COS 24-6
Seahorse (Hippocampus spp.) hotspots and habitat associations in Thailand
Seahorses are heavily traded on the global market but are vulnerable to overexploitation and thus listed under CITES Appendix II. Officially, Thailand is the largest exporter of seahorses globally, with millions of animals exported annually. However, the impacts of trade and nonselective fishing on wild seahorse populations in Thailand remain unknown. Population data is urgently required to advance conservation efforts and ensure CITES compliance for sustainable trade. Because seahorses are rare and patchily distributed, finding extant populations and mapping their density distribution presents a particular challenge. Fixed area transects have a low probability of detecting seahorses at any particular site, unless a high degree of effort is used, a method that is not practical for large geographic areas. We first focus our efforts on finding seahorse populations, through investigative means such as email blasts and interviews with local stakeholders. Interviews also assessed local perceptions of seahorse occurrence and population trends. Seahorses were then counted using haphazard swims at 44 sites, with distance swum and active search time recorded as survey effort, also the basis of our citizen science survey protocol iSeahorse Trends. Data on benthic cover, predatory fish density and water quality were collected at each survey site as well.
Results/Conclusions
At least two seahorse hotpots were identified at Ao Nang and Pattaya. Seahorses were observed at 15 of 44 sites. Hippocampus comes was only found on coral reefs along the Andaman coast, H. spinosissimus was only recorded within the Gulf of Thailand, on sand, silt and rubble, and H. kuda can be found along both coasts in reef and sandy habitats. A fourth species, H. trimaculatus, was never encountered in-water, but was frequently netted as trawling bycatch from waters deeper than 25m. Seahorse occurrence and abundance were not correlated with water quality parameters. The highest abundances of seahorses were found within marine protected areas and areas heavily visited by tourists, which may deter fishing activity in the area. Most interviewees thought that seahorse populations had declined over the past decade, with estimates ranging from 50-90%. While Thailand has several regulatory measures already in place, it is clear from our interviews that enforcement of these regulations may be an issue. Our rapid assessment protocols cover a broad geographic range but provide no temporal trends. Efforts to engage local communities and recruit volunteers for seahorse monitoring were thus facilitated through www.iSeahorse.org, and the launch of a citizen science survey toolkit, iSeahorse Trends.