Large-scale differences, mesoscale similarities: neighbouring marine predator populations provide insights into Southern Ocean productivity

Understanding how marine predators explore dynamic ocean environments is key for assessing the ecological significance of different habitats and for informing conservation efforts. This is particularly critical in remote and poorly surveyed regions, where marine predators can serve as ecosystem sentinels and provide valuable biological and oceanographic data. Here, we examined the foraging strategies of southern right whales (Eubalaena australis, SRW) using a large-scale satellite tagging dataset from two neighbouring populations: Aotearoa New Zealand and Western Australia. We linked foraging behaviour, inferred from bio-logging data, with remotely sensed environmental data to assess habitat use in relation to Southern Ocean oceanographic features. At broad spatial scales, foraging areas were identified near major frontal systems, but while the New Zealand population primarily targeted the Subtropical Front, the Australian population visited a wider range of oceanic features, including the Antarctic ice edge. At finer scales, both populations co-located with mesoscale eddies, preferentially foraging in cyclonic (cold-core) eddies. Satellite tracking data also suggested that foraging SRWs may exhibit quasi-planktonic behaviour by drifting around eddies. Differences in foraging strategies between the New Zealand and Western Australian populations may have important implications for their continued recovery under climate change. Furthermore, this work showcases SRWs as a sentinel species that highlights key foraging habitats that remain overlooked by high seas conservation efforts.