Selectivity of Standard, Narrow and Square Mesh Panel Trawl Codends for Hake (Merluccius merluccius) and Poor Cod (Trisopterus minutus capelanus)

The selectivity of 3 trawl codends, (1) a commercially used standard codend, (2) a narrow codend (100 meshes on its circumference instead of 200) and (3) a square mesh top panel codend, was tested for hake (Merluccius merluccius) and poor cod (Trisopterus minutus capelanus) between 8 and 24 October 2003, in the Aegean Sea. Data were collected using the covered codend technique, and analysed by means of a logistic equation with the maximum likelihood method. The results show that the commercially used standard codend (40 mm mesh size PE codends, 200 meshes on its circumference) retains all the hake that enter and releases only a few specimens of poor cod. The narrow codend has better selectivity than the standard codend (L50 = 14.28 cm for hake and 14.11 cm for poor cod). The selectivity of the square mesh top panel codend was higher than that of the narrow codend for hake (L50 = 15.25 cm), while it was similar for poor cod (L50 = 14.25 cm).