北太平洋两个柔鱼群体角质颚形态及生长特征

根据2011年5—11月我国鱿钓船在北太平洋海域(150°E—176°W)采集的渔获物样本,对柔鱼两个群体各项角质颚外部形态和生长进行分析。结果表明,角质颚参数值雌性均大于雄性,冬春生群体雌雄参数值间差异要大于秋生群体;角质颚各项参数值中,上头盖长(Upper Hood length,UHL)、上脊突长(Upper Crest length,UCL)、下脊突长(Lower crest length,LCL)、下翼长(Lower Wing length,LWL)与胴长、体重分别呈线性和指数关系(P0.01)。主成分分析认为,秋生群体雌、雄个体角质颚第一主成分因子均为UCL/ML,第二主成分因子均为UWL/ML,冬春生群体雌、雄个体角质颚第一主成分因子分别ULWL/ML和LLWL/ML,第二主成分分别与URW/ML和LRL/ML,这些这成分因子代表了角质颚水平和垂直方向上的生长特征。两个群体的雌性个体角质颚形态上存在显著差异,但雄性个体间差异不显著。方差分析(ANOVA)表明,2个群体不同胴长组间的角质颚形态均存在着显著差异(P0.01);LSD法分析认为,除了秋生群体雌性个体上头盖长、上喙长、下头盖长、下喙宽在胴长组250 mm和250—300 mm间不存在差异外,其他组之间均有着显著差异(P0.01)。同一群体不同性腺成熟度等级间的柔鱼角质颚形态存在显著差异(P0.01),但性成熟度为Ⅰ期和Ⅱ期时2个群体角质颚各项形态指标均存在显著差异(P0.01),而性成熟度Ⅲ期时则不存在差异(P0.05)。研究认为,不同群体的柔鱼角质颚形态及生长特征均存在着一定差异。

Morphology and growth of beaks in two cohorts for neon flying squid (Ommastrephes bartramii) in the North Pacific Ocean

Neon flying squid Ommastrephes bartramii an economically and ecologically important cephalopod, is one of main targeted species in the Chinese jigging squid fishery. In this paper, based on the samples collected by the Chinese squid jigging vessels during May to November in 2011 in the high seas of North Pacific Ocean (150°E-176°W), we compared differences in morphology and growth characteristics of beaks for two cohorts of O. bartramii. The results showed that females dominated in both the fall cohort and the winter-spring cohort. The morphological values in females'' beak were larger than those of males, and the difference in these parameters between males and females in the winter-spring cohort was greater than that for the fall cohort. The upper hood length (UHL), upper crest length (UCL), lower crest length (LCL), lower wing length (LWL) had significant linear correlations with mantle length (ML) and significant exponential relationships with body weight (BW)(P < 0.01). The principal component analysis showed that the first principal component for the beak morphology of the fall cohort was related to UCL/ML of both males and females, and the second was UWL/ML. While for the winter-spring cohort, the first principal components of beak morphology were ULWL/ML and LLWL/ML, and the seconds were URW/ML and LRL/ML respectively, both represented the growth characteristics in horizontal and vertical directions. The morphology of beak for the two cohorts of female squid had significant differences, but no differences were found for male squid. The ANOVA indicated that the morphology of beak had significant differences among different ML groups(P < 0.01). However, the Least Significant Difference (LSD) analysis showed that the significant difference existed between the groups(P < 0.01)for all the morphological measurements except for UHL, URL, LHL and Lower Rostral width within the ranges of 250mm ML and 250-300mm ML for females of fall cohort. For the same corhot, the morphology of beak also had significant differences among different sex maturity stages(P < 0.01). The maturity stages I and II showed significant difference between the two cohorts, but no difference was found for stage III. In conclusion, the morphology and growth of beak for the two cohorts of O. bartramii differed with cohort, mantle length and sexual maturity.