南海区张网不同结构网目网囊对凤鲚的选择性比较OA

A comparative experiment using the covered net method was conducted to evaluate the effect of different mesh structures on size selectivity of Coilia mystus stow net fishery in the South China Sea.Two types of codends were tested:a traditional diamond-mesh(control)and a combined diamond-and-square-mesh(test),with a uniform mesh size of 35 mm.Selectivity curves were fitted using the Logistic and Richards models;parameters were estimated using the maximum likelihood method.The results showed that the 50%selection length(L50)of C.mystus in the combined-mesh codend was 109.54 mm,which was 7.50 mm higher than that of the diamond-mesh codend(102.04 mm).Selection range(SR)decreased from 57.07 to 42.49 mm,indicating improved size selectivity precision.Proportion of juvenile C.mystus in the combined codend decreased by 31.31%,whereas the total catch escape rate increased by 11.29%.These findings suggest that the combined-mesh structure effectively enhances the escape of small individuals and overall selectivity of stow net fishing.The results indicate that the combined diamond-square mesh structure,via the complementary selectivity of different mesh configurations for various catches,can effectively improve overall selectivity of the fishing gear,exhibiting enhanced ecological friendliness and application potential.Combined diamond-square mesh codends should be promoted in stow net in the South China Sea to further enhance efficiency and sustainability of the C.mystus fishery.