Zuercher, Rachel; Harborne, Alastair

Modelling and Mapping Fishing Impact and the Current and Potential Biomass of Coral-Reef Fisheries in South Florida

2019

Florida International University; The Nature Conservancy

"The key aims of this work were to model and map fishing impact, model and map the current fish biomass, and assess the potential benefit of conservation and management measures, such as the potential biomass on a reef following the cessation of fishing, on the Florida reef tract from Martin Country, FL to the Dry Tortugas. These analyses demonstrated that biophysical gradients were important factors affecting the biomass of fishery species, particularly the depth, rugosity and habitat type. The human influence on fish populations, assumed to be through fishing, was predicted by the number of recreational fishermen within 50 km of a reef, the number of marina slips within 25 km of a reef, with fish biomass generally decreasing as the number of recreational fishermen and number of marina slips increased. A map of relative fishing impact (specifically the total cumulative impact of fishing on the fish assemblage) to all coral reef and hardbottom habitat sites across the Florida reef tract was created at a resolution of 1 ha reef cells. The snapper-grouper model demonstrated that biomass decreased with increasing fishing impact, and was also affected strongly by depth, rugosity and habitat type at the site. This model was then used to extrapolate estimates of current biomass across the reef tract to generate a previously unavailable map of fish biomass. Finally, the model of current biomass was adjusted to represent two potential management scenarios: fishing impact reduced to zero to simulate the establishment of a no-take reserve (of, to estimate the biomass possible on a reef given the biophysical conditions there), and reef rugosity increased by 10% to simulate restoration that increases reef complexity. This allowed the production of maps estimating patterns of potential biomass across the region. Using the maps of predicted current and potential biomass of the snapper-grouper complex under a simulated no-take reserve, the project generated a map of the predicted time of recovery following the cessation of fishing. The maps generated by this project represent the first spatially explicit, continuous maps of fishing impact and current and potential biomass for the Florida reef tract."

South Florida, Florida reef tract, coral reef, map, model, fisheries, fishing impact, biomass

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OCM

FY2016 CRCP Project ID 31103; Project Title: FY16/FY17/FY18/FY19 - Non-Governmental Organization Partnership; Principal Investigator: Craig Reid; Grant NA16NOS4820106.

NA16NOS4820106