Crowdsourcing conservation: unveiling Taiwan's sea turtle foraging grounds, emerging threats, and residency with broad societal engagement.

Background: Determining sea turtle foraging grounds, emerging threats, and population status are essential for conservation management. Crowdsourced science is a recently recognized approach that enables internet-based data collection, providing important contributions to scientific goals while also benefiting society and public education. This study is based on the published dataset from TurtleSpot Taiwan (2017-2022) with the aim to leverage crowdsourced data to determine sea turtle foraging grounds, emerging threats, demography, and residency patterns in Taiwan.

Results: We identified three green turtle (Chelonia mydas) foraging grounds in Taiwan (Liuqiu Island, Kenting, and Green Island), defined as sites with > 100 sightings and > 50 individuals. Among all sites, Liuqiu Island contributed 77% of the total sightings, suggesting this island is a hotspot. Emerging threats to foraging aggregations of sea turtles in Taiwan were evident from the reported sightings, with ~ 10% of the total sightings involving turtles with fishing line entanglement, ingested debris, missing flippers, or injuries. Most of these sightings occurred in Liuqiu Island, indicating a significant level of human-turtle disturbance. Residency patterns identified from sighting data showed that 43.4% of individuals stayed in the same area for one or more years, with adult-sized turtle residency greater than that of immature turtles.

Conclusions: Taiwan supports healthy foraging grounds for green turtles, where adults often stay for more than one year and with dynamic populations of younger individuals. However, despite a certain number of foraging green turtles observed in Liuqiu Island, many of these turtles displayed injuries. This high population density combined with increased injury frequency suggests that a comprehensive management plan for turtle foraging grounds is urgently needed, including measures to reduce boat speeds in hotspot areas and strict regulations on coastal human activity.