Predicting seasonal occurrence of leatherback turtles ( Dermochelys coriacea) in eastern Canadian waters from turtle and ocean sunfish ( Mola mola) sighting data and habitat characteristics

• Published in: Canadian Journal of Zoology
• Main Authors: Mosnier, A., Gosselin, J.-F., Lawson, J., Plourde, S., Lesage, V.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2019
• Subjects: Newfoundland
• Online Access: http://dx.doi.org/10.1139/cjz-2018-0167; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjz-2018-0167; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjz-2018-0167

Part of the western Atlantic population of leatherback turtles (Dermochelys coriacea (Vandelli, 1761)) forage in Canadian waters, where high-use areas have been identified using satellite telemetry and opportunistic sightings. Here, we use sightings of leatherback turtles and ocean sunfish (Mola mola (Linnaeus, 1758)) obtained during a systematic large-scale aerial survey, along with opportunistic turtle sightings, to examine the seasonal occurrence and distribution of leatherback turtles in eastern Canada. Using environmental correlates, we predict the spatial and seasonal development of potentially suitable habitats. All data sets confirmed the presence of leatherback turtles off Nova Scotia during summer. They also highlighted turtle occurrence off southern Newfoundland. Opportunistic sightings suggest a seasonal shift in main turtle concentrations from southwest to northeast, with use of southern Newfoundland waters extending into September. A generalized additive model linking environmental characteristics and turtle observations suggests adding the Grand Banks off Newfoundland and waters east of Anticosti Island in the Gulf of St. Lawrence to the potentially important habitat for leatherback turtles. Direct observations helped delineate habitat currently used by leatherback turtles. In the context of climate change, this modelling approach may improve our ability to forecast changes in turtle habitat suitability and the risks of entrapment or collision associated with potentially changing usage patterns.