A RETROSPECTIVE (1979-1996) MULTISPECIES ASSESSMENT OF CORAL-REEF FISH STOCKS IN THE FLORIDA KEYS

A baseline assessment of 35 economically and ecologically important Fl orida Keys reef fish stocks is provided by using a systems approach th at integrates sampling, statistics, and mathematical modeling. Quantit ative fishery-independent data from reef fish visual surveys conducted by SCUBA divers from 1979 to 1996 were used to develop estimates of p opulation abundance, assemblage composition, and stock structures in r elation to key physical and habitat factors. Exploitation effects were assessed with a new length-based algorithm that calculates total mort ality rates from estimates of ''average length of fish in the exploita ble phase of the stock.'' These estimates were highly correlated for t wo statistically independent data sources on reef fish: fishery-indepe ndent diver observations and fishery-dependent head boat catches. We d eveloped a reef fish equilibrium exploitation fishery simulation (REEF S) model and used estimates of fishing mortality to assess yield-per-r ecruit in relation to fishing intensity and gear selectivity and to as sess spawning potential ratio (SPR) in relation to U.S. federal ''over fishing'' standards. Our analyses show that 13 of 16 groupers (Epineph elinae), 7 of 13 snappers (Lutjanidae), one wrasse (Labridae), and 2 o f 5 grunts (Haemulidae) are below the 30% SPR overfishing minimum. Som e stocks appear to have been chronically overfished since the late 197 0s. The Florida Keys reef fishery exhibits classic ''serial overfishin g'' in which the largest, most desirable, and vulnerable species are d epleted by fishing. Rapid growth of the barracuda population (Sphyraen idae) during the same period suggests that fishing has contributed to substantial changes in community structure and dynamics.