The effects of larval dispersal and spatial heterogeneity on the design of marine reserves

For marine reserves to be an effective fishery management tool, they must increase the persistence of the population particularly if the population is overfished. Many marine species, including many economically important species, have a life history that includes planktonic larvae and relatively sedentary adults. Throughout this work a discrete time, continuous space model framework is used to address such populations. With the current paucity of information regarding meroplanktonic larval transport processes, understanding the robustness of theoretical results with respect to persistence is of key importance. This work extends the current knowledge of reserve theory first by applying a range of dispersal kernels to semelparous populations occupying both a homogeneous bounded coastline and an infinite coastline with equally spaced reserves with fishing resulting in the complete removal of all individuals. The model demonstrates that the mean dispersal distance and not the kurtosis, or size of the tail of the kernel, is the critical factor in determining the minimum reserve size.; An approximation for the equilibrium dynamics of a metapopulation consisting of semelparous populations with different stock-recruitment relationships is developed. The usefulness of the approximation is demonstrated by relaxing the conditions for heterogeneous habitats to allow for a bounded domain and fishing pressures less than complete removal. Larvae that are transported beyond the boundary are lost resulting in higher population growth rates or larger reserve sizes for sustainability when compared with an infinite domain. As fishing pressure is reduced the effect is to allow populations with lower growth rates to persist for a given reserve pattern. The reserve size required for a given fishing pressure is sensitive to the population growth rate and for small growth rates the reserve size can excessively large, even with moderate levels of fishing.; Finally, the discrete time, continuous space model is extended to incorporate age structure and allow for fishing limited by age class. A spatial approximation for both homogeneous and heterogeneous habitats is derived, with the accuracy of the approximation similar to that of the semelparous models. The inclusion of age structure modifies the persistence requirements but does not obviate previous results based on semelparity.