Ling Jian-zhong, Li Sheng-fa, Yan Li-ping, Cheng Jia-hua
Key Laboratory of Marine and Estuarine Fisheries of Agriculture Ministry, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, China.
Ying Yong Sheng Tai Xue Bao. 2008 Jan;19(1):178-82.
In this paper, the population structure of Trichiurus japonicus in East China Sea was analyzed based on the data of its age composition and anus length in 2002-2004, and the rational utilization of T. japonicus resources in the Sea was approached by using the catch (in mass) per recruit theory of Beverton-Holt model. The results revealed that: (1) there was a miniaturization trend of the T. japonicus population in East China Sea. The range of age composition changed from 0-6 year in the late 1950's to 0-4 year in the early 21st century, and the population was dominated by the group of 0-1 year now. The percentage of 2-year old T. japonicus decreased from 12.84% in the late 1950s' to 6.91% in the early 21st century, and that of 3-year old T. japonicus decreased from 4.92% in the late 1950s' to 0.57% in the early 21st century; (2) the exploitation rate of T. japonicus in the period of 2000-2003 was 0.864, which was beyond of the optimum exploitation rate of 0.51, suggesting that the T. japonicus in East China Sea was under over-fishing; and (3) to enhance the age value at first capture (t(c)) was the best measure of increasing the catch (in mass) per recruit of T. japonicus. The age at recruitment (t(r)) and the t(c) of T. japonicus in East China Sea was 0. 25 and 0.5 at present, respectively. If the t(c) changed from 0.5 to 1, the unit catch would be increased by 55.38%, and if the t(c) changed to 1.5, 2 or 2.75, it would be increased by 100.81%, 130.52% or 145.23%, respectively. It was suggested that due to the difficulties in greatly reducing catching intensity, it could be available to properly increase the to value while decrease the catching intensity to protect the T. japonicus resources in East China Sea and realize their sustainable use.
本文基于2002 - 2004年日本鲐年龄组成和肛长数据，分析了东中国海日本鲐的种群结构，并运用Beverton - Holt模型的单位补充量渔获量（质量）理论探讨了东中国海日本鲐资源的合理利用。结果表明：（1）东中国海日本鲐种群存在小型化趋势。年龄组成范围从20世纪50年代末的0 - 6龄变为21世纪初的0 - 4龄，目前种群以0 - 1龄组为主。2龄日本鲐的比例从20世纪50年代末的12.84%降至21世纪初的6.91%，3龄日本鲐的比例从20世纪50年代末的4.92%降至21世纪初的0.57%；（2）2000 - 2003年日本鲐的开发率为0.864，超过了最佳开发率0.51，表明东中国海日本鲐处于过度捕捞状态；（3）提高首次捕捞年龄（t(c)）是增加日本鲐单位补充量渔获量（质量）的最佳措施。目前东中国海日本鲐的补充年龄（t(r)）和t(c)分别为0.25和0.5。若t(c)从0.5变为1，单位渔获量将增加55.38%，若t(c)变为1.5、2或2.75，单位渔获量将分别增加100.81%、130.52%或145.23%。建议由于大幅降低捕捞强度存在困难，在降低捕捞强度的同时适当提高t值以保护东中国海日本鲐资源并实现其可持续利用是可行的。
