我国南海区海洋捕捞现状分析

拖网是南海区海洋渔业生产最重要的渔具，拖网渔业在南海区海洋渔业生产中占主导地位。南海区拖网渔船数量从1986年的6 730艘增长至2003年的14 599艘，随后减少，2010年后基本维持在9 000艘左右；其总吨位在212 864~876 045 t波动，呈显著上升趋势；而总功率从1986年的440 438 kW上升至2005年的1 735 173 kW，之后呈下降趋势。1986—2020年单船平均吨位和功率均呈显著上升趋势。拖网渔船产量在59.24×10⁴~181.66×10⁴ t之间波动，占南海区总捕捞产量的38.35%~62.96%，呈逐年下降趋势；单位功率和单位吨位的产量分别在0.72~1.40 t和1.18~3.90 t之间波动，1999年最高，之后呈下降趋势。根据8种重要经济鱼类幼鱼占比统计结果，1992—2020年底拖网渔获物中幼鱼生物量占比均值为24.35%~84.28%，数量占比均值为40.09%~89.84%，其中白姑鱼 (Pennahia argentata)、带鱼 (Trichiurus japonicus) 和竹荚鱼 (Trachurus japonicus) 幼鱼比例最高。鉴于拖网渔业选择性不强，对幼鱼资源及海洋环境影响较大，建议逐步压减拖网渔船规模，严格执行网目尺寸和可捕规格制度，引导渔民使用资源节约型、环境友好型的作业方式，以利于近海渔业资源养护和可持续利用。

Long-term change of a fish-based index of biotic integrity for a semi-enclosed bay in the Beibu Gulf

Trawl is the most important fishing gear in the marine fishery production of the South China Sea, in which trawl fishery occupies a dominant position. The number of trawlers increased from 6 730 in 1986 to 14 599 in 2003, then dropped and had remained at about 9 000 since 2010, with the gross tonnage of trawlers ranging from 212 864 t to 876 045 t, showing a steady increasing trend. However, the total power of trawlers increased from 440 438 kW in 1986 to 1 735 173 kW in 2005, and then showed a decreasing trend. The average tonnage and power of single vessels showed a significant increasing trend from 1986 to 2020, and the yield of trawl fishery ranged from 59.24×10⁴ t to 181.66×10⁴ t, accounting for 38.35%–62.96% of the total fishing production in the South China Sea with a decreasing trend. The yield per kilowatt ship and per ton ship ranged from 0.72 to 1.40 t and from 1.18 to 3.90 t, respectively, both were highest in 1999 and then showed a decreasing trend. According to the statistical results of the proportion of juveniles of eight important economic fish species, the proportion of juvenile biomass and average proportion of quantity in the trawl catches from 1992 to 2020 was 24.35%–84.28% and 40.09%–89.84%, respectively. Pennahia argentata, Trichiurus japonicus and Trachurus japonicus had the highest proportions of the juveniles. In view of the low selectivity of trawl fishery, it has a great impact on juvenile fish resources and marine environment. We propose to gradually reduce the size of trawlers, strictly implement the system of mesh size and catching specification, and guide fishermen to use resource-saving and environmentally friendly methods of operation, so as to promote the conservation and sustainable use of offshore fishery resources.