Exploring Ecosystem and Economic Factors Influencing Fishery Development Patterns

Understanding the factors influencing patterns of fisheries development and their effects on ecosystems is essential for sustainable harvests in the marine environment.  Both ecosystem and economic factors may play a role in fishery development (i.e., fishing down, up or though the food web), and different patterns of development may have varying impacts on the ecosystem dynamics.  An ecosystem model was developed that incorporates dynamic fishery development based on economic factors.  Specifically, example ecosystems were explored that varied by simplicity (food-chain vs. web), shape (wasp-waist or pyramid-shaped), and controls (top-down vs. bottom-up), and how these interacted with economic drivers to produce varying fishing patterns and fishing intensities.  Economic drivers explored were different profitabilities across trophic levels, and the ease of entry / exit from the fishery.  Finally, a range of ecosystem indicators was calculated for comparison with the mean trophic level of catch (TLC), a metric often assumed to describe ecosystem health.  Results indicate that both ecosystem and economic factors can influence the patterns of fishery development and intensity, and these patterns can have different effects on the ecosystem dynamics, but that the TLC may not be the best indicator of the changes occurring in the ecosystem.