Using an integrative approach to evaluate shrimp bycatch from subtropical data-poor fisheries

Abstract

Tropical and subtropical shrimp fisheries occur mainly nearshore, where numerous non-target species (bycatch) are captured. Bycatch is a serious issue for fishing activity and understanding its impacts through integrative analyses of the bycatch structure is necessary. In Brazil, information on bycatch composition and structure is limited. As such, we conducted a study on the target species and bycatch communities from a fishery area in the southern Brazilian coast, considering a 20-year dataset. The target species abundance was influenced by seasonal conditions, where peaks of abundance occurred from February to May and August to October. The trawl captures comprised 149 species, of which 116 species were discarded and 33 were considered usable by the fishermen. The bycatch composition had few abundant and several rare species, with a high bycatch rate associated with salinity and TSS, mainly in the latter years of study. Bycatch diversity showed association with salinity, and multiyear oscillations, but generally maintained a stable trend over years. Our analysis revealed bycatch patterns and the influence of environmental variables in a single ecosystem. In the context of scarce data and an incipient management structure, these findings are crucial to develop a coherent approach for fisheries management.