Green Sea Turtle Fact Sheet
Green Sea Turtle
Chelonia mydas
New York Status: Threatened
Federal Status: Threatened
Description
Distributed widely throughout the world's tropical and semi-tropical oceans, populations of this once abundant sea turtle have drastically declined. The only sea turtle with four large costal plates on each side of its smooth-edged shell, the green sea turtle is olive-brown to black above and yellowish-white below. It is named for the color of its body fat. The head has one pair of prefrontal plates. The largest of the hard-shelled turtles, this species can reach 4 feet (1.2 m) in length and weigh 500 pounds (227 kg) (average 3 feet and 250+ pounds).
Life History
The age at which these turtles reach sexual maturity is unknown. The approximate length of the shell at sexual maturity, however, is about 35 inches. Green sea turtles are believed to be long lived (20+ years), but longevity in the wild is also unknown. Breeding does not take place annually, but on varying cycles of two, three or four years, with three years being the predominant cycle. In many cases, the foraging grounds and nesting grounds are far apart and a long migration is required. During nesting, the female deposits 80-200 eggs which hatch in 48-70 days. Over the season, she may lay 1-7 clutches at 12-14 day intervals. Upon emerging from the sand, the hatchlings run towards the ocean and swim out in what is referred to as a "swimming frenzy."
Distribution and Habitat
In the Atlantic Ocean, green sea turtles are found from Massachusetts south to Florida, and throughout the Gulf of Mexico and the Caribbean Sea. They inhabit shallow waters such as shoals and lagoons with submerged vegetation including grasses and algae. Inlets, bays and estuaries are preferred habitats. Nesting occurs in all subtropical to tropical oceans of the world between 35 degrees north and south latitude, in waters that remain above 68 degrees F (20 degrees C) during the coldest months.
Status
Great commercial food value is the cause for population declines; the meat is an important source of protein. In the 1940's, demand for green sea turtle products decreased as concern over the species grew. Interest shortly renewed, however, as the demand grew for gourmet foods, cosmetics, leather, flesh, oil and skin. Population estimates before exploitation are unknown, but by the 1970's only 100,000-400,000 green sea turtles were thought to remain.
This species is affected by pollution, dredging and sand mining, and predators attracted to human garbage. The introduction of exotic vegetation on nesting beaches may inhibit nesting by forming barriers and dense root mats. Also, sargassum weed, where some green sea turtles spend the early part of the life cycle, accumulates oil, styrofoam and other plastic. Degradation of feeding areas also occurs.
Management and Research Needs
Turtles migrating during summer months are known to come as far north as Labrador. Although these turtles do not nest on New York beaches, they occasionally become stranded on or near the shore. In order to aid those that may still be alive and to facilitate the timely and efficient handling of carcasses, a Stranding Network was established in 1980 through the cooperation of the New York State Department of Environmental Conservation, the National Marine Fisheries Service, and the Riverhead Foundation. Through this system, strandings can be reported by calling a hotline: (631)369-9829, enabling marine biologists at Riverhead to handle the stranded and dead specimens.
In response to sea turtle mortality in trawl nets, the U. S. Fish and Wildlife Service has issued regulations requiring shrimp trawlers on the southeastern and Gulf coasts to have a turtle excluder device (TED) on their nets. This device allows turtles and other large marine life to escape should they enter a net.
Additional References
Bjorndal, K. A., Ed. 1981. Biology and Conservation of Sea Turtles. Smithsonian Institution Press, Washington, DC
Carr, A. 1952. Handbook of Turtles. Cornell University Press, Ithaca and London.
Conant, R. and J. T. Collins. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Third Edition Expanded. Houghton Mifflin Co., Boston.
Hopkins, S. R. and J. Richardson. 1984. Recovery Plan for Marine Turtles. National Marine Fisheries Service.
Sternberg, J. 1981. Sea Turtles. Center for Environmental Education, Washington, DC
Drawing by Carol Decker
