Effects of some destructive fishing methods on coral cover and potential rates of recovery

Abstract

Effects of fishing with explosives (blastfishing) and sodium cyanide and of anchor damage on live coral were investigated on a heavily exploited fringing reef in Boli-nao, Philippines from 1987 to 1990. A simple balance-sheet model indicated that approximately 1.4%/yr of the hermatypic coral cover may have been lost to blasting, 0.4%/yr to cyanide, and 0.03%/yr to coral-grabbing anchors, the potential coral recovery rate reduced by about one third from 3.8%/yr in the absence of disturbances to 2.4%/yr. These figures are subject to considerable uncertainty due to compounding of errors during computation. Reefs with patchy coral cover are more susceptible to damage from blastfishing because of targeting by fishers. Reefs with smaller corals may have greater resilience, because each unit of radial colony growth contributes a greater per cent increase in areal cover. Blastfishing in particular may reduce resilience to natural perturbations, leading to assemblages of small, sparse corals and reduced patchiness.