Sea Cucumbers (Holothuroidea) of Northeastern and Western Mindanao, Philippines: The Potential Role of Marine Protected Areas in Maintaining Diversity and Abundance

Abstract

Marine protected areas (MPAs) are considered strategic tools in conserving biodiversity and maintaining stocks of valuable resources. We assessed sea cucumbers in five provinces in northeastern and western Mindanao to describe the state of diversity and abundance and evaluate the role of MPAs in sustaining stocks of exploited species. We identified 36 species of sea cucumbers from fishery-independent surveys on shallow reef flats and deeper reef slopes, of which 33 species (92%) belong to order Aspidochirotida and three species belong to Order Apodida. The majority are shallow-water holothurians occurring on reef flats and seagrass beds, while a few species are found along reef slopes or in fresh catches by fishers sold to local traders or processors in some sites. Nine species are considered high-value to the global trepang trade but occur at low densities, while the rest are abundant or common species with low commercial value. Species richness (S=17-30 spp.) varies across sites, but species composition similarity is relatively high (Sørensen’s SQ = 0.62-0.78). Mean population densities and variances of high-value species are significantly higher inside enforced MPAs than in non-MPA sites(t-test, p <0.05; F-test, p<0.005) across five survey sites. The abundance of high-value H. scabra in Tubajon and H. fuscogilva in Capayas Island demonstrates the critical role of MPAs in conserving biodiversity, maintaining population levels, and ensuring natural recruitment of sea cucumber resources. Urgent management measures such as formulating a national management plan, regulating harvests, and establishing no-take MPAs are recommended.