闽东北外海光掌蟳数量分布及其生物学特点

根据2008年5月、8月、11月和2009年2月在闽东北外海海域(26°00′~28°00′N、120°00′~125°30′E)开展的蟹类资源调查资料,结合1998~1999年各季度月调查资料,研究分析该海区光掌蟳数量分布变化及其渔业生物学特点。结果表明:光掌蟳在本调查海区分布范围较广,出现频率为39.7%,其渔获量占蟹类总渔获量的19.6%,渔获量平均密度指数为5.91 kg/km2,低于1998~1999年调查的渔获量平均密度指数。春、夏季分布范围相对广泛,其渔获量占年总渔获量的80%,秋、冬季数量很少。两次调查时空分布略有不同,1998~1999年渔获量、出现频率、平均资源密度指数最高值均出现在夏季,2008~2009年则出现于春季;主要分布密集区域为26°30′~27°45′N、123°00′~125°00′E的水深95~110 m海域,在80 m以内海域没有分布;渔获群体甲宽组成27~106 mm,优势甲宽50~70 mm,占48.8%,雌雄性个体有明显的差异,各季雄性个体均大于雌性;雌性性腺成熟度以Ⅱ期和V期为主,分别占42.7%和29.1%,春、夏、秋季均出现V期亲体,尤以夏季比例最高;摄食等级以1级为主,占36.2%,平均摄食等级为1.31。近十年来群体组成变化不大,但要加强对光掌蟳资源的合理利用和保护。

The quantitative distribution and biological characteristics of Charybdis riversandersoni in Northeast Fujian Outer-sea

Based on the data from investigations of crab resources in Northeast Fujian Outer-sea(26°00′-28°00′N,120°00′-125°30′E)in May,August,November of 2008 and February of 2009,and combining with the data from quarterly investigations in 1998 and 1999,the quantitative distribution and biological characteristics of Charybdis riversandersoni in this area were studied.Results showed that the occurrence frequency of Charybdis riversandersoni was 39.7% with a wide distribution,and the catch ratio in total crab catch is 19.6%,and the average catch density was 5.91 kg/km2,which was lower than those of 1998 and 1999.Charybdis riversandersoni had a relatively wide distribution in spring and summer,the catch proportion of these two seasons accounting for 80% in the total catch.The two investigations indicated that the spatial-temporal distribution had certain difference.The maximum of catch,occurrence frequency and mean resource density index of Charybdis riversandersoni all occur in Summer in 1998 and 1999,but they occur in Spring in 2008 and 2009,the catch occupying 56.9% in the total catch.The area where Charybdis riversandersoni was mainly distributed was 26°30′-27°45′N,123°00′-125°00′E,with 95-110 m depth of water,showing no distribution in the sea area within 80 m.The carapace width composition of Charybdis riversandersoni population was from 27-106 mm,with the dominant carapace width from 50-70 mm,accounting for 48.8%;The male was obviously larger than the female.The female were sexually mature mainly at stage Ⅱ and V,accounting for 42.7% and 29.1%,and individuals at stage V appeared in Spring,Summer and Autumn,but mainly in Summer.The feeding intensity was dominated by stage 1,accounting for 36.2%,and the average was 1.31.The change of population composition was not obvious,but measures for reasonable utilization and protection of Charybdis riversandersoni must be taken and improved.