Approaches in Rebuilding Sea Urchin and Sea Cucumber Populations in the Philippines

Abstract

Sea urchins and sea cucumbers are among the most valuable and overexploited fishery resources. Culture and release of juvenile Tripneustes gratilla and Holothuria scabra have been undertaken to rebuild depleted populations and provide a supplemental source of income for fishers. In both cases an integrated socioecological approach was used. Studies on factors affecting growth and survival of released juveniles were conducted alongside active participation of local partners in site management and regular monitoring. For T. gratilla, community-based grow-out in sea cages complemented with restocking of protected areas helped in the recovery of a collapsed fishery. Gonad biomass and quality of sea urchins fed with Sargassum were high. These increased the value of the gonads and reproductive output of cultured sea urchins. In the case of H. scabra, release of juveniles in a communal sea ranch resulted in the build-up in density and biomass. Observations of regular mass spawning in the sea ranch established that a viable spawning population was maintained through selective harvesting. Both the sea urchin cage grow-out culture and sea cucumber sea ranch function as reproductive reserves and source of larval supply to adjacent suitable habitats. In addition, wild recruits in the sea ranch and in the vicinity of the sea urchin sea cages indicate that natural recruitment may be enhanced by the high density of conspecific adults. These models have demonstrated that both ecological and economic benefits can be realized through of responsible culture-based management interventions. The development of appropriate governance mechanisms is a critical consideration for sustainability.