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Potential Changes in Prey Population Structure Following Removal of Predators by Fishing

Ameer Abdulla

CRC Reef & School of Tropical Environment Studies & Geography, TOWNSVILLE, AUSTRALIA

Theme: TH5

Exploiter-mediated coexistence occurs when predation promotes the coexistence of species that otherwise would not occupy the same habitat due to competitive exclusion. This hypothesis is explored using Lotka-Volterra models with differential recruitment and simulated harvest. Catch-effort and visual survey data are used from 24 reefs on the Great Barrier Reef subjected to different protection regimes. The reefs are arranged in 4 clusters spanning seven degrees of latitude, with each cluster including four no-take reefs and two harvest reefs. Eight years of seasonal catch-effort and visual survey data of seven target fish (piscivores) of the Great Barrier Reef Line Fishery and nine potential prey families are used to parametise the model. Preliminary results show that reefs with lower predator abundance due to fishing may exhibit low prey diversity and high species-specific abundance (competitive dominants).