Modeling spatio-temporal variations in the habitat utilization of cetaceans in the East China Sea

Effective conservation of cetaceans requires a clear understanding of their habitat use in relation to dynamic ocean conditions and anthropogenic pressures. The East China Sea (ECS) is an important habitat for cetaceans, yet knowledge regarding their occurrence and distribution in this region remains limited, particularly during the ecologically significant period following the Summer Fishing Moratorium (SFM). This study aimed to model the spatio-temporal variations in cetaceans habitat suitability in the ECS from September to December 2023, immediately after the SFM. Utilizing an ensemble species distribution model (SDM) that integrated five distinct algorithms, the study analyzed incidental sighting data collected through a fisherman-based monitoring network along with a set of oceanographic variables. The ensemble model revealed monthly shifts in distribution hotspots, which were consistently associated with specific isotherm and isobath ranges. Sea surface height (SSH) and sea surface temperature (SST) were identified as the most important predictors of habitat suitability. The results highlight the northeastern offshore and southeastern offshore waters of the ECS as areas of potentially high suitability for cetaceans. This study provided the baseline for cetaceans’ distribution during the post-SFM period, a time of potential prey resource recovery and intensified fishing activity. These findings were essential for formulating targeted marine spatial planning and guiding the development of dynamic ocean management tools such as dynamic Marine Protected Areas (MPAs) and mitigating human impacts on cetaceans in this highly utilized maritime region.