中国沿海蓝点马鲛繁殖群体的耳石形态差异

Morphological comparison in the sagittal otolith of spawning population of Scomberomorus niphonius in coastal waters of China

为阐明中国沿海蓝点马鲛(Scomberomorus niphonius)繁殖群体耳石形态的特异性,科学判定中国沿海蓝点马鲛繁殖群体的种群归属,根据2016-2018年4-6月在莱州湾、海州湾、吕四渔场、象山港、沙埕港等蓝点马鲛产卵场采集的242尾2龄蓝点马鲛成熟个体样本,结合计算出的环率、圆度、椭圆率、矩形趋近率、纵横比、形态因子、半径比和面密度等8个耳石形状指标,运用相似性分析、非参数多维标度分析、相似性百分比分析探讨了耳石形态的群体间差异。结果显示,海州湾和吕四渔场蓝点马鲛繁殖群体的耳石形态不存在显著性差异(P>0.05);象山港和沙埕港蓝点马鲛繁殖群体的耳石形态不存在显著性差异(P>0.05);渤海、黄海和东海3个海区之间繁殖群体的耳石形态差异均达到了极显著水平(P<0.01);半径比、纵横比、面密度和矩形趋近率是对各个繁殖群体组内相似性贡献度较高的耳石形态典型指标;面密度、形态因子和半径比则是对各繁殖群体组间相异性贡献度较高的耳石形态分歧指标。通过逐步判别分析建立了5个蓝点马鲛繁殖群体的判别公式,判别准确率在55.26%~92.59%,综合判别正确率为71.07%。研究结果表明,中国沿海蓝点马鲛繁殖群体之间的耳石形态存在显著差异,渤海、黄海和东海蓝点马鲛繁殖群体的耳石形态呈现出不同的群体特征,存在较高的区分度。

To elucidate the sagittal otolith morphological characteristics of spawning populations of Scomberomorus niphonius in coastal waters of China and divide the stocks scientifically,a total of 2422-year-old samples collected from the Laizhou Bay,Haizhou Bay,Lvsi fishing grounds,Xiangshan Bay,Shacheng Bay from April to June during 2016-2018 were analyzed.Shape indices including circularity,roundness,ellipticity,rectangularity,form-factor,aspect ratio,radius ratio and surface density were used as morphological variables and were statistically analyzed by ANOSIM,NMDS and SIMPER to examine their differences among several spawning populations.The results indicated that there was no significant difference in otolith morphology between the populatinos from Haizhou Bay and Lvsi grounds(P>0.05).Also,the same situation happened between the populatinos from Xiangshan Bay and Shacheng Bay.But the otolith morphology differed significantly between any two populatinos from different sea areas(P<0.01).The radius ratio,aspect ratio,surface density and rectangularity were typical shape indices with high contribution rate to within-populations similarity;and surface density,form-factor and radius ratio were discriminational shape indices with high contribution rate to the every two populatinos dissimilarity.The discriminant function of five spawning groups was established by stepwise discriminant function analysis,which showed the discriminant accuracy ranged from 55.26%to 92.59%,and the general discrimination rate was 71.07%.The results indicated that there was a significant difference in otolith morphology among spawning populations in coastal waters of China.The method based on sagittal otolith morphology was effective in discriminating Scomberomorus niphonius from different sea areas.The morphology of otolith of spawning populations of Scomberomorus niphonius in the Bohai Sea,Yellow Sea and East China Sea showed different stock characteristics and high degree of differentiation.