Vulnerability of species captured by the bottom-gillnet fishery in Southern Brazil: productivity-susceptibility (PSA)

Abstract

During the last decade, the gillnet fishery targeted to monkfish (Lophiusgas trophysus) was developed on the slope areas off southern Brazil, generating important non-intentional catches of a diverse group of benthopelagic species, mostly fish. In order to assess the impacts of this fishery, the Productivity-Susceptibility Analysis (PSA) was used with theinformation obtained during gillnet fishing operations in 2001. According to the fish present in the catches, were established a set of qualitative or semi-quantitative attributes that measure their biological"productivity†and "susceptibility†to this fishery. These attributes were ranked as "high†(3), "moderate†(2) and "low†(1). Mean scores obtained by elasmobranchs for productivity attributes (1.32) were higher than those obtained by teleosts (1.88). Both groups exhibited similar mean scores for susceptibility attributes; 2.00 (elasmobranchs) and 1.96 (teleosts). Among the most vulnerable species to bottom-gillnet fishing were the elasmobranchs Dipturus trachyderma, Echinorhinus brucus, Squalus megalops,Squatina argentina, Atlantoraja castelnaui and Torpedo puelcha. Valuable species as Urophycis mystacea,Merluccius hubbsi, and Lophiusgas trophysus (monkfish) were amongst the most vulnerable teleosts in this fishery. The PSA approach provides a useful empirical qualitative basis to assess the ecosystem impacts of fisheries, prioritizing species components needing management acts, including those data-deficient species.