Humpback whales in the Southwest Atlantic Ocean: investigating their breeding movements by satellite tracking

Abstract

Understanding animals' movements is essential to assess habitat use, life-history strategies, and population dynamics. Here, we investigate the movement and behavior patterns of 153 humpback whales in the Southwest Atlantic Ocean (SWA) using data obtained by satellite telemetry between 2003 and 2019 during the species' breeding season (August–December) off the Brazilian coast. Switching state space models were applied to estimate behavior states (bmode) classified as Area Restricted Search (ARS), Transiting (TRANS), or uncertain. Whales were distributed from 4°S to 24°S, and five clusters of ARS behavior were identified along the Brazilian coast. Generalized linear mixed modeling revealed three main results: (1) a transition towards more sinuous behavioral states with increasing latitude; (2) more sinuous movement behavior around new moons; (3) movement behavior was temporally dynamic throughout the breeding season over the years, particularly in 2019. The results then revealed important regions where humpback whales cluster to engage in mating and nursing behaviors, highlighting the influence of spatial location and environmental cycles on their behavior. Estimated movement behavior presented here improves the knowledge about the habitat use and movement patterns of SWA humpback whales in their breeding ground and can be used to mitigate potential human-related impacts.