MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14790

ABSTRACT: Most marine ecosystems are experiencing increasing cumulative impacts from climate change, fishing, shipping, and land-based pollution. The resulting ecosystem responses are challenging to monitor. Studying the space use of top marine predators may provide insight into how these ecosystems react to these impacts. Natural populations are however composed of unique individuals, that differ in many ways including how they use space. Here we used data from a multidecadal biotelemetry research program on grey seals in the Northwest Atlantic, to investigate temporal changes in space use in a context of environmental changes and increasing population size. We quantified temporal changes in monthly home range size, shape, and distribution of grey seals in the Gulf of St. Lawrence between 1992-2022, while also quantifying interindividual differences. We found that the monthly home ranges of grey seals have increased in size and shifted in distribution over the last three decades, indicating that grey seals appear to have expanded their space use. We detected individual differences in mean home range characteristics and their level of variability, suggesting that individual identity plays a role in the large-scale space use of grey seals. We also found negative correlations between the mean and level of variability in both home range size and shape, hinting to the potential presence of different tactics within the population. This study highlights how top marine predators can modify their behaviour to adapt to environmental changes and illustrates the importance of considering interindividual differences when exploring population space use patterns.