A silvering index for the Japanese eel Anguilla japonica
A silvering index for the Japanese eel Anguilla japonica
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DOI：
10.1007/s10641-006-9121-5
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发表时间：
2007-09-01
影响因子：
1.4
通讯作者：
Tsukamoto, Katsumi
中科院分区：
文献类型：
--
作者：
Okamura, Akihiro;Yamada, Yoshiaki;Tsukamoto, Katsumi
为了建立一个简单可靠的日本鳗鲡（Anguillajaponica）银化阶段的判定指标，对日本沿海地区（三川湾）采集的日本鳗鲡的身体各部位颜色和生物学特性进行了观察。四个镀银阶段的特征是胸鳍和腹面皮肤的颜色如下：（1）Y1，胸鳍基部无金属色的黄鳗，（2）Y2，胸鳍基部有金属色但胸鳍尖端无黑化的晚黄鳗，（3）S1，银鳗，胸鳍尖端完全黑化，但腹部没有黑色或深褐色的完整色素;（4）S2，晚期银鳗，腹部黑色或深褐色。各发育阶段的体尺、卵径和性成熟度均按Y1、Y2、S1、S2的顺序递增，消化道则按Y1、Y2、S1、S2的顺序退化，表明各发育阶段的发育顺序是一致的。Y1，Y2和S1阶段也可以区分典型判别函数分析使用三个内部（性腺-躯体指数，GSI;肝-躯体指数，HIS;和肠道指数）和两个形态计量学（条件因素和眼睛指数）参数，支持这些阶段的意义。这种日本鳗鱼镀银过程的分期方法似乎适用于该物种的所有标本，因为该指数仅使用简单的外部特征，在实地调查中很容易观察到。(c)Springer Science+Business Media B.V. 2006
To establish a simple and reliable index for determining silvering stages of the Japanese eel, Anguilla japonica, we observed the colorations of various body parts and biological characteristics of the eels collected in a coastal area of Japan (Mikawa Bay). The four silvering stages are characterized by the colorations of pectoral fins and ventral skin as follows: (1) Y1, yellow eel without a metallic hue at the base of pectoral fins, (2) Y2, late yellow eel with a metallic hue at the base of the pectoral fins but without melanization at the tip of pectoral fins, (3) S1, silver eel with complete melanization at the tip of pectoral fins but without full pigmented belly in black or dark brown, and (4) S2, late silver eel with black or dark brown belly. The body size, eve diameter and sexual maturity of each stage increased in the order of Y1, Y2, S1 and S2 stages, whereas the digestive tract degenerated in the same order, suggesting a sequential development of these ontogenetic stages identified in the study. The Y1, Y2 and S1 stages could be also distinguished by canonical discriminant function analysis using three internal (gonad-somatic index, GSI; hepato-somatic index, HIS; and gut index) and two morphometric (condition factor and eye index) parameters, supporting the significance of these stages. This method of staging for the silvering process of the Japanese eel appeared to be applicable to all specimens of this species, since this index used only simple external characteristics that would be easy to observe during field surveys. (c) Springer Science+Business Media B.V. 2006