Comparison of The Selectivity of Diamond and Square Mesh Codends for Red Mullet Mullus Barbatus in The Antalya Bay

Abstract

In this study, the selectivities of commercial 44 mm nominal polyethylene (PE) diamond mesh (PE44DM) and square mesh (PE44SM) codends for red mullet Mullus barbatus fisheries in Antalya Bay, Eastern Mediterranean, were compared and modelled. For this purpose, a conventional bottom trawl of 600 meshes was operated onboard R/V “Akdeniz Su” during night time at 25-50 m depths for a total of 21 hauls. Data were collected using the covered codend technique, and analysed using a logistic equation with maximum likelihood by SELNET software. The PE44DM codend had a higher catch rate (89.6%) and 32.5% of M. barbatus were below the minimum landing size whereas catch rates decreased to 42.1% and 9.9%, respectively, in the PE44SM codend. Changing from the diamond mesh to square mesh codend increased the mean L50 and SA values from 8.2 to 13.2 cm and from 2.11 to 2.87 cm, respectively. Both L50 and SA values obtained in the present study show a statistically significant increase (no overlap in 95% confidence limits) with a change in the same mesh size codends from diamond to square for M. barbatus. The use of the PE44SM codend resulted in a significant improvement in the selectivity of M. barbatus compared to the currently used PE44DM codend with a very low escape ratio (10%).

Keywords

• mullus barbatus
• red mullet
• trawl selectivity
• square mesh