Olive Ridley Sea Turtle
Considered the most abundant sea turtle in the world, with nesting females estimated to total about 800,000 per year, the olive ridley was still listed as "threatened" under the Endangered Species Act (ESA) in 1978 because of threats facing all sea turtle species. However, since its listing under the U.S. ESA, there has been a decline in abundance of this species. For this reason, it has been recommended that the olive ridley in the western Atlantic be reclassified as "endangered".
Description: Olive ridleys get their name from the coloring of their heart-shaped shell, which starts out gray but becomes olive green once the turtles are adults. They have one to two visible claws on each of their paddle-like flippers. Western Atlantic olive ridleys usually have a darker coloration than eastern Pacific olive ridleys. Male olive ridleys can be distinguished from females by their tails, which stick out beyond their carapace.
Size: Adult turtles are relatively small, averaging 2 to 2.5 feet (60 to 76 cm) in length and weigh 80 to 110 pounds (36 to 49 kg). The largest animals are observed on the Pacific coast of Mexico.
Diet: The olive ridley is omnivorous, meaning it feeds on both plants and animals, including algae, lobster, crabs, tunicates, mollusks, shrimp, and fish. Olive ridleys can be found foraging for invertebrates to depths of about 500 feet (150 meters).
Typical Lifespan: Individuals surviving to adulthood may live up to 50 years.
Habitat: The olive ridley appears to be more of an open ocean inhabitant or "pelagic" sea turtle, unlike the Kemp’s ridley, which primarily inhabits shallow nearshore coastal waters.
Range: The olive ridley is found in the tropical regions of the Pacific, Atlantic, and Indian Oceans. In the Pacific, it prefers beaches of Mexico south to Colombia. In the Indian Ocean, its greatest abundance is in eastern India and Sri Lanka. Only a small and declining population of olive ridleys nest in the western Atlantic along the West coast of Africa.
Olive ridleys do not nest along U.S. coastal beaches, but do utilize waters of the southwestern U.S. sometimes north to the Oregon coast, during feeding migration.
Life History and Reproduction: These turtles are solitary, preferring the open ocean. They migrate hundreds or even thousands of miles every year for the arribada, when females return to the beaches where they hatched to nest. Arribadas are massive nesting aggregations where thousands of females arrive in simultaneous waves to lay their eggs. The beginning stimulus for this event is unknown, creating a major element of unpredictability in timing at all arribada sites.
Olive ridleys females usually nest 1 to 3 times per season, laying an average 100 to 110 eggs per clutch. Nesting intervals are approximately 14 days for solitary nesters and about 28 days for arribada nesters. The eggs incubate for 50 to 60 days. Age at sexual maturity may be similar to the Kemp’s ridley, at approximately 7 to 15 years.
- Incidental take, particularly in shrimp trawl nets and nearshore gill nets.
- Direct harvest of eggs and adults for their meat and skin.
Marine pollution (including oil spills) and debris.
Olive ridley sea turtles are protected by various international treaties and agreements as well as national laws such as the U.S. Endangered Species Act (ESA).
In 1998 NOAA's National Marine Fisheries Service (NMFS) and the U.S. Fish & Wildlife Service (USFWS) issued the recovery plan for the olive ridley turtle.
Bycatch of olive ridleys (accidental capture by commercial and sport fishermen) is being reduced by fishing gear modifications (i.e. use of TED’s or turtle exclusion devises), changes to fishing practices and closures of certain areas to fishing during nesting and hatching seasons.
Important Mexican nesting beaches have been turned into reserves for the species and continue to be protected for long-term conservation.
Regular monitoring of olive ridley sea turtle populations by NMFS and USFWS, and further research on the biology, life cycle, and migration patterns is needed to help develop effective conservation methods.
US Fish & Wildlife Service
NOAA Fisheries Office of Protected Resources