Estimating captures and discards of the beach seine conducted in Mira (Coimbra)

• Autor(a) principal: Neves, Pedro Manuel Cancela das
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/17464
• topic: Pesca artesanal - Praia de Mira (Portugal); Pescado - Rejeição

Fishing is a vital source of nutrients for human consumption, and Portugal yields one of the highest fish consumption per capita in Europe (61.77 kg per capita in 2007). Being recognized as a worldwide important activity, fisheries have induced serious depletions in natural fish populations due to overexploitation and lack of adequate management. Another issue related with fisheries are the IUU (Illegal, Unreported and Unregulated) captures, which represents a portion of what is extracted from the ocean that it is not known. This includes unreported bycatch and, consequentely, discarded specimens. The knowledge of discards is crucial for more adequate management. Beach seine is an artisanal fishery conducted in the Portuguese coast. Little information is available regarding its activity. Due to its practice, the impacts on the ecosystem needs proper assessment, especially due to large amount of discards that it generates. To address this issue, the present work aims to analyse captures and discards from beach seine fisheries occurring at Praia de Mira (Coimbra, Portugal) during the summer season of 2016 (June-September, week numbers 22 to 36 – W22 to W36) of four crews. Captures data were provided by Docapesca, while discards data (obtained upon analysis of thirteen samples) were only collected from one vessel. Data on captures of 2015 were also studied to assess yearly variations. Differences in Landings Per Unit Effort (LPUE) of the four crews were detected between both years. Results also shows that 99.53 tons (23 taxa) of marine resources (including fish, squids and crustaceans) were landed and auctioned during the study period of 2016 (W22-W36), which was a lower amount when comparing landings from 2015 (219.00 tons, 24 taxa, within the same period). Trachurus trachurus (Linnaeus, 1758) was the most auctioned species in both years (127 tons in 2015 and 69 tons in 2016), also representing the species where fishermen got their most profits. After proper data adjustment, an average 50 kg of marine resources per haul were discarded, representing typically 15-60% of the total captured. The anchovy Engraulis encrasicolus (Linnaeus, 1758) was found to be the most common discarded species, making up to a total of 1.9 tons. Other abundant discards included T. trachurus, Sardina pilchardus (Walbaum, 1792), Trisopterus luscus (Linnaeus, 1758) and the Henslow’s crab Polybius henslowii Leach, 1820. These last three species had an estimated 100% discard rate per haul, while T. trachurus was usually below 3%, except in four hauls. Possible reasons for yearly differences to occur and motives for discarding were discussed. The low contribution of this fishery on the national scenario (estimated 0.46% of multi-gear captures) does not reflect its importance to the local community. Further decrease on operating beach seine crews on a national scenario is expected. To prevent this occurrence, proper assessments should be performed in order to increase its sustainability.