Center for Systems Integration and Sustainability

Journal or Book Title: International Council for the Exploration of the Sea (ICES)

Keywords: Marine reserves; trophic interactions; Red Sea fish; prey release

Page Number(s): 259

Year Published: 2004

Marine reserves can increase fish populations inside their boundaries and potentially enhance adjacent fish stocks through spillover of adult fish from inside reserves or larval export. In South Sinai, a network of marine reserves was established for both conservation and fisheries management. For the Bedouin, who traditionally conducted small-scale artisanal fisheries along the coastline, fishing is now confined to specific areas. Surveys of fish populations along the South Sinai coast revealed that abundances of large carnivorous species such as serranids, lethrinids and lutjanids were generally greater inside reserves. However, populations of herbivorous fish, such as acanthurids and siganids, were significantly greater in fished areas. Although prey release has lead to greater abundance of prey fish in other studies, in South Sinai, these families are commonly targeted species forming high proportions of the catch. The effects of marine reserves on fish populations may be more complex than previously thought with trophic interactions important in structuring populations. Larger predatory fish benefit from decreased fishing pressure inside reserves, while prey species adjacent to reserves benefit through decreased predation pressure. Fishery enhancement may therefore occur through three ways, spillover of adult fish (most likely predators), larval export and prey release within fished areas. The fish stocks of South Sinai are currently not over exploited and this effect would probably not be seen under heavier fishing pressure. When designing and planning marine reserves, thought should be given to these second-order reserves effects and to whether trophic interactions such as prey release may help in fishery management.