Juvenile hake (Merluccius merluccius) discard minimization in otter board trawling by square mesh escaping window selectivity device : proving a mandatory selectivity device in the Basque trawling fleet

Abstract

The aim of this research was to prove a mandatory square mesh panel in the Basque trawling fleet operating in the ICES subzones VIIIabd. Selectivity parameters were calculated for the dual selection system (70 mm codend + 100 mm square mesh panel in extension piece) and for commercial codends (70 mm codend), with the aim to compare them and determine the effect of the square mesh panel in the overall selectivity of the gear for three selected species (Hake, Red mullet and Pout), using a three compartment setup (codend, codend cover and square mesh panel cover). The low escape-panel contact found in the selected species, especially in the case of the hake can be attributed to different factors such as passive behaviour in the trawl, high turbidity and high trawling speed. The data were analyzed with the software SELNET that enables the analysis of data for experimental designs involving multiple compartments by means of complex selection models.