CSIRO Marine Research, HOBART, AUSTRALIA
Designing Marine Protected Areas (MPAs) inherently involves spatial issues in arranging areas gazetted for different uses. The principal management strategy evoked by MPAs is that areas closed to exploitation, especially fishing, enhance exploited stocks, provide harvest refugia, and conserve vulnerable biota. An explicit assumption of such closures is that they are adequately enforced against infringements, or that their features, such as size and arrangement, have been designed to minimise infringement. In most systems, the number of possible arrangements of closed areas is large, but information with which to evaluate their efficacy is scarce. To overcome this paucity of information, we have developed a spatially-structured simulation model of the population dynamics and line fishing exploitation of coral trout (Plectropomus leopardis) on the Great Barrier Reef. In this paper, we use this tool, called the Effects of Line Fishing Simulator (ELFsim), to evaluate the effects of different MPA arrangements on fish biomass and catch rates both inside and outside closed areas. Our model, which involves a detailed spatially-structured operating model of the full life-history of coral trout, and a multiple sector (commercial, charter and recreational) line fishery model, allows us to explore these effects over decadal periods.