Evaluation of 35 mm Square and Diamond Mesh Cod-ends of Commercial Trawl Net with Respect to Cuttlefish Sepia inermis (Van Hasselt, 1835) from East Coast of India

Abstract

Trawling is considered one of the detrimental fishing methods because of its non-selective nature in capturing species, resulting in an enormous quantity of unwanted catch in global marine fisheries. The objective of the present study was to assess the selectivity characteristics of 35 mm square- and diamond-mesh cod-ends of a commercial bottom trawl net with respect to cuttlefish (S. inermis) off Kakinada, Andhra Pradesh, during 2022, using the covered cod-end method. The evaluated L25, L50, and L75 values for the 35 mm square-mesh cod-end were 5.03, 8.66, and 12.32 cm, respectively. The observed selection range (SR), selection factor (SF), and selection ratio (Sr) were 7.29, 2.70, and 2.08, respectively. The recorded L25, L50, and L75 values for the 35 mm diamond-mesh cod-end were 4.50, 7.25, and 9.99 cm, respectively, while the observed selection range (SR), selection factor (SF), and selection ratio (Sr) were 5.49, 2.07, and 1.56, respectively. The observed L25, L50, and L75 values clearly indicated that the square-shaped cod-end had better selectivity than the alternative diamond-mesh cod-end of the trawl net. The length classes escaping from the square-mesh cod-end were also larger than those escaping from the diamond-mesh cod-end. Conversion of the cod-end portion of a trawl net from diamond to square mesh may therefore help reduce the capture of juvenile fishes, sub-adults, and unwanted catch by trawling systems.