Mapping fishing grounds of the multigear coastal fleet in southern Portugal

• Autor(a) principal: Fernandes, Ana Mariana Silva
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/19791
• topic: Target species; Fishing grounds; Gillnets; Gps data; Mapping; Management; Surveys; Trammel nets; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

Managing and monitoring fishing activities has been a major concern in recent years as overfishing and other negative impacts on the environment become increasingly known. The identification of fishing grounds is, therefore, a necessity, that can inform not only the fishing sector but also other maritime sectors. In this work, the fishing practices of the multigear coastal fleet in the southern coast of Portugal are analysed. A series of in-person interviews were performed on a sample of 40 vessels to identify core variables such as the vessel characteristics, fishing gear, species captured and fishing grounds. The fishing grounds indicated by the fishers were aggregated and a fishing intensity map was created. Observational and GPS data was further collected through on-board trips on a set of fishing vessels, which was used to compare with data collected in the interviews. GPS data was processed to identify events of searching, setting and hauling, as well as establish the average velocities for these events. According to one of the main objectives, it was possible to identify the main fishing grounds, which are located generically between one and eight nautical miles at 50 meters deep, highlighting an area between Lagos and Quarteira with greater fishing intensity. The fishing areas indicated by the fishers and those identified through GPS data display some agreement, as do the hauling and setting velocities and times. The same did not happened with the soaking duration in which there were differences between the soaking durations indicated on the interviews and those verified on-board. Evidence of a discrepancy between reported and real practices regarding gear, captures and fishing activities is also discussed, with an emphasis on the negative effects of such practices in fisheries and the environment. Some of the current issues being faced in fisheries are by-catch and discarding, Illegal, Unreported and Unregulated (IUU) fishing, and ghost-fishing. When these are not assessed and remain unknown, they contribute to lack of proper management and sustainability solutions. In the end, the main purpose is to create a clearer picture of what is occurring in the local environment and within the fisheries to produce valuable information (like maps of fishing grounds) and consistent sets of data that can be used for future management decisions.