梭子蟹定置三重刺网设计与试验

摘要

根据捕捞目标的生物学习性和体型特征，设计了一种捕捞三疣梭子蟹（ Portunus trituberculatus）的专用定置三重刺网并进行了生产试验。所设计的刺网主尺度为50．00 m ×1．08 m，上纲长50．00 m，下纲长66．00 m；内网衣规格为1200目×18．5目，目大120 mm；外网衣规格为200目×2．5目，目大500 mm。2015年9月4—26日在莱州湾渔场进行了生产试验。结果表明，新刺网所捕获的三疣梭子蟹平均体重为175．69 g，单位捕捞努力量渔获量（CPUE）为1．61 kg／（片·次），主捕率高，其中梭子蟹产量占总渔获量的99．31％。新设计的刺网，下纲比上纲长32％，网衣底部较松弛，提高了网衣对梭子蟹的缠络性能，因而提高了捕捞效率；内网衣网目较大，利于释放幼鱼，网高较低，减小了捕获中上层鱼类的几率，因此，兼捕率较低，有利于渔业资源的保护。%A set of trammel net for the capture of swimming crab Portunus trituberculatus was designed and tested in field experiments, based on the biological habit and body characteristics of the target species.The designed fishing gear has a principle dimensions of 50 .00 m ×1 .08 m with a 50 m head rope and a 66 m bottom rope.The size of the one inner net suit is 1 200 mesh ×18.5 mesh with a mesh size of 120 mm and that of the two outer net suits is 200 mesh ×2.5 mesh with a mesh size of 500 mm.From 4th to 26th September 2015, the designed fishing gear was used to catch swimming crab in Laizhou Bay.The CPUE of the designed net was 1.61 kg/webbing and the mean body weight of swimming crabs caught was 175.69 g.Swimming crab, as the main species of the catching, accounted for 99.31% of the total catch.The bottom of the net suits of the designed net is loose because the bottom rope is 32 percent longer than the head rope, and this characteristic improves the binding performance on the swimming crab and thus the catching rate.The bigger mesh size of the inner net suit and the lower height of the designed net increases the releasing rate of young fishes and reduces the catching of pelagic fishes, respectively.The low fish catching rate of the designed net is very beneficial for the protection of fishery resources.