Sea trials datasets for the evaluation of trawl selectivity in the multispecific Maltese fisheries case

The current study aims to improve the trawl gear selectivity from the 40 mm square-mesh size currently in use by the Mediterranean demersal trawling fleet so as to reduce discards of hake (Merluccius merluccius), deep-water rose shrimp (Parapenaeus longirostris), and red mullet (Mullus spp) while retaining as much as possible of the legally sized catch. This study targeted the development of four different methods; two of them relied on the codend mesh size and its configuration. The other two assessed the implementation of side escape panels (SEPs) in the trawl body in order to get the fish leaving the trawl net before entering the codend. The new selection system included a V-shaped guiding device to enhance fish contact with the SEPs. For all the investigated species, the good selective properties of the 40-mm square-mesh codend have been confirmed, which were further improved in combination with the 50-mm SEPs. Trawling gears could be made more selective also by using larger mesh sizes in the codend or in the escape panels. Nevertheless, this solution may be difficult to apply in Mediterranean waters for social and political reasons, while the development and compulsory use of square-mesh panels in the trawl body deserve attention