南设得兰群岛次南极电灯鱼(Electrona carlsbergi)鉴龄校验研究

次南极电灯鱼Electrona carlsbergi为栖息于次南极及南大洋水域并具重要生态作用的中上层鱼类,但目前鲜有关于该鱼种年龄的报道。为了鉴定次南极电灯鱼Electrona carlsbergi的年龄,并确定该鱼种最优鉴龄方法,本研究利用2010年1月27日于南设得兰群岛北部水域采集的59尾次南极电灯鱼,共计73个矢耳石样本,对矢耳石年轮进行了计数,鉴定其年龄,并分别对耳石矢平面、横切面及纵切面进行年轮读取。结果表明,矢平面及纵切面年轮在直射光下不易辨识,副轮及假轮较多,影响年轮鉴定,而横切面年轮较为清晰,因此将直射光下横切面年轮的暗带作为年龄鉴定的依据。年龄鉴定结果显示,3、4龄为优势年龄,占总体的67.80%,其余所占比例较小。利用总吻合率(total concordance,TC)、变异系数(coefficient of variation,CV)及平均百分比误差(average percentage error,APE)三个数据量化两名读者三次年龄判读结果的精确性,TC平均值为50.23%,CV平均值为3.67%,APE平均值为8.60%。对各年龄组利用TC、CV及APE量化其精确性,其结果显示CV与TC呈现出相反的变化趋势,APE则呈先上升而后下降的趋势。利用von Bertalanffy生长模型拟合生长方程,其结果为Lt=7.7154(1–e~(–0.5373(t+2.7807)))。

Validation of ageing Electrona carlsbergi in the South Shetland Islands

Electrona carlsbergi is a species of pelagic fish that inhabits the Southern Ocean and hasimportant ecological function. However, to date there have been only a few reports regarding the age of such fish. To determine the age of E. carlsbergi and confirm the method of age determination, the diazone numbers obtained under direct light of 73 sagittal otolith samples from 59 fish samples collected from the South Shetland Islands on January, 2010 are used as evidence of age identification. Because of the accessory and false rings of the sagittal plane, a longitudinal section is more suitable than a transverse one for determining the age of E.carlsbergi.Of the fish whose ages are identified, 67.80% are three or four years old. The Total Concordance (TC), Coefficient of Variation (CV) and Average Percentage Error (APE) are calculated to quantify the accuracy of the age determination. The average of each index is 50.23%, 3.67% and 8.60%, respectively. These three indexes are also used to test the accuracy of different age groups. The results show a negative relationship between CV and TC, whereas APE increases firstly and then decreases. The von Bertalanffy growth function for E.carlsbergi isL_t=7.7154(1-e^{–0.5373(t+2.7807)}).