About The Species
The green turtle is one of the largest hard-shelled sea turtles. They are unique among sea turtles in that they are herbivores, eating mostly seagrasses and algae. This diet is what gives their cartilage and fat a greenish color (not their shells), which is where their name comes from.
Green turtles live all over the world, nest in over 80 countries, and live in the coastal areas of more than 140 countries.
Today, all green turtle populations are listed as either endangered or threatened under the Endangered Species Act. The primary threats facing green turtles are bycatch in commercial and recreational fishing gear, direct killing of turtles and harvest of eggs, vessel strikes, loss and alteration of nesting habitat, degradation and loss of foraging habitat, and entanglement in or ingestion of marine debris. While many countries prohibit the killing of green sea turtles (including the the United States), in other areas, the killing of turtles for their meat and collection of eggs continues today. Illegal fisheries also operate to supply shells to the wildlife trafficking trade. In addition, rising sea levels and an increase in the frequency and severity of storm events are likely to inundate some nesting beaches.
NOAA Fisheries and our partners are dedicated to protecting and recovering green turtle populations worldwide. We use a variety of innovative techniques to study, protect, and recover these endangered animals. We engage our partners as we develop measures and recovery plans that foster the conservation and recovery of green sea turtles and their habitats.
Status
In the United States, nesting green sea turtles are primarily found in the Hawaiian Islands, U.S. Pacific Island territories (Guam, the Commonwealth of the Northern Mariana Islands, and American Samoa), Puerto Rico, the Virgin Islands, and the East Coast of Florida. Lower levels of nesting are found in Georgia, South Carolina, and North Carolina. Juveniles are prevalent in all of these areas, and also coastal areas of the Gulf of Mexico.
Population trends of green turtles vary among regions and nesting populations. For instance, the Hawaiian green turtle population (i.e., the Central North Pacific distinct population segment) has been increasing at a rate of 5 percent per year over the past 2 decades. In addition, nesting populations of green turtles in Florida and on the Pacific coast of Mexico are also increasing due to successful and sustained conservation efforts. In 2016, these populations were identified as distinct population segments and classified as “threatened” under the ESA.
In contrast, the Central South Pacific and Central West Pacific populations were classified as “endangered” populations due to their depleted status and continuing vulnerability.
The two largest green turtle nesting populations in the world are found at:
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Tortuguero on the Caribbean coast of Costa Rica—22,500 females nest per season (on average).
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Raine Island on the Great Barrier Reef in Australia—18,000 females nest per season (on average).
The 2015 ESA status review of the green sea turtle provides additional information on population trends.
Protected Status
ESA Endangered
2 distinct population segments
- Central South Pacific DPS
- Central West Pacific DPS
ESA Endangered - Foreign
1 distinct population segment
ESA Threatened
4 distinct population segments
- Central North Pacific DPS
- East Pacific DPS
- North Atlantic DPS
- South Atlantic DPS
ESA Threatened - Foreign
4 distinct population segments
- East Indian-West Pacific DPS
- North Indian DPS
- Southwest Indian DPS
- Southwest Pacific DPS
Appearance
Green turtles are the largest of all the hard-shelled sea turtles, but have a comparatively small head. A typical adult is 3 to 4 feet long and weighs 300 to 350 pounds. They have dark brown or black shells and a much lighter, yellow underside. Their shells have five scutes (bony plates) running down the middle and four scutes on each side. Another distinct characteristic of the green turtle is their two large scales located between the eyes.
Behavior and Diet
Like other sea turtles, green turtles make long-distance migrations from their feeding areas to nesting beaches in the tropics and sub-tropics.
After settling from their pelagic developmental phase (lasting about 5 to 7 years), into their coastal habitats, green turtles shift to being primarily herbivores. Their diet mainly consists of algae and seagrasses, though they may also forage on sponges and other invertebrates. The East Pacific green turtle tends to eat more animal prey than other populations. Prior to recruiting to nearshore foraging areas, early-stage juveniles forage on plant and animal life found in pelagic drift communities (such as pelagic Sargassum communities).
Where They Live
Adult and juvenile green turtles live are generally found nearshore as well as in bays and lagoons, on reefs, and especially in areas with seagrass beds.
Adults migrate from foraging areas to nesting beaches and may travel hundreds or thousands of kilometers each way. After emerging from the nest, hatchlings swim to offshore areas, where they live for several years. Once the juveniles reach a certain age/size range, they leave the open ocean habitat and travel to nearshore foraging grounds.
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 Pacific, green turtles occur around almost all tropical islands, including the State of Hawaii, and U.S. territories of American Samoa, Guam, and the Commonwealth of the Northern Mariana Islands. The majority of adult green turtles that feed throughout the main Hawaiian Islands migrate to French Frigate Shoals in the Northwest Hawaiian Islands to nest.
World map providing approximate representation of the green turtle's range.
Lifespan & Reproduction
The lifespan for green turtles is currently unknown but thought to be at least 60 to 70 years.
Green turtles become sexually mature at 25 to 35 years, and some may be as old as 40 before they reproduce. Their reproductive lifespan is uncertain, but some individuals have been observed nesting for at least 38 years. We have not been studying green turtles long enough to know how long individuals remain reproductively active.
In the United States, the breeding season occurs in late spring and early summer. Males mate with females on foraging grounds, along migratory pathways, and off nesting beaches. Adult males can breed every year, but females migrate from their foraging areas to nest every 2 to 5 years.
Female green sea turtles lay about 100 eggs per nest and will nest every two weeks over several months before leaving the nesting area and returning to their foraging grounds.
After about 2 months, the eggs hatch and the hatchlings make their way to the water. The newly hatched green sea turtles are susceptible to nighttime predators; however, hatchlings emerge at night when fewer predators are active.They are particularly threatened by artificial beachfront lighting which can disorient them and prevent them from finding the sea. Hatchlings orient themselves towards the brightest horizon. On undeveloped beaches, this is toward the open horizon over the ocean. However, in areas with artificial lighting hatchlings crawl towards bright lights instead of the ocean.
Threats
Bycatch in Fishing Gear
A primary threat to sea turtles is their unintended capture in fishing gear which can drown turtles due to forced submergence or cause injuries that lead to death or debilitation (for example, swallowing hooks). The term for this unintended capture is bycatch. Sea turtle bycatch is a worldwide problem.
Intentional Killing of Turtles and Harvest of Eggs
The main cause of the historical, worldwide decline of the green turtle is long-term harvest of eggs and the intentional killing of green sea turtles on nesting beaches and feeding grounds. Killing turtles and harvesting eggs remains legal in some countries but this can disrupt regional efforts to recover this species.
Loss and Degradation of Nesting Habitat
Coastal development and rising seas from climate change are leading to the loss of critical nesting beach habitat for green sea turtles. Shoreline hardening or armoring (e.g., seawalls) can result in the complete loss of dry sand suitable for successful nesting. Artificial lighting on and near nesting beaches can deter nesting females from coming ashore to nest and can disorient hatchlings trying to find the sea after emerging from their nests.
Ocean Pollution/Marine Debris
Marine turtles may die after ingesting fishing line, balloons, plastic bags, plastic pieces, or other plastic debris which they can mistake for food. They may also become entangled in this or other marine debris, such as lost or discarded fishing gear, and can be killed or seriously injured.
Disease
Fibropapillomatosis is a disease that causes tumors externally on the exposed soft tissues of green turtles and internally on vital organs. These tumors can significantly affect a turtles’ quality of life and can lead to death. For example, if a tumor blocks a turtle’s mouth or eyes, it may not be able to feed properly and/or may be unable to effectively avoid predators. The disease is most prevalent in green turtles and some evidence has linked the disease prevalence to degraded marine habitats.
Scientific Classification
| Animalia |
Chordata |
Reptilia |
Testudines |
Cheloniidae |
Chelonia |
mydas |
