Green Turtle (Chelonia mydas)
Status | Taxonomy | Species Description | Habitat | Distribution |
Population Trends | Threats | Conservation Efforts | Regulatory Overview |
Key Documents | More Info
| Photos
Status
ESA Endangered - breeding populations in Florida and on the Pacific coast of Mexico
ESA Threatened - all other populations
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Family: Cheloniidae
Genus: Chelonia
Species: mydas
Species Description
Green turtles are the largest of all the hard-shelled sea turtles, but have a comparatively small head. While hatchlings are just 2 inches (50 mm) long, adults can grow to more than 3 feet (0.91 m) long and weigh 300-350 pounds (136-159 kg).
Adult green turtles are unique among sea turtles in that they are herbivorous, feeding primarily on seagrasses and algae. This diet is thought to give them greenish colored fat, from which they take their name. A green turtle's carapace (top shell) is smooth and can be shades of black, gray, green, brown, and yellow. Their plastron (bottom shell) is yellowish white.
Scientists estimate green turtles reach sexual maturity anywhere between 20 and 50 years, at which time females begin returning to their natal beaches (i.e., the same beaches where they were born) every 2-4 years to lay eggs.
The nesting season varies depending on location. In the southeastern U.S., females generally nest between June and September, while peak nesting occurs in June and July. During the nesting season, females nest at approximately two week intervals, laying an average of five clutches. In Florida, green turtle nests contain an average of 135 eggs, which will incubate for approximately 2 months before hatching.
 Green Turtle Critical Habitat (click for larger view PDF) |
Habitat
Green turtles primarily use three types of habitat: oceanic beaches (for nesting), convergence zones in the open ocean, and benthic feeding grounds in coastal areas. Adult females migrate from foraging areas to mainland or island nesting beaches and may travel hundreds or thousands of kilometers each way. After emerging from the nest, hatchlings swim to offshore areas, where they are believed to live for several years, feeding close to the surface on a variety of pelagic plants and animals. Once the juveniles reach a certain age/size range, they leave the pelagic habitat and travel to nearshore foraging grounds. Once they move to these nearshore benthic habitats, adult green turtles are almost exclusively herbivores, feeding on sea grasses and algae.
Critical habitat was designated in 1998 for green turtles in coastal waters around Culebra Island, Puerto Rico.
Distribution
The green turtle is globally distributed and generally found in tropical and subtropical waters along continental coasts and islands between 30° North and 30° South. Nesting occurs in over 80 countries throughout the year (though not throughout the year at each specific location). Green turtles are thought to inhabit coastal areas of more than 140 countries.
In U.S. Atlantic and Gulf of Mexico waters, green turtles are found in inshore and nearshore waters from Texas to Massachusetts, the U.S. Virgin Islands, and Puerto Rico. Important feeding areas in Florida include the Indian River Lagoon, the Florida Keys, Florida Bay, Homosassa, Crystal River, Cedar Key, and St. Joseph Bay.
In the eastern North Pacific, green turtles have been sighted from Baja California to southern Alaska, but most commonly occur from San Diego south. In the central Pacific, green turtles occur around most tropical islands, including the Hawaiian Islands. Adult green turtles that feed throughout the main Hawaiian Islands undergo a long migration to French Frigate Shoals in the Northwest Hawaiian Islands, where the majority of nesting and mating occurs.
Population Trends
In a 2004 Green Turtle Assessment 
, the Marine Turtle Specialist Group (MTSG) of The World Conservation Union (IUCN) classified green turtles as endangered globally. Analyses of historic and recent abundance information by the MTSG indicates that extensive population declines have occurred in all major ocean basins over approximately the past 100-150 years. The MTSG analyzed population trends at 32 index nesting sites around the world and found a 48-65% decline in the number of mature females nesting annually over the past 100-150 years.
The two largest nesting populations are found at Tortuguero, on the Caribbean coast of Costa Rica, and Raine Island, on the Great Barrier Reef in Australia, where an annual average of 22,500 and 18,000 females nest per season, respectively. In the U.S., green turtles nest primarily along the central and southeast coast of Florida; present estimates range from 200-1,100 females nesting annually.
 Green Turtle with fibropapillomatosis (Chelonia mydas) Photo: © Ursula Keuper-Bennett/Peter Bennett. Copyright Information |
Threats
The principal cause of the historical, worldwide decline of the green turtle is long-term harvest of eggs and adults on nesting beaches and juveniles and adults on feeding grounds. These harvests continue in some areas of the world and compromise efforts to recover this species. Incidental capture in fishing gear, primarily in gillnets, but also in trawls, traps and pots, longlines, and dredges is a serious ongoing source of mortality that also adversely affects the species' recovery. Green turtles are also threatened, in some areas of the world, by a disease known as fibropapillomatosis (FP). For more information, please visit our threats to marine turtles page.
Conservation Efforts
Green turtles are protected by various international treaties and agreements as well as national laws. Green turtles are listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES), which means that international trade of this species is prohibited. Green turtles are listed in Appendices I and II of the Convention on Migratory Species (CMS ) and are protected under the following instruments of CMS: the Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats of the Indian Ocean and South-East Asia (IOSEA) and the Memorandum of Understanding Concerning Conservation Measures for Marine Turtles of the Atlantic Coast of Africa. Green turtles are protected under Annex II of the Specially Protected Areas and Wildlife (SPAW ) Protocol of the Cartagena Convention. The U.S. is a party to the Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC ), which is the only binding international treaty dedicated exclusively to marine turtles. Additionally, green turtles are protected by the Memorandum of Understanding on ASEAN Sea Turtle Conservation and Protection and the Memorandum of Agreement on the Turtle Islands Heritage Protected Area (TIHPA ).
In the U.S., NOAA's National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) have joint jurisdiction for green turtles, with NMFS having the lead in the marine environment and USFWS having the lead on the nesting beaches. Both federal agencies, and a number of state agencies, have promulgated regulations to eliminate or reduce threats to sea turtles. In the Atlantic and Gulf of Mexico, NMFS has required measures (e.g., gear modifications, changes to fishing practices, and time/area closures) to reduce sea turtle bycatch in pelagic longline, mid-Atlantic gillnet, Chesapeake Bay pound net, and southeast shrimp and flounder trawl fisheries.
NMFS has worked closely with the shrimp trawl fishing industry to develop turtle excluder devices (TEDs) to reduce the mortality of sea turtles incidentally captured in shrimp trawl gear. TEDs that are large enough to exclude even the largest sea turtles are now required in shrimp trawl nets. Since 1989, the U.S. has embargoed shrimp harvested in a manner that adversely affects sea turtles. The import ban does not apply to nations that have adopted sea turtle protection programs comparable to that of the U.S. (e.g., require and enforce the use of TEDs) or to nations where incidental capture in shrimp fisheries does not present a threat to sea turtles (e.g., nations that fish for shrimp in areas where sea turtles do not occur). The U.S. Department of State (DOS) is the principal implementing agency of this law, while NMFS serves as technical advisor. NMFS has provided extensive TED training throughout the world.
In 2003, NMFS developed the Strategy for Sea Turtle Conservation and Recovery in Relation to Atlantic and Gulf of Mexico Fisheries (Strategy) to evaluate and address domestic sea turtle bycatch comprehensively across jurisdictional (i.e., state and Federal) and fishing sector (i.e., commercial and recreational) boundaries on a per-gear basis in fisheries of the Atlantic and Gulf of Mexico.
NMFS is currently involved in cooperative gear research projects designed to reduce sea turtle bycatch in the Gulf of Mexico and Atlantic pelagic longline fisheries, the Hawaii-based deep set longline fishery, the Atlantic sea scallop dredge fishery, the Chesapeake Bay pound net fishery, and non-shrimp trawl fisheries in the Atlantic and Gulf.
 Green Turtle (Chelonia mydas) Photo: © Caroline S. Rogers, USGS |
Regulatory Overview
The green turtle was listed under the ESA on July 28, 1978. The breeding populations in Florida and the Pacific coast of Mexico are listed as endangered; elsewhere the species is listed as threatened.
In 1992, NMFS finalized regulations to require turtle excluder devices (TED)s in shrimp trawl fisheries to reduce interactions between turtles and trawl gear. Since then, NMFS has modified these regulations as new information became available on increasing the efficiency of TEDs (e.g., larger TEDs are now required to exclude larger turtles).
In 1998, NMFS designated critical habitat for green turtles to include the coastal waters around Culebra Island, Puerto Rico.
NMFS implements measures to reduce sea turtle interactions in fisheries by regulations and permits under the ESA and Magnuson-Stevens Fishery Conservation and Management Act. Since the early 1990s, NMFS has implemented sea turtle conservation measures including, but not limited to, TEDs in trawl fisheries, large circle hooks in longline fisheries, time and area closures for gillnets, and modifications to pound net leaders. Click here for a list of NMFS regulations to protect marine turtles.
Key Documents
(All documents are in PDF format.)
| Title | Federal Register | Date |
|---|---|---|
| 5-Year Review | n/a | 08/31/2007 |
| Virginia Pound Net Fishery Regulations | 71 FR 36024 | 06/23/2006 |
| IUCN Red List 2004 Green Turtle Assessment |
n/a | 04/2004 |
| Critical Habitat – Culebra Island, Puerto Rico | 63 FR 46693 | 09/02/1998 |
| Recovery Plan – East Pacific Green Turtle | 63 FR 28359 | 05/22/1998 |
| Recovery Plan – Pacific Green Turtle | 63 FR 28359 | 05/22/1998 |
| TED Regulations for Shrimp Trawls | 57 FR 57348 | 12/04/1992 |
| Recovery Plan – Atlantic Green Turtle | n/a | 10/29/1991 |
| ESA Listing Rule | 43 FR 32800 | 07/28/1978 |
