Identifying correlates of coral-reef fish biomass on Florida's Coral Reef to assess potential management actions

Coral reef fish assemblages are threatened globally, underscoring the need for data-driven management to reduce threats and restore populations. Comparing fishery management approaches is aided by a detailed understanding of the key factors controlling species' abundances.The aims of this study were to assess the importance of biophysical factors compared with fishing impacts on the biomass of reef fishes on Florida's Coral Reef and to evaluate the potential effects of common management interventions on fish biomass.Fishing impact was estimated using a fishery-independent modelling approach and the biomass of the snapper-grouper complex as a proxy for the effects of fishing. Using a separate subset of data from underwater fish surveys, estimated fishing impact was then combined with 18 biophysical variables to model the current biomass of all reef fish species, the snapper-grouper complex, grazing species and species collected for aquaria.Models explained between 51 and 64% of the variance in fish biomass for the fish groups. The strongest predictor of biomass in the snapper-grouper complex was fishing impact (accounting for 25.2% of the explained variance), whereas reef complexity was the strongest predictor for all other groups.High-resolution maps were produced from the statistical models, including maps of current fish biomass and maps of potential biomass under several management scenarios: a no-take marine reserve, moderate and extensive coral restoration and the addition of artificial benthic structure. Adding structure had the largest single impact on predicted fish biomass (23-72% increase from current estimated levels). However, beneficial synergies emerged when combining habitat-based management and fishing closures, with some combinations resulting in a reef-wide averaged 89% increase in biomass relative to current estimated levels.The results suggest that conservation strategies aimed at protecting and increasing structural reef complexity should be an important part of fishery management discussions.