Kemp’s ridley turtle (Lepidochelys kempii)
|Also known as:||Atlantic ridley turtle|
|French:||Lépidochelyde de Kemp, Ridley de Kemp, Tortue de Kemp|
|Spanish:||Cotorra, Tortuga Iora, Tortuga Marina Bastarda|
|Size||Length: 66 – 70 cm (2)|
|Weight||27 – 40 kg (2)|
Classified as Critically Endangered (CR) on the IUCN Red List 2007. Listed on Appendix I of CITES (5), and Appendix I and II of the Convention on Migratory Species (CMS or Bonn Convention) (6).
Kemp’s ridley turtle is the most severely endangered marine turtle in the world; in the 1980s only a few hundred females were observed nesting, although the population is now showing signs of recovery (3). It is also one of the smallest turtles, with adults weighing less than 45 kilograms (4). Kemp’s ridley turtle differs from the olive ridley by its parrot-like beak and flatter, almost completely round carapace (3). Hatchlings are grey-black all over, whilst adults have a lighter grey-olive carapace and are creamy-white underneath (4).
Kemp’s ridley turtles have an extremely restricted range; found mainly in the Gulf of Mexico and some way up the eastern seaboard of the United States (3). The epicenter of nesting is a 20 kilometre beach at Rancho Nuevo in Northeast Mexico (2), with most nesting in the Mexican state of Tamaulipas. Nesting has also been documented in Veracruz and Campeche, Mexico, as well as in various U.S. states. Most U.S. nesting occurs in Texas, with nesting coastwide, but concentrated in the southern part of the state (7).
Adults inhabit crab-rich shallow inshore waters near the coast. Juveniles are also found in shallow waters, often where there are eelgrass beds and areas of sand, gravel and mud (2).
Along with the olive ridley, Kemp’s ridley turtle used to exhibit mass synchronised nestings known as ‘arribadas’ (Spanish for ‘mass arrivals’), where thousands of females came ashore on the same beach to nest at the same time (2). Since the precipitous fall in population numbers however, these spectacular phenomena are now much smaller (3). The nesting season peaks in May and June and unusually amongst turtles, nesting occurs during the day (3). Females lay an average of two to three clutches during the breeding season, each clutch containing about 90 eggs, they return every year or two to nest (3). During 2004, a record 42 Kemp's ridley turtle nests were found on the Texas coast. Most were located in the southern part of the state, but some nests were found on the upper part of the Texas coast as well. In addition to the Texas nests, four others were found in the U.S. during 2004 in northwest Florida (7).
Adults are carnivorous bottom-feeders, eating a wide range of prey including fish, jellyfish, although crabs are the mainstay of their diet (2).
Kemp’s ridley turtle suffered a dramatic decline during the 1950s - 60s, due mainly to the over harvesting of eggs, natural predation and mortality caused by trawl fisheries (4). Because nesting occurs in such large concentrations with shallow, poorly disguised nests, eggs are easily exploited by human collectors (by whom they are valued for their aphrodisiac properties) and by natural predators such as coyotes (3). Today the main threat to the survival of the species comes from shrimp trawlers which often operate in areas where turtles feed, turtles accidentally caught in nets (by-catch) drown to death and it is estimated that between 500 to 5,000 turtles are killed in this way each year (4).
International trade in Kemp’s ridley turtles and products is banned under their listing on Appendix I of the Convention on International Trade in Endangered Species (CITES), and the main nesting beach has been declared a National Reserve since the 1970s (3). During the breeding season nests are protected by armed patrols and subsequently very little illegal trade occurs (2). Turtle Excluding Devices (TEDs) fitted to shrimp nets can help to prevent by-catch by allowing only shrimp-sized objects to enter the net (4). There has been an international drive to introduce these devices worldwide and shrimp trawlers operating in United States waters must now be fitted with TEDs (4). These conservation efforts have led to the slow recovery of Kemp’s ridley turtle numbers and it has been suggested that a population goal of 10,000 nesting females could be reached by 2010 (2), allowing arribadas to once again adorn the Mexican coast.
Many thanks to Donna Shaver of the Division of Sea Turtle Science and Recovery Padre Island National Seashore National Park Service
http://www.nps.gov/pais/pphtml/nature.html and Rod Mast of Conservation International for authenticating the text
- By-catch: In the fishing industry, the part of the catch made up of non-target species.
- Carapace: The top shell of a turtle.
- Carnivore: flesh-eating.
IUCN Red List (July, 2014)