MEPS 154:107-120 (1997)  -  doi:10.3354/meps154107

Effects of an increase in trap mesh size on an overexploited coral reef fishery at Discovery Bay, Jamaica

Sary Z, Oxenford HA, Woodley JD

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 catch rates 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 was initiated 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 total number 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 fishing mortality 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 frequency distributions 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 mesh exchange 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 was implemented. 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 size of 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 the trap 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 from recovery of the reef fish populations, which demonstrates the need for further efforts to eliminate the smaller mesh traps from the fishery.

Coral reef fishery · Trap mesh size · Fishery management

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