Water temperature correlates with baleen whale foraging behaviour at multiple scales in the Antarctic

Abstract

How baleen whales locate prey and how environmental change may influence whale foraging success are not well understood. Baleen whale foraging habitat has largely been described at a population level, yet population responses to change are the result of individual strategies across multiple scales. This study aimed to determine how the foraging behaviour of individual whales varied relative to environmental conditions along their movement path. Biotelemetry devices provided information on humpback whale (Megaptera novaeangliae) movement at two spatial scales in East Antarctica, and a mixed modelling approach was used at a medium scale (tens of kilometres) to determine which environmental factors correlated with a change in foraging behaviour. Water temperature was linked to a change in foraging behaviour at both spatial scales. At the medium scale, warmer water was associated with the resident state, commonly assumed to represent periods of foraging behaviour. However, fine-scale analyses suggested that cooler water was associated with a higher feeding rate. Variation in whale foraging behaviour with changes in water temperature adds support to the hypothesis that whales may be able to track environmental conditions to find prey. Future research should investigate this pattern further, given the predicted rise in water temperatures under climate-change scenarios.