Spatial dynamics of marine reserves: The importance of fish movement and harvester redistribution

This dissertation explores the role of fish movement, population regulation and the spatial patterns of fishing effort in shaping the distribution of fish within marine reserves and across their boundaries. The interplay between spillover and fishing effort is investigated through the integration of spatially-explicit models and empirical patterns of fish abundances found in the marine reserve literature.;Chapter 1 examines how the mechanism of population regulation can influence the build-up of standing stock within a marine reserve and the spillover rate to adjacent fished areas. Two forms of population regulation are compared, density-dependent population growth and density-dependent movement. Standing stock per unit area is bounded for density-dependent population growth, and increases with size for density-dependent movement. With density-dependent population growth, spillover rate per unit area of reserve is maximized with reserves around 50% larger in linear dimension than the minimum size for population persistence. Spillover per unit area of reserve increases with reserve size for populations regulated by density-dependent movement.;Chapter 2 explores the implications of fishing-the-line at the boundary of a marine reserve. The model shows that fishing-the-line is the optimal harvesting strategy for both consolidated and competitive multispecies fisheries near marine reserves when mobile species spillover from the reserve. The consequences of basing the distribution of fishing effort for a multispecies fishery upon the optimality of the most mobile species which exhibits the greatest spillover are explored. The chapter concludes with a comparison between model predictions and empirical findings from a study of game fish in the vicinity of a no-take marine life refuge on Catalina Island, California.;Chapter 3 reviews the patterns of density, biomass and harvesting effort near marine reserve boundaries found in the empirical literature. The limited number of spatial studies demonstrates that fish density, biomass and fishing effort generally decline with distance from the protected area. A theoretical model incorporating a linear decline of fishing effort away from the reserve reveals that this spatial pattern of harvesters can either approximate the empirical patterns of decaying fish density away from the protected area, or produce dips in fish density close to reserve boundary.