西北太平洋北方拟黵乌贼耳石外部形态特性分析

根据2018年9—11月我国鱿钓船在西北太平洋采集的339尾北方拟黵乌贼样本,对其耳石外形生长特征进行了研究。结果发现,北方拟黵乌贼具有长窄的吻区和宽大的翼区。主成分分析表明,耳石总长(TSL)、吻侧区长(RLL)、侧区长(LDL)、翼区长(WL)和最大宽度(MW)可以作为北方拟黵乌贼耳石外形变化的特征因子。协方差分析表明,MW、LDL和WL与胴长的关系存在性别间显著性差异,TSL和RLL则不存在显著性差异;MW、RLL、TSL、LDL和WL与体质量的关系均存在性别间显著性差异。AIC (Akaike’s information criterion)分析表明,TSL、RLL与胴长的生长关系最适合用线性函数表示,雄性个体的MW、LDL和雌雄个体的WL与胴长的关系最适合用幂函数表示,而雌性个体的LDL则最适合用指数函数表示。雄性个体的LDL和MW与体质量的关系最适合用指数函数表示,雌性个体的LDL、MW和TSL最适合用线性函数表示,而其余特征参数则均最适合用幂函数表示。随着胴长增加,耳石绝对尺寸都逐渐增大,但耳石的形态结构比例基本不变:背区、侧区、吻侧区、翼区的长度与耳石总长之比基本保持一致,分别为35.66%、55.84%、75.23%和85.82%左右。

Statolith morphology of Gonatopsis borealis in the northwest Pacific Ocean

The morphology and microstructure of statolith of Gonatopsis borealis were studied for the 339 samples, which were collected by Chinese jigging fleets in the northwest Pacific Ocean from September to November 2018. The study indicated that the statolith has the structure with a wide wing and long, narrow rostrum domes. The principal component analysis showed that the total statolith length (TSL), rostrum lateral dome length (RLL), lateral dome length (LDL), wing length(WL) and maximum width (MW) could be used as the morphological characteristic parameters to study the morphological changes of statolith. The analysis of covariance (ANCOVA) showed that there were significant differences in the relationships between MW, LDL and WL versus mantle length (ML) between males and females, but no significant difference was found in other characteristic parameters. The relationships between all of the statolith characteristic parameters and body weight (BW) differed significantly. The relationships between TSL, RLL and ML were optimally described by the linear growth models, and power functions were optimal for WL, MW of males and LDL of males, however, exponential function was optimal for LDL of females. The exponential functions were optimal for the relationship between the LDL, MW of males, and linear functions were optimal for LDL, MW, TSL of females, and power function for the other parameters. With the squid growth, the size of statolith gradually increased, but the ratios of DLL, LDL, RLL, WL to TSL almost remain at the same level, corresponding to 35.66%, 55.84%, 75.23% and 85.82%, respectively.