Sonsera fishery: by-catch species

Valdivia Poch, Jordi
Not only the species targeted are affected by the commercial fishing, there are several other species that are caught incidentally. This is known as “by-catch”. By-catch is one of the most pressing issue in the commercial fishing industry worldwide. “Sonsera” have a high selectivity when targeting sand eel. “Sonsera” known both, the gear and the boat have Gymnammodytes cicerelus and Gymnammodytes semisquamatus as target species. The study focused on the central-northern Catalan coast (NW Mediterranean). Specifically, 5 fishing ports were considered: Estartit, Palamós, Sant Feliu de Guíxols, Blanes and Arenys de Mar. From 2012 to 2018. The aim of this study is to have knowledge of the biodiversity of the fish community associated with “sonso”, if the by-catch follows a pattern considering the factor year, season and geographical position of the fishing port, why some of these species are captured unintendedly and finally, if some species of seagrass meadows are affected by “sonsera”. A total of 67 species where identified and the relative weight have been calculated with this, using PRIME, a multi-dimensional scaling analysis (MDS) have been done for all the samples first and then considering the factors said before. For the biodiversity study some ecological indexes have been used. Results showed that no distribution pattern has been observed by the non-targeted species at the “sonsera” fishery per year, season and fishing port. However, the lack of seasonality it could be seen for the low by-catch rate observed. Therefore, all the “sonsera” boats are fishing on the same costal community. The community of sandy bottom and shallower waters species. “Sonsera” fishery have a considerably number of unwanted species capture. In addition, some of the captures of the species at the fishery are below the minimum catch size. The average percentage of by-catch is lower than 1%, the lowest rate compared with other typical fisheries of the Mediterranean. Some species are more dominant in abundancy than others for example Bothus podas, Pagellus erythrinus, Xyrichthys novacula and Rhizostoma pulmo. Finally, Posidonia meadows are not damage by “sonsera” fishery ​
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