Eastern Canada hosts one of the largest seasonal aggregations of leatherback turtles (Dermochelys coriacea) in the Atlantic Ocean, and is considered critical foraging habitat. Explaining distributional variation of leatherbacks in this three‐dimensional habitat is relevant to the recovery strategy for this endangered species as human activities are a leading cause of mortality. We identify high‐resolution spatial and temporal patterns in leatherback movements, and associated environmental variables shaping leatherback habitat use in Atlantic Canadian foraging waters. Data loggers were deployed on three female leatherbacks off Halifax, Nova Scotia, and were recovered during subsequent nesting in South and Central America. Time (0.5 Hz), depth (±1 m), water temperature (±0.1°C), and location data were recorded and analyzed for the period when the turtles were resident in their Canadian foraging domain. We demonstrate that leatherback dives are primarily restricted to the main thermocline, suggesting a food‐related water mass association. We also identified low‐ and high‐frequency periodicities in turtle depth‐at‐time, reflecting a diel pattern triggered by nautical twilight and dive periods of 8–10 minutes. We further demonstrate that dive frequency is a function of seasonal change in daylight. Our findings illustrate that solar illumination influences leatherback diving in north temperate waters, consistent with turtles using visual cues for foraging.
Pas de photo pour Water Mass Characteristics and Solar Illumination Influence Leatherback Turtle Dive Patterns at High Latitudes
|IOSEA Marine Turtles