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What is Fisheries-Independent Data?

Proper management of Florida’s marine fisheries resources requires information from numerous sources. Traditional methods of monitoring changes in fish stocks have used catch-per-unit-effort (CPUE) data derived directly from commercial and recreational fisheries. Analysis of these fisheries-dependent data can provide valuable information on the status of fish stocks; however, there are inherent challenges in using data from these sources. Changes in vessel types, fleet size, fishing gear, or methods of operation can make fisheries-dependent data difficult to interpret (Ultang 1977). Additionally, closed seasons, changes in size or bag limits, and fluctuations in market values can further bias catch data and subsequent analyses. Fisheries-independent data comes from scientific surveys which target juvenile and sub-adult fishes that have not been subjected to fishing pressure. These surveys can provide less biased estimates of trends in fish stocks than fisheries-dependent sampling (Myers and Cadigan 1993). Changes in juvenile abundance within a season can be attributed to natural mortality, immigration, emigration, or recruitment. Shifts in juvenile abundance can also be used to forecast changes in the adult stock, allowing necessary modifications to harvest regulations to be implemented before the fish have fully recruited to the fishery (Goodyear 1985). Florida’s Fisheries-Independent Monitoring program was established to provide this type of timely information for use in conjunction with traditional fisheries management plans.