Evaluating how food webs and the fisheries they support are affected by fishing closures in Jurien Bay, temperate Western Australia

Abstract

This project built on collaborative research in the Jurien Bay Marine Park to develop quantitative models of the ecosystem in this region (Ecopath, Ecosim and Ecospace) and qualitative models of different parts of the ecosystem. These models were used to evaluate the effects of different management options, such as controls on fishing effort and different spatial closures, on fished species (e.g. Western Rock Lobster, Dhufish, Pink Snapper) and the trophic interactions in the ecosystem. In addition to evaluating different management options, the process of developing the model through a series of workshops provided a mechanism for integrating research from previous studies and building understanding about the ecosystem and model among researchers, managers, fishers. The Ecopath model consisted of 80 functional groups (more than 200 species), including 31 fish groups, 26 invertebrates, 11 primary producers, two marine mammals, two seabirds and eight non-living groups. The Advisory group for the project, which had representatives from the Department of Fisheries WA, Department of Environment and Conservation, RecFishWest, RLIAC, and WAFIC, provided directions for developing the management scenarios for evaluation by the quantitative models, including recent changes to fishing regulations in the West Coast region. The final stage of the model can address key ecological questions in the system and explore the dynamics of target species such as Western Rock Lobster and top predators under different fishing regimes. The benefits from the spatial closures, evaluated by Ecospace, vary greatly between species – they were much more effective for relatively sedentary species such as Dhufish and Pink Snapper than migratory species such as sharks

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