Comparison of closed area and beach seines exclusion on coral reef fish catches

 

T. R. McClanahan and Tim S. Mangi

 

Coral Reef Conservation Project,

P. O. Box 99470, Mombasa, Kenya,

email: crcp@africaonline.co.ke

 

ABSTRACT

Fish landing data from adjacent the Mombasa Marine National Park (MNP) and seven sites in Diani, a legally gazetted but unprotected marine reserve, were studied over a four-year period to determine the influence of the park and restrictions of beach seines on fisheries catches. Data were based on sampling for 3 to 12 days per month from 1995 to 1999, where fish were separated into the major families, the wet weights estimated by a spring balance, and data analysed based on gear, numbers of fishers, and the area from which the fish were caught. In the case of the Mombasa marine reserve, the beach seine exclusion was done nearly simultaneously with a reduction in the size of the Marine Protected Area. These two factors combined resulted in increased fish catches on a per area and fisher basis. It was, however, difficult to distinguish the effects of the two changes, but the initial pulse in catch is largely due to opening a previously unfished area to fishing. In Diani the two landings that restricted beach seines for over 20 years had the highest per fisher catches, being 13% greater than sites with beach seines (ANOVA, F = 4.5). Catch data showed a progressive decline in per man catches in all the sites irrespective of the management in place or the exclusion of the beach seines. Nevertheless, the site next to the marine reserve had the highest catch per area (5.5 kg/ha) and slowest rate of decline despite having the highest number of fishers per area basis (0.07 0.02 fishers/ha/month).