Abstract
Subsistence and small-scale aquaculture are important economic and livelihood activities in developing countries including the Philippines. Community-based aquaculture of the sea cucumber (sandfish, Holothuria scabra) has been promoted as a sustainable supplemental livelihood activity among rural coastal communities, however, uptake remains poor and the economic viability of communal sea cucumber ranching has yet to be demonstrated. This study assessed the potential of sandfish farming as a supplemental economic activity for established small-scale grouper (Epinephelus coioides) farmers in Bolinao, northwestern Philippines, on the assumption that the adoption of sandfish culture may be more successful when attempted by established aquaculture farmers. The average growth rate of sea cucumbers reared in the pens without groupers was highest at 2.0 ± 0.4 g day–1 during the first 50 days of rearing. By 141 days, sandfish reared without grouper attained an average weight of 234.7 ± 2.2 g. The highest growth rate of sandfish reared with groupers was recorded at 4.2 ± 1.8 g day–1 after 19 days of rearing in the coculture pens whereas the lowest growth rate (-0.73 ± 0.1 g day–1) was recorded by day 128. Additionally, the growth performance and survival of groupers reared with sandfish were high. From an initial average weight of 141.3 ± 35.2 g, groupers attained an average weight of 340 ± 27.8 g and 393.8 ± 17.8 g after 102 and 163 days of rearing, respectively in the grow-out pens. Farmers generated an estimated income of PHP 7,200 and PHP 29,015 from the sale of dried sea cucumbers and live groupers, respectively. Results indicate that the adoption rate, economic viability, and sustainability of sandfish mariculture may increase when technology is transferred to farmers already engaged in aquaculture. More broadly, the integration of sandfish culture with that of fish and other culture species, such as molluscs, utilizes the ability of sea cucumbers to remediate nutrient-rich sediments, improving sustainability.