Sea turtle strandings provide critical insights into population health and anthropogenic threats, yet long-term data remain scarce for East Asia region, including Hong Kong waters. Here we retrospectively analysed 23 years (2002–2024) of 223 sea turtle stranding records to characterize species composition, demographics, temporal trends, spatial hotspots, and causes of strandings. Standardized Level A data were compiled, complemented since 2019 by virtopsy-integrated necropsy (postmortem CT, 3D surface scanning), and analysed using generalized additive models (GAMs; Poisson family) for temporal trends; kernel density estimation (KDE) and Getis-Ord Gi* statistics for spatial clustering and hotspot detection. Green turtles ( Chelonia mydas ) dominated (76.7%, n = 171), primarily juveniles, with hawksbill ( Eretmochelys imbricata ; 7.2%), loggerhead ( Caretta caretta ; 5.4%), olive ridley ( Lepidochelys olivacea ; 3.6%), leatherback ( Dermochelys coriacea ; 0.8%), and unidentified (6.3%). GAMs revealed a significant nonlinear increasing trend over the study period (adjusted R 2 = 0.595, p < 0.001), with the fitted smooth visually levelling after 2018, and seasonal peaks in spring (Mar–May) and autumn (Sep–Nov). Spatial hotspots concentrated in eastern and southern waters, including marine protected areas. Cause of stranding was determined conservatively based on pathognomonic lesions identified through virtopsy-integrated necropsy; undetermined cases predominated (78.5%, n = 175), followed by anthropogenic causes (17.5%, n = 39), other causes (typhoon entrapment, buoyancy disorder) (2.7%, n = 6), and natural causes (1.3%, n = 3). The most common anthropogenic cause of stranding was fishery interaction including bycatch and fishing gear entanglement ( n = 23/39), vessel collision ( n = 9/39), and pollution ( n = 7/39). Limitation of this study included the majority of cause of strandings were classified as undetermined, underscoring the urgent need for enhancements in stranding investigation methodologies. This first long-term assessment for Hong Kong integrates advanced postmortem imaging with spatial and temporal modelling. Eastern and southern spatial hotspots and spring/autumn seasonal peaks warrant priority fishery bycatch mitigation, vessel speed restrictions, and targeted stranding patrols to enhance East Asian sea turtle conservation. • Level A data provide essential knowledge in stranding patterns and population trends. • HK waters is suggested to be part of migratory route for post-nesting green turtles. • HK waters may be an important foraging ground utilized year-round by green turtles. • Increased environmental dynamics & anthropogenic pressure on sea turtle in 2002–2024. • Citizen science approach improves the early detection of stranded sea turtles. • Virtopsy-led investigation and regional collaboration improve sea turtle conservation.
Kot et al. (Sun,) studied this question.