黄海南部小黄鱼洄游分布及种群结构特征

Monthly fishery survey data of the small yellow croaker Larimichthys polyactis in the southern Yellow Sea from2003 and 2013 were employed to evaluate the variation in the resource distribution and biological characteristics(especially body length and sex ratio) in the population on a decadal scale.The results indicated that the small yellow croaker migrated from the Shawai fishing ground to the Dasha fishing ground in spring and was mainly distributed in the central and western parts of the Dasha fishing ground in April and May.Larimichthys polyactis in the Dasha fishing ground migrated eastward to offshore wintering grounds in autumn and reached the central Dasha fishing ground in October and November.The small yellow croaker entered the western waters of the Shawai fishing ground in winter.A large number of age 0+ fish occurred in the Shawai and Jiangwai fishing grounds in October of 2003 and 2013.The body lengths of the spawning stock and wintering stock in 2013 were larger than those in 2003,and the monthly sex ratios(female to male) were significantly less than 1 in both years.The monthly distribution of this fish in the southern Yellow Sea was consistent with a previous finding that "the stock migrated between the wintering grounds in the west of Jeju Island and the Lüsi spawning grounds" but tended to move more northward,with the spawning grounds extending outward.In the past decade,body length variation experienced a decline after an increase,rather than a steady decrease.The sex ratio in the single-stick stow net showed a tendency to increase over the decade,but was either less than or more than 1 depending on the fishing gear;therefore,further studies should be conducted to determine the sex structure.

Migration and population structure characteristics of the small yellow croaker Larimichthys polyactis in the southern Yellow Sea

Monthly fishery survey data of the small yellow croaker Larimichthys polyactis in the southern Yellow Sea from 2003 and 2013 were employed to evaluate the variation in the resource distribution and biological characteristics (especially body length and sex ratio) in the population on a decadal scale. The results indicated that the small yellow croaker migrated from the Shawai fishing ground to the Dasha fishing ground in spring and was mainly distributed in the central and western parts of the Dasha fishing ground in April and May. Larimichthys polyactis in the Dasha fishing ground migrated eastward to offshore wintering grounds in autumn and reached the central Dasha fishing ground in October and November. The small yellow croaker entered the western waters of the Shawai fishing ground in winter. A large number of age 0+ fish occurred in the Shawai and Jiangwai fishing grounds in October of 2003 and 2013. The body lengths of the spawning stock and wintering stock in 2013 were larger than those in 2003, and the monthly sex ratios (female to male) were significantly less than 1 in both years. The monthly distribution of this fish in the southern Yellow Sea was consistent with a previous finding that "the stock migrated between the wintering grounds in the west of Jeju Island and the Lüsi spawning grounds" but tended to move more northward, with the spawning grounds extending outward. In the past decade, body length variation experienced a decline after an increase, rather than a steady decrease. The sex ratio in the single-stick stow net showed a tendency to increase over the decade, but was either less than or more than 1 depending on the fishing gear; therefore, further studies should be conducted to determine the sex structure.