大泷六线鱼鱼笼网具网目选择性的研究

为了对不同网目尺寸的大泷六线鱼Hexagrammos otakii鱼笼的选择性进行研究,依据套网法原理在室内水槽中进行试验,采用Logistic模型曲线拟合得到鱼笼网具不同网目尺寸对大泷六线鱼的体长选择曲线,并采用极大似然法估算选择性参数。结果表明:鱼笼网具网目尺寸分别为5、6、7 cm时,大泷六线鱼的50%选择体长(L50)分别为15.42、18.07、21.68 cm,选择范围(SR)分别为0.78、3.22、5.47 cm,选择因素(SF)分别为6.71、6.02、5.42;随着鱼笼网具网目尺寸的不断增大,大泷六线鱼的L50、SR逐渐增大,SF逐渐减小;大泷六线鱼的L50与鱼笼网目尺寸(m)的线性回归方程为L50=3.127m-0.372,R2=0.992。研究表明,使用网目规格为6 cm的鱼笼网具,较适合保护大泷六线鱼资源。

Selectivity of fish traps with different mesh sizes for masked greenling Hexagrammos otakii

The selectivity of the fish traps with different mesh sizes for masked greenling Hexagrammos otakii was investigated using logistic curve as a selectivity model and by cover-net method in a laboratory flume to find out the optimal mesh size for fishing. Parameters of selectivity were estimated according to the maximum likelihood method. It was found that the 50% selection length L50 of masked greenling was 15. 42 cm at mesh size of 5 cm with selectiv-ity facor(SF) of 6. 71, 18. 07 cm at mesh size of 6 cm with SF of 6. 02, and 21. 68 cm at mesh size of 7 cm with SF of 5. 42, indicating that the L50 and selectivity range(SR) were increased as increase in mesh size of cage, and that the SF reduced as increase in mesh size of cage. The linear regression equation between ( L50 ) and the mesh size of webbing (m) was expressed as L50=3. 127 m-0. 372, R2=0. 992. It was concluded that suitable size of fishing gear for protecting masked greenling resources was of 6 cm mesh size.