ML050480457

License Renewal, NMFS 2004 Leather Sea Turtle

ML050480457
Person / Time
Site:	Millstone
Issue date:	12/06/2004
From:	US Dept of Commerce, National Marine Fisheries Service
To:	Office of Nuclear Reactor Regulation
References
Download: ML050480457 (3)

Text

v - LC-atherback Sea Turtle Pagel of3 Office of Protected Resources NOAA FISHERIES National Marine Fisheries Service (Tm Mardne Mmmal vEq apa itnne tn; nal R iseraNo pwqe Bioaive'rsity A6ils Cons Conslervation t

QFA.9s Leatherback Sea Turtle (Dermochelys coriacea)

Endangered Species The leatherback turtle was listed as endangered throughout its range on June 2, 1970. Nesting populations of leatherback sea turtles are especially difficult to discern because the females frequently change beaches. However, current estimates are that 20,000-30,000 female leatherbacks exist worldwide.

Leatherbacks do not nest frequently enough in the United States to assess an m M.

accurate trend. The recovery plan for the leatherback sea turtle concludes that nesting trends in the United States appear stable, but the population faces significant threats from incidental take in commercial fisheries and marine Populations have declined in Mexico Costa Rica, Malaysia, India, Sri Lanka4 Thailand, Trinidad, Tobago, and Papua I.

New Guniea. Leatherbacks are r;

seriously declining at all major nesting

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beaches throughout the Pacific. The.'~~-

decline is dramatic along the Pacific coasts of Mexico and Costa Rica and coastal Malaysia. Nesting along the Pacific coast of Mexico declined at an annual rate of 22% over the last 12 years, and the Malaysian population represents 1 % of the levels recorded in the 1950s. The collapse of these nesting populations w'as precipitated by a tremendous overharvest of eggs, direct harvest of adults, and incidental mortality from fishing. In the Atlantic and Caribbean, the largest nesting assemblages are found in the U.S. Virgin Islands, Puerto Rico, and Florida.

Nesting data for these locations have been collected since the early 1980's and indicate that the annual number of nests is likely stable; however, information regarding the status of the entire leatherback population in the Atlantic is lacking.

Nesting activity has also declined in French Guiana due to erosion of nesting beaches, the population appears to have shifted to Surinam, where annual numbers of nests have risen from less than 100 in 1967 to 5,565 in 1977 and 9,816 in 1987. Habitat destruction, incidental catch in commercial fisheries, the harvest of eggs and flesh are the greatest threats to the survival of the leatherback.

Biology The leatherback is the largest living turtle, and is so distinctive as to be placed in a separate taxonomic family, Dermochelyidae. The carapace is distinguished by a rubber-like texture, about 4 cm thick, and made primarily of tough, oil-saturated connective tissue. No sharp angle is formed between the carapace and the plastron, resulting in the animal being somewhat barrel-shaped. The average curved carapace length for adult turtles is 155 cm and weight ranges from 200-700 kg. Hatchlings are dorsally mostly black and are covered with tiny scales; the flippers are margined in white, and file://C:\\%20%2ODoerr-W~ork\\Technical%20Work\\NRC\\Task%2015-Mill%20Stone%202... 12/6/2004

Le-atherback Sea Turtle Page 2 of 3 rows of white scales appear as stripes along the length of the back. Hatchlings average 61.3 mm long and 45.8 g in weight. In the adult, the skin is black and scaleless. The undersurface is mottled pinkish-white and black. The front flippers are proportionally longer than in any other sea turtle, and may span 270 cm in an adult. In both adults and hatchlings, the upper jaw bears two tooth-like projections at the premaxillary-maxillary sutures. Age at sexual maturity is unknown.

Distribution The leatherback turtle's range extends from Cape Sable, Nova Scotia, south to Puerto Rico and the U.S. Virgin Islands.

Critical habitat for the leatherback includes the waters adjacent to Sandy Point, St. Croix, U.S. Virgin Islands, up to and inclusive of the waters from the hundred fathom curve shoreward to the level of mean high tide with boundaries at 170 42'12" N and 64°50'00" W. Nesting occurs from February - July with sites located from Georgia to the U.S. Virgin Islands. During the summer, leatherbacks tend to be found along the east coast of the U.S. from the Gulf of Maine south to the middle of Florida.

Leatherbacks are commonly seen by fishermen in Hawaiian offshore waters, generally beyond the 100-fathom curve but within sight of land. Sightings often take place off the north coast of Oahu and the Kona coast of Hawaii. North of the Hawaiian Islands, a high seas aggregation of leatherbacks is known to occur at 350-451N, 1750 -180VW.

Human Impacts on Leatherback Sea Turtles I) Impacts in the nesting environment

1. Historically, leatherback turtles were rarely taken for their meat. However, a few have been killed in recent years.

In Puerto Rico, adults are occasionally taken for meat and oil. In addition, the poaching of eggs from nests continues at low levels in the U.S. Virgin Islands and is widespread in Puerto Rico.

2. Leatherback turtles prefer to nest on open beaches. However, these beaches are prone to erosion, causing egg loss.

Nests are also lost to hurricanes.

3. Development of beachfronts results in fortification to protect property from erosion, resulting in loss of a dry nesting beach. It can also prevent females from getting to nesting sites and wash out nests.

4. Beach nourishment impacts turtles by burial of nests, disturbance to nesting turtles, and changes sand compaction and temperature which may affect embryo development.

5. Artificial lights can cause disorientation or misorientation of both adults and hatchlings. Turtles are attracted to light, ignoring or coming out of the ocean to go towards a light source. This increases their chances of death or injury. In addition, as nesting females avoid areas with intense lighting, highly developed areas may cause problems for turtles trying to nest.

6. Mechanical raking can result in heavy machinery repeatedly moving across a nest and compacting sand as well as causing tire ruts which may hinder or trap hatchllings. Rakes can penetrate the surface and disturb or uncover a nest. Disposing of debris on the high beach can cover nests and may alter nest temperature.

7. The most serious threat of nighttime use of a beach is the disturbance of nesting females. Heavy utilization of nesting beaches by humans may also result in lowered hatchling success due to sand compaction.

8. The placement of physical obstacles on a beach can hamper or deter nesting attempts as well as interfere with incubating eggs and the movement of hatchlings to the sea.

9. The use of off-road vehicles on beaches is a serious problem in many areas. It may result in decreased hatchling success due to sand compaction, or directly kill hatchlings. Tire ruts may also interfere with the ability of hatchlings to get to the ocean.

11) Impacts in the marine environment

1. Leatherbacks become entangled in longlines, fish traps, buoy anchor lines and other ropes and cables. This can lead to serious injuries and/or death by drowning. The setting of "large mesh nets suitable for turtling" is common in the waters of Puerto Rico. Although the practice was outlawed in 1984, it still continues. The nets are intended for hawksbills and green turtles, but leatherbacks occasionally become entangled.

2. Leatherback turtles eat a wide variety of marine debris such as plastic bags, plastic and styrofoam pieces, tar balls, balloons and plastic pellets. Effects of consumption include interference in metabolism or gut function, even at low levels of ingestion, as well as absorption of toxic byproducts. NMFS is currently analyzing stranding data and available necropsy information to determine the magnitude of debris ingestion.

3. It is estimated that even with TEDs, the offshore commercial shrimp fleet is anticpated to capture about 640 leatherbacks a year. The use of TEDs is not expected to reduce leatherback captures and mortality significantly, because TEDs are generally incapable of passing adult leatherbacks through the exit opening. However, beginning in 1993, NMFS established a Leatherback Conservation Zone to restrict shrimp trawl activities from off the coast of Cape Canaveral, Florida, to the North Carolina/Virginia border. This provides for short-term closures when high concentrations of normally pelagically distributed leatherbacks are recorded in more coastal waters where the shrimp fleet operates. This measure is necessary because, due to their size, adult leatherbacks are larger file://C:\\%20%20Doerr-Work\\Technical%2OWork\\NRC\\Task%20 1 5-Mill%20Stone%202...

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Leatherback Sea Turtle Page 3 of 3 than the escape openings of most NMFS-approved TEDs.

4. Leatherbacks are vulnerable to boat collisions and strikes, particularly when in waters near shore. It is not known if open ocean collisions with large ships occur.

5.

Marine turtles are at risk when encountering an oil spill. Respiration, skin, blood chemistry and salt gland functions are affected.

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