What is bycatch?
In general, bycatch can be defined as the incidental capture of nontarget species. Fishing gear, in particular trawling nets, can be very unselective, catching and discarding large quantities of bycatch. These gears represent a serious problem to endangered species and cause severe changes in the ecosystem. In addition, bycatch can also have critical social and economic impacts such as loss in jobs, which can mean hunger in developing countries. Despite the general recognition of the issue and efforts to reduce incidental catches, this is still a major and complex problem.
Shrimp trawls are poorly selective and contribute towards much of the overall total estimate of global discards. In Paraná, Brazil the artisanal shrimp trawl fishery is a very important activity in socioeconomic terms but it is also responsible for the capture of large quantities of bycatch.
During my MSc studies, under the supervision of Matt Broadhurst and Henry Spach, I conducted experiments that aimed to reduce the impacts of the artisanal fishery, through the development of bycatch reduction devices (BRDs). This was a collaborative and participatory project of coastal zone management meaning that fishermen always decided on the location for testing the modified nets and their own boats were used.
The results of this study showed a clear benefit of using BRDs to improve selectivity and thereby to reduce the impacts of fishing. Ongoing research is being conducted for alternative technical solutions to be incorporated into the fisheries management strategy off the coast of Paraná. Check the work of the Centre for Marine Studies.
Publications from this study:
Silva CNS, Broadhurst MK, Medeiros RP, Dias JH (2013). Resolving environmental issues in the southern Brazilian artisanal penaeid-trawl fishery through adaptive co-management. Marine Policy 42, 133-141.
Medeiros RP, Guanais JHDG, Santos LO, Spach HL, Silva CNS, Foppa CC, Cattani AP, Rainho AP (2013). Strategies for bycatch reduction at small-scale shrimp trawl fishing: perspectives for fisheries management. Boletim Instituto da Pesca 39 (3), 339-358.
Silva CNS, Broadhurst MK, Dias JH, Cattani AP, Spach HL (2012). The effects of Nordmøre-grid bar spacings on catches in a Brazilian artisanal shrimp fishery. Fisheries Research 127-128, 188-193.
Silva CNS, Dias JH, Cattani AP, Spach HL (2012). Relative efficiency of square-mesh codends in an artisanal fishery in southern Brazil. Latin American Journal of Aquatic Research 40 (1), 124-133.
Silva CNS, Broadhurst MK, Schwingel A, Dias JH, Cattani AP, Spach HL (2011). Refining a NordmØre-grid for a Brazilian artisanal penaeid-trawl fishery. Fisheries Research 109, 168-178.
Silva CNS (2011). Eficiência de redutores de captura incidental na pesca artesanal do camarão sete-barbas (Xiphopenaeus kroyeri) no Paraná, Brasil. MSc thesis, Federal University of Paraná, Brazil