Leatherback Sea Turtle
(Dermochelys coriacea)Identification
Size
- up to 3 m
Colour
- dark grey / black with white spots
Shell
- no shell
- carapace is covered with a leathery surface and has prominent ridges (looks like the underside of a boat)
- tear-shaped carapace tapers to a point at the rear end
Surface behaviour
- surfaces to breathe for a few minutes
- holds head above water, then slowly sinks back down
Group size / social behaviour
- solitary
Other characteristics
- very large turtle
Can be confused with
- due to its unique “leather back”, lack of shell and enormous size, cannot be confused with any other kind of turtle.
- from a distance, turtle’s head might be confused with a harbour seal at the surface.
Natural History
Globally, leatherback turtles are a critically endangered species; their numbers are only a quarter of what they were 20 years ago. The world population is estimated at 30,000 to 40,000 nesting females in the Atlantic, Pacific, and Indian Oceans. Scientists suggest that Pacific leatherback populations in particular are on the verge of extinction.
SCOTT ECKERT A leatherback turtle surfaces to breathe
Leatherback sea turtles are the widest-ranging marine reptiles, with some migrating more than 11 000 kilometres every year. They have been sighted as far north as Alaska and the North Sea and as far south as Chile and New Zealand. These far-ranging habits are made possible by their ability to regulate their body temperature to survive in colder waters. Dark skin colour, large body size, a thick layer of fat, and the ability to control blood flow to reduce heat loss all allow leatherbacks to maintain a body temperature as much as 18°C higher than the ambient temperature.
Leatherbacks found in colder waters are likely there in search of jellies, their major prey. They seem to be attracted to upwelling areas where jellies are abundant, as well as to boundaries between warm and cold waters; however, much about their migratory patterns is still left to be explained.
STEVE SKORUPINSKI Sport fishermen near Langara Island encounter a leatherback sea turtle in Aug 2004
Every few years, adult female leatherbacks return to nesting beaches in tropical waters to lay eggs. Once the eggs have been laid, the females return to the water, leaving their offspring to hatch and find their way to the open ocean. In the Pacific, leatherback nesting beaches can be found in Mexico, Costa Rica, Indonesia, and Malaysia. Nesting habitat lost to tourism and development, egg poaching, and predation have all affected the nesting success of leatherback populations in these areas, contributing to the decline of the Pacific population.
In the open ocean, leatherbacks face several other threats. Longline fisheries targeting tuna or swordfish regularly catch sea turtles and other marine species as bycatch. Scientists estimate that commercial fisheries in the Pacific caught 4,200 leatherback sea turtles in 2000 alone. Until alternate fishing gear such as circle hooks are in widespread use, the most effective way to help turtles is to avoid buying seafood caught using fishing methods that place leatherbacks at risk. Look for the Ocean Wise logo to choose sustainably-caught seafood.
Drifting plastic is a threat to sea turtles
Marine debris also poses problems for turtles. Their choice of prey leaves them vulnerable to mistakenly ingesting debris such as plastic bags that resemble jellies; attempts to eat such “prey” generally result in the turtle’s death. An action as simple as properly disposing of garbage while on or near the water could save a sea turtle, and help out many other species of marine life.
In the Pacific, leatherbacks make extensive feeding migrations to B.C. coastal waters from nesting beaches and rearing areas in tropical seas.
A study by Wild Whales predicted areas of entanglement risk to sea turtles in B.C.
Adult Pacific leatherbacks are often seen foraging off the coast of B.C. between July and September. Although sightings are infrequent, the B.C. Cetacean Sightings Network database shows that leatherbacks range across the entire B.C. coast, including inshore waters. The collapse of the Pacific stock means that the accidental removal of even a few adults may slow or jeopardize recovery of the species.
Status in Canada
The leatherback sea turtle is designated as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
COSEWIC’s assessment of the leatherback sea turtle (Dermochelys coriacea) is as follows:
The leatherback turtle is undergoing a severe global decline (> 70 % in 15 years). In Canadian waters, incidental capture in fishing gear is a major cause of mortality. A long lifespan, very high rates of egg and hatchling mortality, and a late age of maturity makes this species unusually vulnerable to even small increases in rates of mortality of adults and older juveniles.
PUBLICATIONS
Boulon, R., K. Eckert, and S. Eckert. 1988. Dermochelys coriacea (leatherback sea turtle) migration. Herpetological Review 19(4): 88.
Carr, A. 1987. Impact of nonbiodegradable marine debris on the ecology and survival outlook of sea turtles. Marine Pollution Bulletin 18(6B): 352-356.
Dutton, P. H., B. W. Bowen, D. W. Owens, A. Barragan, and S. K. Davis. 1999. Global phylogeography of the leatherback turtle, Dermochelys coriacea. Journal of Zoology (London) 248:397-409.
Eckert, S. A., and L. Sarti. 1997. Distant fisheries implicated in the loss of the world’s largest leatherback nesting population. Marine Turtle Newsletter 78: 2-6.
Eckert, S.A. 2002. Distribution of juvenile leatherback sea turtle, Dermochelys coriacea, sightings. Marine Ecology Progress Series 230: 289-293.
Eckert, S.A. and L. Sarti M. 1997. Distant fisheries implicated in the loss of the world?s largest leatherback nesting population. Marine Turtle Newsletter 78:2-7.
Eckert, S.A., K.L. Eckert, P. Ponganis and G.L. Kooyman. 1989. Diving and foraging behavior by leatherback sea turtles (Dermochelys coriacea), Canadian Journal of Zoology. 67: 2834-2840.
Eckert, S.A., K.L. Eckert, P. Ponganis, and G.L. Kooyman. 1989. Diving and foraging behavior of leatherback sea turtles (Dermochelys coriacea). Canadian Journal of Zoology 67: 2834-2840.
Fritts, T.H. 1982. Plastic bags in the intestinal tracts of leatherback marine turtles. Herpetological Review 13 (3): 72-73.
Goff, G.P. and J. Lien. 1988. Atlantic leatherback turtles (Dermochelys coriacea) in cold water off Newfoundland and Labrador. Canadian Field Naturalist 102 (1):1-5.
James, M., S.A. Eckert and R.A. Myers. 2005. Migratory and reproductive movements of male leatherback turtles (Dermochelys coriacea). Marine Biology 147:845-853.
James, M.C. 2004. Dermochelys coriacea (leatherback sea turtle) migration and dispersal. Herpetological Review 35: 264. [PDF]
James, M.C., C.A. Ottensmeyer and R.A. Myers. 2005. Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letters. 8: 195-201. [PDF]
James, M.C., C.A. Ottensmeyer, S.A. Eckert and R.A.Myers. 2006. Changes in diel diving patterns accompany shifts between northern foraging and southward migration in leatherback turtles. Canadian Journal of Zoology. 84: 754-765. [PDF]
James, M.C., S.A. Sherrill-Mix, K.E. Martin, and R.A. Myers. 2006. Canadian waters provide critical foraging habitat for leatherback turtles. Biological Conservation. 133: 347-357. [PDF]
James, M.C., Sherrill-Mix, S.A., and R.A. Myers. 2007. Population characteristics and seasonal migrations of leatherback sea turtles at high latitudes. Marine Ecology Progress Series 337: 245-254. [PDF]
Jones, T.T., R.D. Reina, C.-A. Darveau and P.L. Lutz. 2007. Ontogeny of Energetics in Leatherback, Dermochelys coriacea and Olive Ridley, Lepidochelys olivacea Sea Turtle Hatchlings. Comparative Biochemistry and Physiology: Part A 147(2007):313-322. PDF
Jonsen, I.D., Myers, R.A., and M.C. James. 2007. Identifying leatherback turtle foraging behaviour from satellite telemetry using a switching state-space model. Marine Ecology Progress Series 337: 255-264. [PDF]
Martin, K. and M.C. James. 2005. The need for altruism: engendering a stewardship ethic amongst fishers for the conservation of sea turtles in Canada. Maritime Studies (MAST) 3(2) and 4(1): 105-118. [PDF]
Martin, K. and M.C.James. 2005. Conserving sea turtles in Canada: Successful community-based collaboration between fishers and scientists. Chelonian Conservation and Biology 4(4): 899-907. [PDF]
Sarti, M.L., Eckert, S.A., Garcia, T.N., and A.R. Barragan. 1996. Decline of the world’s largest nesting assemblage of leatherback turtles. Marine Turtle Newsletter 74: 2-5.
Spotila, J.R., Reina, R.D., Steyermark, A.C., Plotkin, P.T. and F.V. Paladino. 2000. Pacific leatherback turtles face extinction. Nature 405: 529-530.
Starbird, C. 2000. Dermochelys coriacea (leatherback sea turtle). Fishing net ingestion. Herpetological Review 31: 43.
Suarez, A., and C.H. Starbird. 1996. Subsistence hunting of leatherback turtles, Dermochelys coriacea, in the Kai Islands, Indonesia. Chelonian Conservation and Biology 2(2): 190-195.
