Fishery recovery in a coral reef marine park and its effect on the adjacent fishery
Kaunda-Arara, B.; McClanahan, T. R. (1996). Fishery recovery in a coral reef marine park and its effect on the adjacent fishery. Conserv. Biol. 10(4): 1187-1199. dx.doi.org/10.1046/j.1523-1739.1996.10041187.x
Numbers of fish and their wet weights were estimated in Kenyan coral-reef lagoons on seven reefs over 6 years. Two sites were protected from fishing for over 20 years, whereas the other five sites were heavily fished in recent years. A heavily fished site was converted into a marine park (Mombasa Marine National Park, approximately 10km(2), no fishing allowed), and the number of fishers allowed was slowly decreased between August 1991 and August 1992. The area adjacent to the park was converted into a marine reserve (only fishing traps, lines, and gill nets allowed) that provided fishing grounds for fishers excluded from the park. Data from a fish-landing site adjacent to the newly created marine park were collected for 3 years and analyzed to determine the effect of the park's creation on fish catches. Results suggest that fishing in the reserve reduced fish wet weight by about a factor of 10 and reduced fish numbers and species richness by a factor of two. Both field studies and landing site's fishing grounds were protected with the creation of the park, and 65% of the fishers quit the studied landing, leaving nearly the same density of fishers in the remaining area (similar to 12 fishers/km(2)). Further, fishers using pull seines were excluded from the reserve, and their numbers were replaced by fishers using other gear (mostly basket traps). Although the overall catch per unit effort increased by about 110% after the park's creation, the total fish landed decreased by 35% and the catch per unit effort decreased toward the end of the study period despite increasing fish abundance in the park. Although establishment of small parks elsewhere have increased the total catch, the large park we studied did not; one reason may nave been the lower ratio of edge to park area of the large park. Alternatively, the park's edge may have provided a good fishing area, so fishing effort may have been highest along the park's edge. Consequently, a barrier may have been created that restricted fish dispersal to most of the reserve. Therefore, the area that had an increased catch was small (<1 to 2km from the edge) and could not compensate for the lose fishing area. Most fish species within the park showed recovery after fisher exclusion. Total fish wet weights 3 years after the fisher's exclusion were 25% below the older marine parks. Poor recovery of the herbivorous parrot and surgeonfish can account for much of this shortfall. Competition for resources with sea urchins appear to be slowing recovery of these two groups. A study site 2.5 km from the park's southern boundary, in the reserve section of the protected area, showed no changes in fish abundance over the study period, despite changing gear regulations.
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