Crowdsourcing Conservation: Unveiling Taiwan's Sea Turtle Foraging Grounds, Emerging Threats, and Residency with Broad Societal Engagement

Abstract

In Taiwan, sea turtle research has historically focused on nesting beach monitoring and stranding rescue, with limited understanding of coastal foraging populations. To address this gap, the “TurtleSpot Taiwan” project was launched in 2017 to engage divers in reporting sea turtle sightings. As of today, the Facebook group has grown to over 24,000 members, with more than 450 citizen scientists actively contributing records. Based on the five years of data, Liuqiu Island, Kenting, and Green Island were identified as the primary foraging grounds, each supporting substantial aggregations (>100 sightings) dominated by juvenile green turtles (61%). A total of approximately 750 individual turtles were recorded, of which over 40% showed long-term residency in Taiwan’s coastal waters, with adult-sized turtles generally remaining for longer periods. Approximately 10% of all sightings involved injured turtles, including cases of fishing line entanglement, propeller strikes, ingested marine debris, and injuries of unknown origin such as wounds, amputations, or scars. These findings indicate that human activities in foraging hotspots pose significant threats to sea turtles, underscoring the need for targeted management and conservation measures. Research outcomes from this project have been published in two international SCI journals, with occurrence data openly shared via the Global Biodiversity Information Facility (GBIF) to promote data accessibility. All records have also been integrated into the Taiwan Sea Turtle Photo-ID Database (https://turtlespottw.org/), enabling contributors to assist in manual identification and allowing the general public to learn more about sea turtles, thereby fostering public participation and strengthening marine conservation awareness.

Methodology and Implementation Steps

1. Photographic identification (photo-ID)：The distinctive facial and flipper scale patterns of sea turtles have been validated as reliable natural markers and unique body patterns for individual identification. We used both manual photo-ID and a computer-based program “HotSpotter” to assist this process.
2. Age class：To determine the demographic structure of sea turtles, turtle body size was visually estimated from whole-body photographs and categorized into different life history stages (post-hatchling, juvenile, subadult, or adult), combined with the carapace color pattern and marginal scute roundness characteristics and descriptions provided by the reporters.
3. Residency：To examine the residency of the sea turtles, minimum residency duration (MRD) of green and hawksbill turtles was calculated and plotted separately. The MRD for each turtle was estimated based on total duration (days) between the earliest and latest recorded sighting. Individuals who stayed in the same area for more than 365 days (1 year) were considered residents. To study variations of MRD and number of sightings among estimated age-class groups (i.e., juvenile, subadult, or adult-sized), only green turtles were included due to low sample sizes for other species. Variations in MRD and the number of sightings per individual across different estimated age-class groups were examined using One-Way Analysis of Variance (One-Way ANOVA; factor: estimated age-class groups) in SigmaPlot 11 (Graffiti LLC).
4. Participation and Retention of Citizen Scientists：The number of new and retained citizen scientists from previous years was analyzed for each year from 2017 to 2022 to assess the recruitment and retention trends of TurtleSpot Taiwan. Retention of citizen scientists was calculated as the total duration (in days), including both the first and the last sightings reported by an individual to the Facebook Group. A Pearson correlation coefficient analysis was conducted to examine the correlation between the number of sightings contributed by each participant and their retention time, visualized with a scatter plot in SigmaPlot 11. To avoid bias, sightings directly provided by citizen scientists to us without posting to the Facebook Group were excluded from the above analysis.

Innovation and Cross-Disciplinary Collaboration

This study is Taiwan’s first sea turtle ecological monitoring program integrating citizen science, individual photo-identification, and open data, moving beyond the traditional model dependent on a small number of researchers. Internationally, most sea turtle citizen science projects emphasize ecological results, with limited focus on optimizing participation. Here, we established the Taiwan Sea Turtle Photo-ID Database to allow contributors to engage in data analysis, conducted a quantitative assessment of participation levels, and proposed strategies to improve engagement and retention. Citizen science data also provided evidence of habitat connectivity among sea turtle foraging grounds in the western Pacific, supporting the development of international conservation strategies. During the outreach of this project, we also initiated collaborations with other marine citizen science programs (e.g., Reef Check, Coastal Survey, shark and ray sighting reports) to co-organize the Marine Citizen Science Carnival, serving as a model for cross-program engagement and public outreach.

Expected Results and Contributions

1. Mapping foraging habitats to fill data gaps：
   Sea turtle research in Taiwan has largely focused on nesting beaches and strandings, with limited knowledge of coastal foraging populations. Using five years of citizen science data, we mapped foraging habitats, with Liuqiu accounting for nearly 80% of sightings. The northeastern coast, previously suspected as a foraging area but lacking direct evidence, was confirmed to host resident turtles. The proportion of resident turtles in Liuqiu has risen from 10% in a previous study to over 40% in our data, suggesting improved habitat suitability and/or shifts in population structure.
2. Quantifying anthropogenic threats and proposing management measures：
   About 10% of reports involved injured turtles, including carapace injuries (5.3%), missing/injured flippers (3.2%), and marine debris entanglement or ingestion (1.5%). Recommended measures include vessel speed reduction in hotspots, propeller guards, and regulating recreative fishing. We also invited the National Museum of Marine Biology and Aquarium’s stranding turtle rescue team to Liuqiu for a workshop on injury cases, stranding treatment, and appropriate responses when encountering injured turtles. Related cases and recommendations have been shared with the Ocean Conservation Administration.