Mesh selectivity of gillnet for pointhead flounder Cleisthenes pinetorum

Fishing experiments were carried out in Ishikari Bay, Hokkaido using a bottom gillnet with eight different mesh sizes to estimate the mesh selectivity for pointhead flounder Cleisthenes pinetorum. A total of 957 pointhead flounder were caught. The SELECT analysis with maximum likelihood method was used to fit the different functional models, the normal, lognormal, and bi-normal model. The catch data except for entangling catch was used for calculation. The bi-normal model was found to fit the data best. For the selectivity curve on the bi-normal model, the relative length (the ratio of fish length to mesh size) with the maximum efficiency was obtained as 1.87.