黄海区青岛近海双桩张网网囊网目选择性研究

Selectivity of codend mesh of double stake stow net in Qingdao offshore,Yellow Sea

使用套网法对黄海区青岛近海主要捕捞对象中的鹰爪虾(Trachypenaeus curvirostris)和兼捕对象白姑鱼(Argyrosomus argentatus)进行数据分析,使用Logistic曲线作为其选择性曲线模型,求得不同网目尺寸网囊对鹰爪虾和白姑鱼的体长选择性曲线,并运用极大似然估计法进行曲线参数估算,对桩张网渔具不同网目尺寸的网囊选择性进行分析。结果表明:试验网囊网目尺寸为30mm、33mm、40mm时,鹰爪虾的50%选择体长L50分别为5.309cm、5.778cm、6.972cm,其选择范围(SR)分别为1.091cm、1.290cm、1.571cm;白姑鱼的50%选择体长L50分别为6.581cm、6.908cm、7.441cm,其SR值为1.934cm、2.144cm、2.322cm。随着桩张网网囊网目尺寸的增大,鹰爪虾和白姑鱼的L50随之增大,SR值也逐渐增大。针对鹰爪虾来说,33mm规格网囊的选择性能比30mm和40mm的要好。本研究选择该海区的主要捕捞对象鹰爪虾以及兼捕量较大的白姑鱼为研究对象,旨在为合理确定适合黄海区的张网最小网目尺寸提供科学依据,以保证黄海区渔业资源的可持续利用。

Stow net fishery is one of the important fisheries in Yellow Sea which is rich in shrimp resource,but there is seldom studies on size selectivity of stow net in this sea area.Using covered net method,the selectivity of the codend mesh of double stake net was studied in this sea area.Trachypenaeus curvirostris was the main fishing target in this area and Argyrosomus argentatus was bycatched in the sea area during this study in certain amount.Using the catch data of T.curvirostris and A.argentatus,different mesh sizes selectivity curves of T.curvirostris and A.argentatus were drawn by using Logistic curves as a selectivity model.Parameters of selectivity were estimated according to the maximum likelihood method.The results of the experiment indicated that when the mesh size for T.curvirostris was 30 mm,33 mm and 40 mm,its L50 was 5.309 cm,5.778 cm and 6.9 72 cm,its SR was 1.091 cm,1.290 cm and 1.571 cm,respectively;when the mesh size for the A.argentatus was 30 mm,33 mm and 40 mm,its L50 was 6.581 cm,6.908 cm and 7.441 cm;its SR was 1.934 cm,2.144 cm and 2.322 cm,respectively.When the mesh size of stake stow net increased,the L50 of T.curvirostris and A.argentatus would enlarge,and the SR would enlarge too.According to the results,the authors suggest that codend net with 33 mm mesh size has better selectivity,so it is more suitable than 30 mm and 40 mm mesh sizes in the experimental sea area.