渤海湾火枪乌贼性别和发育阶段对其角质颚外部形态生长特性的影响

Morphology of beak and effect of gender and growth stage on beak for Loligo beka in the Bohai bay

为进一步掌握渤海湾火枪乌贼(Loligo beka)渔业生物学信息和生长特性,以2021年7—11月在渤海湾逐月开展渔业资源科学调查所获得的火枪乌贼为研究对象,通过建立多项式胴长与体质量关系估算形态学初次性成熟胴长,应用威尔科克森秩和检验分析性别和发育阶段对角质颚形态特征的影响,利用多元统计分析建立角质颚形态特征与胴长和体质量的生长模型。结果显示:渤海湾火枪乌贼雌性、雄性和不区分性别时的形态学初次性成熟胴长分别为(3.522±0.009)、(3.505±0.026)和(3.513±0.016)cm。上、下角质颚存在明显的形态差异,其中,头盖长/翼长的差异最大,喙长/侧壁长的差异最小。以决定系数和赤池信息准则值为判别标准,采用多元逐步回归法建立的角质颚形态特征与胴长线性关系及与体质量的对数线性模型优于利用单因子回归和主成分逐步加入法建立的生长模型。研究认为,3.513 cm可作为制定渤海湾火枪乌贼最小可捕捞胴长规格的参考,上角质颚头盖长/脊突长比值可作为群体及种类鉴别的依据,上角质颚脊突长/喙长和头盖长/侧壁长可分别作为性别和发育阶段判定的指标。基于多元逐步回归法建立的生长模型更适于进行渤海湾火枪乌贼胴长和体质量的预测。

In order to better understand the morphological growth characteristics of beak and fisheries biology,polynomial growth model was established for the relationship between mantle length and body mass for Loligo beka collected from fishery independent surveys by trawl net in the Bohai Bay from Jul.to Nov.2021,and the size at first maturity was estimated.Wilcoxon rank-sum test was employed to analyze the influence of maturity and gender on the morphologic growth of beak.In addition,multivariate statistical analysis based on the principal components were applied to establish the relationships between morphologic straits of beak and mantle length or weight for Loligo beka.The analyses showed that polynomial growth model was more suitable for fitting the relationship between mantle length and body mass,and the sizes at first maturity was estimated at(3.522±0.009)cm,(3.505±0.026)cm and(3.513±0.016)cm for female,male and total Loligo beka,respectively.There were obvious differences in the morphologic between upper beak and lower beak.Some ratios between beak length indices,such as hood length and crest length,were nearly consistent with the change of sex and sexual maturity,but others were different,such as the ratios between upper crest length and upper rostrum length and between upper hood length and upper lateral wall length,and there were significant differences in gender and sexual maturity,respectively.Taking the coefficient of determination and Akaike's information criterion(AIC)as the criterion of goodness-of-fit,the optimal relationships between morphologic indices of beak versus mantle length or weight were established by means of stepwise multiple linear regression.The information above mentioned suggested that the behavior of fishing Loligo beka with shorter than 3.513 cm in mantle length should been forbidden.The ratio of upper hood length and upper crest length could be used as stable beak index of the morphological characteristics of Loligo beka,the ratios between upper crest length and upper rostrum length and between upper hood length and upper lateral wall length could be used as the indexes of gender and sexual maturity,respectively.Besides,the relationships described by stepwise multiple linear function were more suitable for predicting the mantle length or weight on the basis of data of beak for Loligo beka.