Regional variation in leatherback dive behavior in the northwest Atlantic

Understanding the movement patterns and behaviors of a migratory species across all stages of migration is critical to informing successful conservation management strategies. While the movement patterns of northwestern Atlantic leatherbacks Dermochelys coriacea have been widely studied, there is still a need to understand area-specific behaviors. We collected and analyzed dive data from 52 satellite-tagged leatherbacks that inhabited documented or proposed foraging areas: the northeastern Gulf of Mexico (NEGOM), the Mid-Atlantic Bight (MAB), and southern New England (SNE). We fit generalized linear mixed models (GLMMs) to these data to determine area-specific dive metrics and their relationship to several environmental variables. The most notable result from the GLMMs revealed area-specific relationships between dive behavior and sea surface temperature (SST). As SST increased, leatherbacks in the NEGOM and MAB were observed to increase their surface duration and decrease dive duration, while the opposite trend was observed off SNE. Additionally, leatherbacks in the NEGOM performed more deep dives to cooler waters with rising SSTs. Our results suggest that leatherbacks in the NEGOM are performing thermoregulatory dive behavior that may reduce time available for feeding, potentially inhibiting foraging success relative to the MAB and SNE. These findings offer a deeper comprehension of leatherback movement ecology in each area, provide critical information needed for population assessments and management, and highlight areas of conservation concern in a warming climate.