Discussion about optimum mesh size of cod end for Chilean jack mackerel trawl

This paper deals with the dominant fork length composition, shape characteristics and the fork length of Chilean jack mackerel (Trachurus murphyi) at the first sexual maturity, based on the relationship between the cod end mesh size and the biological characteristics of the fish body. The measurement results show that the dominant fork length of Chilean jack mackerel in 2000 is between 250-300mm. The linear relationships between the fork length(L) and the height(a), width(b) and girth(c) of fish bodies can be respectively described as 2a=0.1858L-3.5219, 2b=0.1339L-4.299 and c=0.4803L-3.4794. The optimum inner mesh size of the cod end for Chilean jack mackerel trawl is 115-120 mm.