Mesh size selectivity of Harpodon nehereus gillnet in northern South China Sea

To obtain the minimum mesh size of Harpodon nehereus gillnet in northern South China Sea, we tested three different meshes of 36 mm, 38 mm and 40 mm during January, 2015. Normal, Lognormal and Gamma models were used to fit the H.nehereus data, and model parameters were estimated by maximum likelihood method. The results indicated that H.nehereus gillnet had good selectivity, and Gamma curve provided the best fit for gillnet selectivity. The minimum mesh size of H.nehereus gillnet calculated by the body length was more appropriate than that by the maximum body girth. According to the research on the first capture size of H.nehereus in the East China Sea, the minimum mesh size of H.nehereus gillnet was calculated to be 38.71 mm in the South China Sea. In order to achieve rational exploitation of H.nehereus gillnet, the minimum mesh size is suggested to be under control strictly, and the fishing ground and fishing time must be chosen reasonably.