Size Selectivity of Square Mesh Codends for Saurida tumbil (Bloch 1795) and Nibea maculata (Bloch & Schneider, 1801) in Bay of Bengal

Abstract

Saurida tumbil and Nibea maculata are widely exploited by the trawl fishery. Due to the use of conventional diamond mesh codends of small mesh size in the trawl nets, large quantities of juveniles of these species are landed along the east coast of India. The size selectivity of 40 mm square mesh codend for S. tumbil and N. maculata was studied with a 30 m demersal trawl, following covered codend method. The L25, L50 and L75 values for S. tumbil with 40 mm square mesh codend was estimated as 16.2, 19.3 and 22.5 cm respectively. selection range, selection factor and selection ratio for S. tumbil were 6.2, 4.8 and 1.5 respectively. The L25, L50 and L75 values for N. maculata with 40 mm square mesh codend were 9.3, 10.9, and 12.5 cm respectively. Selection range, selection factor and Selection ratio for N. maculata were 3.2, 2.7 and 0.8 respectively. Characteristic smooth sigmoid curves typical for towed gears were obtained for S. tumbil and N. maculata.