Population Dynamics of Cultured Holothuria scabra in a Sea Ranch: Implications for Stock Restoration

Abstract

The potential of sea ranching sandfish (Holothuria scabra) for production and stock restoration was investigated in the Philippines. A total of 14,300 fluorochrome-stained juvenile sandfish (>3 g) were released in 8 batches over a 15-month period in a 5-hectare pilot communal sea ranch. Abundance of sandfish increased from 416 to 5,562 individuals, with a corresponding increase in biomass from 7 to 221 kg ha−1 over the 19-month period. Apparent survival over the study period was estimated at 20–30%. Incidences of in situ spawning were observed in the sea ranch within a year, and estimated densities of reproductively mature sandfish increased from 37 ind ha−1 7 months after initial release to 249 ind ha−1 after 19 months. Average weight at onset of sexual maturity (∼185 g) is estimated to be attained 7–9 months after release. Juveniles without fluorochorome stained ossicles were found during most monitoring periods, indicating presence of wild recruits. A well-managed communal sea ranch has the potential to contribute to fisheries production and stock restoration objectives.