Using Common Age Units to Communicate the Relative Catch of Red Snapper in Recreational, Commercial, and Shrimp Fisheries in the Gulf of Mexico

The natural mortality rates and fecundity of Red Snapper Lutjanus campechanus vary substantially by age, so the age composition of catch is an important consideration when quantifying the relative effects of catch on the Red Snapper population across different fisheries. For example, the shrimp fishery catches many (but younger) Red Snapper, whereas directed commercial and recreational fisheries catch fewer (but older) individuals. We propose a simple approach for comparing catch across sectors. Fish that are caught can be scaled to a common age by multiplying or dividing by natural mortality rates so that the catch data can then be reported in common age units. Applying this approach to the catch data from the 2018 Red Snapper stock assessment, we showed that the shrimp-trawl bycatch typically accounts for <10% of the relative catch, the commercial sectors account for similar to 32%, and the recreational sectors are responsible for similar to 59%. We believe that the effective management of Red Snapper requires regulation and oversight of each fishery that is proportional to its effect on the population. Given the apparently large influence of recreational fisheries on Red Snapper populations, recent management changes that delegate state-by-state control over important aspects of the recreational fishery (Amendment 50) should be accompanied by efforts to improve the understanding of this sector's interactions with Red Snapper.