西白令海阿拉斯加狭鳕矢耳石形态特征研究

Morphometric features of sagittal otolith for Alaska pollock Gadus chalcogrammus in the western Bering Sea

为研究阿拉斯加狭鳕Gadus chalcogrammus耳石与鱼体生长的关系,对采自西白令海水域53尾阿拉斯加狭鳕样本的矢耳石外部形态进行了观察与测量。结果表明:阿拉斯加狭鳕矢耳石外形较大,呈近椭圆形,基叶和翼叶明显,主间沟不明显;体长为35~43 cm的个体耳石长和耳石宽分别为12.93~17.05 mm和5.70~7.78 mm;左、右矢耳石形态无显著性差异(P>0.05),随着个体体长的增加,耳石绝对尺寸增加,但相对尺寸减小,耳石的形态结构比例基本不变;通过对耳石外部形态9个指标主成分分析,可以用耳石面积、背长和耳石长来描述阿拉斯加狭鳕耳石的主要外部形态特征,耳石主要形态指标与体长、湿体质量的关系显示,耳石长、耳石宽、背长、基叶长、翼叶长、耳石面积和耳石周长与鱼体体长呈指数关系;而背宽与鱼体体长呈幂函数关系;耳石长、背宽、背长、基叶长、耳石面积和耳石周长与鱼体湿质量呈幂函数关系,耳石宽、翼叶长与鱼体湿质量呈指数关系。本研究结果可为阿拉斯加狭鳕年龄鉴定和种群鉴别提供基础数据。

The morphologic features of sagittal otolith were investigated in 53 Alaska pollock Gadus chalcogrammus samples collected from western Bering Sea to evaluate the relationship between otolith and growth of Alaska pollock.The Alaska pollock has large and nearly oval sagittal otolith,with obvious rostrum and antirostrum,without obvious excisura,and Alaska pollock with body length of 35-43 cm had otolith with length(OL)of 12.93-17.05 mm and width(OW)of 5.70-7.78 mm.There is no significant difference in otolith morphology between left and right otolith(P>0.05).The statolith was increased gradually in size with the increase in body length(L),but the ratio of each morphologic parameter to body length was decreased slowly,with almost constant proportion of morphological structure.The principal component analysis(PCA)of the nine indices describing the otolith morphology revealed that otolith acreage(A),dorsal length(DL)and otolith length(OL)was used as typical morphological characteristics of Alaska pollock otolith.The relationship between the main morphological indices of the otolith and body length and wet body weight(W)indicated that there was an exponential function between OL,OW,DL,rostrum length(RL),antirostrum length(ARL),and tolith area(S)and circumference(P)and wet body weight.There was a power function relationship between OL,and DW,and wet body weight.The findings provide basic data for age determination and population identification.