First trial of wild juvenile collection of tropical sea cucumbers from settling larvae, using coconut fibre from waste husks in Solomon Islands: A new conservation tool

Abstract

Abstract Wild juvenile collection (WJC) from settling larvae has been reported for two temperate holothurians (Apostichopus japonicus and Apostichopus californicus), mainly for the objective of restocking, but its applicability to tropical holothurians is unknown. This study, for the first time, tested the applicability of WJC for tropical sea cucumbers. First, hatchery‐produced larvae of peanutfish (Stichopus horrens) before settlement were introduced in a tank in which bundles of coconut fibre, rolled mesh bags, and oyster shells were suspended to identify the most suitable settlement material. The results showed that the coconut fibre and mesh bags collected more settling larvae than the oyster shells. Second, 25 collectors were installed for 3 months in the field in Nggela, Solomon Islands. The newly designed simple collector comprised between two and four net bags filled with coconut fibre, which were tied to a rope vertically moored between a concrete block anchor and polyethylene terephthalate (PET) bottle floats. A total of 14 juvenile holothurians were collected, including Stichopus cf. horrens, stonefish (Actinopyga lecanora), kingfish (Synapta maculata), and five unidentified species. It is characteristic of tropical WJC that diverse species can be collected simultaneously (including rare, non‐culturable species), which is advantageous over hatchery production for restocking purposes. The total yield corresponded to approximately 1% of the total abundance of the ambient holothurian community, demonstrating potential for restocking, considering the ease of the extension and repetition of the trials. Collection in the inner bay areas was successful, whereas rough weather physically damaged the collectors in areas open to the ocean. These results show that WJC is a viable option for tropical holothurians. Thus, the use of the low‐cost, simple collectors using coconut fibre could be a new conservation measure for endangered holothurian resources, and are manageable by local communities.