【摘要】 对长江口桁杆拖虾网采用套网法进行了选择性试验,分析研究了桁杆拖虾网3种网目尺寸的网囊对脊腹褐虾Cargon affini、葛氏长臂虾Palaemon gravieri和总体虾类的选择性。结果表明:当网囊网目尺寸为20、25、35 mm时,脊腹褐虾的50%选择体长分别为41.36、46.42、57.68 mm;葛氏长臂虾的50%选择体长分别为43.35、47.20、62.01 mm;总体虾类的50%选择体长分别为47.45、50.56、64.87 mm。虾类网囊网目内径(Me)与50%选择体长(L0.5)之间的关系:脊腹褐虾,L0.5=1.0964Me+19.179,R2=0.9984;葛氏长臂虾,L0.5=1.2779Me+16.777,R2=0.9814;总体虾类,L0.5=1.999Me+22.297,R2=0.9729。更多还原

【Abstract】 The selectivity tests of codend mesh in beam shrimp trawl were conducted in the entrance of Changjiang River by covered net method to evaluate the selectivities of three condend mesh size for shrimp Cargon affinis,Palaemon gravieri and conventional shrimps.The results showed that the shrimp Cargon affinis had 50% escapable body length(L0.5) of 41.36 mm at the codend mesh size of 20 mm,46.42 mm at the codend mesh size of 25 mm,and 57.68 mm at the codend mesh size of 35 mm.In Palaemon gravieri,the 50% escapable body length(L0.5) was 43.35 mm at the mesh size of 20 mm,47.20 mm at the mesh size of 25 mm,and 62.01 mm at the mesh size of 35 mm.The 50% escapable body length(L0.5)of the conventional shrimps were found 47.45 mm at the mesh size of 20 mm,50.56 mm at the mesh size of 25 mm,and 64.87 mm at the mesh size of 35 mm.The relationship between 50% escapable shrimp body length(L0.5) and mesh size(Me) is expressed as:Cargon affinis:L0.5=1.0964Me+19.179,R2=0.9984;Palaemon gravieri:L0.5=1.2779Me +16.777,R2=0.9814;The conventional shrimp:L0.5=1.999Me+22.297,R2=0.9729.更多还原