Assignment tests, telemetry and tag-recapture data converge to identify natal origins of leatherback turtles foraging in Atlantic Canadian waters
Article first published online: 6 MAR 2013
© 2013 NOAA - National Marine Fisheries Service. Journal of Animal Ecology © 2013 British Ecological Society
Journal of Animal Ecology
How to Cite
Stewart, K. R., James, M. C., Roden, S., Dutton, P. H. (2013), Assignment tests, telemetry and tag-recapture data converge to identify natal origins of leatherback turtles foraging in Atlantic Canadian waters. Journal of Animal Ecology. doi: 10.1111/1365-2656.12056
- Article first published online: 6 MAR 2013
- Manuscript Accepted: 8 JAN 2013
- Manuscript Received: 11 APR 2012
- Canadian Wildlife Federation
- Environment Canada
- Fisheries and Oceans Canada
- George Cedric Metcalf Foundation
- Habitat Stewardship Program for Species at Risk
- National Fish and Wildlife Foundation (USA)
- National Marine Fisheries Service (USA)
- Natural Sciences and Engineering Research Council of Canada
- World Wildlife Fund Canada
- combine methods;
- stock structure;
- Investigating migratory connectivity between breeding and foraging areas is critical to effective management and conservation of highly mobile marine taxa, particularly threatened, endangered, or economically important species that cross through regional, national and international boundaries.
- The leatherback turtle (Dermochelys coriacea, Vandelli 1761) is one such transboundary species that spends time at breeding areas at low latitudes in the northwest Atlantic during spring and summer. From there, they migrate widely throughout the North Atlantic, but many show fidelity to one region off eastern Canada, where critical foraging habitat has been proposed. Our goal was to identify nesting beach origins for turtles foraging here.
- Using genetics, we identified natal beaches for 288 turtles that were live-captured off the coast of Nova Scotia, Canada. Turtles were sampled (skin or blood) and genotyped using 17 polymorphic microsatellite markers. Results from three assignment testing programs (ONCOR, GeneClass2 and Structure) were compared. Our nesting population reference data set included 1417 individuals from nine Atlantic nesting assemblages. A supplementary data set for 83 foraging turtles traced to nesting beaches using flipper tags and/or PIT tags (n = 72), or inferred from satellite telemetry (n = 11), enabled ground-truthing of the assignments.
- We first assigned turtles using only genetic information and then used the supplementary recapture information to verify assignments. ONCOR performed best, assigning 64 of the 83 recaptured turtles to natal beaches (77·1%). Turtles assigned to Trinidad (164), French Guiana (72), Costa Rica (44), St. Croix (7), and Florida (1) reflect the relative size of those nesting populations, although none of the turtles were assigned to four other potential source nesting assemblages.
- Our results demonstrate the utility of genetic approaches for determining source populations of foraging marine animals and include the first identification of natal rookeries of male leatherbacks, identified through satellite telemetry and verified with genetics. This work highlights the importance of long-term monitoring and tagging programmes in nesting and high-use foraging areas. Moreover, it provides a scientific basis for evaluating stock-specific effects of fisheries on migratory marine species, thus identifying where coordinated international recovery efforts may be most effective.