Artisanal fishery with surface gillnets and megafauna strandings

Abstract

Bycatch is an issue of worldwide relevance involving conflicts between conservation and fishery interests. In Brazil, this conflict has been highlighted in relation to the regulation of small-scale fishery with surface gillnets. To promote management and transformation of this conflict, we analyzed the relationship between catch unloadings from small-scale fishing with surface gillnets and strandings of marine megafauna. We used fishery monitoring data and beach monitoring data in São Paulo between 2015 and 2021, relating to Chelonia mydas, Caretta caretta, Lepidochelys olivacea, Pontoporia blainvillei and Sotalia guianensis. The analyses included (i) overview of catches unloadings from small-scale fishing with surface gillnets and strandings that resulted in the death of each of these species over the course of the year; (ii) correlation tests between those variables for the northern, central, and southern regions; and (iii) performing regression analyses for municipalities within these regions, exhibiting statistically significant positive correlations. The fisheries harvest period was found not to overlap with the stranding distribution. In correlation tests, only strandings of C. mydas in the northern and southern regions, S. guianensis in the southern region and P. blainvillei in the central region showed relationships with fishing landings. The regression analysis was significant for C. mydas and S. guianensis. At the municipal level, the results were statistically significant for C. mydas in São Sebastião, Ubatuba, Ilha Comprida and Cananéia and for S. guianensis in Cananéia. However, the regression explained a small part of the mortality and other impact factors were pointed out. Non-prohibitive management measures, participatory studies, and direct methods for evaluating the interaction between fisheries and megafauna associated with environmental factors should be implemented, along with analyses on other impacts on megafauna.