A 24-year record of Cetacean strandings in Taiwanese waters: Signals of escalating threats

Cetacean strandings provide critical insights into the health of marine ecosystems and are indicative of both natural and anthropogenic stressors. Leveraging an 1884-stranding-event, 2225 -individual dataset spanning 24 years across Taiwan's main and outlying islands, we quantified long-term spatiotemporal trends and their drivers around Taiwan which is a strategic node with complex boundary-current environment in the Western Pacific. The aim was to uncover the factors driving a significant rise in strandings over the past decade, with a particular focus on species-specific vulnerabilities, spatial distribution, and seasonal trends. The increase in strandings since 2015 reflects a complex interplay of environmental and anthropogenic factors. Environmental events such as the 2015–2016 El Niño and marine heatwaves disrupted ocean conditions and impacted cetacean habitats, potentially contributed to the overall increase. Concurrently, bottlenose dolphins (Tursiops truncatus and T. aduncus) and finless porpoises (Neophocaena phocaenoides and N. asiaeorientalis) exhibited significant increases in strandings, pointing to potential fishery interactions across the Taiwan Strait. Furthermore, species such as Kogia spp. and pygmy killer whale (Feresa attenuata) exhibited fluctuating stranding patterns likely driven by episodic human activities, while increased disease-related strandings of Fraser's dolphin (Lagendelphis hosei) and spinner dolphin (Stenella longirostris) underscored growing environmental pressures. These findings indicate a persistent yet escalating threat landscape, driven by the interplay of climate-induced habitat disruption and seasonal fishery interactions. This study highlights the urgent need for continued monitoring and targeted management interventions to mitigate risks to cetaceans in the Taiwanese waters which provide complex and dynamic habitats for cetaceans, particularly in the face of growing human disruptions on marine ecosystems.