Kemp's Ridley Sea Turtle

Photo Credit: U.S. Fish and Wildlife Service

SCIENTIFIC NAME: Lepidochelys kempi (Garman)

OTHER NAMES: Atlantic Ridley, Tortuga Lora (Mexico).

DESCRIPTION: One of the smallest sea turtles with adult carapaces measuring approximately 60 to 70 centimeters (23.6 to 27.6 inches) long straight-line carapace length (Magnuson et al. 1990, Ernst et al. 1994, Eckert et al. 1999). Typical adults weigh 35 to 40 kilograms (77 to 88 pounds). Adult shell very wide and typically as wide as it is long. Carapace smooth, low domed, and grey to grey-green. Plastron white to light yellow. Head rather large and broad, with a short snout that has two pairs of prefrontal scutes just above the nostrils. Forelimbs and hindlimbs modified into long front flippers and short rear flippers, normally with two claws on each flipper. In adult males, one claw on each of front flippers distinctly thickened and curved. Additionally, adult male has a long muscular tail that extends well beyond the carapace.

DISTRIBUTION: Throughout Gulf of Mexico and along Atlantic coast of the United States (Magnuson et al. 1990, Ernst et al. 1994). Normally associated with coastal and bay waters. Stranding data indicate occurrence in coastal and bay waters of Alabama, and historically, relatively large numbers reported to inhabit those coastal waters (Carr 1980).

HABITAT: Well known for inhabiting and feeding in the coastal and estuarine waters of the entire Gulf of Mexico and Atlantic Coast of the United States. Primarily nest on a stretch of beach located in the western Gulf of Mexico near Rancho Nuevo, Mexico (approx. 400 km [250 mi.] south of the U.S.- Mexico border) (Marquez-M 1994). Although the great majority nest in Mexico, a few nests are reported each year in the United States ranging from Texas to Florida. At least one nest has been documented in Alabama in recent years. Additionally, historical data suggest the bay waters of Alabama serve as foraging areas for juveniles during times of the year when blue crabs are abundant (Ogren 1989).

LIFE HISTORY AND ECOLOGY: During breeding season, migrate in coastal waters to primary nesting beach in Mexico. Exhibit synchronized nesting behavior in which relatively large numbers of females will nest on the same day over a small area of the nesting beach (called an “arribada,” which refers to the arrival of turtles). A historic film from 1947 shows an estimated 40,000 turtle arribada on a short stretch of beach near Rancho Nuevo. In contrast to other sea turtles, normally nests during the day. Nesting season usually begins in April, with the majority of nesting occurring in May and June. A typical female will lay approximately two nests in a nesting season, with each nest containing approximately 100 eggs (Rostal et al. 1997). A female may nest yearly or may skip a year between nesting seasons. Eggs take approximately 45 to 55 days to hatch depending on the incubation temperature of the nest. Gender of hatchlings determined by incubation temperature in nest. Hatchlings emerge primarily during early morning hours and proceed down beach to the surf. Hatchlings assume a pelagic existence until they grow large enough to begin foraging in coastal waters and bays, which serve as developmental habitats. Sexual maturity reached in as little as seven years in captivity. Growth data from turtles in the wild suggest that seven to 13 years are needed to reach sexual maturity (Caillouet et al. 1995). Feed in the coastal and bay waters throughout the Gulf of Mexico and along the Atlantic Coast of the United States (Ogren 1989, Magnuson et al. 1990). Known to feed on a variety of crab species as well as other benthic invertebrates. Captive-reared specimens that have never seen a crab quickly devour blue crabs when they are placed in their tanks.

BASIS FOR STATUS CLASSIFICATION: Considered the most endangered sea turtle in the world. The nesting population steadily declined from the late 1940s through the mid-1980s. During the 1980s and early 1990s there were fewer than 1,000 nests laid per year at Rancho Nuevo, suggesting approximately 500 nesting females in the breeding population (Marquez-M 1994, Turtle Expert Working Group 2000). Since then, the number of nests and nesting females has gradually increased, and during the 2001 and 2002 nesting seasons, approximately 3000 to 4000 nests were laid annually near Rancho Nuevo (Turtle Expert Working Group 2000). While this increase is encouraging, the current numbers are still very small compared with the estimated 40,000 nesting females on a single day back in 1947. The National Research Council Committee on Sea Turtle Conservation estimated that prior to the use of turtle excluder devices, a minimum of 11,000 (and possibly as high as 44,000 or more) sea turtles (primarily loggerheads and Kemp’s ridleys) died each year in the United States’ coastal waters of the Gulf of Mexico and Atlantic due to shrimping-related mortality (Magnuson et al. 1990). There are many examples from necropsies of stranded sea turtles indicating the ingestion of marine debris (Balazs 1985). Additionally, derelict fishing gear (e.g. nets, fishing line, etc.) has been implicated in the injury of marine turtles due to entanglement. Listed as endangered by the U.S. Fish and Wildlife Service in 1970.

Author: Thane Wibbels


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