Natural fishing experiments in marine reserves 1983-1993: roles of life history and fishing intensity in family responses

This study examined the effect of fishing on the abundance and species rich ness of families of coral reef fish at two islands (Sumilon and Apo) in the Philippines from 1983 to 1993. Natural fishing experiments occurred in mar ine reserves at each island, where long term estimates of fishing intensity were available. Responses to fishing were interpreted in terms of life his tories of fish. The intensity of fishing and fish life histories were gener ally good predictors of the differential rates of decline and recovery of a bundance in response to fishing. Large predators had vulnerable life histor ies (low rates of natural mortality, growth and recruitment) and were subje cted to high intensity fishing. They declined significantly in density when fished and increased significantly but slowly when protected from fishing. Caesionidae, a family with a life history resilient to fishing (high rates of natural mortality, growth and recruitment) but fished intensively also declined rapidly in abundance when fished. Thus, knowledge of life history alone was insufficient to predict response to fishing. Acanthuridae were fi shed relatively hard and had a life history of intermediate vulnerability b ut displayed weak responses to fishing. Thus level of fishing intensity alo ne was also not sufficient to predict response to fishing. For Chaetodontid ae, effects of fishing conformed to expectations based on life history and fishing intensity at one island but not the other. Three families with inte rmediate vulnerability and subjected to intermediate to light fishing (F. S caridae, Labridae and Mullidae) displayed predictably weak responses to fis hing, or counter-intuitive responses (e.g., increasing in abundance followi ng fishing). These counter-intuitive responses were unlikely to be secondar y effects of increase in prey in response to declines of predators. Two lig htly-fished families with resilient life histories (F. Pomacentridae, Sub F . Anthiinae) predictably displayed weak numerical responses to fishing exce pt during a period of use of explosives and drive nets.