Dynamic Migratory Strategies and Foraging Habitats of Southern Right Whales Revealed by Satellite Telemetry

Understanding the migratory and foraging behaviour of wide-ranging marine predators is crucial for effective conservation planning, particularly in capital breeders where foraging success directly influences reproductive success and population dynamics. For South Africa's southern right whale (SRWs), reproductive success has declined over recent decades, yet contemporary offshore migratory routes and foraging habitats remain poorly known. Here, satellite-linked tags deployed on 34 adult SRWs between 2021 and 2024 were used to investigate migratory strategies and identify environmental correlates of offshore area-restricted search (ARS) behaviour. ARS locations derived from a movement-persistence model were linked to environmental covariates using a random-forest habitat model to identify predictors of foraging behaviour, map suitable offshore foraging habitat, and predict habitat suitability across the wider Southern Ocean foraging range of the South African population. Whales ranged widely across the South Atlantic and southwest Indian Oceans, concentrating foraging effort within the Antarctic Circumpolar Current (ACC), the high-latitude seasonal ice zone, around the Crozet Islands, and within the Benguela upwelling system. Seven individuals (21%) undertook trans-Atlantic migrations to foraging grounds shared with the SRW population of the Southwest Atlantic, demonstrating basin-scale connectivity between populations. Random forest analyses identified environmental covariates associated with ARS behaviour across multiple oceanographic regions with high predictive performance (AUC = 0.90). Predicted habitat suitability highlighted suitable offshore foraging habitat associated with frontal systems, shelf-associated habitats, upwelling regions, and high-latitude seasonal ice habitats across the Southern Ocean. These findings provide the first environmentally explicit habitat-modelling assessment of contemporary offshore foraging habitat for the South African SRW population. Results show this population exhibits diverse migratory routes and foraging behaviours, relying on a wide range of oceanographic habitats that may facilitate behavioural responses and plasticity to variability in foraging conditions across the Southern Ocean.