A Comparison of Different Age Estimation Methods for the Northern Snakehead

Abstract

We used otoliths, scales, pectoral fins, dorsal fins, basioccipital bones, opercular bones, interopercular bones, vertebrae, teeth, and cleithra sampled from 221 known-age Northern Snakeheads Channa argus argus representing five age-groups to determine and compare age estimation methods for this species. Results showed that accuracy of age estimation methods varied among structures: 85.68% of otoliths, 68.91% of scales, 49.25% of pectoral fin rays, and 27.67% of opercular bones yielded age estimates that were consistent with the actual fish ages. Ages determined from other structures, such as interopercular bones, dorsal fins, basioccipital bones, and vertebrae, had lower rates of agreement (<20%) with actual ages. The current results suggest that age estimation with otoliths, especially sagittal otoliths, is the most accurate method for use with Northern Snakeheads. Furthermore, analysis of scales can be used as a supplementary approach, especially for younger (age < 3) Northern Snakeheads.

Received March 14, 2013; accepted June 27, 2013

ACKNOWLEDGMENTS

The current study was financially supported by grants from the State Key Laboratory of Freshwater Ecology and Technology (2010FB19), the Hunan Department of Education (09A032), and the Research Program of Hunan Province, China (2009NK3095). We appreciate the two journal reviewers who helped us to improve the manuscript.