Conservation of the tri-spine horseshoe crab and its habitat in Palawan, Philippines

Lea Janine Gajardo

Horseshoe crab research in the Philippines is developing. As such, important baseline data are missing.    Repeated monitoring in a nursery habitat in Palawan revealed that increasing human impact strongly altered the juveniles’ distribution. 13 growth stages of Tachypleus tridentatus have been delimited, but no trilobite larvae were found and spawning has never been observed. Successful reproduction is crucial for the species survival but numerous fishing nets may block adults' access to the shore (bycatch data are lacking). Given the progressive loss of habitats vital to the survival of horseshoe crabs, we aim to raise public awareness about their conservation needs through community engagement and by providing cross-generational information materials. By conducting monthly surveys in North-, Central-, and South-Palawan, we expect to collect sound data on the species’ spawning behaviour, any seasonality, habitat requirements, and nest characteristics. During perception surveys (interviews at fish markets), we aim to identify the main threats these living fossils face in Palawan. Our study will thus provide the scientific basis to convince decision makers to develop conservation plans for Palawan and actively contribute to their design, e.g. by proposing guidelines regulating areas and periods for the installation of stationary fishing nets or public access to beaches near spawning grounds.