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 rf> gggteg 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 00 rd c tT Q) M Q) Q) U A cn c M M-i QJ +J W c SM •H OJ -P +J 3 M-| X} < ■H ^ +J w W (1) •H x: T3 u (0 -P a) C X> cu w en cu c h ■H Q.-M QJ to U QJ C w Q) -l W •H (1) u e P Cn •H 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 T3 nd rH tnco h e Q) u •H M-l s M-l •H -M •H M-l IH ■4-> w W 0) •H jC T3 <0 -M 0) C .Q d) to tp a* c >-i ■H cu-p >i H 0) U H >-l T> •H •H u M • «3" 0) 5-i 3 cn •H fe 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 1 H •H 00 rH O O rH M-l •» O &1 M C u c CD X -H C •P >-( 3 -l CO •H CD u C • 0) ^ C7^ •H tn '» szzzs 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. 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