东海细点圆趾蟹数量分布的研究

Study on distribution of Ovalipes punctatus (crab) in the East China Sea

本文依据1998年5月(春)、8月(夏)、11月(秋)和1999年2月(冬)在东海26°00’-33°00’N,127°00’E以西海域的蟹类资源调查资料,分析了东海细点圆趾蟹(Ovalipes punctatus)数量分布特征。结果表明:春、夏、秋和冬季调查海域细点圆趾蟹平均资源密度重量和个体数分别为65.00 kg·km-2、2076 ind·km-2,43.71 kg·km-2、395 ind·km-2,26.27 kg·km-2、643 ind·km-2和0.36 kg·km-2、7 ind·km-2。冬春季,东海北部近海细点圆趾蟹重量占蟹类总重量的一半以上,出现率和优势度远远高于其它水域,以产卵群体为主,是目前细点圆趾蟹最大的生产渔场。东海南部近海80-120m水深和北部外海80 m以深海域,各有一个细点圆趾蟹的高数量分布区。细点圆趾蟹的生产旺汛在春季的3-6月。夏季由于该种渔获个体规格和经济价值较高,加上有一定的资源密度,也是较好的捕捞季节。该种虽然能够适应广泛的温度和盐度,但具有明显的温水种特征,在东海北部近海又具有较低盐度的分布趋向性。

Based on the data of four seasonal oceanographic censuses in the East China Sea (26°00' - 33°N, 120°00' - 127°E)in 1998 - 1999, this paper discussed the variation of a swimming crab Ovalipes punctatus resources in the East China Sea with mathematical analysis. Results showed that there was clearly seasonal change of resources density of the crab that was the highest in spring(2 076 ind·km-2and 65.00 kg·km-2) ,then summer(395ind·km-2 and 43.71 kg·km-2), winter (643ind·km-2 and 26.27 kg·km-2) and the lowest in autunm(7ind·km-2and 0.36 kg·km-2). The yield of O. punctatus, whose dominance and occurrence frequency were higher than other waters of the East China Sea, was equal to 50% of total crab in weight at northern offshore water area where the resources of 0. punctatus are mainly distributed in spring and winter. The central fishing ground, which was the greatest ground in the East China Sea, lay in water area of 31°30'-33°00'N, 122°30' - 124°00'E where the crowd of the crab is mainly composed in spawn group in spring. Besides this, other two high abundant fishing ground of the crab lay in 26°00' - 26°30'N, 122°00' - 123°00'E and 30°00' - 31°00'N, 124°30' - 126°30'E. They are both potential fishing ground of the crab in East China Sea because their resources were not exploited fully by now. The fishing season of the crab was from March to June in spring. Because draw net and crab cage were used widely in crab fishing, proper net mesh should be adopted to protect supplement group of the crab in the fishing. Summer was also a good fishing season like spring because the crab resources had greatest individual size, highest ecomonical value and amount of the crab resources in this fishing season. Though it can adapt to wide temperature and salinity as an eurythermic and euryhaline species the crab showed a character of temperature-water species and tended to distribute in low salinity waters. Ovalipes punctatus was a most imporant species in crab community in the East China Sea because the change of amount would affect total resources of crab remarkably in this water area.