东海日本蟳的数量分布和生物学特性

The quantity distribution and biological property of Charybdis japonica in the East China Sea

根据1998-1999年东海区虾蟹类资源调查所获的日本资料,以渔获密度表示调查海域日本资源分布的数量指标,定量描述了日本在东海调查海域的数量分布。并根据同年逐月生物学测定资料进行了日本生物学特性的分析研究。结果表明:日本主要分布在31°00′N以北的大沙、长江口渔场,在31°30′N以南很少有分布,底质为沙或泥沙质。高密集区出现在20～30m水深海区,年间最高渔获密度达363.06kg/km2,常年可以进行生产作业,但以秋冬季数量最多,渔获优势甲宽组为45～75mm,雄蟹略大于雌蟹,雌雄蟹周年性比为1∶0.82,繁殖盛期为5-8月,最小抱卵个体甲长为35mm,甲宽为50mm,体重为25g。最后,提出了规定日本最小可捕规格甲宽为50mm,对于甲宽小于50mm者禁止销售,同时应考虑设立禁渔期等合理利用日本资源,加强人工育苗繁殖技术研究、开展增殖放流等有关建议。

Based on the data of Charybdis japonica obtained from the resource investigation of crustaceans in the East China Sea from 1998 to 1999, the quantity index was expressed by the catch rate, the quantity distribution of Charybdis japonica was described quantitatively in the survey sea area. According to the biological data of Charybdis japonica, measured every month of the same year, its biological property is analyzed. The results indicate that Charybdis japonica is distributed mainly in the Dasha, Changjiangkou fishing ground that is in the north of (31°00′N), few is distributed in the south of (31°30′N). The bottom sediment is sandiness or muddiness. The high biomass density occurs in the sea area at depth of 20-30 m, the largest catch rate of a year can reach 363.06 (kg/km^(2)).Fishing can be carried on the whole year, with the great output in autumn and winter. The predominant carapace width ranges from 45 mm to 75 mm. The male grows a little larger than the female, with the sex ratio (1∶(0.82)). The spawning period is mainlly from May to August and the weight of the least breeding individual is 25g, with the carapcae length 35 mm, carapace width 50 mm. In the end, this paper put forward some proposals, such as: make rational use of Charybdis japonica resource, strengthen the study on the technology of artificial rearing, and tighten up the regular management.