Coral reef ecosystems play an important role in ecological processes, community composition and fishery yields. In many tropical countries whose oceans contain a coral reef, these areas act as the primary income for fisheries and fishermen. In this study, the authors sought out to study the areas located within and near marine protected areas, and the effects of fishing on the fish populations and size of individuals. When individuals from the population within the reserve migrate out to adjacent areas, they may increase local fish catches. The authors attempted to test this “spillover effect and compare species abundance before and after the creation of marine protected areas, and determine whether the spillover enhances the income of fisheries as the number and abundance of fish within the protected area increase. Their three hypotheses were that (1) fishing is dramatically reducing the abundance of fish in Kenyan Lagoons; (2) recovery of fosh from fishing should be rapid (1-5 year); (3) creating a marine park will increase the catch of fish in adjacent fishing grounds.

Prior to the study, fish abundance data from seven reefs, collected over a time period of 6 years, was obtained for comparison. These consisted of two older protected reefs, three reefs that have heavy fishing yields, one reserve site, as well as one site within the Mombasa MNP, in which fishing was illegal in its entirety. Reported data from all the sites included: monthly catches, number of fishers, fishing area, fisher density, total catch, total catch/person/month, total cath/boat/ month, total catch/area, and benthic catch/ area/month. During a portion of the study, researchers even compared the fish catches near and far from the park boarder.
Species within the same area displayed a 25% reduction in richness between the protected and unprotected areas.
One limitation the researchers mentioned was that, “ around 20% of catch is kept by fishermen for food and is not reported in the landing statistic. Also, although the created of the marine park temporarily increased fishery yields, toward the end of the study, they were about the same as before the parks creation. One possible explanation is that, as the number and abundance of species increase, the number of fishermen also increased until ”equilibrium” was once again established. They did state that further information and studies would be needed to determine the effects of gear types, opportunity cost, and fisher density