茎柔鱼耳石和角质颚微结构及轮纹判读

为了研究耳石和角质颚微结构在茎柔鱼年龄鉴定中的应用,实验根据2013年7—10月中国鱿钓船在秘鲁外海(79°57’~83°24’W、10°54’~15°09’S)采集的茎柔鱼样本,提取出39尾茎柔鱼的耳石、上角质颚和下角质颚,对其微结构进行分析,并对微结构的生长纹进行计数及其差异性比较。结果显示,角质颚微结构头盖背侧区域的生长纹较为完整,通过观察头盖背侧边缘的生长纹可以消除喙部被腐蚀所产生的影响;下角质颚与上角质颚的微结构十分相似,均具有喙部纵向生长纹和喙部截面纵轴,然而,在形态和色素沉着等方面又有所不同。分析认为,耳石轮纹数与上颚轮纹数、耳石轮纹数与下颚轮纹数以及上颚轮纹数与下颚轮纹数均呈线性相关关系,并且直线的斜率与1差异性不显著(P>0.01),相关系数均接近1。研究表明,上、下角质颚微结构均能较好地估算茎柔鱼的日龄,角质颚可被用于头足类年龄与生长的研究。

Microstructure of statolith and beak for Dosidicus gigas and its determination of growth increments

In order to research the application of microstructures of statolith and beak to age validation of jumbo flying squid, the samples of the jumbo flying squid were collected by the Chinese squid jigger fleet during July to October in 2013.The statolith, upper beak and lower beak were extracted from 39 samples.Their microstructures were analysed and the growth increments were counted.Meanwhile, the differences between the numbers of statolith, upper beak and lower beak increments were analysed by variance analysis.Results showed that the increments in the dorsal region of the beak's hood were more complete.And to avoid the tip erosion effects, the first increments could be counted in the dorsal area of the rostral sections.This study found that the microstructures of the upper and lower beaks were very similar, and both of them contained longitudinal increments and internal rostral axis.However, in terms of the morphology and the pigmentation process, there are differences between the microstructures of upper and lower beaks.Results indicated that the growth increments of the upper and lower beaks obtained were lineally related with that of the statolith.Values of r² and slope close to 1 were obtained(P < 0.01).Results indicated that both of the microstructures of the upper and lower beaks can better estimate the age of the jumbo flying squid.And the beak should be widely used in the research of age and growth of cephalopod.