RAPID BUILDUP OF FISH BIOMASS IN A CARIBBEAN MARINE RESERVE

Marine reserves, where fishing is excluded, have been argued to be an effective means of managing complex reef fisheries and of protecting p opulations of species vulnerable to overfishing. Tbe argument vests on predictions of increases in abundance and size of fishes after the el imination of fishing mortality, which in turn lends to greater egg pro duction per unit of reef and greater export via pelagic dispersal to f ishing grounds This study reports responses of fish populations to are a closure in a small Caribbean marine reserve surrounding the island o f Saba in the Netherlands Antilles. Part of the reserve has been close d to fishing since 1987, and the remainder is subject only to light fi shing. Fish populations were visually censused and sizes of individual s present estimated from counts in fished and unfished areas of the ma rine park in 1991 and 1993. For four of five commercially fisher famil ies, biomass was greater in the unfished area than in the fished. Pred ictions of greater abundance and size in the unfished area were upheld for many of the species observed. Between 1991 and 1993 overall bioma ss of commercially important families increased 60%, based largely on increases in abundance between years The predatory snappers (Lutjanida e) increased 220%. Fishing pressure in Saba was reduced between census es due to changing employment opportunities. It was notable that popul ations increased in both fished and unfished areas of the park, and th e fatter is probably an effect of this reduced fishing intensity Reser ves have been suggested as refuges for species vulnerable to overexplo itation, especially groupers. Despite protection from fishing, the Sab a Marine Park has low population densities of such species, perhaps du e to a lack of supply of larvae from unprotected source areas My study shows that target fish populations may respond swiftly to reductions in fishing pressure and that reserves could play an important role in fisheries management But protection of vulnerable species is only like ly to be successful if networks of reserves are established throughout species ranges to lint larval supply and settlement areas.