Jing Yuan ¹ Yili Gao ¹ Nan Wang ¹ Tianhua Jiang ¹ Zhaolong Cheng ^2*

• ¹ Ningbo Key Laboratory of Agricultural Germplasm Resources Mining and Environmental Regulation, College of Science and Technology, Ningbo University, Cixi 315300, China
• ² Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences (CAFS), Qingdao, China

Cetacean ecology has been poorly studied in the Shanghai-Zhejiang waters of the East China Sea, seriously hindering appropriate local conservation practices. Here, stranding records from 1953 to 2023 around the Shanghai-Zhejiang waters were collated and used to clarify species composition and spatio-temporal variations of cetacean strandings. A total of 138 stranding records involving 197 individuals across 23 species were identified, comprising four Mysticeti and 19 Odontoceti species. Cetacean stranding records occurred extensively along the Shanghai-Zhejiang coastline throughout the year and grown swiftly since the 2000s. Narrow-ridged finless porpoise Neophocaena asiaeorientalis and common minke whale Balaenoptera acutorostrata were the most frequently stranded species. Over 84% of stranding events involved only a single individual. Melon-headed whale Peponocephala electra predominated in mass stranding incidents. Spatially, the stranding reports showed a significant cluttering distribution pattern. Clustering of cetacean records occurred in the Yangtze River estuary, downstream region of Qiantang River, southeastern of Ningbo, and Oujiang River estuary. Seasonal analysis showed increased cetacean stranding events in spring, yet without significant difference. Post-mortem examinations of stranded individuals showed that coastal fisheries and port activities were probably the dominant causes of local cetacean strandings. Standardizing cetacean stranding records, strengthening fisheries regulations and rescue training programs are recommended to establish a dedicated cetacean stranding monitoring network, which is vital for cetacean conservation in this region. hampered in most geographic regions. In this context, the collection of cetacean stranding records emerges as a cost-effective monitoring method for providing valuable cues on their ecology (IJsseldijk et al., 2020;Silva et al., 2021). This method boasts several advantages compared to traditional methods, such as aerial surveys and passive acoustic techniques. First, long-term stranding datasets with detailed coordinates and time information have shown consideration potential in providing insights into species diversity, spatial distribution, population dynamics, group structure, and relative abundances (IJsseldijk et al., 2020,