蓝点马鲛(Scomberomorus niphonius)大网目流刺网参数优化研究

Studies on Parameter Optimization of Scomberomorus niphonius Big-mesh Drift Gillnet

中文关键词: 蓝点马鲛  流刺网  大网目  参数  优化

英文关键词: Scomberomorus niphonius  Drift gillnet  Big-mesh  Parameters  Optimization

中文摘要:

      在对黄渤海区蓝点马鲛(Scomberomorus niphonius)流刺网进行10种网型主要参数分析和筛选的基础上，2013年4月10日—5月15日，使用鲁昌渔64068渔船在黄海中南部对蓝点马鲛大网目流刺网网片做了4种规格网目尺寸的优化对比实验。结果显示，120 mm网目尺寸的网片渔获尾数和重量最大，单位捕捞努力量渔获量(Catch per unit effort, CPUE)为0.1696尾/片·日和373.78 g/片·日，渔获效果优于110、115、125 mm的网目。2015年4月12日—5月27日，使用鲁昌渔64068和鲁莱州渔66287渔船分别在黄海中南部、烟威外海、莱州湾海域对蓝点马鲛大网目流刺网主要参数做了网型优化对比实验。结果显示，鲁昌渔64068渔船使用120 mm网目尺寸网型捕获的蓝点马鲛平均叉长为764.18 mm，最大个体叉长为1000 mm，最小个体叉长为490 mm；平均重量为3623.27 g，最大重量为7500 g，最小重量为850 g；CPUE分别为0.1379尾/片·日和517.65 g/片·日。鲁莱州渔66287渔船使用122 mm网目尺寸网型捕获的蓝点马鲛平均叉长为780.47 mm，最大个体叉长为910 mm，最小个体叉长为600 mm；平均重量为4065.17 g，最大重量为7400 g，最小重量为2000 g；CPUE分别为0.0778尾/片·日和283.35 g/片·日。120 mm网目尺寸网型的渔获效果优于122 mm网目尺寸的网型，春季捕捞大个体蓝点马鲛的流刺网网目尺寸以120 mm左右适合当前的蓝点马鲛群体组成。120 mm网目优化网型主要参数为：渔具主尺度33.00 m×18.54 m，网衣规格500目×175目，网目尺寸为120 mm，网线材料为直径0.48 mm的尼龙单丝(PAM)，横向缩结系数为0.55，静浮力配备为267.9 g/m，浮沉比为1.768∶1。120 mm网目优化网型的另一特点为通过缩小上缘网网目尺寸，用上缘网替代上缘纲和浮子纲2根纲索，既保持了渔具主要结构和性能不变，又节约了渔具材料。设计方法为：上缘网的网目尺寸=主网衣网目尺寸×主网衣横向缩结系数。

英文摘要:

      In this study, 10 typical types of Scomberomorus niphonius gillnets used in the Bohai Sea and the Yellow Sea area were identified and investigated. Based on the analysis of the main parameters of the 10 net types mentioned above, we selected nets with 4 different mesh sizes (110 mm, 115 mm, 120 mm, and 125 mm) to perform a comparative experiment on the fishing boat “Luchangyu-64068” operated in the central and southern Yellow Sea from 10 April to 15 May in 2013. The highest number and weight of fish were caught with net of mesh size 120 mm, and the CPUE was 0.1696 ind/webbing/day and 373.78 g/webbing/day respectively. The fishing efficiency of 120 mm mesh size was also the highest among the 4 studied sizes. Further optimization of main parameters of big-mesh gillnets for S. niphonius were conducted on fishing vessels “Luchangyu-64068” and “Lulaizhouyu-66287” in the central and southern Yellow Sea, offshore of Yantai, Weihai and Laizhou Bay, from 12 April to 27 May in 2015. Using the net of 120 mm mesh size on “Luchangyu-64068”, we caught S. niphonius with the mean fork length of 764.18 mm and mean body weight of 3623.27 g. Among them the longest was 1000 mm; the shortest was 490 mm; the heaviest individual weighed 7500 g, and the lightest was 850 g. The CPUE was 0.1379 ind/webbing/day and 517.65 g/webbing/day. “Lulaizhouyu-66287” employed net of 122 mm mesh size, and the mean fork length and mean body weight of fish caught was 780.47 mm and 4065.17 g respectively. The longest was 910 mm; the shortest was 600 mm; the heaviest individual was 7400 g; the lightest was 2000 g. The CPUE was 0.0778 ind/webbing/day and 283.35 g/webbing/day. Because nets of 120 mm mesh size showed higher fishing efficiency than that of 122 mm, it should be more suitable for catching the spring cohort of S. niphonius. The main parameters of a net of 120 mm mesh size were as follows: 33.00 m×18.54 m in the principal dimension of fishing gear, 500 mesh×175 mesh, 120 mm in mesh size, PA monofilament (Φ=0.48 mm) as the netting material, T-direction hanging ratio 0.55, static buoyancy distribution 267.9 g/m, and buoyancy to sinker-weight ratio 1.768∶1. Due to the replacement of the upper hanging line and float line by decreasing the mesh size of cork line selvedge strip, less net material was need to maintain the major structure and performance of the net. The proper mesh size of cork line selvedge strip should be equal to mesh size of main netting multiplied by T-direction hanging ratio of main netting.