南海区金线鱼刺网网目选择性研究

为科学制订南中国海区金线鱼(Nemipterus virgatus)刺网最小网目尺寸标准,2008年5月在南海北部进行了5种网目(40mm、45mm、50mm、55mm、60mm)刺网联合捕鱼实验,渔获种类合计达72种,其中5种网目刺网均有捕获的仅13种.根据刺网渔获的种类、数量和生物量,利用研究生物群落的多样性指数、相似性指数和ABC曲线方法,研究了金线鱼刺网的种问选择性,探讨了不同网目刺网作业对渔业资源的影响.结果表明,不同网目实验刺网的渔获组成存在明显差异,随着网目尺寸的缩小,渔获种类和数量呈上升趋势,渔获平均体质量则呈下降趋势.多齿蛇鲻(Saurida tumbil)、长尾大眼鲷(Priacanthus tayenus)、金线鱼、带鱼(Trichiurus haumela)和花斑蛇鲻(Saurida undosquamis)为主要渔获种类,其渔获生物量分别占总渔获量的21.35%、15.76%、14.78%、8.43%、7.20%,40 mm和45 mm刺网中多齿蛇鲻和花斑蛇鲻的渔获比例较高,50mm、55 mm和60 mm刺网中长尾大眼鲷、金线鱼和带鱼的渔获比例较高.根据ABC曲线计算的40 mm、45 mm、50 mm、55 mm和60 mm 5种网目刺网W统计值分别为-0.023、-0.012、0.039、0.083和0.073.40mm和45mm刺网对渔获生物群落的干扰较大.南海区金线鱼刺网最小网目尺寸标准的制订应综合考虑金线鱼、带鱼、长尾大眼鲷这3种主捕经济种类的尺寸选择性和最小可捕标准,同时注意网线粗度对捕捞能力的影响.

Mesh selectivity of Nemipterus virgatus gillnet in South China Sea

gillnet in the South China Sea, fishing trials for gillnets with five different mesh sizes (40, 45, 50, 55 and 60 mm with twine diameters of 0.25, 0.25, 0.30, 0.30 and 0.35 mm, respectively) were carried out in the northern of South China Sea in May 2008. The catches were composed of 72 species in all, of which only 13 species were occurred in all experimental gillnets. Based on the species, abundance and biomass of catch, the methods of diversity index, similarity index and abundance-biomass comparison(ABC) curve was used in the study of intra-selection of gillnet and the effect of different mesh size gillnets on fishery resources. The results indicate that the catch species composition were different between the experimental gillnets. With the mesh size , the species and abundance of catch have increased, the average individual weight decreased. Trichiurus haumela and were the dominant catch species, biomass percentage of all catches was 21.35 %, 15.76 %, 14.78 % ,8.43 % and 7.20 %, have higher of percentage 40mm and 45mm gillnets, 50mm, 55mm and 60mm gillnets. The stability of biological community of catches have downward trend with mesh size reduced. Statistical value of 40, 45, 50, 55 and 60 mm gillnets was -0.023 , -0.012, 0.039, 0.083 and 0.073 respectively, 40 and 45 mm gillnets have a serious effect on fisheries resources. were the targeted species in the fishery. Minimum mesh size of should be d based on the size selection and the minimum fishing size regulation of the three species,the effect of twine diameters on fishing power of gillnets should also take into account.