Kemp's Ridley Sea Turtle (Lepidochelys kempii)
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Scientific Classification
Class: Reptilia
Order: Testuidae
Family: Cheloniidae
Genus: Lepidochelys
Species: kempii
Species Description
Conservation
Status
Endangered throughout its range
Threats
- Hunting
- Interaction with commercial fishing gear
- Habitat destruction
- Pollution
- Climate change
- Lack of information
Natural History
Range
Throughout the Gulf of Mexico and the U.S. eastern seaboard from Florida to New England.
Habitat
Open ocean
Shallow bays and lagoons
Open sandy beaches
Diet
Carnivore: crabs, fish, jellyfish, and mollusks
Life History
Reproduction - Seasonal
Sexual maturity: 11 to 30 years (females usually 10-17 yrs)
Breeding: April to July
Average clutch size: 100 eggs
Average clutches per season: 1-4
Range of nest incubation: 45-65 days
Lifespan
30 – 50 years
- The Kemp’s ridley turtle was named after Richard Kemp, a fisherman from Key West, Florida. He was the first person to submit the species for identification in 1906.
- The Kemp’s ridley is one of only two species to sea turtles that nest in arribadas.
- The Kemp’s ridley turtle is the only sea turtle to nest predominantly during the day.
Description
Adult Kemp’s ridleys are the smallest of the sea turtles, with the carapace rarely exceeding 29 inches in length. The carapace of an adult Kemp’s Ridley is broad and light gray-olive in color and the plastron is creamy white. The carapace is usually as wide as it is long and has a distinctive pattern of scutes. The head is large with ridged, powerful jaws. Each of the front flippers has one claw, while the back flippers may have one or two. Hatchlings are grey-black all over.
Distribution
Kemp’s ridleys can be found throughout the Gulf of Mexico and the U.S. eastern coast from New England to Florida. Almost all the Kemp’s ridleys in the world nest on one beach at Rancho Nuevo, Tamaulipas, Mexico. Nesting has also been reported throughout the Gulf of Mexico, as well as along the eastern coasts of Florida, Georgia, South Carolina and North Carolina.
Habitat
Kemp’s ridleys occupy different habitats depending on their age. They mature, feed and nest in very different areas.
As hatchlings and youngsters, they spend the first few years in the open ocean. Here they associate with floating mats of sargassum seaweed. When the turtles reach a carapace length of about 8 inches (20 cm), they travel to the shallow bays and lagoons of the Gulf of Mexico or northwestern Atlantic Ocean to feed and develop until they reach adulthood.
Adult Kemp’s ridleys mainly stay near shallow coastal regions (less than 160 ft deep) and can be found in bays and lagoons. These turtles prefer waters that have sandy or muddy bottoms. They can also be found in the open ocean, especially when traveling between feeding and nesting areas. At sea, this species have been known to dive to great depths.
Diet
Their diet consists mainly of swimming crabs, but may also include fish, jellyfish and an array of mollusks.
Life History
Once turtles have entered the sea, they seldom return to land. Males never come ashore. Females only come on shore to nest. With many reptiles, size is a more reliable indicator of sexual maturity than age. This is the case with sea turtles. Kemp’s ridleys take from 11 to 35 years to reach maturity. Females usually start nesting when they are between 10 and 17 years of age.
Individual male Kemp’s ridleys may have different breeding strategies. Some males migrate annually between feeding and breeding grounds. Others do not appear to migrate at all. They stay in one area and breed with females they encounter by chance.
Female Kemp’s ridleys migrate to and from nesting beaches approximately every two years. Breeding season occurs from March to August.
Nesting peaks between in May and June. Unlike most other sea turtles, nesting occurs during the day. Kemp’s ridley turtle exhibit mass synchronized nesting known as ‘arribadas‘ (Spanish for ‘mass arrivals’). During arribadas, thousands of females come ashore to nest on the same beach at the same time. No one knows for sure what triggers an arribada.
Nesting females crawl onto the beaches above the high tide line and dig a nest cavity with their rear flippers. They deposit their eggs into the nest, cover the nest with sand and return to the sea. The entire process takes about an hour. Females repeat this process two or three times during the breeding seasons at approximately 14 day intervals. Each clutch contains about 100 eggs. After females have completed nesting, they return to their foraging areas.
Eggs incubate for 48-56 days. Like most reptiles, the temperature at which an egg is incubated determines its sex. This is referred to as temperature dependent sex determination, or TSD.
It may take several days for a hatchling to emerge from the nest. They usually emerge at night. Once on the surface, they quickly orient and move towards the ocean. They use moonlight and starlight reflected from the surface of the water as a guide.
After entering the water, the hatchling swims continuously for 24 to 48 hours. It is thought that they find beds/rafts of sargassum algae to float around with. It is there that they begin to eat and grow.
Threats
The Kemp’s ridley turtle is the most endangered sea turtle in the world. This species faces threats both on nesting beaches and in the ocean environment. The greatest causes of population decline are accidental capture in fishing gear and over-harvesting.
Sea turtles face different predators as they age.
Eggs and hatchlings are the most vulnerable. They may be eaten by a wide range of coastal predators, such as crabs, large lizards, small mammals (e.g. raccoons, coatis, dogs, coyotes, genets, mongooses) and a variety of birds of prey and shorebirds.
Young sea turtles can be eaten by cephalopods, sharks and other large fish once they are in the ocean.
Adults face fewer serious predators, although large marine predators such as orcas and sharks occasionally attack and eat sea turtles.
Nesting females are also attacked or harassed by feral dogs, large predators, biting flies and humans.
Hunting. Historically, the principal cause of decline in the Kemp’s ridley sea turtle population was long-term harvest. Eggs and adult females were harvested on nesting beaches. Juveniles and adults were harvested on feeding grounds. Although this practice is much less common now, it still occurs in many areas around the world.
Commercial Fishing. Accidental capture in fishing gear is a serious ongoing cause of death that also negatively affects the population.
Pollution:
Trash. Turtles eat a wide array of the 24,000 metric tons of floating trash dumped in the ocean each year. This includes such items as bags, sheets, pellets, balloons and abandoned fishing line. Sea turtles may mistake the floating plastic for jellyfish, a common food item. When turtles eat plastic, it causes many health concerns, including blocked intestines, malnutrition, suffocation, ulcers and starvation. Ingested plastics also release toxins that accumulate in the turtles tissues. These toxins lead to thinner eggshells, tissue damage and unusual behavior.
Artificial lighting. Artificial light impacts nesting females and hatchlings. Females appear to prefer nesting on beaches free of artificial lighting or shadowed. Hatchlings automatically move towards the ocean using reflected moonlight or starlight on the water as a guide. Artificial light is brighter and can confuse them so they navigate inland towards that light and away from the ocean. This results in dehydration and predation. Artificial lighting causes tens of thousands of hatchling deaths per year.
Climate Change. Changes in global temperatures can affect the turtles in many ways.
- Since the sex of sea turtle hatchlings depends on the temperature at which the eggs were incubated, high sand temperatures may change sex ratios resulting in too few males to sustain the population.
- As water levels rise, a number of good nesting beaches will be lost.
- The areas where sea turtles feed may be dramatically altered by climate change.
Click here for more information on the impact of climate change on sea turtle populations.
Habitat Destruction. Habitat destruction and intrusion on the habitat by humans is a serious threat to sea turtles. Beach development for people deprives the turtles of good nesting areas, forcing them to leave or nest closer to the water.
Growth of cities often leads to the siltation of sandy beaches and the construction of docks and marinas can destroy near-shore habitats. Boat traffic and dredging damages habitat and can also injure or kill turtles when boats collide with turtles at or near the surface.
Our lack of knowledge about the population and life history of Kemp’s ridley sea turtles makes it very difficult to understand what this species needs to survive and thrive.
Conservation
All over the world the sea turtles continue to decline. Their conservation and recovery requires international cooperation in order to address all of the threats to these species. The Kemp’s ridley sea turtle is the most endangered sea turtle in the world.
In the U.S., the National Oceanic and Atmospheric Administration (NOAA) Fisheries and the U.S. Fish and Wildlife Service (USFWS) protect sea turtles. NOAA monitors the turtles while they are in the ocean and USFWS while they are on land. Federal and state agencies have developed regulations to eliminate or reduce threats to sea turtles. For example, NOAA works closely with the shrimp trawl fishing industry to develop turtle excluder devices (TEDs) and reduce the death of sea turtles accidentally caught in shrimp trawl gear. TEDs that are large enough to exclude even the largest sea turtles are now required in shrimp trawl nets. The USFWS, in partnership with other organizations, provides protection for sea turtles and their nests during the nesting season.
You can help too. In many places, workers and volunteers from many different organizations help protect the turtles during the nesting season. Volunteers help locate and protect nests, relocate nests threatened by disturbance or guide hatchlings to the ocean. Even after the eggs hatch, these volunteers can assist scientists as they uncover and count eggs and hatchlings left in the nest.
There are many other ways that we can help as well:
- Limit our use of plastics
- Refuse, Reduce, Reuse, Recycle (see Womble’s Tale)
- Use only turtle friendly products
- Respect sea turtles beaches and nests
- Support sea turtle research
- Volunteer with a recommended sea turtle conservation organization
- Support your local sea turtle conservation organizations
Ernst, C. H.; Lovich, J.E. (2009). Turtles of the United States and Canada (2 ed.). JHU Press. ISBN 978-0-8018-9121-2.
Janzen, Fredric J (1994). “Climate change and temperature-dependent sex determination in reptiles” (PDF). Population Biology 91 (16): 7487–7490.
Lorne, Jacquelyn; Michael Salmon (2007). “Effects of exposure to artificial lighting on orientation of hatchling sea turtles on the beach and in the ocean” (PDF). Endangered Species Research 3: 23. doi:10.3354/esr003023.
Spotila, James R. (2004). Sea Turtles: A Complete Guide to their Biology, Behavior, and Conservation. Baltimore, Maryland: Johns Hopkins University Press and Oakwood Arts. ISBN 0-8018-8007-6.
US Fish and WIldlife Service, North Florida Ecological Services, Kemp’s Ridley Turtle Fact Sheet.
Witherington, Blair (2006). “Ancient Origins”. Sea Turtles – An Extraordinary Natural History of Some Uncommon Turtles. St Paul, Minnesota: MBI Publishing Company. ISBN 0-7603-2644-4.
Wynne, Kate; Schwartz, Malia (1999). Guide to Marine Mammals and Turtles of the U.S. Atlantic and Gulf of Mexico. illustrated by Garth Mix (2nd ed.). Rhode Island Sea Grant. ISBN 0-938412-43-4.