The effect of a closed area and beach seine exclusion on coral reef fish catches

Fish landing data from the Mombasa Marine National Park (MNP) and a marine reserve exploited by various gears were studied over a 5-yr period to deter mine the influence of the closed area and different gears in fisheries. The number fishing and boats per landing site was constant, but total and catc h per unit effort progressively declined in all sites on an annual basis ir respective of the existence of a marine reserve, exclusion of the beach sei nes or use of gear. Differences between landing sites were most pronounced when analysed on a catch per area as opposed to the more standard catch per fisherman, suggesting compensation in human effort when catches decline. A marine reserve next to a closed area that excluded beach seines had the hi ghest catch per area (5.5 kg ha(-1) month(-1)) despite having the highest d ensity of fishermen (0.07 +/- 0.02 fishermen ha(-1) month(-1)). The annual rate of decline in the catch was lower than the other sites at around 250 g day(-1) compared with 310-400 g day(-1) in the other sites. One landing si te, which excluded beach seine landings for mure than 20 yrs, had a high ca tch per area (similar to5.3 kg ha(-1) month(-1)), but after experiencing a doubling in the effort of other gears (line, speargun and trap), the catch per fisherman and area were reduced. Environmental or habitat degradation a nd excessive effort remain the most likely explanation for the overall decl ines in catch from 1995 to 1999. Closed areas and beach seine exclusion hav e the potential to increase catch rates, but the first often reduces the to tal fishing area and possibly leads to a loss of total catch, at least on a time scale of less than 10 yrs. The exclusion of beach seines can lead to an increase in other gear types that can also cause reductions in catch.