At-sea biology and movements of leatherback turtles, Dermochelys coriacea, in the northwest Atlantic

The endangered leatherback turtle, Dermochelys coriacea , has the broadest distribution of any sea turtle; however, research on this species has principally been limited to studies of the biology of nesting females, their internesting behaviour, and more recently, their post-nesting movements. To hasten this species' recovery, research on the biology of leatherbacks and the threats they face in other areas of their range is needed. In collaboration with the fishing industry, I developed a field research program to study leatherbacks in waters off eastern Canada, where turtles aggregate seasonally to forage on gelatinous plankton.; In this thesis, I report on the degree to which leatherbacks maintain body temperature above ambient in northern waters, and discuss the implications of endothermy for leatherbacks in temperate and tropical areas. To study the local and long-distance movements of leatherbacks, I equipped 42 subadult and adult turtles with satellite tags in Canadian waters, the largest satellite telemetry study of this species in the Atlantic. I use movement data from this sample and morphometrics from foraging animals to identify previously unrecognized high-use habitat for leatherbacks in temperate shelf and slope waters of the northwest Atlantic, where entanglement data demonstrates turtles are at risk of interacting with both mobile and fixed-gear fisheries. I present tracklines that confirm annual return migrations to feeding areas, and describe patterns in turtle movement during these migratory cycles. I identify diel patterns in diving and surfacing behaviour both in northern foraging areas and during southward migration, and explore the potential biological significance of these patterns. Finally, I report on the first deployments of satellite tags on male leatherbacks, which provide new information on the location and timing of mating activity and suggest male fidelity for breeding areas.; Collectively, this work presents new information on the life history of the leatherback and demonstrates the importance of northern latitudes, and especially waters off Canada and the northeastern United States, to this species.