Effect of codend mesh size increases on the size selectivity of commercial species in a small mesh bottom trawl fishery

Summary The effects of increasing codend mesh size from 11.6 to 25 and 28.7 mm (inside stretched mesh) on the selectivity of greater lizardfish ( S aurida tumbil ), squid ( L oligo sp.), and penaeid shrimp caught by an inshore otter trawling fishery at N ha T rang C ity, V ietnam were assessed. The proportion of escaping trash fish from the studied codends was also examined. In general, the lengths at 50% retention ( L 50 ) of the studied species increased with increasing codend mesh size. L 50 values of greater lizardfish for the 25 and 28.7 mm codends were 109.4 and 145.9 mm, respectively. The 11.6, 25, and 28.7 mm codends selected shrimp at L 50 s of 8.33, 11.86, and 13.92 mm, respectively, and squid (mantle lengths) at 13.1, 36.1, and 41.9 mm, respectively. The mean proportions of escaping trash fish were 0.06, 0.68, and 0.85 for the three codends, respectively. A minimum mesh size of 25 mm is a good compromise between management goals and fishery demands.