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Full text of "Five-year status reviews of sea turtles listed under the Endangered Species Act of 1973 / prepared by Andreas Mager, Jr"

Five-year Status Reviews 
of Sea Turtles Listed Under 
the Endangered Species 
Act of 1 973 



January 1985 




<*>* OFc °, 






U.S. DEPARTMENT OF COMMERCE 
National Oceanic and Atmospheric Administration 

S ^H^ National Marine Fisheries Service 



Digitized by the Internet Archive 

in 2012 with funding from 

LYRASIS Members and Sloan Foundation 



http://www.archive.org/details/fiveyearstatusreOOmage 



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r/ Wf NT Of 



Five-year Status Reviews of 
Sea Turtles Listed Under 
the Endangered Species 
Act of 1 973 



Prepared by Andreas Mager, Jr. 
National Marine Fisheries Service 
Protected Species Management Branch 
Duval Building, 9450 Kroger Boulevard 
St. Petersburg, Florida 33702 

January 1985 



■ 

r 






U.S. DEPARTMENT OF COMMERCE 

Malcolm Baldrige, Secretary 

National Oceanic and Atmospheric Administration 

Anthony J. Calio, Acting Administrator 

National Marine Fisheries Service 

William G. Gordon, Assistant Administrator for Fisheries 
Jack T. Brawner, Southeast Regional Director 



CONTENTS 

Introduction 1 

Acknowledgements 3 

STATUS REVIEWS 

Green Sea Turtle 4 

Hawksbill Sea Turtle 21 

Loggerhead Sea Turtle 35 

Kemp's Ridley Sea Turtle , 46 

Olive Ridley Sea Turtle 56 

Leatherback Sea Turtle 70 

Literature Cited 82 



i i 



INTRODUCTION 

Section 4 of the Endangered Species Act requires the 
National Marine Fisheries Service (NMFS), an agency of the 
Department of Commerce, and the Fish and Wildlife Service 
(FWS), an agency of the Department of the Interior, to review 
the status of listed species at least once every five 
years. The Services use these status reviews to determine 
whether a designation as threatened or endangered accurately 
reflects the current status of a listed species. If the 
status of the species has either improved or deteriorated, 
appropriate action will be taken to ensure that the species 
is listed accurately. 

Information published between 1978 and 1984 is 
summarized in this review by NMFS, and an assessment is made 
of the current status of the populations of sea turtles that 
are listed pursuant to the Endangered Species Act of 1973 
(ESA). The leatherback sea turtle ( Dermochelys coriacea ) and 
hawksbill sea turtle ( Ere tmochelys imbricat a ) were listed as 
endangered throughout their range on June 2, 1970. The 
population of Kemp's ridley ( Lep idochelys kempi ) was listed 
as endangered on December 2, 1970. The green sea turtle 
( Chelonia mydas ) was listed on July 28, 1978, as threatened 
except for the breeding populations of Florida and the 
Pacific coast of Mexico which are listed as endangered. At 
the same time, the olive ridley ( Lepidochelys olivacea ) was 
listed as threatened, except for the breeding populations of 
the Pacific coast of Mexico which are listed as endangered. 
On July 28, 1978, the loggerhead sea turtle ( Caretta caretta ) 
was listed as threatened wherever it occurs. These sea 
turtles were listed because, to varying degrees, their 
populations had declined as the result of human activities. 
Many of their nesting beaches had been destroyed by 
encroachment of the human population into coastal habitats. 
Sea turtle populations had been reduced by uncontrolled 
harvesting for commercial purposes and by mortality 
incidental to activities such as commercial fishing. In many 



ij. 5. 



cases, existing regulatory mechanisms were not providing 
sufficient encouragement for conservation. 

To prepare this document, the National Marine Fisheries 
Service reviewed a considerable amount of literature 
published between 1978 and 1984. However, our knowledge of 
the status of the various sea turtle populations has 
increased very little since 1978. 

Descriptions of the status of all sea turtle populations 
in the Atlantic, Pacific, and Indian Oceans are presented by 
species. The terms population and stock are generally used 
to define a group of sea turtles nesting within the 
boundaries of a given political entity rather than biological 
stocks. The breeding biology and taxonomy of most sea turtle 
stocks have not been sufficiently investigated to define 
distinct breeding populations or stocks. Tagging studies 
demonstrate that green, olive ridley, Kemp's ridley, and 
loggerhead sea turtles return to their natal beaches to breed 
and nest. If breeding is restricted to near these nesting 
beaches and male sea turtles return with the females, then a 
mechanism for genetic isolation exists and each nesting 
population could be considered a distinct stock for 
management purposes. Leatherback sea turtles are not such 
strict remigrators and may change nesting beaches. The 
breeding biology and migration patterns of hawksbill turtles 
are not well documented, largely because of the diffuse 
nesting habitats of other species. Consequently, mechanisms 
for stock di f f erenta t ion may be different or nonexistent for 
leatherback and hawksbill sea turtles. Until a thorough 
systematic study is completed to define biological stocks, 
the Services will continue to divide populations of sea 
turtles along political boundaries. 

The ESA requires the consideration of five factors in 
determining whether a population, stock, or higher taxon 
qualifies for listing on either the threatened or endangered 
species lists. This review re-evaluates these factors to 
determine if information developed over the last five years 
continues to support the designation of each sea turtle 
population as threatened or endangered. The Assistant 
Administrator for Fisheries has agreed with the conclusions 
and recommendations reached in this report that no changes 
should be made concerning the listing of sea turtles except 
to list the nesting populations of olive ridleys as 
endangered rather than threatened in the Western North 
Atlantic (Surinam and adjacent areas). 



ACKNOWLEDGEMENTS 



This opportunity is taken to thank the many people 
involved in providing information and constructive comments 
on the status reviews. Specific thanks go to George Balazs, 
Dr. Kenneth Dodd, Dr. Charles Karnella, James Lecky, 
William N. Lindall, Margaret Lorenz, Gene Nitta, Larry Ogren, 
Charles A. Oravetz, Dr. Peter Pritchard, Dr. Nancy Thompson, 
and Wayne Witzell. Secretarial assistance was provided by 
Carol B. Fowler, Cecelia Quinn, and Brenda MCCloud. 



GREEN SEA TURTLE 



C€h«lonl« nytful 






Green Sea Turtle 
( Chelonia my das ) 

Biological Background 

Although there is insufficient taxonomic information to 
distinguish between stocks, there may be geographically and 
genetically distinct populations of the green sea turtle. 
Replacement of extinct populations by transplanting 
individuals from another population has not succeeded, and, 
even if it were to succeed, the animals would be biologically 
different (Ehrenfeld 1982). Although the treatment of the 
species as a single stock may be ill-advised, because of its 
worldwide distribution, the lack of data indicating discrete 
stocks, and the difficulties in distinguishing separate 
stocks, populations and subspecies, the species is 
necessarily considered a single stock in the Indo-Pacific 
region and a single stock in the Atlantic Ocean and adjacent 
seas for puposes of this review. 

In various parts of its range, the green sea turtle also 
may be called tortuga verde, greenback turtle, edible turtle, 
soup turtle, tortue verte, tortuga blanca, tartaruga verde, 
aruana and krape (Pritchard et al . , 1983). It is 
distinguishable from other sea turtles by its four large 
plates on each side of its upper shell and one pair of 
prefrontal scales (scales found on the head between the nasal 
opening and eye socket); shell plates that do not overlap; 
and paddle shaped limbs that normally have only one claw 
(Carr, 1952). The color of the shell in most adult green sea 
turtles is highly variable, but background color may be light 
to dark brown, green, buff, black, or olive (Pritchard, 
1979). The underside is usually white to pale yellow 
(Pritchard, 1979). 

Size, weight, and shell shape probably vary between 
turtles from different parts of the world. Using Hirth's 



(1971) classifications, hatchlings are identified by 
conspicuous umbilical scars; juveniles by a carapace length 
up to 16 inches; sub-adults by a length of 16 to 32 inches; 
and adults by a length greater than 32 inches. The typical 
adult has an average shell length of about 40 inches and 
weighs between 300-350 pounds ( Groombr idge , 1982). Very 
large individuals have been observed with shell lengths of 
over five feet and weights of 850 pounds (Rebel, 1974). 
There is no sexual-dimorphism in subadult male or female 
turtles; however, adult males have long tails that reach well 
beyond the rear edge of the shell, while adult females have 
shorter tails that barely reach beyond the rear edge (Hirth, 
1971). Green sea turtles are believed to be long lived (20 
years or longer), but longevity in the wild is unknown 
(Hirth, 1971). Estimates of age at sexual maturity range 
from 4 to 59 years depending on the locale (Hirth, 1971; 
Balazs, 1980; Owens, 1980). Length at sexual maturity is 
about 35 inches. 

Green sea turtles are primarily herbivores that eat sea 
grasses and algae. Other organisms living on sea grass 
blades and algae add to the diet. Predators of adult turtles 
include man, killer whales, and sharks (Bacon et al . , 
1984). Eggs are eaten by man, raccoons, coatimundi, dogs, 
pigs, foxes, peccary, lizards, rats, crabs, and birds (Hirth, 
1971). Hatchlings are eaten by dogs, hogs, rats, mongoose, 
cats, lizards, snakes, jackfish, kingfish, snook, barracuda, 
groupers, rock cod, and sharks (Hirth, 1971). The loss of 
eggs and hatchings to predation is assumed to be very high. 
Only one to three percent of the hatchlings reach sexual 
maturity and only about 50 percent of the eggs hatch (Hirth, 
1971). 

Shallow water areas such as shoals and lagoons vegetated 
with sea grasses and algae are preferred habitat. Inlets, 
bays, and estuaries containing abundant submerged vegetation 
are also used. Green sea turtles nest in all subtropical to 
tropical oceans of the world within 35° north and south 
latitude (Figure 1) in waters that remain above 20°C in the 
coldest months (Rebel, 19 74; Groombr idge, 19 82). 

In the Atlantic Ocean and adjacent seas, they roam from 
Massachusetts southward to Florida and throughout the Gulf of 
Mexico and the Caribbean Sea (Rebel, 1974). They occur off 
Mexico and off South America to the Argentine coast at Mar de 
la Plata and Necochea (Carr, 1952). The green sea turtle 
rarely is encountered in European Atlantic waters 
(Brongersma, 1982). Only two specimens are reported; one 






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from Petten, the Netherlands and one from the Ria de Arosa, 
northwest Spain. In Macaronesian waters, it is known from 
only a few records from the Azores and in Madeira. In west 
African waters, it is reported from Morocco, Mauritania, Cape 
Verde Islands, Senegal, Sierra Leone, Liberia, Ghana, Togo, 
Fernando Poo, Sao Thome, Ilha do Principe, Congo, Zaire, 
Angola, Bahia dos Tigres, southwest Africa, Sal Island, 
Boavista Island, Maio Island, Fogo Island, and Sao Tiago 
Island (Brongersma, 1982). They also occur in the 
Mediterranean and Aegean Seas (Sella, 1982; Geldiay et al ., 
1982). 

Green sea turtles are also widely distributed in the 
Pacific and Indian Oceans. Along the eastern Pacific, 
records are available from British Columbia to Chiloe, 
Chile. They are distributed throughout the Central Pacific 
and Indian Ocean, and, in the western Pacific, are found from 
Japan, China, and Kaia in the north to the Kermadec Islands 
and New Zealand in the south. 

The nesting season varies with location. Nesting is 
reported between May and August at the Yucatan Peninsula; 
between April and August in the West Indies; from September 
to January off the coast of West Africa; between July and 
September at Senegal; November to February at Fernando Poo 
(Hirth, 1971), and between May and November in Florida. 
Nesting was observed between May and September in the 
Mediterranean Sea (Geldi ay et at . , 1982). In the Pacific and 
Indian Ocean, nesting has been reported between July and 
December in Chiapas, Mexico; December to March at the 
Galapagos Islands; August and September at Rose Atoll; 
October to December at French Polynesia; November to February 
at the Tonga Islands; December and January at New Caledonia; 
February to August at Mazivi Island, Tanzania; January to 
March at the Seychelles Islands; June and July at Jurayd 
Island in the Persian Gulf; and in June at Masira Island, 
Oman (Hirth, 1971). 

Most females nesting on a given beach are never seen 
again (Hughes, 1981). The ones that do return to nest do not 
return at a universal interval; however, returns to nest have 
been observed in two, three, or four year cycles (Carr et 
al . , 1978). The females deposit between three and seven 
clutches per season at about 10 to 18 day intervals. Average 
clutch sizes vary between 81 and 147 eggs that hatch usually 
within 48-72 days (Hirth, 1971; Groombridge, 1982). 
Hatchlings emerge, mostly at night, travel quickly to the 
water, and swim out to sea in what is called a "swimming 



frenzy". At this point, they enter their "lost year" period 
before they begin diving behavior. This period may be spent 
in areas where currents concentrate debris and floating 
vegetation such as sargassum (Groombr idge , 1982). 

Since the breeding and nesting grounds are often 
separated by long distances from the foraging area, long 
distance migrations are required between these sites. 



Population Size 

Table 1 includes the information available on the green 
sea turtle. This information is obtained mainly from Bacon 
(1981), Balazs (1982), Bjorndal (1982), Carr et _d. (1982), 
Groombr idge (1982), Bacon et al . (1984) and others. 

The number of green sea turtles that existed before 
commercial exploitation and the total number that now exists 
are not known. Therefore, information on the decline of 
these turtles is based on nesting females (since sex ratios 
have not yet been determined, the number of males that exists 
cannot be determined). The decline and elimination of many 
nesting beaches and the less frequent encounters with green 
turtles in the wild provide inferential evidence that stocks 
are generally declining. 

Although the species probably has always been an 
important source of protein for coastal dwellers, the 
commercial exploitation during the 16th and 18th centuries 
decimated the stocks. Lund (1973) estimated that the 
Caribbean stocks during the era of Spanish exploration may 
have been 50 million turtles. By the 1940's, the commercial 
demand for green sea turtles dropped to a minimum based on 
declines of wild populations. However, renewed interest and 
exploitation which began soon after was based on the demand 
for gourmet foods, cosmetics, leather, flesh, calipee, oil 
and skin. This renewed exploitation was curbed in the 
United States when the species was listed pursuant to the 
Endangered Species Act. Ehrenfeld (1974) later estimated 
that the world population of sexually mature green sea 
turtles in the 1970s number only between 100,000 and 400,000 
males and females. Greater detail on the status of the 
stocks prior to this review can be found in the Final 
Environmental Impact Statement on Listing and Protecting the 
Green Sea Turtle (Anonymous, 1978). 



Table 1. Population information, population trends and 

exploitation of the green sea turtle ( Chelonia mydas ) 



ATLANTIC OCEAN AND ADJACENT SEAS 





Location 


Population Information 


Trend 2/ 


Exploitation 




Angola 


613 F 3/ (197*) 4/ 


U 








Antigua 


39 F 71982) 


U 


150 turtlea/year 






Ascension I. 


1,000 - 2,000 F/year 


S 








Bahama 


+ 


D 


11,090 pounds (1980-82) 






Belize 


19 F (1982) 


U 








Brazil 


3,000 - 10,000 F/year 


U 


8,399 pounds/year 






British Virgin la. 


75 F (1981) 


U 


100 turtlea/year 






Cape Verde la. 


+ 


D 








Caymen Islands 


+ 


D 


170 turtles/year 






Colombia 


+ 


D 








Costa Rica 


4,392 F (1981) 


U 


237,571 pounds (1980-82) 






Cuba 


+ 


D 


329 turtles/year 






Dominica 


2 F/year 


U 








Dominican Republic 


260 F (1980) 


D 








French Guiana 


112 F (1979) 


D 








Grenada 


200 F (1982) 


U 


15,750 pounda (1980-82) 






Guada loupe 


+ 


D 








Guatemala 


+ 


U 








Guyana 


+ 


D 








Haiti 


+ 


D 


250 pounds/year 






Honduras 


+ 


D 








Jamaica 


100 F (1982) 


D 


4,980 pounds/year 






Mexico 


502 F (1981) 


D 


Harvested 






Nicaragua 


+ 


D 


104,434 pounds (1980), 100 turtles 


(1983) 




Panama 


+ 


D 








Puerto Rico 


4 F (1982) 


D 








St. Lucia 


+ 


D 


5 turtles/year 






Surinam 


4,500 F (1982) 


S 


250,000 eggs/year 






Turks/Calcoa 


75 F (1982) 


U 


4,000 pounds/year 






United States 


182 F/year 


I 








Venezuela (Aves I.) 


200 F (1982) 


u 










PACIFIC OCEAN AND ADJA 


CENT SEAS 






American Samoa 


+ 


. 1 


I 






Australia 












No. 7 /No. 8 Sandbanks 


Several hundred F/year 


S 








Bushy I. 


Several hundred F/year 


s 








Bell Cay 


Several hundred F/year 


s 








Australia 












Raine I. 


80,000 F/year 


s 








Lacepede Is. 


10,000 F/year 


s 








Torres Strait 


+ 


s 


10,000 turtles/year 






Cook Is. 


+ 


u 








Esster I. 


+ 


u 








Fed. Ststes of Micronesia 


+ 


D 


Harvested 






Fiji 


+ 


D 








French Polyneala 


+ 


D 








Hawaiian Islands 


■ 










French Frigate Shoals 


750 F/year 


S 








Indonesia (Western) 


25,000 F/year 


D 


Increasing harvest of eggs end adults 




Japan 


+ 


U 


83,600-398,200 pounds (1959-1970) 


H 




Line la. 


+ 


U 








Kermadec I. 


+ 


U 








Malaysia (East) 


+ 


D 


401,400 eggs harvested/year 






Mexico 


+ 


U 








New Caledonia 


+ 


S 








New Hebrides 


+ 


s 


Harvested 






New Zealand 


+ 


u 








Panama 


+ 


D 








Papua New Guinea 


+ 


D 


Increasing harvest 






Phlllppeana 


+ 




Intensive commercial harvest 




Phoenix la. 


up to 200 F/year 


U 






1 Republic of Palau 


1 


D 




..., 



10 



Table 1. (continued) 



Location 


Population Information 


Trend 2/ 


Exploitation 


Republic of the Ha ra halls 










Bikar Atoll 


711 breeding F 


U 






Society Islands 


♦ 


D 


Barveatad 




Solomon lalanda 


10 - 100 F/year 




Harvested 




Thailand 


1,000 P/year 


U 






Tuamotu Archipelago 


+ 


D 


Kgge harvaatad 




United Statea 


+ 


(1 






Weatern Saaoa 


120 P/yaar 


D 


Barveated 




INDIAN OCEAN AND ADJACENT SEAS 




Bangladesh 


+ 


D 






Brltlah Indian Ocean Ter. 


+ 


U 






Burma 


+ 


U 






Comorea 


1,900 P/yaar 


U 


Barveatad 




Egypt 










Abu-Rhodea 


80 P/yaar 


D 






India 


+ 


U 


Increasing harvest of agga 


and adults 


Iran 


300 P/year 


8 






Kenya 


200 P/year 


D 


Barveated 




Madagascar 


+ 





Barveated 




Halayala (Meat) 


+ 


D 


Barveated 




Maurltlua 


- 


D 


295 or more turtlea/year 




Hayotte 


500 P/year 


D 






Mozambique 


200 P/yaar 


D 






Oiaan 


7,000 P/year 


S 






Peoplea Dent. Rep. Yemen 


10,000 P/yeer 


S 


Commercial harvest 




Rep. South Africa 


- 


S 






Raunlon 










Europe 


1,500 - 18,000 P/year 


S 






Tromelln 


200 to more than 4,000 P/yaar 


S 






Saudi Arabia 


500 P/year 


s 






Seychelles 


2,500 P/year 


D 


Intensive harvest 




Somalia 


Several thouaand P/year 


D 


Commercial harvest 




Sri Lanka 


+ 


D 


Harvested 




Tantanla 


+ 


U 






Tonga 


+ 


D 


Harvested 




Yemen 


200 P/year 


s 







+ turtlea neat, but no population Information la available 

turtlea no longer meet, but found In adjacent vatera 

D decreaalng 

P neatlng females 

I Increasing 

S stable 

U no Information 

1/ Based on information from numerous literature aourcea - see text references 

7/ Population trends aa Inferred from literature aourcaa 

7/ Includes both graen and leatherback aea turtlea 

7/ Latest date of Information If known 

5/ Creen and loggerhead aea turtlea combined 



11 



Population estimates since the species was listed in 
1978 are still unavailable although sea turtle experts 
believe there is a generally steady decline in stocks. King 
(1982) has documented the decline of the Cayman Islands green 
sea turtle fishery. The turtle fishery in Florida, Bermuda, 
and the Dry Tortugas was also rapidly depleted by over 
exploitation. Brongersma (1982) reports depletion of green 
turtle fisheries at Bahia dos Tigres and Glandiole in west 
African waters. Similar accounts of population declines are 
reported from the Mediterranean Sea, the Pacific Ocean and 
adjacent seas, and the Indian Ocean and adjacent seas. 



Listing Factors 

1. The Present or Threatened Destruction, Modification or 
Curtailment of its Habitat or Range 

Green sea turtles are found in estuarine and offshore 
coastal waters that provide breeding, nesting, feeding, and 
developmental habitat. The natural habitats of the green sea 
turtle are being encroached upon as a consequence of 
increased human population growth along the coastal areas. 
In many areas, green sea turtle habitat has been lost, 
altered, or degraded by development, recreational activity, 
dredge and fill for land development, sea bed mining, 
construction and maintenance of navigation channels, and the 
discharge or spills of pollutants ( Coston-Clements and Hoss, 
1983). 

These habitat losses are not limited to developed or 
industrially based nations but also occur in lesser developed 
nations and other political entities as they strive to keep 
pace with the world economy, and, at the same time, deal with 
expanding human populations. However, such diverse areas as 
Hawaii (U.S.), American Samoa (U.S.), the Trust Territory of 
the Pacific Islands, Indonesia and India demonstrate that 
habitat degradation is not necessarily the result of economic 
or political status. 

Green sea turtles may be adversely affected by the 
following activities (McFarlane, 1963; Coston-Clements and 
Hoss, 1983): 

1. Domestic development — including artificial lighting, 
man-made barriers, rip-rap, jetties, beach cleaning 
and traffic; 



12 



2. Industrial deve lopment--t hernial discharge, 
agrobusiness, radioactive waste, insect control, and 
trace metals; 

3. Pollution—including spills of oil and hazardous 
materia Is ; 

4. Dredging and mining; and 

5. Predators attracted to human refuse. 

Other habitat alterations that affect green sea turtles 
include the introduction of exotic vegetation by man on 
nesting beaches and pollution of the turtles' oceanic 
habitat. Exotic vegetation may inhibit nesting by forming 
barriers and dense root mats (Hopkins and Richardson, 
1982). The currents which accumulate sargassum weed, where 
some green sea turtles may spend the early part of their 
cycle (Pritchard, 1979), also accumulate pollutants such as 
oil, styrofoam, and other plastic (Groombridge , 1982; Witham, 
1978). Numerous young green sea turtles have been found dead 
or moribund along Florida beaches with their jaws and throats 
obstructed by tar (Groombridge, 1982). 

While the loss of nesting habitat and its effects on 
green sea turtles is unquant if ied, with diminishing nesting 
and feeding habitat, the distribution of green sea turtles is 
being reduced as well. Further, if separate breeding 
aggregations do exist, as is now suspected in many instances, 
then the loss of nesting habitats will lead to the eventual 
extinction of certain stocks or races. Available information 
also suggests that chemical pollution (e.g. oil) may be 
adversely affecting green sea turtles and could pose a threat 
to their survival (Groombridge, 1982). 



2. Overu tilization for Commercial, Scientific or Educational 
Purposes 

The NMFS does not believe the use of this species for 
scientific and educational purposes constitutes a cause for 
declines in stocks. In the United States, this form of take 
is regulated by a permit system designed to protect 
endangered and threatened species. Much research on the 
green sea turtle involves population surveys and ways to 
increase its numbers. Therefore, research benefits rather 
than harms these turtles. 



13 



The greatest cause for decline of this species is the 
use of adults and eggs for food. In addition, small turtles 
are stuffed for curios, the skin is used for leather, and the 
shell is used for jewelry. Green sea turtles are prized for 
their meat, calipee/calipash, fins, etc. Soup made from 
various parts of this species is especially prized. 

Declines in stocks due to commercial exploitation is 
perhaps more evident for the green sea turtle than other sea 
turtles (Table 1). Stocks were almost decimated by 1900. 
King (1982) recounts the fate of several of the largest green 
sea turtle rookeries. The Cayman Islands is believed to have 
supported one of the largest known rookeries. Extensive 
exploitation for food decimated the population by the late 
1700s. The population was extinct by 1900, and the fishermen 
moved to Nicaragua to harvest turtles. Nicaragua began 
large-scale harvesting of green sea turtles in 1970, 
processing an average of 10,000 turtles per year for shipment 
primarily to the United States. This endangered the sea 
turtle rookery nesting at Tortuguero, Costa Rica. 

In Florida, similar depletion of stocks is evident. The 
green sea turtle fisheries of the Indian and Halifax River 
estuaries ceased in 1900 for lack of turtles, and the nesting 
population of the Dry Tortugas was destroyed within 100 years 
of the start of exploitation (King, 1982). 

Hildebrand (1982) reports that a cannery for green sea 
turtle soup began operation in Texas about 1849. By 1900, 
turtle supplies were so low that the industry shut down. In 
the past, at least 30,000 turtles (not all greens) were 
caught in the Mediterranean off Israel with similar numbers 
caught off Turkey (Sella, 1982). Green sea turtle rookeries 
of Bermuda were decimated by 1620 (King, 1982). Similarly, 
other declines in stocks are reported in the final 
environmental impact statement prepared by NMFS and FWS for 
listing the green sea turtle under the Endangered Species Act 
of 1973. 

Commercial exploitation of wild green sea turtles has 
now been greatly curbed. However, Cayman Turtle Farms owned 
by the Government of the Cayman Islands still exports green 
sea turtle products, but not into or through the 
United States. Also, Mexico and Ecuador may still be 
exporting meat (Mack et_ a_l . , 1982). Green sea turtles are 
still taken in Turkey and throughout the western Atlantic. 
The remaining consumption of turtle meat is primarily local, 
and, although its effects are unknown, continued use of 



14 








4 



j^^lpW* 




J^SST* 



'-■^ 




Green Sea Turtles. 



Photos by Larry Ogren , Southeast Fisheries 
Center, National Marine Fisheries Service. 

15 



depleted turtles can only further jeopardize this turtle's 
survival prospects. 

The consumption of eggs is probably local. The amount 
of egg harvesting is not known except in Surinam where 
250,000 eggs are harvested annually (Bacon _et_ _al_. , 1984). 
However, in protein poor countries, and those without 
protective laws for wildlife, the take of eggs is likely very 
high which must impact the survival of green sea turtles. 



3. Disease or Predation 

Little is known about diseases and disease-induced 
mortality of green turtles. Balazs (1980) has noted the 
presence of apparently benign tumors ranging from small warts 
to masses up to 25 cm. in diameter on 5 percent to 10 percent 
of the green turtles observed while breeding at French 
Frigate Shoals. Other organisms isolated from captive 
turtles include the bacteria Salmonella weltevreden , and 
Mycobacterium avium . The overall affect of disease on 
natural populations of green sea turtles is not understood. 

Adult green sea turtles are preyed on mostly by man. 
Only sharks, whales, and large groupers would be able to take 
adults and the larger subadults. The number of turtles lost 
to natural predation and the effect of this take on the 
population is unknown. However, predation on hatchlings and 
eggs is usually very high. Hirth (1971) estimated that only 
50 percent of the eggs hatch successfully, and only one to 
three percent of the hatchlings reach sexual maturity. At 
Tortuguero, Coasta Rica, Archie Carr once estimated that 
survival from egg to sexually mature adult was probably 0.1 
percent . 



4. Inadequacy of Existing Regulatory Mechanisms 

In the United States, green sea turtles probably are 
adequately protected under the ESA. However, in other areas 
of the world, laws and enforcement measures are not adequate 
to protect this species and its products from international 
trade and local consumption. The Convention on international 
Trade in Endangered Species of Flora and Fauna (CITES) is not 
universally accepted and some signataries continue to deal in 
turtle products. Also, countries such as Japan, Germany, and 
France have taken exceptions to the ban on trade in green sea 



16 



turtle products and still import meat, leather, 
calipee/calipash, and shell. 

Some of the major breeding colonies in and off the 
Atlantic Ocean have been provided protection. However, the 
population at Tortuguero, Costa Rica is stressed by harvest 
in Nicaragua. Also, local consumption of adults and eggs is 
believed to be very high (since much of their take is by 
poaching, the extent cannot be quantified). Within the 
Caribbean region, most existing laws afford only partial 
protection (Bacon, 1981). Also, the region is so diverse and 
large that the enforcement of existing laws is probably poor 
to non-existant (see Carr et al . , 1982). Protection in the 
Indo-Pacific region ranges from no protection at all for 
adults or eggs to complete bans on harvesting for any 
purpose. In many areas such as the Philippines and the 
Seychelles, poaching for commercial uses as well as local 
consumption occur despite laws and regulations prohibiting 
such activities. In Australia, commercial harvest is for the 
most part prohibited, but local take for subsistence purposes 
is permitted and both activities are apparently controlled. 



5. Other Natural or Manmade Factors Affecting its Continued 
Existence 

Severe weather conditions such as storms or heavy rains 
may destroy eggs and hatchlings. Also, the natural erosion 
of beaches as well as erosion during storms may impact 
rookeries. For example, the nesting beach at Aves Island, 
one of the larger green sea turtle rookeries in the Atlantic, 
was almost entirely eroded in 1979 by Hurricane David. 
However, the beach has been rebuilt and results of new 
surveys of nesting on the island are being evaluated. Schulz 
(1982) reported that Organabo Beach in French Guiana had also 
eroded and virtually disappeared by 1979. Loss of foraging 
habitat through natural causes such as siltation, sinking and 
volcanic action can also adversely affect the distribution 
and survival of specific populations of green turtles. 
Volcanic action through lava flows forming new coastal lands 
can also provide enhanced substrate for algae growths and 
provide increased feeding areas. 



Human Activities 

The effect of human activities on turtle populations is 
divided into two categories: the impact on nesting success 



17 



and the impact on oceanic survival (after Coston-Ciements and 
Hoss f 1983). Destruction or modification of nesting habitat 
probably has the greatest impact on the ability of turtle 
populations to maintain their numbers. Artificial 
illumination from industrial or domestic development can 
result in hatchling disorientation and a reduction in the 
numbers of females coming ashore to nest. Offshore and 
nearshore construction may also deter females from utilizing 
preferred nesting beaches. Clearing of vegetation can reduce 
shade and increase nest temperatures while also reducing the 
structural rigidity of the nests by removing the root systems 
of native plants. Construction of large buildings may 
increase shade and lower nest temperatures. Since 
temperature is an important factor in hatching success and 
sex determination, even small changes may result in increased 
mortality, imbalanced sex ratios and reduced hatching 
success. 

The impact of oil spills on nesting and hatching can be 
considerable. Hatchlings entering the water during a 
nearshore spill would suffer respiratory distress from the 
volatile components of the oil and perhaps suffocation and 
eye irritation from the heavier components. Nesting females, 
if undeterred from coming ashore, could suffer similar 
effects such as respiratory difficulty and eye irritation. 
Oil spill clean up activities (vehicular traffic) can destroy 
nests and prevent nesting by pregnant females. 

Factors affecting oceanic habitat include pollutant 
discharges, pesticide/herbicide spills and runoff, heavy 
metal/radionuc lide discharges, PCB contamination, sewage and 
domestic discharges, energy development, dredging/mining and 
fishing activities. The discharges and spills of 
hydrocarbons, heavy metals, biocides, and radionuclides 
result primarily in the degradation of the physical health 
and fitness of individual animals which can be manifested by 
direct mortality, injury, body fouling, sensory disruption, 
reduced reproductive success, and possible unknown 
carcinogenic impacts. Secondary effects of these sources of 
contamination range from destruction of foraging habitat to 
disruption of breeding behavior. One possible positive 
result of certain types of sewage discharge is the 
enhancement of benthic algae utilized by green sea turtles 
for food (Corps of Engineers, 1983). 

Energy development impacts include entrapment in cooling 
water intakes, dispersion or attraction to thermal effluent 
plumes, and degradation of foraging and resting habitat by 



18 



effluent. A secondary impact of energy development is the 
attraction of hatchlings to lighted offshore structures which 
results in increased predation. The degradation of foraging 
and resting habitat by mining and dredging can result from 
disposal of spoil, alteration of bottom topography and direct 
destruction. 

Although fishing activities are not directly associated 
with turtle harvesting, they can have significant adverse 
effects through incidental entanglement and entrapment in 
gear such as trawls, set nets, pound nets and gill nets (Tow 
and Moll, 1982; deSilva, 1982; Hillestad et _al_. , 1982; and 
Hopkins and Richardson, 1982). In the United States, an 
estimated 432 green sea turtles per year are caught in shrimp 
trawls with an estimated annual mortality of 97 (Bacon e_t 
al. , 1984). Trawling activities also reportedly cause 
significant mortalities off the Pacific coast of Panama, the 
western Mediterranean (possibly 1,000 per year), Colombia, 
Honduras, Australia, Ecuador, Peru, the Guianas, and Pacific 
Central America (Groombridge , 1982). Turtles are also 
incidentally taken in net fisheries (e.g. shark nets, 
sturgeon nets, and pound nets), trap fisheries, and by hook 
and line (Crouse, 1982). Hatchlings attracted to deck lights 
may suffer significant mortality through enhanced 
predation. Green turtles are also affected by fishing 
methods using dynamite and chlorine bleach. Miscellaneous 
impacts of fishing-related activities include ingesting and 
entanglement in litter such as styrofoam, plastic, line, and 
discarded netting. 

Since few if any of these activities and their effects 
have been quantified, an evaluation of their impacts, both 
singular as well as cumulative, cannot be made at this time. 



Conclusions 

Overexploitation for its meat, calipee/calipash, skin, 
eggs and other parts has led to the depletion of green sea 
turtle stocks wherever they occur. Areas where populations 
were decimated (e.g. Cayman Islands, Bermuda, and Dry 
Tortugas) have still not recovered even though commercial 
exploitation ceased before 1900. Reports by turtlers and sea 
turtle experts throughout the world indicate most populations 
are still reduced (e.g. King, 1982). The protected 
population in Florida is showing some encouraging signs of 
recovery, and the Surinam population as well as the nesting 
colony at Tortuguero, Costa Rica may be secure. 



19 



In protein poor countries, the local consumption of 
adult turtles and eggs continues to place great pressure on 
this species. Also, because of the long time it takes for 
sea turtles to reach sexual maturity, the relatively poor 
survival rate of eggs and hatchlings, and the susceptibility 
to predation and take due to its terrestrial nesting, the 
species is still stressed and requires continued protection. 

Therefore, NMFS believes that the best available 
commercial and scientific data indicate that most of the 
green sea turtle populations are depleted or endangered. 
Information generated since the final environmental impact 
statement submitted by NMFS and FWS in 1978 for listing and 
protecting the green sea turtle is insufficient to warrant a 
change in the status of the species. Accordingly, it is our 
opinion that the green sea turtle should remain listed as 
endangered in Florida and on the Pacific Coast of Mexico and 
threatened in the rest of its range. 



20 



HAWKSBILL SEA TURTLE 



( I r«tmoch«ly • Imbricate) 






21 



Hawksbill Sea Turtle 
( Eretmochelys imbricata ) 



Biological Background 

The hawksbill sea turtle is distributed throughout the 
western hemisphere, where it also may be called the carey, 
oxbull, tortue des bonnes ecilles, tortue imbriquee, karet, 
and tartaruga de pente (Pritchard et at . , 1983). This sea 
turtle can be recognized by four pairs of overlapping plates 
on the shell except in very young and very old individuals; 
two pairs of prefrontal scales (scales found between the 
nasal opening and the eye socket) on the head; paddle-shaped 
limbs with two claws, overlapping and serrate shell margins; 
jaws that are modified and beak-like; and a rather long neck 
compared to other sea turtles (Pritchard, 1979). The adult 
shell is usually amber with streaks of red-brown, 
black-brown, and/or yellow; the underside of the turtle is 
whitish yellow and may have some black spots (Rebel, 1974). 

Although the adult hawksbill is usually larger than 
ridleys, it is smaller than other sea turtles. Shell length 
(straight line) for nesting females examined from various 
locations varied between 24.6 and 37.4 inches in the Atlantic 
Ocean; between 23.6 inches and 36.5 inches in the Pacific 
Ocean; and between 21 inches and 32.7 inches in the Indian 
Ocean (Witzell, 1983). Weights for nesting hawksbills 
examined from various locations varied between 60 and 190 
pounds in the Atlantic Ocean; 80 and 170 pounds in the 
Pacific Ocean; and 78 and 110 pounds in the Indian Ocean 
(Witzell, 1983). Pritchard (1979) reports that the largest 
record for hawksbills was a 37-inch long specimen, and the 
heaviest weighed 280 pounds. There are no apparent external 
morphological differences between subadult male and female 
hawksbills. Adult males have tails that extend some distance 
beyond the rear edge of the shell while the tails of females 
are short, barely reaching beyond the rear edge of the shell 



22 



(Witzell, 1983). Also, the claws on males are longer and 
heavier than on females and the underside is soft and 
concave. The pigmentation of males may also be more intense 
(Marquez, 1970; Witzell, 1983). 

The longevity of hawksbills in the wild is unknown. A 
specimen at least 16 years old was reported from the Berlin 
Zoological Garden (Rebel, 1974) and Witzell (1983) cites an 
alleged record of a 32-year old hawksbill. Carr et al . 
(1966) believe that hawksbills mature sexually at about 78 
pounds. However, in the wild, age to sexual maturity is not 
known. Under favorable rearing conditions, Bustard (1979) 
reported age to maturity at three to four years in 
Australia. Witzell (1980) indicated that captive Samoan 
hawksbills may reach maturity at about 3.5-4.5 years of 
age. The age and size at maturity probably varies between 
the sexes and individuals within breeding populations 
(Witzell, 1983). 

Hawksbills are ominvorous and eat plants and animals 
such as algae, sea grasses, soft corals, crustaceans, 
molluscs, sponges, jellyfish, and sea urchins (Carr and 
Stancyk, 1975; Groombridge, 1982). The chief predators of 
adults and juveniles include man, sharks, crocodiles, and 
perhaps fish such as large groupers (Witzell, 1983). 
Predators of eggs and hatchlings include man, feral hogs, 
dogs, cats, insects, crabs, coatimundi, and lizards (Witzell, 
1983). The loss of eggs and hatchlings to predation is very 
high. 

Hawksbills are a circumtropical species, preferring warm 
shallow water areas that are usually less than 50 feet deep 
(Carr and Stancyk, 1975; witzell, 1983). Coral reefs, 
lagoons, shoals, and bays with good populations of plants and 
animals are ideal habitats. 

The non-nesting range of the hawksbill is extensive. In 
the eastern and mid-Atlantic Ocean, hawksbills have been 
reported from the European coast of the English Channel; 
Mauritania, Senegal, Sierra Leone, Liberia, Ghana, Cameroon, 
Gabon, South Africa, Morocco, Gambia, Togo, and Angola, 
Africa; the islands of Madeira, Cape Verde, Ascension, 
St. Helena, and Azores; and west of Cape St. Vincent, off 
Portugal (Witzell, 1983). Hawksbills have been observed in 
the Mediterranean Sea from France to its eastern coast. 
(Witzell, 1983). 



23 



Distribution in the western Atlantic includes the area 
from Cape Cod, Massachusetts to northern Brazil (Witzell, 
1983). Hawksbills are rarely or occasionally encountered in 
most of their distributional area in the western Atlantic 
Ocean. However, Witzell (1983) indicates that hawksbills are 
still common throughout the southern Gulf of Mexico, in the 
Caribbean Sea, and the northern part of South America. 

In the Pacific Ocean, hawksbills have been observed in 
the Gulf of California as far as 29° north, throughout the 
northwestern states of Mexico, and south along the Central 
and South American coasts to Columbia and Ecuador (Witzell, 
1983). Records are available from Revillagigedo Islands, 
Galapagos Islands, Easter Island, the Hawaiian Archipelago in 
the eastern Pacific and throughout the many island groups in 
the Central and western Pacific (Witzell, 1983). There are 
records of the hawksbill from the Sea of Japan, China, 
Formosa, and from Indonesia to New Zealand in the western 
Pacific (Witzell, 1983). 

Hawksbills have been recorded also in the Indian Ocean 
from Burma, Pakistan, the Persian Gulf, the Red Sea, South 
Africa, and in many of the oceanic island groups (Witzell, 
1983) . 

Nesting sites are widely spread throughout the 
hawksbill's range (Figure 2); they prefer to nest on small, 
isolated beaches usually between the Tropics of Cancer and 
Capricorn, except the Persian Gulf populations which nest 
farther north (Witzell, 1983). Ideal nesting sites are on 
clean beaches with more oceanic exposure and little 
disturbance that would inhibit nesting. This species wanders 
more in search of nesting sites and is more agile than other 
sea turtles since it has the ability to climb over rocks, 
vegetation, and other obstructions. It tends to nest among 
the thick vegetation at the rear of the beach platform 
(Mortimer, 1982). 

Females typically nest in two or three year cycles (four 
year returns are known), and deposit one to four clutches a 
season at about 15 to 19 day intervals (Witzell, 1983). 
Hawksbills are thought to be remarkably faithful to their 
breeding beaches (Hughes, 1981). However, Carr and Stancyk 
(1975) reported only a 4.6 percent return of 130 hawksbills 
tagged at Tortuguero, Costa Rica. Clutch size usually varies 
between 73 and 163 eggs which hatch in about 60 days (Hirth, 
1980; Witzell, 1983). Most hatchlings emerge at night and 
head directly to the sea where they are pelagic for some 



24 




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25 








Hawksbill Sea Turtles. 



Photos by Larry Ogren , Southeast Fisheries 
Center, National Marine Fisheries Service. 

26 



time. Some hatchling hawksbills may drift in sargassum rafts 
(Carr and Meylan, 1980a; Groombridge, 1982). 



Population Size 

Available population information is presented in 
Table 2. This information is obtained from Groombridge 
(1982), Bjorndal (1982), Hopkins and Richardson (1982), Carr 
e_t _al_. (1982), Witzell (1983), and Bacon etal. (1984). 

Female hawksbills generally nest alone and very quickly; 
they are easily dissuaded from nesting by distributions on 
the nesting beach. Moreover, diffuse and remote beaches are 
preferred and nests are often hidden under vegetation. 
Therefore, the hawksbill is a difficult turtle to census by 
techniques such as aerial surveys. Because of the general 
lack of intensive effort needed to survey hawksbill 
populations, reliable estimates for population size are 
generally not available. The number of reproduct ive ly active 
females has been estimated for some populations, but Witzell 
(1983) indicates that these estimates are apparently 
unreliable or vary greatly from year to year. 

The hawksbill is still widespread in tropical waters, 
but nesting density is low in most of its range with moderate 
nesting in only a few localities such as the Torres Straits 
Islands; Jabal Aziz, Perim, and Seil Ada Kebir in the Red Sea 
and Gulf of Aden; the Arnavon Islands; northern Australia; 
Micronesia; the Maldives, Lavan, and Shetvar in the Persian 
Gulf; Masirah Island, Oman; northern Madagascar; parts of the 
Seychelles Republic; possibly at several sites in Indonesia; 
Antigua; British and U.S. Virgin Islands; Grenada; Jamaica; 
Mexico; and the Turks and Caicos (Groombridge, 1982; Bacon e_t 
al. , 1984). However, it is generally accepted that most 
nesting populations are declining due to habitat destruction 
and over-exploitation (Witzell, 1983). 

Listing Factors 

1. The Present or Threatened Destruction, Modification or 
Curtailment of its Habitat or Range 

Destruction, modification, or curtailment of habitat or 
range has not been quantified for the hawksbill. Therefore, 
the effect of habitat loss or alteration on hawksbill 
populations cannot be determined. Groombridge (1982) 



27 



Table 2. Population information, population trends and 
exploitation of the hawksbill sea turtle 
(Eretomochelys imbricata) 1/ 



ATLANTIC OCEAN AND ADJACENT SEAS 



Location 


Population Information 


Trend 2/ 


Exploitation 




Angullla 


76 F (1982) 3/ 


D 


Harvested 




Antigua 


- 


D 


108 lbs shell (1983) 




Bahamas 


+ 


D 


13,866 lbs meat, 3,324 lbs shell (1980-82 




Barbados 


- 


D 


24 lbs shell (1982) 




Belize 


31 P (1982) 


D 


2,728 lbs shell (1982-83) 




Bermuda 


- 


D 


Harvested 




British Virgin Islands 


50 F (1981) 


D 


Harvested 




Cayaen Islands 


+ 


D 


11,616 lbs shell (1981-82) 




Colombia 


+ 


D 


Harvested 




Costa Rica 


+ 


D 


699.6 lbs shell (1981-83) 




Cuba 


+ 


D 


32,120 lbs shell (1981-83) 




Dominica 


3 P (1982) 


D 


306 lbs shell (1981-83) 




Dominican Republic 


420 F (1980) 


D 


3,249 lbs shell 




French Guiana 


+ 


D 


Harvested 




Grenada 


500 F/year 


D 


33,000 lbs meat (1980-82) 




Guadaloupe 


+ 


U 


Harvested 




Guatemala 


+ 





Harvested 




Guyana 


+ 


D 


Harvested 




Haiti 


+ 


D 


8,510 lbs shell (1981-83) 




Honduras 


+ 


D 


6,607 lbs shell (1981-83) 




Jamaica 


300 F (1982) 


U 


6,266 lbs shell (1981-83) 




Martinique 


+ 


D 


Harvested 




Mexico 


568 F (1981) 


D 


79 lbs shell (1983) 




Nicaragua 


25 F (1981) 


D 


19,714 lbs shell (1980-82) 




Panama 


+ 


D 


20,115 lbs shell (1981-83) 




Puerto Rico 


22 F (1982) 


D 


Harvested 




St. Lucia 


11 F (1982) 


D 


1,978 lbs shell (1981-83) 




St. Vincent 


+ 


D 


434 lbs shell (1981-83) 




Surinam (Blglsantl) 


29 F (1974) 


D 


Harvested 




Trlnldad/Tobogo 


+ 


D 


724 lbs shell (1983) 




Turks/Calcos 


200 +/- 75 F (1982) 


D 


Harvested 




United States 


2 F/year 


S 


48 lbs shell (1983) 




U.S. Virgin Islands 


25 F (1982) 


S 






Venezuela 


* 


D 


Harvested 






PACIFIC OCEAN AN 


D ADJACENT 


SEAS 




Australia (Torres Strait) 


Several hundred/year 


D 


Harvested 




China 


+ 


D 


Harvested 




Colombia 


+ 


D 






Cook Island 


•f 


U 






Costa Rica 


+ 


D 






Ecuador 


+ 


D 


Harvested 




El Salvador 


+ 


D 


Harvested 




French Polynesia 


+ 


D 


Harvested 




Hawaii 


+ 


D 






Honduras 


+ 


U 


Harvested 




Indonesia 


+ 


D 


35,000 hawksbllls/year 




Japan 


+ 


D 


Harvested 




Malaysia (East) 


+ 


D 


18,600 eggs harvested/year 




Mexico 


+ 


D 


Harvested 




Micronesia 


+ 


D 


Intensive harvest 




New Caledonia 


+ 


U 






Nicaragua 


+ 


U 


Harvested 




Panama 


+ 


D 


Harvested 




Papua New Guinea 


+ 


D 


Intensive harvest 




Philippines 


+ 


D 


5,000 hawksbllls/year 




Solomon Islands 


725 - 1,087 F/year 


D 


Intensive harvest 




Thailand 


4 


D 


Harvested 


Western Samoa 


+ 


D 


Harvested 


Tonga 


+ 


' 


Harvested 





28 



Table 2. (continued) 



INDIAN OCEAN AND ADJACENT SEAS 



Andaaan/Nlcobar Is. 


♦ 


D 


Sea turtles and their eggs harvested 




Bum 


+ 


V 


Eggs harvested 




Chagoa Archipelago 


300 F/year 









Coaores 


50 F/year 


D 


Harvested 




Ethiopia 


♦ 


V 






India 


+ 


V 


Harveeted 




Iran (Gulf Islands) 


400-600 F/year 


V 






Kenya 


Leea than 50 F/year 


V 






Madagascar 


■f 


D 


About 2,500 havkebll la/year 




Maldives 


+ 


D 


Intensive harvest 




Mozambique 


Leea than 100 F/year 


D 






Oman (Omedu Beach) 


50 - 80/year 


D 






Peoplea Dea. Rap. Yemen 


Hundreds F/year 








Qatar 


+ 


D 






Location 


Population Information 


Trend 2/ 


Exploitation 




Reunion (Clorleuae) 


50 F/year 


D 






Saudla Arabia 


•f 


D 






Seychelles 


More than 700 F/year 


D 


Intensive harvest 




Sri Lanka 


♦ 


D 


Harvested 




Sudan 


350 or acre F/year 


D 






Tanzania 


50 F/year 










+ turtles neat, but no population Information la available 

turtlea no longer neat 

D decreaalng 

F neatlng feaales 

I Increasing 

S stable 

V unknown 



1/ Baaed on Information froa numerous literature sources 
T/ Population trenda aa Inferred froa literature sources 
57 Lateat date of information If knovn 



see text references 



29 



identified the loss of nesting beaches in Malaysia, Sri 
Lanka, and the eastern Caribbean as a threat to this species. 

The following summarizes habitat alterations that may 
affect hawksbills (Coston-Clements and Hoss, 1983): 

1. Pollution—includi ng spills and oil and hazardous 
materials 

2. Dredging and mining 

3. Domestic development 

4. Industrial development--thermal discharge, 
agrobusiness, radioactive waste, insect control, and 
trace metals 

Female hawksbills are especially susceptible to 
disturbance by light and moving shadows from people, animals, 
trees, etc. during the early stages of nesting (Witzell, 
1983). Disturbed turtles will rapidly return to sea without 
finishing the nesting process (Carr ^t ^1_. , 1966). Witzell 
(1983) reports that avoidance behavior is evident in areas 
where the human population has moved near nesting sites and 
built residences, resorts, military installations, airports, 
and highways. Artificial lighting, physical barriers, and 
vehicular traffic have been identified as development-related 
activities that also affect hawksbills (Witham, 1982). 



2. Overut i lization for Commercial, Recreational, Scientific 
and Educational Purposes 

The use of hawksbills for scientific and educational 
purposes, while unquantif ied , is undoubtedly small and not a 
contributing factor in the decline of hawksbill 
populations. In the United States, the scientific take of 
hawksbills is controlled by a permit program designed to 
protect the species. 

The main cause of depletion of hawksbill populations is 
the exploitation of eggs, meat, shell, and whole young 
animals (see Table 2). However, the greatest threat to 
populations is the continuing demand for "tortoise shell", 
i.e. the carapace, and plastral scutes of the animal 
(Groombridge, 1982). 

In many lesser-developed villages, hawksbill eggs are 
eaten wherever and whenever found and are an important 
protein source (Witzell, 1983). Surveys of important 
hawksbill populations in Cays off the east coast of Nicaragua 



30 



in July 1971 showed that only 5 percent of the hawksbill eggs 
laid were uncollected (Rainey and Pritchard, 1972). Also, 
the meat generally is eaten wherever these turtles occur 
although it is often reported to be dark and oily with a 
strong flavor (Witzell, 1983). The hawksbill meat is 
preferred over the meat from other sea turtles at Caymen 
Brae, San Andres, and Old Providence Islands in the Caribbean 
Sea and is eaten in other Caribbean areas, the Solomon 
Islands, and New Guinea. Although, it is reportedly 
poisonous in many areas of the world such as the Gulf of 
Guinea, Australia, Sri Lanka, India, Mauritius, West Africa, 
Seychelles, Senegal, Sudan, and Oman (Groombr idge , 1982; 
Witzell, 1983). In a 1971 survey taken in Nicaragua, 50-60 
percent of nesting females were killed (Rainey and Pritchard, 
1972). Calipee is also prepared for consumption in many 
parts of the world, and the oil and fat is often used for 
cooking (Witzell, 1983). Other products from harvested 
hawksbills include leather, oil, perfume, and cosmetics 
(Witzell, 1983). 

A major threat to the species is the collecting of 
immature specimens that are stuffed and sold as curios to 
tourists and the sale of polished whole shells. Main 
producers of stuffed turtles and turtle shells for the 
tourist trade are the Philippines, Indonesia, Thailand, the 
Maldives, the Seychelles, Madagascar, Caribbean countries, 
and Hawaii (Groombridge , 1982). Japan is a major consumer of 
stuffed turtles, receiving virtually all of its supplies from 
Singapore (Groombridge, 1982). The turtles traded at 
Singapore come mainly from Indonesia (Sumatra) with some 
obtained from Sulawesi, and a large number of very young 
animals are reared in pens in Indonesia until they are large 
enough for the curio trade (IUCN, 1982). Estimates for the 
number of stuffed turtles produced annually in Singapore and 
the Philippines range between 32,000 and 105,000. Stuffed 
turtles are also common in the Caribbean region, but data on 
the quantity is unavailable. It is illegal to bring curios 
or other hawksbill products into the United States. 

Another major threat to hawksbills is the use of the 
scutes (tortoise shell) for medicinal and ceremonial 
purposes, modern day articles, and especially for jewelry 
(Witzell, 1983). The scutes removed from the shell are 
reworked to produce hair pins, broaches, fans, belts, 
miniature animals, inlayed furniture, eyeglass frames, 
cuff-links, tie tacks, buttons, snuff boxes, jewelry boxes, 
model pagodas, and model ships (Witzell, 1983). 



31 



Available catch statistics generally reflect only the 
amount of shell produced, but cannot be used to determine the 
number taken from the wild during the report period. 
Although in some areas hawksbill shells may be stockpiled and 
held to enter the market as higher prices encourage sales, 
the trade in tortoise shell is probably greater now than ever 
before. Indonesian exports increased from 22,000 pounds a 
year between 1971 and 1977 to 483,087 pounds in 1978 (Mack et 
al. , 1982). Exports from India, the Philippines, and 
Thailand also increased as did exports from a number of Latin 
American countries (King, 1982). Taiwan imported 6,600 
pounds in 1974 to over 281,600 pounds in 1978. Since 1965, 
Japan imported a minimum of 814,000 pounds of hawksbill shell 
from Caribbean countries (Hopkins and Richardson, 1982). 
Between 1981 and 1983, over 99,000 pounds of shell were 
imported from various countries around the world (Table 2). 

It is estimated that about 5,000 hawksbills are being 
killed annually in the Philippines and 35,000 in Indonesia 
( Groombr idge , 1982). Major exporters of shell are Indonesia, 
Thailand, Philippines, India, and Fiji, while major importers 
of shell are Japan, Taiwan, and Hong Kong (Groombr idge , 
1982). Japan and Taiwan import probably about 75 to 80 
percent of the world's production of shell (King, 1982) 
primarily in the use of jewelry and art objects that are a 
part of their cultural tradition. 

Because of the high prices the shell and items made from 
the shells command, the continued exploitation of hawksbills 
is virtually assured. A shell may be worth between $50 and 
$59 a pound, and a large turtle may be worth $200 or more 
(Carr and Meylan, 1980b). However, prices paid for preferred 
shell in Japan have been as high as $102 per pound (Hopkins 
and Richardson, 1982). Small items made from shell may cost 
as little as a few dollars for hair clips and rings to as 
high as $4,000 for eyeglass frames (Groombr idge , 1982). 



3. Disease or Predation 

Natural predation on hawksbills by carnivores is 
probably very high although documented cases are scarce 
(Witzell, 1983). Vaughn (1981), however, reported that 24 
percent of nesting hawksbills in the Solomon Islands had 
predator damage. Predation apparently is so common in some 
places that Japanese longline fishermen cut open shark 
stomachs to look for shell (Witzell, 1983). The effects of 
predation on hawksbill populations are not known. 



32 



Published information on parasites and diseases of 
hawksbills is incomplete (Witzell, 1983). However, 
baranacles, several species of worms (usually trematodes), 
amphipods, bacteria, a possible parasitic crab, hydroids, 
bryozoans, and various algae have been found either in 
hawksbills or on external surfaces (Witzell, 1983). The 
effects of diseases and parasites on hawksbill populations 
are not known. 



4. Inadequacy of Existing Regulatory Mechanisms 

The hawksbill receives adequate protection in the United 
States because of the ESA; however, since the population is 
not plentiful in this country, international protection is 
vital to its survival. The hawksbill is listed on Appendix I 
of CITES, but compliance is voluntary, and countries 
subscribing to CITES may accept or not, at their discretion, 
the bans imposed by this Convention. Unless widespread 
acceptance of CITES (especially by Japan, Taiwan, and other 
countries that import hawksbill products) is gained, 
prospects for international protection of the species are not 
good. 



5. Other Natural or Manmade Factors Affecting its Continued 
Existence 

Natural forces that affect hawksbills, especially during 
the nesting process, include storms, temperature, rain, and 
wave surge (Witzell, 1983). These forces can prevent turtles 
from nesting, destroy eggs and hatchlings, and reduce nesting 
success. Hawksbills may also die of hypothermia when they 
venture away from the tropics. However, the effects of 
natural factors on the continued existence of the hawksbill 
are unknown. 

Hawksbills are incidentally taken in fishing operations 
directed at other species. The effects of incidental take 
are unknown, but may become important if population levels of 
hawksbills decline further. They have been captured in pound 
nets on the eastern United States coast; in fishing nets in 
West Africa; in shark nets in southern Africa; in shrimp 
trawls in Nicaragua, the United States, the Caribbean, and 
other parts of the western Atlantic; and in fish gill nets in 
India and Hawaii (Witzell, 1983). Divers fishing for 
lobster, snapper, and grouper also spear hawksbills because 
of the high price the shell brings (Groombr idge , 1982). 



33 



Also, hawksbills may become trapped in the ocean water 
intakes of power plants and other industries. 



Conclusion 

Estimates of population sizes for hawksbills are 
generally not available. The diffuse nesting habits and the 
speed with which the female nests make this turtle difficult 
to census. Also, since the hawksbill often nests under 
vegetation, aerial surveys are generally not adequate, and 
little information is available to adequately assess the 
status of the species or to change its listing. King (1982), 
Groombridge (1982), and Witzell (1983) report that the 
decline of most nesting populations is generally accepted by 
sea turtle researchers. The only known apparent stable 
populations are in Yemen, northeastern Australia, the Red 
Sea, and Oman (Witzell, 1983). The main factor leading to 
depletion is over-exploitation which King (1982) indicates is 
greater than ever before. The high price the shell commands 
and the demand for hawksbill products will likely prevent 
effective conservation of the species in the near future in 
most of its range. 

The NMFS believes that the best available commercial and 
scientific data indicate that the hawksbill should remain 
listed as an endangered species pursuant to Section 4 of the 
Endangered Species Act. Considerably more information on 
this species (e.g. population dynamics, life history, and 
biology) is necessary before we can determine if any change 
in the listing status of this species is warranted. 



34 



LOGGERHEAD SEA TURTLE 



(Ccr«tt« ••r«tta) 






35 



Loggerhead Sea Turtle 
(Caretta caretta) 



Biological Background 

In various parts of its range, the loggerhead sea turtle 
also may be called lanternback, caguama, cabezona, logait, 
onechte kaut, caguanne, and avo de tartaruga (Pritchard et 
al . , 1983). It can be distinguished from other sea turtles 
by five or more pairs of large boney plates along the margin 
of the upper shell and two pairs of pre-frontal scales 
(scales found between the nasal opening and eye sockets) on 
the head; shell plates that do not overlap; paddle-shaped 
limbs with two claws; a large, (up to 10 inches wide) 
block-like head; and a shell which in adults is reddish brown 
to brown on top and yellowish underneath and lacks pores 
along the smaller plates along the margin where the upper and 
lower shells meet (Pritchard, 1979). 

The shell in full grown adults averages about 42 inches 
long with a known maximum of 45 and 1/4 inches (Pritchard, 
1979). Reports of turtles with larger shells are either 
inaccurate or unsubstantiated (Pritchard, 1979). Adults 
rarely weigh more than 350 pounds, but some very large 
individuals weigh more than 500 pounds (Rebel, 1974). 

There are no apparent external morphological differences 
between the sexes of subadult turtles. Adult males have a 
longer tail (extending well past the rear edge of the shell) 
than adult females. The oldest loggerheads were recorded at 
the Lisbon Aquarium where they died after 35 years in 
captivity (Rebel, 1974). Longevity in the wild is not 
known. Estimates of age to sexual maturity range between 4 
and 30 years (Hopkins and Richardson, 1982; Groombridge, 
1982). Loggerheads sexually mature at a weight of about 200 
pounds and a shell length of about 31 inches (Pritchard, 
1979) . 



36 



Loggerheads are mainly omnivorous feeding on shellfish, 
crabs, hermit crabs, barnacles, oysters, conchs, sponges, 
jellyfish, squid, sea urchins and sometimes fish, algae, and 
seaweed (Carr, 1952; Brongersma, 1972; Rebel, 1974). 
Predators of adults include man, killer whales, and sharks; 
eggs are eaten by man, raccoons, dogs, rats, feral pigs, 
foxes, crabs, etc; and hatchlings are eaten by gulls, crows, 
raccoons, dogs, etc. (Hopkins and Richardson, 1982; Bacon e t 
al . , 1984). Predation on eggs and hatchlings is very high 
(Caldwell et _al_. , 1959). 

Loggerheads can generally be found in warm waters on the 
continental shelf and among islands where food is 
available. They enter estuaries, coastal streams, 
saltmarshes, and the mouths of large rivers (Carr, 1952). 
This species is circumglobal , preferring temperate and 
subtropical waters (McDiarmid, 1978). In the Atlantic Ocean, 
it has been observed as far north as Murmansk, U.S.S.R., and 
as far south as Rio de la Plata, Argentina, and is regularly 
seen in the Gulf of Mexico and the Caribbean Sea (Brongersma, 
1982; Carr et al . , 1982; Groombridge, 1982). Brongersma 
(1982) cited records from the western coast of Europe, 
Portugal, and the English Channel. Loggerheads also occur in 
the Azores, the Madeira Archipelago, the Selvagens Islands, 
the Canary Islands, in the Mediterranean Sea, and West 
African waters. They have also been observed from the 
Pacific coasts of Panama, Nicaragua, Chile, and possibly 
Costa Rica, but not Peru (Pritchard, 1979; Brown and Brown, 
1982; Sternberg, 1981). They occur along the Chinese coast, 
Australia, and other areas in the western Pacific such as New 
Guinea, New Caledonia and Noumea (Limpus, 1982; Sternberg, 
1981). In the Indian Ocean, they occur off southern Africa 
(Mozambique, Tongaland), Madagascar, Oman, Sri Lanka, Burma, 
Pakistan, West Sumatra, Indonesia, and Thailand (Groombridge, 
1982) . 

The breeding range is "ant i tropical" (Pritchard, 1979) 
with almost all nesting areas located north of the Tropic of 
Cancer and south of the Tropic of Capricorn except for those 
nesting in the western Caribbean (see Figure 3). 

Loggerheads have been reported nesting from November to 
January in Tongaland, South Africa; May to August in Florida 
and South Carolina; and May to October at Masirah Island, 
Oman (Ross and Barwani, 1982; Groombridge, 1982). Females 
nest generally at night, depositing an average of 120 eggs 
with a range of 72 to 130 on Masirah Island and 64 to 198 at 



37 




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38 



Cape Romain, South Carolina (Caldwell et al. , 1959; Hirth, 
1980). 

Females typically nest four to five times per season, 
but a maximum of seven nests has been recorded for a female 
at Cumberland Island, Georgia (Groombridge , 1982). The 
interval between nestings usually ranges from 14 and 17 days 
(Pritchard, 1979). Most females nesting on a given beach are 
never seen again (Hughes, 1982). The ones that do return to 
nest have no universal remigration pattern; however, the most 
commonly observed remigration interval is two to three years 
(Hughes, 1982). At Tongaland, South Africa, females have 
nested up to six seasons in a nine year period at the same 
location (Groombridge, 1982). 

The incubation period for the eggs is usually between 55 
to 65.6 days with hatchlings typically emerging at night when 
the temperature drops (Caldwell et al. , 1959; Pritchard, 
1979). Hatchlings swim directly to sea where many may spend 
the early part of their life associated with mats of 
sargassum weed and other flotsam (Pritchard, 1979). 



Population Size 

Available population information is presented in Table 
3. This information was obtained mainly from Bacon (1981), 
Bjorndal (1982), Carr e_t _al_. (1982), Groombridge (1982), 
Bacon e_t _al_. (1984), Murphy and Hopkins (1984), and other 
sources cited in these publications. Population estimates 
for loggerheads are difficult to obtain because so little is 
known about their life history. Hatchlings and juveniles are 
almost impossible to census in the water, the males never 
leave the water, and it is difficult to tell males from 
females in aerial surveys. Accordingly, most estimates are 
based on the number of nesting females. 

Listing Factors 

1. Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range 

In the United States, loggerheads are commonly found in 
estuarine and offshore coastal waters which provide breeding, 
nesting, feeding, and developmental habitat. The natural 
habitats of the loggerhead are being encroached upon as a 
consequence of increased human population growth along the 



39 



Table 3. Population information, population trends and 
exploitation of the loggerhead sea turtle 
(Caretta caretta)i/ 



ATLANTIC OCEAN AND ADJACENT SEAS 



Locat Ion 



Population Information 



Trend 2/ 



Exploitation 



Angola 

Azores 

Bahamas 

Belize 

Be rmuda 

Brazil 

Canary Islands 

Cape Verde Islands 

Caymen Islands 

Colombia 

Cuba 

Cyprus 

Dominican Republic 

Greece 

Grenada 

Guatemala 

Haiti 

Honduras 

Israel 

Italy 

Jamaica 

Madel ra 

Mexico 

Netherlands Antilles 

Nicaragua 

Panama 

Puerto Rico 

Senegal 

St. Lucia 

St. Vincent 

Turkey 

Turks/Calcos 

United States 



+ 

+ 

+ 

+ 
40 F (1982) 
Less than 2,000 F/year 

+ 

+ 

+ 
400 F/year 

+ 

+ 
60 F (1980) 3/ 
41.7 F/night (1981) 
100 F (1982) 

+ 

+ 

+ 

+ 

+ 



210 F (1982) 

H 

385 F (1981) 



50 F (1982) 
14,150 (1983) 



Harvested 

Harvested 

9,620 pounds aeat (1980-82) 

Harvested 

Harvested 

Harvested 

Harvested 
Harvested 
Harvested 

Harvested 

9,900 pounds meat (1980-82) 

Harvested 

Heavy exploitation in past 
2,000/year harvested in Sicily 
Harvested 
2,000/year (1979) 
Heavy exploitation 

Harvested 

Harvested 

Harvested 

Harvested 

Harvested 

Harvested 

Extensive harvest 

Harvested 



PACIFIC OCEAN AND ADJACENT SEAS 



Aust ralia 

Hon Repos 

Capricorn /Bunker Is. 

Wreck I. 
China 
Colombia 
Indonesia 
Japan 
Mexico 

New Caledonia 
New Zealand 
Panama 



200 F/year (1967) 
1,000 F/year (1972) 
1,000 F/year (1981) 

+ 
+ 
+ 
+ 
+ 
+ 
+ 
+ 



Harvested 
Harvested 
Harvested 
Harvested 
Harvested 
Harvested 
Harvested 
Harvested 



Harvested 



INDIAN OCEAN AND ADJACENT SEAS 



Burma 

Madagascar 
Malagasy Republic 

Fort Dauphin 
Mozambique (Paradls 
Oman 

South Africa 
Sri Lanka 



I.) 



300 F/year 

300 F (1974) 
300 F (1974) 
30,000 F/year 
408 F (1978/79) 

+ 



Eggs harvested 
Harvested 

Harvested 
Harvested 



Intense Harvest 



+ turtles nest, but no population information is available 

- turtles no longer nest 

D decreasing 

F nesting females 

I Increasing 

S stable 

U unknown 



1/ Based on information from numerous literature sources 
see text references 

2/ Population trends as Inferred from literature sources 
3/ Latest date of Information if known 



40 



coastal areas. In many areas, loggerhead habitat has been 
lost, altered, or degraded by development, recreational 
activity, dredge and fill for land development, sea bed 
mining, construction and maintenance of navigation channels, 
and the discharge or spills of pollutants ( Coston-Clements 
and Hoss, 1983). Little information is available on the 
extent of this loss of habitat and how these activities 
affect loggerhead populations. However, the available 
information suggests that chemical pollution may be adversely 
affecting loggerheads and could pose a threat to their 
survival (Groombridge , 1982). 

Loggerheads may be adversely affected by the following 
activities (McFarlane, 1963; Coston-Clements and Hoss, 1983): 

1. Domestic development—includi ng artificial lighting, 
man-made barriers, rip-rap, jetties, beach cleaning and 
traffic 

2. Industrial development--thermal discharge, 
agrobusiness, radioactive waste, insect control, and trace 
metals 

3. Pollution--including spills of oil and hazardous 
materials 

4. Dredging and mining and 

5. Predators attracted to human refuse 

Among the greatest threats to loggerheads are 
development and increased use of nesting beaches by man 
(Witham, 1982). Virtually the entire coastline of Florida, 
where most loggerheads in the United States nest, is 
developed, under development, or subject to development. 
Also, only 33 miles of 88 miles of beach in Georgia are still 
suitable for nesting (Lund, 1974). 

Evidence that loggerheads do not prefer developed areas 
is also suggested by movement of turtles from developed to 
undeveloped beaches to nest. Increased nesting at Cape Sable 
in the Everglades National Park may have resulted from 
development of beaches outside the Park (Davis and Whiting, 
1977). Declines in the successful nesting attempts by 
loggerheads on Hutchinson Island have been attributed to 
urban development (Williams-Walls et jal^. , 1983). In South 
Carolina, increased nesting at Cape Romain National Wildlife 
Refuge may be connected to increased development outside the 



41 



refuge, and, at Kiawah Island, nesting was observed to be 
lowest in areas with beach homes and no restrictions on 
lighting and traffic (Shabica, 1982). Areas in the 
Mediterranean and Caribbean have been subjected to intense 
development activities such as sand mining which have 
adversely impacted nesting beaches (Sella, 1982; Groombridge, 
1982). Also, concern has been raised about the rapid 
development of a village near the largest loggerhead rookery 
in the world at Masirah Island, Oman (Groombridge, 1982). 

Other habitat alterations that affect loggerheads 
include the introduction of exotic vegetation by man on 
nesting beaches and pollution of the turtles' oceanic 
habitat. Exotic vegetation may inhibit nesting by forming 
barriers and dense root mats (Hopkins and Richardson, 
1982). The currents which accumulate sargassum weed, where 
some loggerheads may spend the early part of their life cycle 
(Pritchard, 1979), also accumulate pollutants such as oil, 
styrofoam, and other plastic (Groombridge, 1982). Numerous 
loggerhead hatchlings have been found dead or moribund along 
Florida beaches with their jaws and throats obstructed by tar 
(Groombridge, 1982). Also, pieces of a plastic bottle were 
found in a stranded loggerhead from Texas waters (Rabalais 
and Rabalais, 1980) . 

These activities remove available nesting habitat or 
reduce the quality of available habitat which may reduce 
nesting frequency or survivorship. Richardson and Richardson 
(1982) predicted that in Georgia only 389 females from the 
original cohort of 300,000 eggs will reach sexual maturity. 
Accordingly, any permanent reduction in nesting or survival 
would adversely impact the species. 

2. Overut i lization for Commercial, Scientific, or 
Educational Purposes 

The NMFS does not believe the use of this species for 
scientific and educational purposes is a cause for declines 
in stocks. In the United States, this form of take is 
regulated by a permit system designed to protect endangered 
and threatened species. Much current research in the United 
States and elsewhere mainly involves surveys of nesting 
beaches and offshore areas for the presence of turtles and is 
geared toward determining population size. Some research 
also involves hatchery rearing of sea turtle eggs and 
protection of the hatchlings from land-based predators. 
Retween 1971 and 1982, at least 67,263 hatchlings were 



42 



released by such programs in North Carolina, South Carolina, 
Georgia, and Florida (Bacon et al . , 1984). 

The Endangered Species Act prohibits commercial 
exploitation of the loggerhead in the United States. 
However, exploitation occurs in many places around the World 
(Table 3). 

There is no reported commercial exploitation of eggs, 
but local subsistence take and/or some poaching occurs 
wherever the loggerhead nests (Hopkins and Richardson, 1982). 



3. Disease or Predation 

Little is known about the diseases of loggerhead in the 
wild. However, Wolke (1981) discovered spirorchiasi s, 
enteritis, anemia, spleenitis, hepatitis, gastritis, 
nephritis, trematodiasis , myoceydilis, endocardiles , 
pneumonia, peritonitis, glomerulonephritis, nephrosis, and 
nephrocalcinosis from postmortem examinations of 52 
loggerheads from the U.S. Atlantic seaboard in March 1980. 
Larval anisakid nematodes ( Sulcascari s ) , tremadoes, and 
cestodes were also reported from loggerheads (Sey, 1977; 
Lichtenfels et al. , 1980). 



e s t i ma t e 



Predators of loggerheads have previously been 
identified. Data is insufficient for a reasonable ^o^j. 
of the extent of mortality due to disease and predation. 
However, predation of eggs by raccoons is severe along the 
southeast Atlantic seaboard of the U.S. (Pritchard, 1982b; 
Groombridge, 1982). 



4. Inadequacy of Existing Regulatory Mechanisms 

In the United States, existing regulatory mechanisms are 
believed to be adequate for the protection of loggerhead sea 
turtles. 

5. Other Natural or Manmade Factors Affecting Its Continued 
Existence 

On some beaches, natural processes may be a significant 
source of mortality to loggerhead nests (Hopkins and 
Richardson, 1982). Some nests are flooded by high tides if 
placed too low on the beach. Also, severe storms, heavy 



43 






Ity *s^» 














Loggerhead Sea Turtles 



Photos by Larry Ogren, Southeast Fisheries 
Center, National Marine Fisheries Service. 

44 



rains and high tides destroy nests. Beach erosion is another 
source of egg mortality. Hypothermia or cold shock has been 
identified as an additional source of natural mortality by 
Wolke (1981). The effects of natural events on loggerhead 
populations are unknown, but probably are not limiting for 
this species. 

Loggerheads are incidentally taken in industrial water 
intakes (Witham, 1982) and in some dredging operations (e.g. 
channel maintenance of the Port Canaveral ship channel in 
Florida where 71 loggerheads were killed by dredging in 
1980). However, the total level of this take is unknown. 
Loggerheads are also incidentally taken in fishing operations 
especially by bottom trawlers fishing for shrimp and demersal 
fish (Rabalais and Rabalais, 1980; Shoop and Ruckdeschel, 
1982). In the United States, an estimated 42,868 loggerheads 
per year are caught in shrimp trawls with an estimated annual 
mortality of 11,738 (Bacon et aj^. , 1984). Trawling 
activities also reportedly cause significant mortalities off 
the Pacific coast of Panama, the western Mediterranean 
(possibly 1,000 per year), and Colombia (Groombr idge , 
1982). Trawling probably results in the incidental take of 
loggerheads in Australia, Brazil, Guyana, Honduras, India, 
Indonesia, Mexico, Sri Lanka, and Surinam. Turtles are 
incidentally taken in net fisheries (e.g. shark nets, 
sturgeon nets, and pound nets) trap fisheries, and by hook 
and line (Crouse, 1982). The effect of incidental take on 
the survival of the species is unknown. 



Conclusions 



Since the loggerhead sea turtle was listed in 1978, 
adequate information has not been developed to assess whether 
its status has changed. Loggerhead populations throughout 
the world are still under severe pressure from local 
exploitation. Also, some populations are known to have 
declined. These include the populations in Honduras, Mexico, 
Colombia, Israel, Turkey, Bahamas, Cuba, Greece, Japan, and 
Panama (Ross, 19 82; Sella, 1982; Groombr idge, 1982). 
Accordingly, NMFS believes that based on the best available 
commercial and scientific information, the loggerhead sea 
turtle should remain listed as threatened throughout its 
range. 



45 



KEMP'S RIDLEY SEA TURTLE 



(L«pldeeh«ly« k«mpl) 






46 



Kemp's Ridley Sea Turtle 
( Lep idochelys kempi ) 



Biological Background 

In various parts of its range, the Kemp's ridley sea 
turtle also may be called the tortuga lora del Atlantico, 
Atlantic ridley, Mexico ridley, grey loggerhead, tortuga boba 
and bastard turtle (Pritchard et a.l . , 1983). Distinguishing 
features are two pairs of prefrontal scales (scales found 
between the nasal opening and the eye sockets) on the head; 
five or more pairs of large boney plates along the margin of 
the upper shell with the first pair touching the 
f oreward-mos t plate in the middle of the upper shell; paddle 
shaped limbs with one claw; and pores along the smaller 
plates bordering the upper and lower shells (Pritchard and 
Marquez, 1973). The shell is heart-shaped to round and may 
be shades of gray brown, black, or olive. The underside is 
white in hatchlings and yellowish in adults. 

As adults, the ridleys are the smallest of all sea 
turtles. They usually weigh between 86 and 109 pounds, and 
their shells usually range between 20 and 28 inches long. 
Although subadult males and females look alike externally, 
the adult male's tail extends some distance beyond the rear 
edge of the shell while the adult female's tail barely 
extends beyond this edge (Pritchard and Marquez, 1973). 

Although ridleys maya be long-lived in the wild, 
longevity is not known. In captivity, a life span of over 20 
years has been observed (Ernst and Barbour, 1972). At sexual 
maturity, which likely takes six or more years, ridleys have 
a carapace length of about 26 to 27 inches and weigh about 80 
pounds (Pritchard and Marquez, 1973; Pritchard, 1979). 

Kemp's ridleys eat crabs, fish, jellyfish, squid, 
snails, clams, starfish and probably some marine vegetation 



47 



(Pritchard and Marquez, 1973; Hildebrand, 1982). Predators 
of adult turtles include primarily man and sharks; predators 
of eggs and hatchlings include man, coyotes, crabs, vultures, 
jackfish, red drum, and sharks (Pritchard and Marquez, 
1973). Hatchling ridleys (probably olive ridleys) have also 
been found in the stomach of a leatherback turtle (Rebel, 
1974). Survivorship of Kemp's ridleys from eggs to adults is 
very low (Marquez, et al . , 1982). 

This species prefers sheltered areas along coasts and 
frequents larger estuaries, bays, and lagoons. Based on 
favorable temperatures, prevailing currents, and abundant 
food, the estuaries and offshore waters of Louisiana may be a 
primary developmental area and feeding ground (Hildebrand, 
1982). The Tabasco-Campeche area of the Gulf of Mexico is 
also a major feeding ground (Carr et al . , 1982). The 
Atlantic coast of the U.S. may also be a part of the 
developmental and foraging range of the species. 

Adult Kemp's ridleys have been recorded mainly from the 
Gulf of Mexico from Florida to the Mexican border and around 
the Bay of Campeche. Juveniles occur in the same general 
area, but are also found along the Atlantic coast of the U.S. 
from Florida to New England (Lazell, 1980). Juveniles are 
also reported from European shores and the Mediterranean Sea 
(Brongersma, 1982). Kemp's ridleys in the Atlantic Ocean and 
Mediterranean sea may have been passively carried from the 
Gulf of Mexico and northward in the Gulf stream (Groombr idge, 
1982). The fate of ridleys carried away from the Gulf of 
Mexico is unknown. They may migrate back to the Gulf of 
Mexico to mature and breed or they may be unable to return to 
the Gulf and are lost to the reproductive portion of the 
population ( Hendrickson , 1980; Groombridge, 1982). 

Before its depletion began in the 1940 's, Kemp's ridley 
was an abundant species along the Atlantic seaboard of the 
U.S. from Florida to Massachusetts. Also, it occurred 
regularly in New England waters and is still reported to be 
seasonally common in Massachusetts (Lazell, 1980). 

Nesting is mainly restricted to a stretch of beach from 
Baha Coma to Boca San Vincente near Rancho Nuevo, Tamaulipas, 
Mexico (Pritchard and Marquez, 1973). Occasional nesting has 
been reported at Padre Island, Texas, and scattered nesting 
reported at southern Veracruz, Mexico (Carr et al . , 1982; 
Hopkins and Richardson, 1982). Marquez et al . (1982) 
reported that on May 20, 1979, 20-30 nesting females came 
ashore at Lauro Villar near the border between Mexico and 



48 



Texas (about 140 miles north of Rancho Nuevo). See Figure 4 
for locations. 

Nesting occurs in aggregations called arribadas (meaning 
arrival) between April and mid-August during optimal weather 
conditions such as cloudy, relatively cool days with a strong 
north wind (Pritchard, 1979). Most returning females nest on 
a one or two year cycle laying one to three clutches per 
season at intervals of 20-28 days (Hirth, 1980). However, 
most females are observed nesting only one time (Hughes, 
1982). For example, of 1,038 females tagged in Mexico, only 
17 returns were observed (Hughes, 1982). Clutches average 
110 eggs (Pritchard, 1979). Incubation takes between 50 and 
70 days with most hatchlings emerging about dawn after 53-56 
days (Pritchard, 1979). Hatchlings enter the sea and swim 
actively ("swimming frenzy") for hours or days after which 
they drift with the currents and perhaps at times become 
associated with rafts of floating sargassum weed (Pritchard, 
1979). It is not known how long it takes for these turtles 
to begin active swimming and diving. 



Population Size 

In 1947, about 40,000 turtles nested in one arribada 
(Pritchard and Marquez, 1973). The number of nesting females 
declined to about 5,000 in the mid 1960's; the largest 
arribadas in 1970 and 1971 consisted of 2,000 to 2,500 
turtles; and in 1973, the largest arribada included about 
1,000 turtles (Pritchard and Marquez, 1973; Groombridge, 
1982). By 1975, only about 500 females nested (Carr et al. , 
1982). Carr (1977) estimated the number of mature ridleys at 
162,400 in 1947, 10,150 in 1970, and 4,872 in 1974. 
Estimates of nesting females since 1975 are 656 in 1978; 754 
in 1979; 693 in 1980; 705 in 1981; and 621 in 1982 (Bacon et 
al . , 1984). There are no reliable estimates of the number of 
Kemp's ridleys of all developmental stages (i.e., the total 
population) . 



Listing Factors 

1. The Present or Threatened Destruction, Modification or 
Curtailment of its Habitat or Range 

Since 1966, the Kemp's ridley nesting beach in Mexico 
has been protected with armed patrols. Moreover, the beach 
is remote and has not been developed yet. This area, Playa 



49 




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50 



de Rancho Nuevo, is one of seven proposed nature preserves 
along the Mexican coast (Marquez, 1972; Groombridge, 1982), 
and, presumably, it will be protected from development. 
Accordingly, the nesting habitat is not yet threatened by 
destruction or modification. 

In its oceanic environment, the Kemp's ridley may be 
adversely affected by the following activities and substances 
(Coston-Clements and Hoss, 1983): 

A. Pollutants from industrial and residential 
development. These include oil, pesticides, herbicides, 
radionuclides, PCB's, heavy metals, and sewage. The effects 
of pollutants are difficult to detect and evaluate, except 
for oil and tar balls that are known to have killed ridleys 
by fouling and/or ingestion. The other contaminants may 
cause physiological problems that can reduce the reproductive 
success of this species. Frazier (1980) questions whether 
the decline of Kemp's ridley is related to pollution 
discharges from the Mississippi River. 

B. Exploratory oil and gas drilling. These activities 
may affect ridleys by attracting them to lighted platforms 
where they may be susceptible to increased predation; by 
disrupting feeding habitat when disposing of drilling muds 
and sediments; and by discharging oil which may contaminate 
turtles and cause irritation or permanent damage to eyes, 
affect respiration, and produce abnormal behavior, etc. 

C. Disposal of garbage at sea. Plastic and other 
foreign materials that are ingested by turtles may cause 
death. Also, turtles may be fouled by plastic which could 
adversely affect survival if the animals are unable to shed 
the plastic. Additionally, turtles attracted to refuse may 
be subjected to more predators such as sharks which may also 
be attracted to the refuse. 

D. Dredge and fill. These activities may affect 
habitat that turtles use or the equipment (e.g. dredge cutter 
head) may harm or kill turtles if encountered during the 
dredging operation. Louisiana estuaries, which may be 
important developmental habitat, are being lost at a rate of 
39 square miles per year (Fruge, 1981). This is due mainly 
to land subsidence (sinking), canal construction, wetland 
reclamation, sediment starvation, and natural and man-induced 
erosion primarily from oil and gas exploration. Other 
estuaries, such as those on the Atlantic coast of the United 
States, may also provide developmental habitat, but they are 



51 



also subject to dredging and filling. However, we do not 
know the amount of habitat loss in these areas and its effect 
on sea turtles. 

E. Power boats. Power boats can injure or kill sea 
turtles . 



2. Overu til iza t ion for Commercial, Recreational, Scientific 
and Educational Purposes 

Several factors such as intensive predation on eggs by 
local people and coyotes, fishing for juveniles and adults, 
and killing nesting adults for meat and leather led to the 
decline of Kemp's ridley (Pritchard, 1979; Groombridge, 
1982). Exploitation for eggs and meat is now illegal and, 
presumably, the directed take of this species has been 
reduced . 

Since the scientific research on endangered species is 
controlled by a permit system based on provisions of the ESA, 
taking of Kemp's ridleys for research is not considered to 
adversely impact this species. 



3. Disease or Predation 

Diseases and parasites identified for ridleys include 
barnacles, hepatitis, nematodiasis and nephrosis (Wolke, 
1981). Predators of eggs, hatchlings, juveniles, and adults 
have previously been identified. We do not know the level of 
mortality from disease and predation, and, consequently, the 
impact on the population. 



4. Inadequacy of Existing Regulatory Mechanisms 

In the United States, the Kemp's ridley is protected by 
the Endangered Species Act of 1973 (35 FR 18310) and has been 
protected in Mexico since 1966. The species is also listed 
under Appendix I of CITES, and trade of all Kemp's ridley 
products are banned. Existing regulatory mechanisms are 
believed to be adequate for the protection of Kemp's 
ridley. However, this species has been reduced to such low 
numbers that it may not recover (Groombridge, 1982). 



52 




Kemp's Ridley Sea Turtles. 



Photos by Larry Ogren , Southeast Fisheries 
Center, National Marine Fisheries Service. 

53 



5. Other Natural or Manmade Factors Affecting its Continued 
Existence 

During nesting seasons, severe weather conditions such 
as storms and heavy rains could damage the production of eggs 
and hatchlings. Some turtles also die of hypothermia when 
trapped in areas where water temperature drops too low 
(Lazell, 1980). However, the effects of these natural forces 
on the population are not known. 

Subadults and adults are taken by hook-and-li ne 
fishermen and are incidentally caught in shrimp trawls, shark 
nets, pound nets, etc. (Chavez, 1969; Groombridge, 1982; 
Bacon et al . , 1984). There are too few data to reliably 
estimate the numbers caught or killed by hook and line, shark 
nets, and pound nets. In U.S. waters, the incidental take of 
Kemp's ridley sea turtles in shrimp trawls was estimated to 
be 843, of which 27 5 died, each year from 1980 to 1982 (Bacon 
JLlL iLL* ' 1^84). Kemp's ridleys are also susceptible to being 
taken by industries such as power plants that have sea water 
intakes. Power plants located from Florida to New Jersey 
have reported the incidental catch of sea turtles by their 
cooling systems ( Coston-Clements and Hoss, 1983). 



Conclusion 

A number of man-induced and natural factors have 
drastically reduced the number of nesting females (estimated 
at 42,000) in the 1940s. Estimates of nesting females were 
only 680 in 1977, 656 in 1978, 754 in 1979, 693 in 1980, 705 
in 1981, and 621 in 1982 (Bacon et al. , 1984). Despite the 
conservation efforts that have been undertaken since 1966, 
this species has been so drastically depleted that recovery 
may not be possible (Groombridge, 1982). 

In 1963, a private effort was begun to transplant ridley 
eggs to Texas beaches to start a new nesting population 
(Lund, 1974). This was superseded in 1978 by an interagency 
effort between the U.S. Fish and Wildlife Service, NMFS, 
National Park Service, Texas Parks and Wildlife Department, 
Florida Audubon Society, and the Mexican Government (Hopkins 
and Richardson, 1982). This interagency program called for 
increased protection of the nesting beach, an attempt to 
establish a breeding site at Padre Island, Texas, by 
transplanting eggs, and head-starting ridleys by raising them 
for about a year at the NMFS Galveston Laboratory before 
their release. Between 1978 and 1982, 17,855 hatchlings were 



54 



headstarted in the U.S. and Mexico and released in the Gulf 
of Mexico (Bacon et al . , 1984). The benefit of these 
programs cannot yet be determined since these projects need 
to run for a long time before their effect on the Kemp's 
ridley population can be assessed (Pritchard, 1981). 

If widely used, the Trawling Efficiency Device (TED) 
developed by the National Marine Fisheries Service would 
reduce the number of Kemp's ridleys incidentally taken in 
shrimp trawls by more than 90 percent. 

The best available commercial and scientific information 
indicates that the Kemp's ridley sea turtle is severely 
depleted and in danger of extinction. Therefore, this 
species should continue to be listed as an endangered species 
throughout its range. 



55 



OLIVE RIDLEY SEA TURTLE 



<L«pl4oeh»ty» otfvac**) 





56 



Olive Ridley Sea Turtle 
( Lep idochelys olivacea ) 



Biological Background 

In various parts of its range, the olive ridley sea 
turtle also may be called tortuga golfina, tortuga bestia, 
manila, mani, batali, Pacific ridley, warana, tortue 
olivatre, xibirro, carpintera, penyu lipas, penyu rantau, and 
penyu abu abu (Pritchard and Trebbau, 1984; Pritchard et al . , 
1983; Tow and Moll, 1982; Suwelo et aj.. , 1982). Its 
appearance is similar to the Kemp's ridley, but it has a 
thinner, more narrow shell and a smaller, more lightly built 
skull. The upper shell also is generally higher than Kemp's 
ridley and has a greater variation in the number of plates 
(five to nine pairs). Other characteristics are two pairs of 
prefrontal scales (scales found between the nasal opening and 
the eye sockets) ; a pore near the rear of the plates 
bordering the upper and lower shells; and shell plates that 
do not overlap (Pritchard e_t jal_. , 1983). The shell is 
heart-shaped to round and may be gray brown, black, or 
olive. The underside of adults is usually yellow but is 
white in immature turtles and grey to black in hatchlings. 

As adults, the olive ridleys are the smallest of the sea 
turtles. They may weigh as much as 100 pounds with shells 
generally between 24 and 30 inches long. Although subadult 
males and females look alike externally, the adult male's 
tail extends some distance beyond the rear edge of the shell 
whereas the adult female's tail is much shorter (Pritchard et 
al . , 1983). Males also have one of two claws on each 
forelimb enlarged and strongly curved (Pritchard and Trebbau, 
1984). 

Olive ridleys may be long-lived in the wild, but exact 
longevity is not known. At sexual maturity, which likely 
takes at least seven to nine years in wild populations, the 



57 



shell usually is about 24 to 25 inches long (Cornelius and 
Robinson, 1983), and the turtle weighs about 80 pounds 
(Pritchard, 1979). 

This turtle has been observed eating fish, crabs, 
snails, oysters, jellyfish, sea urchins, fish eggs and 
vegetation (Ernst and Barbour, 1972). Olive ridleys are 
believed to be capable of feeding far offshore and forage at 
great depths (Groombridge , 1982). Predators of adults are 
primarily man, sharks, and large cats such as jaguars and 
cougars on particular beaches. Hatchlings and/or eggs fall 
prey to man, crabs, birds, fish and other mammals such as 
coyotes, pigs, coatimundi, and feral dogs (Dodd, pers. 
comm. ) . Survivorship from eggs to adults is probably very 
low (Marquez et al. , 1982). 

Preferred habitats are tropical bays and lagoons. In 
the South Atlantic, primary foraging areas are located 
between French Guiana and Venezuela and along the west 
African coast between Congo and Mauritania. In the Indian 
Ocean, foraging areas are found along Mozambique, east 
Africa, Madagascar, Sri Lanka, and the east coast of India. 
In the Pacific Ocean, the main foraging areas are between 
Columbia and Mexico, along the northern coast of Australia, 
Vietnam, Malaysia, and Indonesia, (Ernst and Barbour, 1972; 
Rebel, 1974). 

Nesting sites have been identified throughout tropical 
areas around the world (Figure 5). Major nesting beaches are 
located along the Pacific coast of Mexico and Costa Rica and 
the east coast of Malaysia (Sternberg, 1981). In the 
Atlantic Ocean, the main nesting beaches are in Surinam 
(Bacon et al . , 1984). India, Pakistan, Mozambique and the 
Andaman Islands have major nesting aggregations within the 
Indian Ocean (Ross, 1982; Sternberg, 1981). 

Nesting usually occurs in aggregations called arribadas 
(meaning arrival) on mainland beaches during nights with 
strong winds (Groombridge, 1982). Specific nesting times 
vary with location. For example, nesting occurs year-round 
in Costa Rica (Dodd, pers. comm.), between June and July in 
Surinam, into August in Pacific Mexico, and from September to 
November in other areas of the East Pacific (Pritchard, 1979; 
Cliff ton et al. , 1982). Females usually nest in intervals 
ranging from 14 to 48 days, depositing two to three (average 
1.4 in Surinam) clutches of eggs (Groombridge, 1982). Mean 
clutch size varies usually between 105 and 116 eggs which 
hatch in 50 to 70 days (Groombridge, 1982). Most hatchlings 



58 




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59 



emerge at night and little is known about the juvenile and 
subadult phases of the life cycle since these stages have 
been only rarely observed at sea. Most returning females 
nest annually, but remigrations (return of females to nest in 
succeeding years) have been observed in 2, 4, 5, and 6-year 
intervals (Hughes, 1982). 



Population Size 

The population data presented in Table 4 are based on 
information from sources in Sternberg (1981), Bjorndal 
(1982), Groombridge (1982), Cornelius and Robinson (1983), 
Bacon et al . (1984), Pritchard and Trebbau (1984), and 
others. There is not enough systematic information to allow 
separation of olive ridleys into taxonomic subunits. 
However, geographically and genetically different populations 
likely exist. Therefore, consideration of this species as 
other than a single species is ill advised and for purposes 
of this review, the species is considered a single population 
in the Indo-Pacific region and eastern Atlantic, and a single 
population in the western Atlantic. 

The population levels of olive ridleys that existed 
before commercial exploitation or the numbers that now exist 
are not known. Insight can only be gained into the decline 
of these turtles based on the number of nesting females (sex 
ratios have not yet been determined so the number of males 
cannot be determined). Also, no information is available on 
the number of hatchlings, juveniles, and subadults in the 
water. The decline in nesting females and the low frequency 
of encounters with turtles in the wild provides inferential 
evidence that populations are generally declining. For 
example, of all known nesting locations, only in Australia (a 
minor nesting location) is the population considered stable. 

Where more complete information is available, especially 
in the major nesting regions, alarming declines in the 
remaining olive ridley populations are evident. Pacific 
Mexico supported an estimated 10 million adults before 1950; 
an estimated 1,185,000 adults (including 593,667 females) 
prior to 1969; and 485,000 adults in 1976 (Cliff ton et al. , 
1982). In the early 1970s, between 179,000 and 400,000 
nesting females arrived at various beaches in Mexico 
(Groombridge, 1982). Only the Oaxaca beaches (La Escobilla) 
still support large-scale nesting populations (Cliffton e t 
al . , 1982). The breeding populations at other Mexican 
beaches have reportedly all but disappeared (Cliffton et al . , 



60 



Table 4. Population information, population trends and 
exploitation of the olive ridley sea turtle 
( Lepidochelys olivacea ) 1/ 



ATLANTIC OCEAN AND ADJACENT SEAS 



Location 


Population Information 


Trend 2/ 


Exploitation 




Angola 


♦ 


U 


Mainly egga harvested 




Brazil 


+ 


U 






French Guiana 


♦ 









Guyana 


+ 


D 






Senegal 


+ 


U 






Surinam 


550 F (1977) J/, *50 P (1978), 

400 F (1979), 500 F (1980), 
600 F (1981)1 400 F (1982) 


D 






Venezuela 


+ 


D 








PACIFIC OCEAN AND ADJACENT SEAS 






Australia 


+ 


S 






Colombia 


♦ 


U 






Coaca Rica 


S 








Nanette 


221,000 F/yaar (1982) 









Ostional 


260,000 - 435,000 F/year (1982) 


D 


Intensive egg harvest 




Ecuador 


- 


D 


290,000 - 320,000 adulta (1978-1981) 




El Salvador 


♦ 





Harvested 




Guatemala 


♦ 


D 


Commercial egg harvest 




Indonesia 


♦ 


U 


Harvested 




Honduras 


3,000 F/ye*r 


D 


Harvested 




Malayaia (Eaat Coast) 


♦ 





305,000 eggs/year harvested 




Mexico 


79,900 adulta (1983) 


D 


100,000 turtles/season 




Nicaragua 


12,475 F (1982) 


D 


100,000 eggs harvested (1983) 




Panama 


♦ 


D 






Papua New Guinea 


♦ 


D 


Harvested 




Peru 


♦ 





Harvested 




Philippine* 


+ 


D 


Harvested 




Thailand 


+ 


D 


Harvested 





61 



Table 4. (continued) 



INDIAN OC&AN AND ADJACENT SEAS 



Burma 


+ 


D 


Harvaated 


India (Orlaaa) 


300,000 P/year 


D 


Intensive Harvest 


Indonesia 


+ 


D 




Laccadivaa 


+ 


U 




Madagaacar 


+ 


D 


Harvested 


Mozambique 


500 - 1,000 neeta/year 


D 




Oman (Maalrah I.) 


150 P/year 


D 


Harvaated 


Paklatan 


+ 


U 




Reunion 


♦ 


u 




Sri Lanka 


Savaral thouaand P/year 


D 


Harvaated 


Tanzania 


♦ 


U 





+ turtlea neat, but no population information la available 

turtle* no longer neat, but found In adjacent vatera 

D decreaalng 

P neatlng femalea 

I lncreaalng 

S atabla 

U no Information 

W Baaed on information from numeroua literature aourcea ~ aee text referencea 
2/ Population tranda aa Inferred from literature aourcea 
3/ Laceat date of Information If known 



62 



19 82). More recent population estimates for adult olive 
ridleys from the Pacific coast of Mexico are 153,300 in 1981, 
164,200 in 1982, and 79,900 in 1983 (Woody, pers. comm. ) . 

The Surinam population of olive ridleys apparently has 
undergone a startling decline in the number of nesting 
females over the years (Bacon et al . , 1984; Pritchard and 
Trebbau, 1984). The nesting population estimated at 2,100 to 
3,000 females in 1967-68, dropped to an estimated 550-800 
females in 1978 and 1979 (Schulz, 1982). Population 
estimates are 550 nesting females in 1980, 600 in 1981, and 
only 400 in 1982 ( Bacon et al_. , 1984). The survival 
prospects for this population is poor possibly because of 
killing of turtles in shrimp trawls (Schulz, 1982) and an 
active market for skin in the leather trade (Hemley, 1984; 
Roet, 1984). Even with protection, the olive ridley 
population has dropped to low levels. Also, physical changes 
in the nesting beaches may present a problem. Erosion and 
deposition occur constantly. Presently, turtles must cross 
extensive soft mud flats to reach the beach (Pritchard, pers. 
comm.). These environmental changes may inhibit future 
nesting by the olive ridley at Surinam. 

Nesting populations at Nancite and Ostional, Costa Rica, 
were considered fairly secure. However, the nesting 
population at Ostional has dropped about 30 percent, probably 
due to egg poaching. The nesting population at Nancite is 
plagued by extremely low egg survival (Groombr idge , 1982). 
Between 15 and 30 percent of eggs deposited during one 
arribada may be destroyed by turtles nesting later 
(Cornelius, 1982). Also, hatchling success may be lower than 
one percent largely due to actions of ghost crabs, dipterans, 
and infections by bacteria and fungi (Groombr idge , 1982; 
Cornelius and Robinson, 1983). 

Populations in India and Sri Lanka also may be 
declining. Although sea turtles are protected there, the 
poaching of eggs and adults is active, especially at Orissa 
and West Bengal. Kar and Bhaskar (1982) believe that all the 
sea turtle populations in India and Sri Lanka are declining 
steadily. Even though sea turtles are protected, enforcement 
of laws protecting these animals is poor. 



63 



Listing Factors 

1. The Present or Threatened Destruction, Modification or 
Curtailment of its Habitat or Range 

Little information is available on effects of habitat 
alterations on the olive ridley. Some recently cited adverse 
impacts include development in the vicinity of Hawkes Bay and 
Sandspit beaches in Pakistan for holiday accommodations that 
is encroaching on the nesting area (Ross, 1982) and driftwood 
washing up at Sarawak often blocks access to the nesting 
beaches (Groombridge , 1982). Nevertheless, within its 
distributional area, olive ridleys should be adversely 
affected by habitat alterations to the same degree as other 
sea turtles. The following list is provided as an example of 
activities and substances that may adversely affect the olive 
ridley sea turtle (Coston-Clements and Hoss, 1983). 

A. Pollutants from industrial and residential 
development. These include oil, pesticides, herbicides, 
radionoclides, PCB's, heavy metals and sewage. The effects 
of pollutants are difficult to detect and evaluate, except 
for oil and tar balls that are known to have killed ridleys 
by fouling and/or ingestion. The other contaminants may 
cause physiological problems, such as reducing the 
reproductive success of this species. 

B. Exploratory oil and gas drilling. These activities 
may affect ridleys by attracting them to lighted platforms 
where they may be susceptible to increased predation; by 
disrupting feeding habitat when disposing of drilling muds 
and sediments; and by discharging oil which may contaminate 
turtles and cause irritation or permanent damage to eyes, 
affect respiration, and produce abnormal behavior. 

C. Disposal of garbage at sea. Plastic and other 
foreign materials that are ingested by turtles may cause 
death. Also, turtles may be fouled by plastic which could 
adversely affect survival if the animals are unable to shed 
the plastic. Additionally, turtles attracted to refuse may 
be subjected to more predators such as sharks which may also 
be attracted to the refuse. 

D. Dredge and fill. These activities may affect 
habitat that turtles use, or the equipment (e.g. dredge 
cutter head) may harm or kill turtles if encountered during 
the dredging operation. 



64 



E. Power boats. Power boats can injure or kill sea 
turtles. 



2. Overut ilization for Commercial, Recreational, Scientific, 
and Educational Purposes 

The use of olive ridleys for scientific and educational 
purposes, while unquant if ied, is small and not a contributing 
factor in population declines. Research is geared toward 
enhancing populations, and, therefore, benefits rather than 
harms the species. 

The local and commercial harvest (Table 4) of olive 
ridley populations for meat, leather, and eggs ( Groombr idge, 
1982) is the primary cause of depletion. For example, this 
species is the most economcially important sea turtle in 
Mexico where legal and illegal fisheries exist ( Groombr idge , 
1982). In the five years prior to 1969, Cliffton et al. 
(1982) estimated that at least 2,000,000 olive ridleys were 
landed by the legitimate commercial fishery. About 70,000 
turtles were taken from La Escobilla in 1977, 58,000 in 1978, 
and 24,500 in 1979 ( Groombr idge , 1982). The main turtle 
processing plant in Mexico was nationalized in 1981. 
Subsequently, the turtle quota set by the Mexican government 
for the 1981/82 season was increased by 72 percent over the 
previous season and allowed a take of 69,000 turtles (Mack, 
1983). By December 1981, 56,000 turtles had been taken 
(Hemley, 1984). The quota for the 1983/84 season was set at 
50,000 turtles. Only 26,000 turtles were taken by December 
1983, and an additional 2,000 were taken by the end of 
January 1984 (Hemley, 1984) suggesting a substantial decline 
in availability. The legal commercial harvest in Mexico is 
overshadowed by poaching; Cliffton et ^]^. (1982) indicate 
that millions of eggs and thousands of animals are taken 
illegally each year— an estimated one million eggs were 
poached at La Escobilla in 1969 alone. 

From 1970 to 1977, between 132,000 and 147,000 adults 
were harvested in Ecuador for the international skin trade 
(Green and Ort iz-Crespo, 1982). From 1978 to 1981, the 
harvest increased to between 290,000 and 320,000 adults as 
estimated from the weight (approximately 1,273,000 pounds) of 
skins that were exported (Hurtado, 1981). Although Ecuador 
banned the export of turtle products in 1981, Japan imported 
from Ecuador 18,623 pounds of skin in 1981, 74,272 pounds of 
skin in 1982, and 6,600 pounds of skin thru October 1983. 
While commercial exploitation has at least slowed in Ecuador, 



65 






^-- , „«— jfcg — - . .rwr ■'"...•.- -' *..".' 






«| 





Olive Ridley Sea Turtles: 



Photos by Dr. Peter Pritchard, 
Florida Audubon Society. 

66 



there are some indications that this activity has now shifted 
to Colombia (Dodd, pers. comm. ) . 

In India, _L. olivacea populations are being depleted 
primarily by illegal harvest of eggs and turtles for food and 
by human colonization of many nesting beaches (Kar and 
Rhaskar, 1982). Apparently, thousands of turtles are taken 
yearly off the coast of Orissa, one of the largest remaining 
breeding colonies of L_. ol i vacea in the world (Kar and 
Bhaskar, 1982). This take is reportedly increasing (Bobb, 
1982). Also, more than 100,000 eggs were reportedly taken in 
1982 at Gahirmatha alone and sold in Calcutta (Bobb, 1982). 

In other areas where olive ridleys are found, such as 
Pakistan and Sri Lanka, the take of turtles for human 
consumption is very large (Kar and Bhaskar, 1982). Also, 
hundreds of thousands of eggs are removed from Ostional 
Beach, Costa Rica, each year (Cornelius, 1982). The removal 
of virtually all of the olive ridley eggs at Eilanti, 
Surinam, by the Carib Indians up until the late 1960s 
(Pritchard and Trebbau, 1984) may have caused the drastic 
decline there. 



3 . Disease or Predation 

Diseases and parasites of olive ridleys are not well 
known. Predators of eggs, hatchlings, juveniles, and adults 
have previously been identified. At Nancite, Costa Rica, an 
extremely low percent hatch rate has been attributed to 
bacterial and/or fungal contamination (Dodd, pers. comm.). 
The level of mortality from disease and predation and the 
effect on the species are unknown. 



4 . Inadequacy of Existing Regulatory Mechanisms 

In the United States, the olive ridley is protected by 
the Endangered Species Act of 1973. It is listed as 
threatened throughout the world, except the breeding colony 
populations on the Pacific coast of Mexico which are 
endangered. The species is also listed on Appendix I of 
CITES which bans the trade of its products. Some large 
importers, such as Japan, have taken reservations on this 
species which means they still import products from olive 
ridleys. 



67 



Nominal protection is afforded by legislation in much of 

its range, but enforcement is often poor to non-existent. 

Accordingly, the prospects for reducing the continued take of 
this species is poor. 



5 . Other Natural or Manmade Factors Affecting Its Continued 
Exi stence 

The effects of natural forces on the continued existence 
of the olive ridley are not known. However, natural forces 
that affect olive ridleys, especially during the nesting 
process, include storms, temperature, rain, and wave surge. 
These forces can create beach erosion or accretion, prevent 
turtles from nesting, destroy eggs and hatchlings and reduce 
nesting success. The build up of a huge mud flat in front of 
the major olive ridley nesting beach in Surinam may pose a 
threat to the population nesting there (Pritchard and 
Trebbau, 1984). 

An additional threat in parts of this turtle's range is 
incidental catch by shrimp trawlers. This is considered to 
be serious in the Pacific and in the Atlantic and is believed 
to be a factor in the decline of the olive ridley in Surinam 
(Schulz, 1982; Roet, 1984). Other fishing gears are also 
believed to take olive ridleys (Pritchard, 1982). 

Few, if any of the activities and their effects outlined 
above have been quantified; thus an evaluation of their 
impact, both singular as well as cumulative, cannot be made 
at this time. 



Conclusions 

Overexploitat ion for its meat, skin, and eggs; 
incidental take in various fisheries; and alteration of 
nesting habitats has led to the depletion of the olive ridley 
throughout much of its range. These factors continue to 
deplete this sea turtle. 

The NMFS believes the best available scientific and 
commercial data indicate that most olive ridley populations 
are experiencing declines. Information generated since the 
species was listed is insufficient to warrant a change in the 
listing status with the exception of the nesting populations 
in the western Atlantic (i.e. Surinam and adjacent areas) 
where the population has declined more than 80 percent since 



68 



1967. Accordingly, it is our opinion that the current 
threatened and endangered status of the olive ridley should 
remain unchanged except that the nesting population in the 
western North Atlantic (Surinam and adjacent waters) should 
be reclassified as endangered. This change in listing is 
supported by numerous scientists and conservationists working 
on sea turtle biology (e.g. Pritchard, pers. comm. ; Dodd, 
pers. comm.; Ogren, pers. comm.; Carr, 1984; Meylan, 1984; 
Bjorndal, 1984). 

The NMFS in coordination with the Fish and Wildlife 
Service should initiate appropriate action to propose the 
above change in listing status. 



69 



LEATHERBACK SEA TURTLE 



(Dirmoe 






70 



Leatherback Sea Turtle 
( Dermochelys coriacea ) 



Biological Background 

In various parts of its range, the leatherback is 
commonly called the tinglada, leathery turtle, trunk turtle, 
trunkback turtle, tortue luth, coffin back, siete filos, 
chalupa, baula o laud, aitkanti, and tartaruga de couro 
(Pritchard ^t_ al_. , 1983) and luth (Rebel, 1974). It is 
distinctive from other sea turtles and belongs to the family 
Dermochelyidae. Characteristic anatomical features include a 
barrel-shaped body covered with leathery skin (rather than 
hard plates) ; a shell with five to seven ridges or keels 
running lengthwise; an underside usually with five 
longitudinal ridges; and very large front flippers 
(Pritchard, 1971). It is usually black or dark brown on top, 
white underneath, and often has white spots on the dorsal 
surface (Pritchard, 1979). 

Leatherbacks are the largest sea turtles with adults 
measuring between five and six feet long and weighing about 
800 pounds (Pritchard, 1979); the maximum weight is about 
1300 pounds (Pritchard, 1979). There is little external 
morphological difference between sexes, but the adult males 
have longer tails than females. Because tagging programs 
have not been conducted long enough or with sufficient 
intensity to obtain age and growth data in the wild 
(Pritchard, 1971), little is known about the lifespan of the 
leatherback. 

This sea turtle eats primarily soft foods such as 
jellyfish and tunicates. On one occasion, hatchling ridley's 
were found in a leatherback stomach from Pacific Mexico 
(Rebel, 1974). 



71 



Predators of adult leatherbacks include man, killer 
whales, sharks, and large cats such as jaguars (Pritchard, 
1971; Bacon e_t _al_. , 1984). Eggs and hatchlings are eaten by 
man, pigs, mongooses, dogs, ants, lizards, birds, crabs and 
fish (Pritchard, 1971; Hopkins and Richardson, 1982). 

Leatherbacks have a circumglobal distribution and occur 
in the Atlantic, the Indian, and the Pacific Oceans 
(Groombr idge , 1982). The species nests primarily on beaches 
between 30 degrees north and 20 degrees south (Figure 6), but 
regularly moves into temperate seas to feed. Leatherbacks 
commonly range farther north than other sea turtles probably 
because of their ability to maintain warmer body temperatures 
over longer time periods (Frair, e_t_ jal_. , 1972). 

In the Atlantic, the leatherback regularly occurs off 
New England (especially Massachusetts and the Gulf of Maine) 
and in the Gulf of Mexico off the United States (Lazell, 
1980; Leary, 19 57). Also, they have been reported from 
Canada, the British Isles, Iceland, Europe, Spain (Pritchard, 
1971; Brongersma, 1982), and Mar del Plata, Argentina to the 
south (Carr, 1952). In the Pacific, the species has been 
recorded along the coast of South America, (especially 
between Peru and Ecuador) as far north as Alaska in the 
United States, off Australia, south of New Zealand, as far 
north as the South China Sea, and occasionally in the Yellow 
Sea (Chu-Chien, 1982; Groombridge, 1982). 

More preferred nesting beaches for leatherbacks are 
located on mainland shores (Pritchard, 1971). Coarse sand 
beaches free of large debris and rocks and adjacent to deep 
water are apparently preferred nesting sites. Although most 
females nest up to seven times per season, a few nest eight 
or nine times. The interval between nestings during one 
season is usually from seven to 13 days (Pritchard, 1971). 
Clutch sizes are variable, but usually contain between 50 and 
160 eggs that hatch in 60-70 days (Pritchard, 1979). There 
is little information on the period between nesting seasons, 
but some leatherbacks are reported to wait two to three years 
before nesting again (Rebel, 1974). Most females tagged 
while nesting for the first time are never seen again 
(Hughes, 1982). 

The nesting season varies according to location. For 
example, nesting has been reported in Surinam and Guyana from 
May to early June (Pritchard, 1969); in Costa Rica from April 
to mid July (Carr and Ogren, 1959); in Trinidad from March to 
August (Bacon, 1970); in the West Indies from March to May 



72 




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73 



(Schmidt, 1916); and in Tongaland, Natal from November to 
February (Hughes et al. , 1967). 

Population Size 

Carr et_ al_. (1982), Bjorndal (1982), Groombridge (1982), 
Bacon e_t _al_. (1984), and the papers by Dr. P. C. H. Pritchard 
provide information about nesting females in various areas 
throughout the world. These are summarized in Table 5. 
Population estimates for leatherbacks are generally available 
only for nesting females. Nesting females, nests, and crawls 
can be readily observed. Since males, juveniles, and 
hatchlings stay at sea, they are rarely observed and thus are 
difficult to count (Groombridge, 1982). 

Fitter (1961) estimated that 1,000 pairs of leatherbacks 
existed in the world. However, based on the discovery of 
additional nesting beaches, Pritchard (1971) estimated that 
about 4,000 leatherbacks nested at Trengganu, Malaysia; 
15,000 in French Guiana; at least 1,000 at Matina Beach, 
Costa Rica; 200-400 each in Trinidad, Surinam, Tongaland and 
Ceylon (south India); and perhaps at least 8,000 on the 
eastern Pacific shores from Jalisco, Mexico to northern 
Peru. Pritchard's estimate for the total number of breeding 
females ranged between 29,000 and 40,000. Additional major 
nesting was observed along the Pacific coast of Mexico in 
Michoacan, Guerrero, and Oaxaca. An estimated 500 turtles 
nested per night on a 25-mile long beach at Tierra Colorado, 
Mexico between October and January (Pritchard and Cliffton, 
1981). Based on the discovery of this nesting area, 
Pritchard (1982a) increased his estimate of the number of 
nesting females to about 100,000. Based on reports of two 
additional nesting localities at Playa Chiriqui and Playa 
Chanquinola, Panama, by Carr et al. (1982), Pritchard (1983) 
increased his estimate of the total population of nesting 
females to 120,000. 

An aerial survey of a 19-mile beach on the north coast 
of the Kepala Burung (Vogelkop) region of Irian Jaya provided 
evidence of around 3,500 sea turtle nests; many were thought 
to be leatherbacks (Groombridge, 1982). Similarly, aerial 
surveys of beaches in Costa Rica provided evidence of nesting 
by at least 600 leatherbacks (Bacon e_t^ aj^. , 1984). Also, 
aerial surveys of the coastal area between Cape Hatteras, 
North Carolina to Nova Scotia, Canada out to the 2,000 meter 
depth contour revealed a minimum of 967 leatherbacks 
(University of Rhode Island, 1981). 



74 



Table 5. Population information, population trends and exploitation 
of the leatherback sea turtle (Dermochelys coriacea) jv 



ATLANTIC OCEAN AND ADJACENT SEAS 



Location 


Population Information 


Trend 2/ 


Exploitation 


Angola 


30 F (Dec, 1971) 3/ 


U 




Anguilla 


3 F (1982) 


U 




Antigua 


1 P (1982) 


U 


1/year 


Bratil 


♦ 







Brltlah Virgin Ialanda 


2 F (1982) 





2/year 


Colombia 


100 - 230 P/year 


u 


Harvested 


Coaea Eica 


Use than 4,000 P (1982) 


u 




Dominica 


3 (1982) 







Dominican Ilapubllc 


380 P (1980) 





Intensive egg harvest 


French Guiana 


3,197 P (1979) 


D 


Intensive egg harvest 


Granada 


23 P (1982) 


D 


6,600 pounds (1980-82) 


Guatemala 


♦ 


U 




Guyana 


♦ 





Bar-vested 


Honduras 


+ 







Mexico 


73 P (1982) 


U 


Ear-vested 


Nicaragua 


■f 


U 




Panama 


Less than 1,000 P/year 







Puarto Rico 


26 P (1981) 







St. Kltts-Nevls 


Less than 20 P/yaar 


D 




St. Lucia 


22 P (1982) 







St. Vincent 


+ 


U 




Surinam 


3,900 P (1977); 1,300 P (1978); 








2,700 P (1979); 1,000 P (1980); 


I 






1,300 P (1981); 2,500 P (1982) 






Trinidad and Tobogo 


Less than 230 P/year 


u 


Harvested, especially eggs 


United Statea 


38 P/year 


I 




D.S. Virgin Ialanda 


26 P (1981); 19 P (1982) 







Venezuela 


+ 


u 






PACIFIC OCEAN AND 


ADJACENT 


SEAS 


Australia (Quesland) 


2 F/year 


D 




Coeta Rica 


+• 





Intensive egg harvest 


China 


♦ 


U 


Harvested 


El Salvador 


+ 


D 


Intensive egg harvest 


Pijl 


♦ 


D 


Harvested 


Indonesia 


May be as high aa 2,000 P/year 





Harvested, especially eggs 


Malaysia (Eaat) 


1,000 - 2,000 P/year 


D 


294,300 eggs/year are harvested 


Mexico 


About 30,000 P/year 


U 


Several hundred P/yeer 


Nev Guinea 


+ 


D 


Harvested 


Nicaragua 


+ 


D 


25,000 eggs (1983) 


Panama 


+ 





Harvested 


Papua Nev Guinea 


♦ 


U 


Harvested 


Peru 


+ 


u 


Harvested 


Philippines 


+ 





Harvested 


Solomon Ialanda 


+ 







Thailand 


■¥ 


D 


Harvested 


INDIAN OCEAN AND 


ADJACENT 


SEAS 


Andaman/Nicober Is. 


* 


U 


Eggs harvested 


Arabia 


+ 





Intensive harvest 


Burma 


+ 


U 




Ceylon 


100 P/year 


D 


Harvested 


India 


+ 


D 


Intensive harvest 


Malaysia (Vest) 


+ 


D 


Eggs harvested 


Oman 


+ 





Harvested 


South Africa 


70 F (1977-78) 


I 




Sri Lanka 


+ 


U 


Intensive egg harvest 



+• turtles nest, but no population information la available 

turtles no longer nest 

D decreasing 

F nesting females 

I increasing 

S stable 

U unknown _ 



1/ Baaed on information from numerous literature sources 
- see text references 

2/ Population trends aa Inferred from literature sources 
37 Lataat date of information if known 



Listing Factors 

1. The Present or Threatened Destruction, Modification or 
Curtailment of its Habitat or Range 

Although there is little information on the effects of 
habitat loss on the leatherback sea turtle, there is concern 
about the loss of habitat due to development. For example, 
development is reported to be a threat to the leatherbacks 
nesting at Sandy Point, U.S. Virgin Islands (Anonymous, 
1981). In India, granite blocks used to control erosion may 
be preventing leatherbacks from using beaches along most of 
the Kerala coast ( Groombr idge , 1982). Development along 
Florida beaches in the United States (e.g. construction of 
buildings, seawalls, groins, and rip-rap erosion barriers and 
renour ishment of eroded beaches) may adversely affect 
leatherbacks by eliminating or reducing the quality of their 
nesting beaches. Also, beach mining has been implicated as 
causing leatherback mortality (Bacon et al . , 1984). 

In some locations, exotic plants introduced by man may 
interfere with nesting by blocking the path of leatherbacks 
or inhibiting nesting because of dense root mats or excessive 
shade (Hopkins and Richardson, 1982). In its oceanic 
environment, the leatherback is also vulnerable to fouling 
and ingestion of petroleum and plastic products. For 
example, Mrosovsky (1981) reported that 50 percent of the 
non-breeding leatherbacks he examined had plastic or 
cellophane in their stomach. Plastic can block the 
leatherback ' s intestines causing death. However, the 
magnitude of the effects of habitat destruction and 
modification, or curtailment of range, on the leatherback are 
not known. 



2. Overu tilization for Commercial, Recreational, Scientific 
and Educational Purposes 

Although there is little trade in leatherback products 
(Pritchard and Cliffton, 1981), and their meat is reportedly 
not as palatable as other turtles because their flesh is oily 
and malodorous, they are heavily exploited in some areas for 
their flesh and eggs. Groombridge (1982) reports that 
subsistence take of leatherback meat and eggs is increasing 
througout its range (see Table 5). 

The harvest of leatherbacks has been reported from 
Mexico, Peru, Trinidad, New Guinea, Indonesia, the Solomon 



76 



Islands, the Caribbean region, and Larak Island in the 
Persian Gulf. Each year, hundreds of leatherbacks may be 
slaughtered in Pacific Mexico and elsewhere (Mrosovsky, 1979; 
Pritchard and Cliffton, 1981). In October 1978, 167 
slaughtered leatherbacks were seen on beaches of Peru 
(Pritchard and Cliffton, 1981), and a local industry in that 
country reportedly captures nonbreeding leatherbacks for food 
(Ross, 1982). Bacon (1970) estimated that between 20 and 30 
percent of the annual breeding population in Matura Bay, 
Trinidad was killed. In Papua, New Guinea, and Indonesia, 
adults are usually killed for food. Inhabitants of a single 
village in the Ka i Islands near Irian Jaya , Indonesia 
reportedly kill 100 leatherbacks each year, and similar 
levels of exploitation occur in other areas of this region 
(Pritchard and Cliffton, 1981). 

The slaughter of leatherbacks occurs in Guyana where 
females are killed because they are believed to be useless 
(Hopkins and Richardson, 1982). Other reported takes of 
leatherbacks are one per year from Antigua, two per year from 
the British Virgin Islands, and 2,200 pounds per year from 
Grenada (Bacon et al . , 1984). Leatherbacks are rendered into 
oil for caulking boats in India and on Larak Island in the 
Persian Gulf and for oil lamps in Papua, New Guinea (Ross, 
1982; Groombridge, 1982). They are used for ceremonial 
purposes in the Solomon Islands (Groombridge, 1982); 
medicinal purposes in India and parts of the Caribbean 
(Anonymous, 1981; Ross, 1982); and bait in Mexico and 
Indonesia (Groombridge, 1982). 

The take of eggs, which is increasing, probably 
constitutes the greatest threat to leatherback populations 
(Ross, 1982; Groombridge, 1982). Almost all the eggs laid in 
Mexico and at Trengganu, Malaysia are harvested (Groombridge, 
1982). Egg harvest at Trengganu has declined about 66 
percent since 1956 (Siow and Moll, 1982). Declines in 
populations of leatherbacks in Sri Lanka, India, and Thailand 
are also probably due to egg harvesting (Ross, 1982). The 
harvesting and poaching of eggs is also believed to be a 
serious problem in the Dominican Republic, Trinidad, Peru, 
and French Guiana (Ross, 1982; Fretey and Lescure, 1976) and 
probably occurs throughout the nesting range of this species 
(Groombridge, 1982). 

In areas where eggs are protected from harvesting (e.g. 
Surinam, the United States and South Africa), populations 
have increased in recent years (Ross, 1982). 



77 



Little information is available on the effect of 
utilization of the leatherback for scientific purposes. Work 
with leatherbacks deals mostly with population surveys, 
hatching programs, and other activities that do not involve 
the loss of these animals. In the United States, the take of 
leatherbacks for scientific purposes is controlled by a 
permit system designed to protect endangered and threatened 
species . 



3. Disease or Predation 

The impact of predation on the species has not been 
studied, but predation probably is not a significant factor 
affecting the survival of the species. 

Little is known about diseases of leatherbacks. 
Pritchard (1971) reported parasites such as barnacles, 
trematodes, nematodes, and amoebae, and Wolke (19 81) reported 
a case of enteritis. 



4. Inadequacy of Existing Regulatory Mechanisms 

In the United States, the Endangered Species Act and 
CITES provide adequate protection for the leatherback. 
However, in other parts of the leatherback ' s range, there is 
large-scale poaching of eggs on many nesting beaches. The 
nests at Trengganu, Malaysia are subjected to intense egg 
harvest (nearly 100 percent of the eggs are harvested). 
Elsewhere (e.g. Peru, Asia, India, Ceylon, Dominican Republic 
and Mexico), eggs and adults are taken in large numbers. 
Additional protective mechanisms and stricter enforcement of 
existing laws are needed to adequately protect the 
leatherback (Carr et al . , 1982). For example, only 7 of 19 
known leatherback nesting beaches listed by Ross (1981) 
receive some degree of protection. 



5. Other Natural or Manmade Factors Affecting its Continued 
Existence 

Severe weather events such as storms, heavy rains, 
erosion, and cold destroy adults, juveniles, hatchlings, and 
eggs (Bacon e_t al_. , 1984). For example, erosion and 
subsequent loss of eggs is reported to be severe in the 
Guianas (Mrosovsky, 1983). Adult females often die on the 
beach because they become trapped by obstructions and debris 



78 



(Fretey and Lescure, 1976). Leatherbacks often nest in 
places where their eggs are destroyed by high tides, thereby 
posing problems in conservation. For example, poor nest site 
selection ranges from less than 2.5 percent in Malaysia to 
around 40 percent in the Guianas and as high as 50 percent in 
Surinam (Mrosovsky, 1983). In Surinam; French Guiana; 
Tongaland, South Africa; Mexico; and Malaysia, at least two 
million eggs are lost each year (Mrosovsky, 1983) due to poor 
nest selection. 

Incidental take in fisheries also results in mortality 
of leatherbacks. Large mesh gillnets, longlines, shark nets 
and shrimp trawls kill leatherbacks (Bacon e t a 1 . , 1984); 
Groombridge, 1982). In the United States, each year, an 
estimated 1476 leatherbacks are caught in shrimp trawls with 
subsequent mortality estimated at 505. During February, 
March, and April, 1979, Japanese longliners caught an 
estimated 96 turtles of which 16 percent were identified as 
leatherbacks. The remaining 84 percent were not identified 
(Roithmayer and Henwood, 1982). 

Leatherbacks are also incidentally captured in water 
intakes of industrial facilities such as power plants. For 
example, three leatherbacks were trapped in the St. Lucie, 
Florida Nuclear Power Plant in 1979 and two were trapped in 
1981 (Roithmayer and Henwood, 1982). 

Conclusion 



Populations appear to have declined in Trengganu, 
Malaysia; India; Sri Lanka; Thailand; Trinidad and Tobago; 
and French Guiana. Only four nesting populations larger than 
1,000 females are known (Silebache, French Guiana; Trengganu, 
Malaysia; Chacahua, Mexico; and Tierra Colorado, Mexico). 
Most known nesting females are concentrated in only a few 
nesting populations, and these are not under the control of 
the United States. 

By far, the greatest threat to the survival of the 
leatherback is the excessive harvest of eggs. In some areas 
(e.g., Trengganu, Malaysia), nearly 100 percent of the eggs 
are harvested, and existing laws that are supposed to 
alleviate this problem often are not enforced (Carr et al . , 
1982). Also, the direct and incidental take of leatherbacks 
still occurs (Bacon jst_ jj^. , 1984; Groombridge, 1982) in many 
areas . 



79 



The NMFS believes that the best available commercial and 
scientific data indicate that the leatherback sea turtle 
should remain listed as an endangered species throughout its 
range pursuant to Section 4 of the Endangered Species Act. 
The species is still subjected to intense egg harvest and 
directed and non-directed take of adults which result in 
adverse effects to local populations. Considerably more 
information (e.g., population dynamics, life history, and 
biological status) is necessary before we can determine if 
any change in the listing status of this species is 
warranted . 



80 








Leatherback Sea Turtles. 



Photos by Larry Ogren , Southeast Fisheries 
Center, National Marine Fisheries Service. 



81 



LITERATURE CITED 

Anonymous. 1978. Listing and protecting the green sea turtle ( Chelonia mydas ), 
loggerhead sea turtle ( Caretta caretta ), and Pacific ridley sea turtle 
( Lepidochelys olivacea ) under the Endangered Species Act of 1973. Final 
Environmental Impact Statement. NMFS, Washington, D.C. 14A pp. 

Anonymous. 1981. Recovery plan for St. Croix population of the leatherback 
turtle Dermochelys coriacea . U.S. Fish and Wildlife Service, Region IV, 
Atlanta, Georgia. 

Bacon, P.R. 1970. Studies on the leatherback turtle, Dermochelys coriacea 
(L.), in Trinidad, West Indies. Biol. Conserv. 2(3):213-217. 

Bacon, P.R. 1981. The status of sea turtle stocks management in the western 
Central Atlantic WECAF Studies No. 7. 38 pp. 

Bacon, P., F. Berry, K. Bjorndal, H. Hirth, L. Ogren, and M. Weber (Eds.). 
1984. Proceedings of the Western Atlantic Turtle Symposium. Vol. 1. 
San Jose, Costa Rica, 17-22 July 1983. IOCARIBE and FAO. RSMAS Printing, 
Miami, Florida. 306 pp. 

Balazs, G.H. 1980. Synopsis of biological data on the green turtle in the 

Hawaiian Islands. NOAA Tech. Memorandum, TM-NMFS-SWFC-7, National Marine 
Fisheries Service, Southwest Fisheries Center. 141 pp. 

Balazs, G.H. 1982. Status of sea turtles in the Central Pacific Ocean, 
243-252. In K.A. Bjorndal (ed.). The Biology and Conservation of 
Sea Turtles. Smithsonian Institution Press, Washington, D.C. pp. 243-252. 

Bjorndal, K.A. [Ed.]. 1982. Biology and conservation of sea turtles. 
Smithsonian Institution Press, Washington, D.C. 583 pp. 

Bjorndal, K. 1984. Letter to U.S. Fish and Wildlife Service. Deputy 

Chairperson, IUCN/SSC Marine Turtle Specialist Group. University of 
Florida, Gainesville, Florida. 

Bobb, D. 1982. Massacre at Digha. India Today. 31 March:64-65. 

Brongersma, L.D. 1972. European Atlantic turtles. Zool. Verhand. Leiden, 
121:1-318. 

Brongersma, L.D. 1982. Marine turtles of the eastern Atlantic Ocean. In_ K.A. 
Bjorndal (ed.). Biology and Conservation of Sea Turtles. Smithsonian 
Institution Press. Washington, D.C. pp 407-416. 

Brown, C.H. and W.M. Brown. 1982. Status of sea turtles in the southeastern 
Pacific: emphasis on Peru. In K.A. Bjorndal (ed.). Conservation and 
Biology of Sea Turtles. Smithsonian Institution Press, Washington, D.C. 
pp 235-240. 

82 



Bustard, J. 1979. Population dynamics of sea turtles. In M. Harless and 

H. Morlock (eds.). Turtles: Perspectives and Research. New York, John 
Wiley and Sons. pp. 523-40. 

Caldwell, D.K. , A. Carr, and L.H. Ogren. 1959. Nesting and migration of the 
Atlantic loggerhead turtle. Bull. Fla. State Mus. 4(10):295-308. 

Carr, A.F. 1952. Handbook of turtles: The turtles of the United States, 

Canada and Baja, California. Comstock Publishing Associates, Ithica, N.Y. 
542 pp. 

Carr, A. 1977. Crisis for the Atlantic ridley. Marine Turtle Newsletter, 
4:2-3. 

Carr, A. 1984. Letter to U.S. Fish and Wildlife Service on five year status 
review. University of Florida, Gainesville, Florida. 

Carr, A., and A.B. Meylan. 1980a. Evidence of passive migration of green turtle 
hatchlings in Sargassum . Copeia (2): 366-368. 

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