Gillnet Selectivity on the Small Yellow Croaker Larimichthys polyactis in the Southern Yellow Sea

Gillnet selectivity on the small yellow croaker, Larimichthys polyactis, was investigated in the southern Yellow Sea. Ten gillnet series were tested: two net heights (6 and 10 m) and five mesh sizes (35, 40, 45, 50, and 55 mm). The age 0+ and 1+ groups dominated the catch with proportions of 43% and 53%, respectively. The sex ratio was found to be size- and age-dependent in gillnet surveys, with males increasingly dominant in the smaller size and younger age classes. Nets with heights of 10 m caught selectively more age 0+ individuals and males than 6 m height nets. Gillnet selectivity estimates derived from girth frequency distribution were represented by a binormal model, and the optimal mesh size for 50% retention for the proposed minimum landing size (body length 148.3 mm) of L. polyactis was estimated as 45 mm. We suggest that a gillnet with a mesh size of 45 mm and net height of 6 m is optimal for exploiting L. polyactis as it is less selective for juveniles and smaller males.