Coral Trout Population Analyses Tests the Effectiveness of Marine Reserves

Coral Trout Population Analyses Tests the Effectiveness of Marine Reserves

Tropical Ecosystems Hub researchers are unlocking vital information for species of coral trout on the Great Barrier Reef that has important implications for coral trout conservation and fisheries management in the World Heritage Area.

The team from Project 8.3 Significance of no-take marine protected areas to regional recruitment and population persistence on the Great Barrier Reef is seeking to understand how larval connectivity in networks of marine reserves contribute to biodiversity conservation and sustaining fisheries; and whether the benefits of larval connectivity are influenced by reserve design.

The project is focused on two species of coral trout, Plectropomus leopardus and P. maculatus. These species are primary target species in the Coral Reef Finfish Fishery on the Great Barrier Reef and iconic species that are readily associated with the Great Barrier Reef.

The project team undertook genetic parentage analysis to track dispersal of larval fish from marine reserves; developed a biophysical model to simulate larval dispersal; and established a metapopulation model to forecast future population changes and fishery yield. A metapopulation consists of a group of spatially separated populations of the same species that have some form of migration or mixing behavior among them.

The research provides empirical estimates of larval dispersal within and among three clusters of reefs over 100km apart in the southern Great Barrier Reef region. The research refines an existing biophysical model for this region to better predict regional dispersal; compares observed and predicted patterns of larval dispersal from the biophysical model; and evaluates the effects of marine reserve network design using the metapopulation model.

Preliminary analysis determined a degree of hybridization between the two species. Dispersal studies showed both local retention of larvae within reef clusters and significant connectivity among them. Understanding connectivity is critical to successfully determining recruitment dynamics for these important reef species.

The findings have important implications for understanding the effectiveness of current spatial management within the Great Barrier Reef Marine Park. This is fundamental to understanding how reserves in the Great Barrier Reef are demographically linked to fished areas and therefore can potentially influence fishery yields.

The next stages for this component of the project are to further develop the preliminary metapopulation models to answer questions about whether the establishment of the Great Barrier Reef reserve network has benefited fishery yields in the short- term, compared to a no-reserve scenario.

The project team will also consider the effects of marine reserves in the long-term, accounting for the natural habitat heterogeneity and disturbance events. This will provide a holistic understanding of the fishery and conservation implications of the Great Barrier Reef Marine Park zoning plan on coral trout.



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