Kemp's Ridley Sea Turtle
Kemp's ridleys are considered the smallest marine turtle in the world. Known for their unique synchronized nesting habit, large groups of Kemp's ridleys gather off a particular nesting beach near Rancho Nuevo, Mexico. Females then come ashore in subsequent waves to nest. This event is known as an arribada, which means "arrival" in Spanish.
Kemp's ridleys have been designated as "endangered" since 1970 under the Endangered Species Act. It is considered the most seriously endangered of the sea turtle species, but appears to be in the early stages of recovery.
Description: The Kemp's ridley has a triangular-shaped head with a slightly hooked beak with large crushing surfaces. Hatchlings are black on both sides. In adults, the almost circular carapace has a grayish green color while the plastron (bottom shell) is pale yellow to cream in color. The carapace is often as wide as it is long and contains 5 pairs of costal "scutes". Each of the front flippers has one claw while the back flippers may have one or two.
Size: Adult Kemp's ridleys weigh on average around 100 pounds (45 kg) with a carapace (top shell) measuring between 24-28 inches (60-70 cm) in length.
Diet: Their diet consists mainly of swimming crabs, but may also include fish, jellyfish, and an array of mollusks. Foraging zones range from the Yucatán Peninsula to southern Florida.
Typical Lifespan: Individuals surviving to adulthood may live 30 years and possibly up to 50 years.
Habitat: Kemp's ridleys are usually found in nearshore and inshore waters of the northern Gulf of Mexico, especially Louisiana waters. Kemp's ridleys are often found in salt marsh habitats. The preferred sections of nesting beach are backed up by extensive swamps or large bodies of open water having seasonal narrow ocean connections.
Hatchlings spend two to ten years in an open ocean environment, then return to the shore area to develop until they reach adulthood. These "neritic" zones typically contain muddy or sandy bottoms where prey can be found. Kemp's ridleys rarely venture into waters deeper than 160 ft (about 50 meters).
Range: Depending on their breeding strategy, male Kemp's ridleys appear to occupy many different areas within the Gulf of Mexico. Some males migrate annually between feeding and breeding grounds, yet others may not migrate at all, mating with females opportunistically encountered.
Life History and Reproduction: Nearly 95% of worldwide Kemp's ridley nesting occurs in one confirmed arribada ("arrival") in the state of Tamaulipas, Mexico. A small amount of females nest consistently in Veracruz, Mexico, and at Padre Island National Seashore, Texas.
Sexual maturity is estimated to be 7 to 15 years of age.
Female Kemp's ridleys return to nest on the same beach where they were hatched (from May to July) — usually in the daylight hours — to lay two to three clutches of approximately 100 eggs, which incubate for 50-60 days. Upon emerging from the buried nest, hatchlings weigh roughly half an ounce (14 g) and measure around 1.5 inches (3.8 cm).
Historically, there has been a dramatic decrease in arribada size. An amateur video from 1947 documented an extraordinary Kemp's ridley arribada near Rancho Nuevo. It has been estimated that approximately 42,000 Kemp's ridleys nested during that single day! This video has also served to measure the species' collapse. Forty years after the video was filmed, the largest arribada was down to 734 nests. Annual nesting numbers at Rancho Nuevo increased significantly after the 1980s, to more than 4,000 by 2002 and 7,866 in 2006. Protection provided by Mexico since 1966 has helped to bring about this increase. However, despite the recent increase, the trend is toward a major population decline estimated at more than 90 percent.
In addition to threatened nesting habitat, incidental capture in fishing gear like shrimp trawls, gill nets, longlines, traps, and dredges continues to be the primary threat to the Kemp's ridley.
Oil spills are an additional threat to the Kemp’s ridley. Swimming through oil, a turtle loses its ability to "cry" away extra salt, and respiration becomes difficult. Learn more about how the oil spill in the Gulf of Mexico has affected sea turtles.
Kemp’s ridley sea turtles are protected by various international treaties and agreements as well as national laws. Mexico's protection of the turtle’s nesting areas in that country has provided significant gains towards conservation of the species.
Recent research on the turtle's biology, distribution, threats and population trends has contributed to a better understanding of the species and development of conservation strategies. In addition, this wealth of information helped the NOAA's National Marine Fisheries Service (NMFS) and the U.S. Fish & Wildlife Service (USFWS) to update the recovery plan for the turtles. The joint draft revised recovery plan was published in March 2010.
Bycatch of ridley turtles (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.
Regular monitoring of Kemp’s ridley turtle populations by NMFS and USFWS.
US Fish & Wildlife Service
NOAA Fisheries Office of Protected Resources
Texas Parks and Wildlife