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Leatherback Sea Turtle

Dermochelys coriacea

Family: Dermochelyidae

COSEWIC status:
  • Endangered
SARA status:
  • Endangered
IUCN status:
  • Vulnerable

Description

The Leatherback Sea Turtle is the largest turtle species in the world and can grow to over 2 m in carapace length and weigh over 900 kg. The leathery, smooth carapace is elongate with seven pronounced longitudinal ridges and it tapers to a point at the rear. Individuals are dark brown to bluish-black with white or light blue blotches adults have a pink spot on the head. The plastron (lower shell) is pinkish-white. Leatherback Sea Turtles have flippers and lack claws. The front flippers are large and are usually at least half as long as the carapace. Hatchlings have an average carapace length of 6 cm and generally resemble the adults, but they are covered in small scales and the edges of the flippers and carapace keels are yellow.

Similar Species

No other sea turtles have a leathery shell with longitudinal ridges.

Distribution

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Leatherback Sea Turtles are widely distributed in both inshore and offshore waters in Atlantic Canada from April to December. This species also occurs at low densities in Pacific Canada off the coast of British Colombia. Individuals that forage in Atlantic Canada nest at tropical latitudes in the Western North Atlantic from Florida south to French Guiana, while individuals that forage along the Pacific coast of Canada nest in tropical regions of the West Pacific, primarily in Papua, Indonesia. The Leatherback has the largest global range of any reptile; it occurs throughout the temperate and tropical regions of the Atlantic, Pacific and Indian Oceans and nests on every continent except Europe and Antarctica.

Habitat

Leatherback Sea Turtles are aquatic and inhabit marine environments. In Canada, individuals forage in coastal areas as well as deep offshore waters. Females that forage in Canadian waters nest along sandy beaches in tropical regions. In the northwest Atlantic, migration corridors between temperate foraging areas and tropical nesting beaches are generally close to the coastline in shallower water (< 70 m deep).

Biology

Leatherback Sea Turtles can migrate 10,000 km or more between foraging and nesting grounds, and females typically return to the same beaches where they have previously nested. The seasonal timing of nesting varies by location. Leatherback Sea Turtles that forage in the Canadian Atlantic generally nest in tropical regions from April to July, but they may also nest in French Guiana from November to February. Females reproduce every 2–4 years and lay 1–11 clutches during a nesting season, usually spaced 8–12 days apart. Nesting typically occurs at night. Females excavate a nest cavity that is often more than 1 m in depth and deposit 22–166 eggs. The eggs hatch after approximately 2 months, and the hatchlings use light cues to orient toward the ocean. The sex of the offspring is temperature-depend; incubation temperatures below 28.75°C produce only males while temperatures above 29.75°C produce only females. Individuals reach sexual maturity between 6–15 years of age. Maximum lifespan is unknown, but like other sea turtles they can likely live more than 50 years. Leatherback Sea Turtles forage primarily on jellyfish, but they also consume a variety of other prey including sea urchins, snails, crustaceans and small fish. Like other Sea Turtles, the Leatherback Sea Turtle cannot retract its head and flippers into its shell. Unlike most reptiles, Leatherback Sea Turtles are able to generate internal heat and maintain body temperatures higher than the surrounding environment. This is accomplished through physiological adaptations such as fat layers, countercurrent blood flow in the flippers, a high surface-area-to-volume ratio, and the generation of heat through metabolic activity (like mammals and birds). These allow Leatherbacks to venture further north than other sea turtle species and spend extended periods of time in cold northern waters.

Threats

By-catch and entanglement in commercial fishing gear can result in high mortality rates and is the most significant threat to Leatherback Sea Turtles in Canadian waters. Ingestion of garbage and plastic, particularly plastic bags that superficially resemble jellyfish, also causes the death of many sea turtles. Other threats in marine environments include oil spills and other environmental population, as well as propeller strikes from large ships that cause injury and mortality. Female sea turtles are especially vulnerable when they are nesting, and poachers slaughter gravid females for meat, oil or eggs throughout the range of this species. Illegal poaching of eggs is also a widespread threat that can result in 100% loss of nests at beaches that are not monitored and protected. Climate change may also negatively affect Sea Turtles in several ways, including increased incidence of nesting beach erosion or shifts in sex ratio resulting from changes to nest incubation temperatures. Populations of Leatherback Sea Turtles in the western Atlantic appear to be relatively stable, but Pacific populations have undergone a precipitous decline of about 95% in the past few decades.

Additional Information About This Species In Canada