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根据在长江口东旺沙、横沙、铜沙、南汇和奉贤等水域(121°45’-121°58’E、30°48’-31°36’N)的专项调查数据,对1997-2008年长江口鳗苗监测期渔获规格和捕捞量进行了研究,并对最大持续产量进行了估算。长江口鳗苗主汛期为2月至3月,捕捞量占各年总捕捞量的比例为64.53%～94.10%,平均为79.32%。各年苗汛高峰最早出现于2月3日,最晚出现于3月15日,捕捞量分布形态主要有单峰型和双峰型,其中1999年、2000年、2004年和2006年为双峰型,两峰间隔平均为36d。鳗苗平均全长和体重分别为(54.9±3.4)mm和(92±18)mg,全长和体重呈幂函数相关。1-4月平均全长和体重均呈上升趋势,其中全长的月均增幅为3.10%,体重则为9.74%。1997-2008年长江口鳗苗监测期有证捕捞船数量为954～4713艘,平均为2190艘,同期总捕捞量为0.830～8.897t,平均为3.784t。应用Schaefer模式估算长江口鳗苗最大持续捕捞量为4.828t,相应捕捞努力量为2041艘。1-4月鳗苗成活率逐月上升,单船捕捞量为2月>3月>1月>4月;铜沙水域鳗苗成活率最高,单船捕捞量则为南汇水域最高。结果表明鳗苗捕捞量自2003年起大幅回升,但年间波动剧烈,且近期已呈下降趋势。为实现鳗苗资源可持续利用,建议采取措施严厉打击无证作业,动态安排捕捞证发放数量,合理控制鳗苗出口比例以及将捕捞期调整为2月-3月。
According to the special survey data of Dongwangsha, Hengsha, Tongsha, Nanhui and Fengxian in the Changjiang Estuary (121 ° 45’-121 ° 58’E, 30 ° 48’-31 ° 36’N) The catch specifications and catch of the Yangtze River Eel during the monitoring period in 2008 were studied and the maximum continuous production was estimated. The main flood season for the eel fry in the Yangtze River estuary was from February to March. Catches accounted for 64.53% ~ 94.10% of the total catch in each year, with an average of 79.32%. The peak of the flood season in each year first appeared on February 3 and the latest occurred on March 15, and the distribution pattern of the catch was mainly unimodal and bimodal, of which the year of 1999, 2000, 2004 and 2006 were double Peak, the average interval of two peaks 36d. The average length and weight of the eel (54.9 ± 3.4) mm and (92 ± 18) mg, respectively, were linearly correlated with the body weight. From January to April, the average full-length and body weight showed an upward trend, with an average monthly increase of 3.10% for full-length and 9.74% for body weight. During the period of 1997-2008, there were 954 ~ 4713 licensed fishing vessels during the monitoring period of the Yangtze River Eel, with an average of 2, 190 vessels. The total catch during the same period was 0.830 ~ 8.897 tons with an average of 3.784 tons. According to the Schaefer model, the maximum sustained catch of the eel fry in the Changjiang Estuary was 4.828t, and the corresponding fishing effort was 2041. From January to April, the survival rate of eel seedlings increased month by month. The single-vessel fishing volume was February> March> January> April. The survival rate of eel seedlings was the highest in the copper-littoral waters. The single-vessel fishing volume was the highest in the waters of Nanhui. The results show that eel seedlings catch soared sharply since 2003, but the volatility during the year, and has been declining recently. In order to achieve the sustainable utilization of eel resources, it is suggested that measures be taken to crack down on undocumented operations, the number of fishing licenses should be dynamically arranged, the proportion of eel export should be rationally controlled, and the fishing season should be adjusted from February to March.