Age, growth, and gonadal condition of the Giant mottled eel, Anguilla marmorata, were estimated from 303 specimens collected at Okinawa-jima Island, Japan. Otolith opaque zones that formed every year correlated with high water temperature and were thought to be annual rings. The growth of this species differed between males and females, and females were longer lived and larger than males. The mean gonadosomatic index (GSI) and the appearance of silver eels showed no clear seasonality. Comparing life history characteristics of this species between natural (northern specimens) and urban rivers (southern specimens), the growth of southern specimens was faster than that of the northern specimens, leading to the development of gonads and their downstream migration at younger ages. Therefore, we conclude that the life history characteristics of A. marmorata strongly influence by the river environments.

中文翻译：

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日本冲绳岛的巨型斑鳗 Anguilla marmorata 的年龄、生长和性腺状况

从日本冲绳岛收集的 303 份标本中估计了巨型斑鳗 Anguilla marmorata 的年龄、生长和性腺状况。每年形成的耳石不透明带与高水温相关，被认为是年轮。该物种的生长在雄性和雌性之间存在差异，雌性比雄性寿命更长，体型更大。平均性腺体指数（GSI）和银鳗的出现没有明显的季节性。比较该物种在自然（北方标本）和城市河流（南方标本）之间的生活史特征，南方标本的生长速度快于北方标本，导致性腺发育和向下游迁移的年龄较小。因此，我们得出结论，A.的生活史特征。