Ecological and economic assessment of two marine protected areas in the island garden city of Samal, Davao Gulf, Philippines

摘要

The performance of two marine protected areas (MPAs) in Samal Island, Coral Garden and Aundanao MPAs were evaluated after more than 10 years of existence. The evaluation tools used were fishery dependent (i.e. focus group discussion) and independent (i.e. fish census, benthic assessment and crown-of-thorns density) samplings. All sampling was conducted at least twice for one year. In all sites, COTs densities were just above the alarming stage (～1 individual.250m~(-2)). Aundanao MPA showed a positive feedback system by supporting the spillover effect. There is high density of sexually mature fish (<30cm Total length and significantly higher fish biomass estimates of target species (16mt km~(-2)) inside than outside the MPA. The relatively small catch (20mt year~(-1)) from fishing adjacent to the MPA is attributed to the limited capacity of the core zone (only 3ha) to support the fishery. It also serves as a refuge site for small pelagic fishes (i.e. ox-eye scad, Selar boops ) that aggregate along the slope. In contrast, the Coral Garden MPA had very low fish biomass (4.0mt km~(-2)) and only a couple of sexually mature individuals both inside and outside the sites. Intermittent guarding which have resulted to occasional poaching in the no-take area was one of the reasons. Further, a newly introduced fishing gear bintol (modified lift net), for subsistence targeting damselfishes has started to operate near the area. This is an evidence of a lesser density of targeted food fish to catch. Coral Garden MPA has shown that the rate of extraction exceeded the presumed turnover rate of the associated reef fish standing stock suggesting an overfishing of the area.