Research on biological characteristics, catches, catch per-unit of effort (CPUE) , efforts and MSY of Coilia mystus in the Yangtze River Estuary was carried out based on the data during 1998 -2006. The reasons of the fish catch reduction and management advice were analyzed. The results showed that the average total length decline from 130 mm in 1998 to 50 mm in 2006, which means the size of the fish became more and more smaller; the average total length and body weight of the fish in the catch were ( 150 ±21. 1 )mm and ( 13. 6+5. 16) g, respectively. Correlation ship between total length and body weight can be expressed as W = 0. 017 8×L2.4227. In the above period, annual average catch was 728 tons. Maximum sustainable yield (MSY) was calculated as 651.0 tons with the model of Fox, and the corresponding fishing effort (fMSY) appear at 625.0 boats. Compared with the historical data, stock of Coilia mystus dropped sharply.%对1998 ～ 2006年长江口凤鲚生物学、渔获量、单位捕捞努力量渔获量、捕捞努力量以及最大持续产量数据进行了研究,分析了长江口凤鲚产量下降的原因,并提出了相应的管理意见.结果表明,凤鲚平均全长呈下降趋势,从1998年的130 mm,降低到2006年的50mm,凤鲚种群全长明显小型化；平均全长为(150±21.1)mm,平均体重为(13.6±5.16)g,全长和体重呈幂函数相关,拟合方程为W=0.017 8×L2422 7.同期凤鲚年均捕捞量为728 t,应用Fox模式估算最大持续产量(MSY)为651.0 t,相应捕捞努力量(fMSY)为625.0艘.与历史资料相比,凤鲚资源量急剧下降.
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