ABSTRACT: One of the most popular management tools for Caribbean reef fisheries is a minimum mesh size for traps. It is believed that increasing the mesh size of traps in overexploited fisheries will result in higher catch rates in the long term, but lower catchrates in the short term. This study represents the first attempt to document the short-term and long-term effects of partly replacing small mesh with a larger mesh size in an artisanal coral reef fishery. A community level mesh exchange program wasinitiated in the Discovery Bay trap fishery in March 1991, whereby active fishers were given large mesh (1.5 inch: 3.8 cm) wire to construct traps in exchange for handing in their small mesh (1 inch: 2.5 cm and 1.25 inch: 3.2 cm) traps. Although the totalnumber of active traps and the total number of hauls per month did not significantly change in the fishery, the proportion of small mesh traps decreased substantially as a result of the mesh exchange program, leading to a concurrent reduction of fishingmortality in smaller sized fish. Changes in the fish populations were examined by comparing catch-per-unit-effort (CPUE as number of fish per trap per haul, and kg per trap per haul); mean size of individual fish; catch composition; and length frequencydistributions for the 2 most common species, for both 1.25 inch and 1.5 inch traps in 3 separate 6 mo periods (July to December) in 1990 (10 mo before the implementation of the mesh exchange program), 1991 (immediately after the implementation of the meshexchange program) and 1994 (3 yr after the implementation of the mesh exchange program). The results indicate that reef fish populations at Discovery Bay, and hence yields to the fishery, have increased in the 3 yr since the mesh exchange program wasimplemented. The number of fish caught per trap haul has increased; the total weight of the catch per trap haul, at least of the smaller mesh sizes, has increased; the catch composition has shifted towards larger and more valuable species; the mean sizeof fish taken by the fishery is larger; and the population of 1 narrow-bodied species investigated has shifted towards larger size classes since the increase in mean mesh size in the fishery. However, despite an increase in the gross catch per week by thetrap fishery, catch rates still differ markedly between small and large mesh traps, with small mesh traps catching less per haul but more per week than large mesh traps. As a consequence, fishers still using small mesh traps are benefitting the most fromrecovery of the reef fish populations, which demonstrates the need for further efforts to eliminate the smaller mesh traps from the fishery.