我国近海不同地理群体龙头鱼耳石形态分析

Morphological analysis of otolith among different Bombay duck(Harpodon nehereus)populations in China offshore

为比较龙头鱼不同地理群体间耳石形态差异,对其矢耳石几何中心到基叶的距离(A_(1))、几何中心到腹侧的距离(A_(2))、几何中心到背侧的距离(A_(3))、几何中心到主间沟的距离(A_(4))和几何中心到次间沟的距离(A_(5))共5个测量指标进行配对t检验。结果表明,龙头鱼左、右矢耳石的5个测量指标的显著性水平P>0.05,即不存在显著性差异。A_(1)~A_(5)、矢耳石长轴长(L)和短轴长(H)共7个测量指标均值的第1主成分累积贡献率为93.114%,椭圆率(X_(1))和辐形比(X_(2))2个形态指标均值的第1主成分累积贡献率为99.950%。单因素方差分析结果表明,椭圆率可作为区别舟山群体与其他几个群体的主要特征。聚类分析结果显示,东海南部和南海群体聚为一支,随后与三门和舟山群体聚类;海口群体位于聚类树的最外层,与其他群体关系较远。7个群体的平均综合判别正确率为80.63%,其中,舟山群体判别正确率最高(89.29%),宁德群体最低(71.43%)。上述结果说明,耳石形态指标的多元统计分析可作为龙头鱼群体鉴别的依据之一。

In order to compare the morphological differences of otoliths among different Harpodon nehereus populations,five measurement indexes of sagittal otoliths including distance from geometric center to rostrum(A_(1)),distance from geometric center to veutro(A_(2)),distance from geometric center to dorsal(A_(3)),distance from geometric center to excisural notch(A_(4))and distance from geometric center to excisural minor notch(A_(5))were examined by paired t-test.The results showed that the P values were greater than 0.05,indicating no significant differences between left and right otoliths.The cumulative contribution rates of the first principal component(PC1)in seven measurement indexes,including A_(1)-A_(5),major axis length(L)and minor axis length(H),and the ellipticity(X_(1))and radial ratio(X_(2))were 93.114%and 99.950%,respectively.The results of one-way analysis of variance showed that the ellipticity could be used as the main feature to distinguish Zhoushan population from the others.The hierarchical clustering tree demonstrated that the specimens from the southern East China Sea and the South China Sea first gathered together into one branch,and then followed by Sanmen and Zhoushan populations.Haikou population was located at the outermost of the clustering tree and separated apart from other populations.The average discriminant accuracy rate was 80.63%,of which Zhoushan population was the highest(89.29%),while Ningde population was the lowest(71.43%).The above results suggest that the multivariate statistical analysis of morphological characteristics of otolith could be used as the basis for population identification of H.nehereus.