花斑裸鲤年龄鉴定材料的比较与年龄判别

Comparison of aging methods and discrimination analysis on age classification for Gymnocypris eckloni

鱼类年龄的准确鉴定是研究鱼类生态学和保护生物学的基础。本文对黄河上游花斑裸鲤（Gymnocypris eckloni）耳石、背鳍条和臀鳞等3种年龄材料的年龄解释一致性以及最佳年龄材料的选择进行了比较和分析,并首次建立了花斑裸鲤低龄个体年龄判别方程。结果表明：花斑裸鲤3种年龄材料上年轮可读性依次是耳石〉背鳍条〉臀鳞,最大鉴定年龄分别为25龄、17龄和16龄;对于6龄及以下个体,背鳍条作为年龄鉴定材料更有优势;对7龄及以上个体,耳石效果最佳;同时对6龄及以下个体以全长、体长、体重和空壳重为自变量,采用逐步选择法进行判别分析,最终提取全长和体重建立年龄的分类函数;全部样本正判率和交叉验证正判率显示,该年龄判别模型的正确区分度较高,可用于6龄及以下个体（全长93~259 mm;体重6.25~177.10 g）的年龄判别。

The ability of precisely determining the age of fish is essential for surveying fish eco- logical traits and fish conservation. In this study, we compared the readability and consistency of age readings, which obtained from three calcified structures （otolith, dorsal spine and anal scale） of Gymnocypris eckloni from the upper reaches of the Yellow River, China, and established a discrimination equation to age the low-age individuals. The readability ranked in a descending order of otoliths 〉 dorsal spines 〉 anal scales. The maximum ages assigned by the otolith, dorsal spine and anal scale were 25, 17 and 16, respectively. Results indicated that dorsal spine was optimal for the individuals aged 6 or less, while otolith was the most suitable structure for those aged 7 or greater. All the samples aged 6 or less were clustered by total length, weight, length and somatic weight. With stepwise discriminant analysis method, total length and weight with significant discrimination ability were selected to establish a discriminant function. The sta- tistical results showed that 88.90% of original grouped cases were correctly classified, and 88.40% of cross-validated grouped cases were correctly classified, indicating that G. eckloni aged 6 or less could be directly aged by discriminant analysis of total length and weight, with total length ranging from 93 to 259 mm and weight ranging from 6.25 to 177.10 g.