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日本鳗鲡(Anguilla japonica)广泛分布于亚洲东部,具有重要的经济价值。但是对于降海洄游的日本鳗鲡年龄、生长特性等的研究有限,以至于不能有效管护。本研究于2012年10月在长江靖江段捕得121尾降海洄游日本鳗鲡,并对其年龄和生长特性进行了分析,结果显示:(1)雌性个体要明显多于雄性,雌雄比例为78∶43;(2)雌雄鳗鲡年龄、生长等存在着显著的差异,雌鳗的平均年龄、体长、体质量以及平均生长速度[(5.50±1.18)龄、(654.9±67.6)mm、(522.1±176.2)g、(110.48±12.76)mm/a)]均显著大于雄鳗[(5.00±1.23)龄、(527.8±40.1)mm、(249.8±63.7)g、(96.46±16.75)mm/a)];(3)整个生活史中生长速度存在很大变化,随着年龄的增加,体长生长速度逐渐趋于0,而体质量生长速度存在拐点,雌鳗出现在4.80龄,雄鳗出现在2.63龄;(4)与其他水域相比,长江口降海洄游日本鳗鲡的年龄结构较小,而体长、体质量、渐进体长和渐进体质量则较大,这表明长江水域可能更适合日本鳗鲡的生长;(5)雌、雄个体生长的差异可能源于生长策略的差异。
Anguilla japonica widely distributed in the eastern part of Asia, has important economic value. However, studies on the age, growth characteristics and the like of Japanese eel anguilla are limited so that they can not be effectively managed and managed. In this study, 121 downward-migrating Japanese eel (Anguilla anguilla) were caught in the Jingjiang section of the Yangtze River in October 2012, and their age and growth characteristics were analyzed. The results showed that: (1) The number of female individuals was significantly higher than that of males, with a male / female ratio of 78 The average age, body length, body weight and average growth rate of female eel [(5.50 ± 1.18), (654.9 ± 67.6) mm, (522.1 ± 176.2) g and (110.48 ± 12.76) mm / a, respectively, were significantly higher than those in male eel [(5.00 ± 1.23), (527.8 ± 40.1) mm, (249.8 ± 63.7) g and (96.46 ± 16.75) mm / )]; (3) There was a great change in the growth rate throughout the life history. With the increase of age, the growth rate of body length tended to 0, but there was a turning point in the growth rate of body weight. At 2.63 years old; (4) Compared with other waters, the age structure of the Japanese eel anglerfish migrating down the Yangtze River estuary was smaller, while the body length, body weight, ascending body length and asymptomatic body mass were larger, indicating that the Yangtze River might be more Which is suitable for the growth of Japanese eel. (5) The difference of growth of female and male may result from the difference of growth strategy.