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Kemp's Ridley Sea Turtle

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Kemp's Ridley Sea Turtle Kemp’s Ridley Sea Turtle Scientific Name: Lepidochelys kempii Federal Status: Endangered, 12/2/70• State Status: Endangered Description Distribution estuary for summer feeding. They The Kemp’s ridley is the smallest and Range occupied shallow foraging areas over extensive seagrass beds and fed member of the sea turtle family Che- Kemp’s ridley adults are generally mostly on blue crabs. In Texas, loniidae. Adults have a carapace only found in the Gulf of Mexico. Kemp’s ridley and loggerhead sea tur- (upper shell) length of up to 28 Juveniles have been reported most tles are thought to partition food inches and can weigh 75 to 100 commonly in the northern Gulf of resources: the ridleys forage on rela- pounds. Juvenile Kemp’s ridleys have Mexico between Texas and Florida. tively fast blue and spotted crabs, broad, heart-shaped, keeled carapaces Juveniles are also found along the whereas the loggerheads feed on that are serrated along the trailing eastern seaboard of the United States seapens and slow-moving crabs. edge. In adults, the carapace is as far north as Nova Scotia, Canada. The nesting beach at Rancho round and can be wider than it is Apparently, drifting hatchlings and Nuevo, in the Mexican State of long. Hatchlings and juveniles have a juveniles from the western Gulf enter Tamaulipas, is the primary land habi- dark-charcoal colored carapace, but as the eastern Gulf Loop Current and are tat (used only for nesting) for Kemp’s carried by the Florida Current and the ridley. This remote stretch of beach Gulf Stream up the eastern coast of the United States. Some juveniles even cross the Atlantic and have been reported from Ireland and the Azores. Habitat Shallow waters are preferred habitat for juvenile and adult Kemp’s ridleys. Satellite-tracked females migrating away from the nesting beach at Rancho Nuevo, Mexico and Padre Kemp’s Ridley turtle © TPWD Bill Reaves Island, Texas, generally remained in near shore waters less than 165 feet deep, and spent less than an hour each day at the sur- face. It is thought that juvenile and adult Kemp’s ridleys feed primarily near the bottom, although some items may be taken from the surface or water column. along the Gulf of Mexico is located Hatchlings spend many months about 100 miles north of Tampico, as surface drifters in the open ocean Mexico. It is the only known major (pelagic phase). Recent evidence sug- nesting beach for this species in the gests that they may be found in sur- world. However, lower levels of nest- face water areas where drifting ing also occur every year on other material, such as floating marine veg- beaches in Tamaulipas, the Mexican etation and debris, accumulate. state of Veracruz, and in Texas, par- These areas are called convergence ticularly in the southern part of the zones or drift lines. Little is known state. Nesting also occasionally regarding how long they drift, what occurs in other U.S. states along the Kemp’s Ridley hatchling they eat, or how they get back to the © TPWD Mary E. Candee Gulf and Atlantic coasts. coast. Studies have shown that, after they age this color changes to olive- the pelagic phase, body size of green or gray. The lower shell (plas- Kemp’s ridley is related to water Life History tron) is charcoal-colored in hatchlings depth. For example, the smallest The diet of juvenile and adult Kemp’s and later changes to a light cream juveniles are found in shallow waters ridley turtles consists primarily of color. Adult males often have a con- of bays or lagoons, often foraging in crabs, shrimp, snails, bivalves, sea cave plastron and long tails that less than 3 feet of water, whereas urchins, jellyfish, sea stars, fish, and extend beyond the rear of the cara- larger juveniles and adults are found occasionally marine plants. Crabs are pace. Kemp’s ridleys have large, in deeper water. somewhat triangular heads and pow- Juvenile Kemp’s ridleys studied erful, massive jaws. in the Chesapeake Bay area used the Kemp’s Ridley Sea Turtle 1 a preferred food and several species To escape a variety of land are eaten. In some regions, the blue predators, hatchlings move quickly crab is the most common food item. from the beach through the surf zone Although feeding habits of hatchlings and into open waters of the Gulf of have not been observed in the wild, Mexico. Scientists think the baby they are presumed to eat swimming turtles may remember or “imprint” and floating animal matter located at on the particular smell, chemical or near the surface of the open Gulf make-up, or magnetic location of the of Mexico and Atlantic Ocean. beach where they hatched. Other Reproduction in Kemp’s ridley dif- predators await them in the water. fers from that of other sea turtles in Most breeding females return to the four important ways. First, most shallow waters of the western Gulf of female Kemp’s ridleys, along with their Mexico to nest at the same beach sister species Olive ridleys (Lepi- where they hatched. Wild Kemp’s Nesting female dochelys olivacea), arrive at nesting ridleys require 10 to 20 years to © NPS D. J. Shaver beaches in large groups. These nesting reach sexual maturity. events are called “arribazones.” Many females gather in the waters near the Threats and Reasons nesting beach and emerge to nest for Decline simultaneously over a period of several The Kemp’s ridley population crash hours or days. Second, Kemp’s ridleys that occurred between 1947 and the nest mainly during the daytime, early 1970’s was probably a result of whereas other sea turtles usually nest the combination of intensive annual at night. Third, most nesting occurs on harvest of eggs and mortality of juve- one stretch of beach, which is unique niles and adults in shrimp trawl nets. for sea turtles. Fourth, Kemp’s ridley Kemp’s ridley eggs were (and females nest every 1 to 3 years, with still are in many places) considered a an average of every 2 years, whereas delicacy. Between about 1947 and other sea turtles nest about every 2 to 1966 people dug up truckloads of Marine debris ingested by Kemp’s Ridley turtle 3 years. eggs and sold them in the towns and © NPS R. W. Wilder During the breeding season, cities of Texas and Mexico. Since female Kemp’s ridleys migrate toward many of the eggs were either taken human caused deaths of juvenile and the nesting beach. A large portion of by people or eaten by predators, adult loggerheads and Kemp’s ridleys the adult male population may remain there was a drastic decline in the tur- resulted from shrimp trawling. offshore from the nesting beach year- tle population. Also, prior to its Trash discarded at sea is another round. Courtship and mating occur being listed as endangered by the serious problem facing this species in nearby offshore waters several U.S. Fish and Wildlife Service in and other marine animals. Some of weeks prior to and during the nesting 1970, Kemp’s ridleys, along with this debris never makes it to shore period. Nesting usually occurs during green and loggerhead turtles, were because it is eaten by fishes, sea tur- April, May, and June, although it can taken for meat by commercial fisher- tles, birds, and marine mammals that occur in July and August if cool spring men in the northern and northeast- mistake it for food. Postmortem weather delays the onset of the repro- ern Gulf of Mexico. Human examinations of sea turtles found ductive period. consumption of turtle eggs and meat stranded on the south Texas coast A well-defined and elevated dune has declined with national and inter- from 1986 through 1988 revealed area, above the tidal zone, is pre- national protection. Although nesting 54% (60 of the 111 examined) of the ferred for nesting. The female digs a turtles and nests are protected at sea turtles had eaten some type of hole in the sand, deposits her eggs, Rancho Nuevo, the harvest of eggs marine debris. Plastic materials were and returns to the sea, a process and slaughter of animals continue to most frequently ingested, and which takes about 45 minutes. be potential problems in other areas. included pieces of plastic bags, Styro- Females generally deposit one to Because the Kemp’s ridley sea foam, plastic pellets, balloons, rope, three clutches per season, laying an turtle is a shallow water inhabitant, it and fishing line. Non-plastic debris average of about 100 soft, leathery, is frequently caught in shrimp trawl such as glass, tar, and aluminum foil white eggs per clutch. After about 45 nets that may drown or exhaust the were also ingested by the sea turtles to 55 days of incubation in the sand, turtle. There is strong evidence that examined. Much of this debris comes the eggs hatch. The temperature of shrimp trawling is a primary agent from offshore oil rigs, cargo ships, the incubating eggs during the mid- for sea turtle mortality today. The commercial and recreational fishing dle third of the incubation period National Marine Fisheries Service esti- boats, research vessels, naval ships, determines the gender of the develop- mated that, prior to the 1990 law and other vessels operating in the ing embryo. Warmer temperatures requiring Turtle Excluder Devices Gulf of Mexico. Laws enacted during produce primarily females and colder (TEDs), about 12,000 sea turtles the late-1980’s prohibit the disposal temperatures primarily males. drowned each year in nets. The of all types of plastics, and regulates National Research Council’s Commit- the distance from shore that non-plas- tee on Sea Turtle Conservation esti- tic debris may be discarded.
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