRATION 

6.1. North Pacific Ocean DPS 

We used two approaches to compute extinction risk for the North Pacific Ocean DPS: (1) 

computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based deterministic 

model to determine negative effects of known threats to the DPS. Based on nest count data for 

nearly the past two decades, the North Pacific population of loggerheads is small. The SQE 

approach suggested that the North Pacific Ocean DPS appears to be declining, is at risk, and is 

thus likely to decline in the foreseeable future. These results are based on nesting beach census 

data from 33 nesting beaches in Japan over a 17-year period (in Snover 2008). We note that the 

SQE approach we used is based on past performance of the DPS (nesting data) and does not fully 

reflect ongoing and future threats to all life stages within the DPS. The stage-based deterministic 

modeling approach used a hypothetical population that was at its maximum population growth 

rate and computed the population growth potential under known or suspected threats to different 

life stages of the North Pacific Ocean DPS. This approach provided a range of results: in the 

case of the lowest anthropogenic mortality rates (or the best case scenario), the deterministic 

model suggests that the North Pacific Ocean DPS would grow slightly, but in the worst-case 

scenario, the model indicates that the population would be likely to substantially decline in the 

foreseeable future. These results are largely driven by the mortality of juvenile and adult 

loggerheads from fishery bycatch that occurs throughout the North Pacific Ocean, including the 

coastal pound net fisheries off Japan, coastal fisheries impacting juvenile foraging populations 

off Baja California, Mexico, and undescribed fisheries likely affecting loggerheads in the South 

China Sea and the North Pacific Ocean. Although national and international governmental and 

non-governmental entities on both sides of the North Pacific are currently working toward 

reducing loggerhead bycatch, and some positive actions have been implemented, it is unlikely 

that this source of mortality can be sufficiently reduced in the near future due to the challenges of 

mitigating illegal, unregulated, and unreported fisheries, the lack of comprehensive information 

on fishing distribution and effort, limitations on implementing demonstrated effective 

conservation measures, geopolitical complexities, limitations on enforcement capacity, and 

availability of comprehensive bycatch reduction technologies. In addition to fishery bycatch, 

coastal development and coastal armoring on nesting beaches in Japan continues as a substantial 

threat. Coastal armoring, if left unaddressed, will become an even more substantial threat as sea 

level rises. Therefore, the BRT concluded that the North Pacific Ocean DPS is currently at risk 

of extinction. 

6.2. South Pacific Ocean DPS 

We used two approaches to compute extinction risk for the South Pacific Ocean DPS: (1) 

computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based deterministic 

model to determine negative effects of known threats to the DPS. The SQE approach suggested 

that, based on nest count data for the past three decades, the population is at risk and thus likely 

to decline in the foreseeable future. These results are based on recently published nesting census 

data for loggerheads at index beaches in eastern Australia (Limpus 2009). The stage-based 

deterministic modeling approach used a hypothetical population that was at its maximum 

population growth rate and computed the population growth potential under known or suspected 
162

threats to different life stages of the South Pacific Ocean DPS. This approach provided a wide 

range of results: in the case of the lowest anthropogenic mortality rates (or the best case 

scenario), the deterministic model suggests that the South Pacific Ocean DPS will grow slightly, 

but in the worst-case scenario, the model indicates that the population is likely to substantially 

decline in the foreseeable future. These results are largely driven by mortality of juvenile and 

adult loggerheads from fishery bycatch that occurs throughout the South Pacific Ocean. 

Although national and international governmental and non-governmental entities on both sides 

of the South Pacific are currently working toward reducing loggerhead bycatch, and some 

positive actions have been implemented, it is unlikely that this source of mortality can be 

sufficiently reduced in the near future due to the challenges of mitigating illegal, unregulated, 

and unreported fisheries, the continued expansion of artisanal fleets in the southeastern Pacific, 

the lack of comprehensive information on fishing distribution and effort, limitations on 

implementing demonstrated effective conservation measures, geopolitical complexities, 

limitations on enforcement capacity, and availability of comprehensive bycatch reduction 

technologies. Therefore, the BRT concluded that the South Pacific Ocean DPS is currently at 

risk of extinction. 

6.3. North Indian Ocean DPS 

Two approaches to computing extinction risk for the North Indian Ocean DPS were considered: 

(1) computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based deterministic 

model to determine negative effects of known threats to the DPS. The SQE approach is based on 

nesting data; however, an adequate time series of nesting data for this DPS was not available to 

the BRT. Therefore, we could not use this approach to evaluate extinction risk. The stage-based 

deterministic modeling approach used a hypothetical population that was at its maximum 

population growth rate and computed the population growth potential under known or suspected 

threats to different life stages of the North Indian Ocean DPS. The model indicated the North 

Indian Ocean DPS is likely to decline in the foreseeable future. These results are driven by 

cumulative mortality from a variety of sources across all life stages. Threats to nesting beaches 

are likely to increase, which would require additional and widespread nesting beach protection 

efforts. Little is currently being done to monitor and reduce mortality from neritic and oceanic 

fisheries in the range of the North Indian Ocean DPS; this mortality is likely to continue and 

increase with expected additional fishing effort from commercial and artisanal fisheries. 

Reduction of mortality would be difficult due to a lack of comprehensive information on fishing 

distribution and effort, limitations on implementing demonstrated effective conservation 

measures, geopolitical complexities, limitations on enforcement capacity, and availability of 

comprehensive bycatch reduction technologies. Therefore, the BRT concluded that the North 

Indian Ocean DPS is currently at risk of extinction. 

6.4. Southeast Indo-Pacific Ocean DPS 

Two approaches to computing extinction risk for the Southeast Indo-Pacific Ocean DPS were 

considered: (1) computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based 

deterministic model to determine negative effects of known threats to the DPS. The SQE 

approach is based on nesting data; however, an adequate time series of nesting data for this DPS 

was not available to the BRT; therefore, we could not use this approach to evaluate extinction 
163

risk. The stage-based deterministic modeling approach used a hypothetical population that was 

at its maximum population growth rate and computed the population growth potential under 

known or suspected threats to different life stages of the Southeast Indo-Pacific Ocean DPS. 

This approach provided a wide range of results: in the case of the lowest anthropogenic 

mortality rates, the deterministic model suggests that the South Pacific Ocean DPS will grow 

slightly, but in the worst-case scenario, the model indicates that the population is likely to 

substantially decline in the foreseeable future. These results are largely driven by mortality of 

juvenile and adult loggerheads from fishery bycatch that occurs throughout the region, as can be 

inferred from data from Australia’s Pacific waters. Although national and international 

governmental and non-governmental entities are currently working toward reducing loggerhead 

bycatch, and some positive actions have been implemented, it is unlikely that this source of 

mortality can be sufficiently reduced in the near future due to the challenges of mitigating illegal, 

unregulated, and unreported fisheries, the continued expansion of artisanal fleets, the lack of 

comprehensive information on fishing distribution and effort, limitations on implementing 

demonstrated effective conservation measures, geopolitical complexities, limitations on 

enforcement capacity, and availability of comprehensive bycatch reduction technologies. 

Therefore, the BRT concluded that the Southeast Indo-Pacific Ocean DPS is currently at risk of 

extinction. 

6.5. Southwest Indian Ocean DPS 

Two approaches to computing extinction risk for the Southwest Indian Ocean DPS were 

considered: (1) computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based 

deterministic model to determine negative effects of known threats to the DPS. These two 

approaches provided different, although not incompatible, results for the Southwest Indian 

Ocean DPS. The SQE approach, based on a 37-year time series of nesting female counts at 

Tongaland, South Africa (1963-1999), indicated this segment of the population, while small, has 

increased, and the likelihood of quasi-extinction is negligible. We note that the SQE approach 

we used is based on past performance of the DPS (nesting data from 1963-1999) and does not 

fully reflect ongoing and future threats to all life stages within the DPS. The stage-based 

deterministic modeling approach used a hypothetical population that was at its maximum 

population growth rate and computed the population growth potential under known or suspected 

threats to different life stages of the Southwest Indian Ocean DPS. This approach provided a 

wide range of results: in the case of the lowest anthropogenic mortality rates, the deterministic 

model suggests that the South Pacific Ocean DPS will grow slightly, but in the worst-case 

scenario, the model indicates that the population is likely to substantially decline in the 

foreseeable future. These results are largely driven by mortality of juvenile loggerheads from 

fishery bycatch that occurs throughout the Southwest Indian Ocean. This mortality is likely to 

continue and may increase with expected additional fishing effort from commercial and artisanal 

fisheries. Reduction of mortality would be difficult due to a lack of comprehensive information 

on fishing distribution and effort, limitations on implementing demonstrated effective 

conservation measures, geopolitical complexities, limitations on enforcement capacity, and 

availability of comprehensive bycatch reduction technologies. Therefore, the BRT concluded 

that although the Southwest Indian Ocean DPS is likely not currently at immediate risk of 

extinction, the extinction risk is likely to increase in the foreseeable future. 
164

6.6. Northwest Atlantic Ocean DPS 

We used two approaches to compute extinction risk for the Northwest Atlantic Ocean DPS: (1) 

computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based deterministic 

model to determine negative effects of known threats to the DPS. The SQE approach suggested 

that, based on nest count data for the past two decades, the population is at risk and thus likely to 

decline in the foreseeable future. These results are based on nesting data for loggerheads at 

index/standardized nesting survey beaches in the USA and the Yucatan Peninsula, Mexico 

(NMFS and FWS 2008). The stage-based deterministic modeling approach used a hypothetical 

population that was at its maximum population growth rate and computed the population growth 

potential under known or suspected threats to different life stages of the Northwest Atlantic 

Ocean DPS. This approach indicated the Northwest Atlantic Ocean DPS is likely to decline in 

the foreseeable future, even under the scenario of the lowest anthropogenic mortality rates. 

These results are largely driven by mortality of juvenile and adult loggerheads from fishery 

bycatch that occurs throughout the North Atlantic Ocean. Although national and international 

governmental and non-governmental entities on both sides of the North Atlantic are currently 

working toward reducing loggerhead bycatch, and some positive actions have been implemented, 

it is unlikely that this source of mortality can be sufficiently reduced across the range of the DPS 

in the near future because of the diversity and magnitude of the fisheries operating in the North 

Atlantic, the lack of comprehensive information on fishing distribution and effort, limitations on 

implementing demonstrated effective conservation measures, geopolitical complexities, 

limitations on enforcement capacity, and availability of comprehensive bycatch reduction 

technologies. Therefore, the BRT concluded that the Northwest Atlantic Ocean DPS is currently 

at risk of extinction.

6.7. Northeast Atlantic Ocean DPS 

Two approaches to computing extinction risk for the Northeast Atlantic Ocean DPS were 

considered: (1) computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based 

deterministic model to determine negative effects of known threats to the DPS. The SQE 

approach is based on nesting data. However, we had insufficient nest count data over an 

appropriate time series for this DPS and could not use this approach to evaluate extinction risk. 

The stage-based deterministic modeling approach used a hypothetical population that was at its 

maximum population growth rate and computed the population growth potential under known or 

suspected threats to different life stages of the Northeast Atlantic Ocean DPS. The model 

indicated the Northeast Atlantic Ocean DPS is likely to decline in the foreseeable future, even 

under the scenario of the lowest anthropogenic mortality rates. These results are largely driven 

by the ongoing directed lethal take of nesting females, low hatching and emergence success, and 

mortality of juveniles and adults from fishery bycatch that occurs throughout the Northeast 

Atlantic Ocean. Currently, conservation efforts to protect nesting females are growing, and a 

reduction in this source of mortality is likely to continue in the near future. Although national 

and international governmental and non-governmental entities in the Northeast Atlantic are 

currently working toward reducing loggerhead bycatch, and some positive actions have been 

implemented, it is unlikely that this source of mortality can be sufficiently reduced across the 

range of the DPS in the near future because of the lack of bycatch reduction in high seas fisheries 

operating within the range of this DPS, lack of bycatch reduction in coastal fisheries in Africa, 
165

the lack of comprehensive information on fishing distribution and effort, limitations on 

implementing demonstrated effective conservation measures, geopolitical complexities, 

limitations on enforcement capacity, and availability of comprehensive bycatch reduction 

technologies. Therefore, the BRT concluded that the Northeast Atlantic Ocean DPS is at 

immediate risk of extinction.

6.8. Mediterranean Sea DPS 

Two approaches to computing extinction risk for the Mediterranean Sea DPS were considered: 

(1) computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based deterministic 

model to determine negative effects of known threats to the DPS. The SQE approach is based on 

nesting data; however, region-wide nesting data for this DPS were not available to the BRT. 

Therefore, we could not use this approach to evaluate extinction risk. The stage-based 

deterministic modeling approach used a hypothetical population that was at its maximum 

population growth rate and computed the population growth potential under known or suspected 

threats to different life stages of the Mediterranean Sea DPS. The model indicated the 

Mediterranean Sea DPS is likely to decline in the foreseeable future, even under the scenario of 

the lowest anthropogenic mortality rates. These results are largely driven by mortality of 

juvenile and adult loggerheads from fishery bycatch that occurs throughout the Mediterranean 

Sea, as well as anthropogenic threats to nesting beaches and eggs/hatchlings. Although 

conservation efforts to protect some nesting beaches are underway, more widespread and 

consistent protection is needed. Although national and international governmental and nongovernmental entities in the Mediterranean Sea are currently working toward reducing 

loggerhead bycatch, it is unlikely that this source of mortality can be sufficiently reduced across 

the range of the DPS in the near future because of the lack of bycatch reduction in commercial 

and artisanal fisheries operating within the range of this DPS, the lack of comprehensive 

information on fishing distribution and effort, limitations on implementing demonstrated 

effective conservation measures, geopolitical complexities, limitations on enforcement capacity, 

and availability of comprehensive bycatch reduction technologies. Therefore, the BRT 

concluded that the Mediterranean Sea DPS is at immediate risk of extinction. 

6.9. South Atlantic Ocean DPS 

We used two approaches to compute extinction risk for the South Atlantic Ocean DPS: (1) 

computation of susceptibility to quasi-extinction (SQE), and (2) a stage-based deterministic 

model to determine negative effects of known threats to the DPS. These two approaches 

provided different, although not incompatible, results for the South Atlantic Ocean DPS. The 

SQE approach suggested that, based on nest count data for the past two decades, the population 

is unlikely to decline in the foreseeable future. These results are consistent with Marcovaldi and 

Chaloupka’s (2007) nesting beach trend analyses. We note that the SQE approach is based on 

past performance of the DPS (nesting data) and does not fully reflect ongoing and future threats 

to all life stages within the DPS. The stage-based deterministic modeling approach used a 

hypothetical population that was at its maximum population growth rate and computed the 

population growth potential under known or suspected threats to different life stages of the South 

Atlantic Ocean DPS. This approach indicated the South Atlantic Ocean DPS is likely to decline 

in the foreseeable future, even under the scenario of the lowest anthropogenic mortality rates. 
166

This result is largely driven by mortality of juvenile loggerheads from fishery bycatch that occurs 

throughout the South Atlantic Ocean. Although national and international governmental and 

non-governmental entities on both sides of the North Atlantic are currently working toward 

reducing loggerhead bycatch in the South Atlantic, it is unlikely that this source of mortality can 

be sufficiently reduced across the range of the DPS in the near future because of the diversity 

and magnitude of the commercial and artisanal fisheries operating in the South Atlantic, the lack 

of comprehensive information on fishing distribution and effort, limitations on implementing 

demonstrated effective conservation measures, geopolitical complexities, limitations on 

enforcement capacity, and availability of comprehensive bycatch reduction technologies. 

Therefore, the BRT concluded that although the South Atlantic Ocean DPS is not currently at 

immediate risk of extinction, the extinction risk is likely to increase substantially in the 

foreseeable future. 
167

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