大西洋中上层鲨鱼资源状况的初步探讨

据1994—2001年4个航次在金枪鱼延绳钓渔船对热带大洋性中上层鲨鱼资源进行调查，并分析国际大西洋金枪鱼资源保护委员会提供的关于中上层鲨鱼的渔业数据。结果表明：延绳钓渔业共兼捕13种鲨鱼，其中，尖吻鲭鲨和大青鲨是优势种类。尖吻鲭鲨在第1、第2和第4航次的CPUE分别为每千钩0．3502、0．1754和0．0642尾，呈下降趋势。大青鲨在第1～3航次的的CPUE达到每千钩5～7尾，而在第4航次下降为每千钩0．8尾。研究报告了中国金枪鱼船队自1993年开始在大西洋兼捕尖吻鲭鲨和大青鲨的渔获量，并根据捕捞死亡系数和大西洋总渔获量数据，初步探讨了尖吻鲭鲨和大青鲨年平均资源量，影响CPUE的因素和大西洋中上层资源状况。

Preliminary research on stock of pelagic sharks in the Atlantic Ocean

Based on the data from four trips surveyed, the paper made analysis on the stock of pelagic sharks in the tropical Atlantic Ocean. Fishery data on pelagic sharks are obtained from International Commission for Conservation on Atlantic Tunas(ICCAT). Results shows that there are 13 pelagic sharks occurring in the Atlantic longline catch and dominant species are short mako(Isurus oxyrinchus) and blue shark(Prionace glauca). The shortfin mako catch per unit of effort(CPUE) of the first, second and fourth trips tend to decline, with the values of 0.3502, 0.1754 and 0.0642 per thousand hooks respectively. The blue shark catch per unit of effort(CPUE) of preceding three trips fluctuated between 5-7 per thousand hooks. The blue shark CPUE(0.8 per thousand hooks) of the fourth trip declines dramatically. The paper reported the catches of shortfin mako and blue shark caught by China tuna fleet since 1993. The paper also estimates the yearly average biomass of two dominant sharks based on the fishing mortality and catch data, and discusses affecting factors for shark CPUE and stock status.