A comparison of whole and thin-sectioned otolith aging techniques and validation of annuli for Arctic grayling
Gettel, Gretchen M.
Deegan, Linda A.
Harvey, Chris J.
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Information on age and growth is essential for the conservation and management of fish species. Age is often estimated using the banding structure in otoliths, but the technique used can influence the estimate, especially in slow-growing, long-lived species. Counts of translucent bands from both whole and thin-sectioned Arctic grayling (Thymallus arcticus) otoliths from the Kuparuk River, Alaska, gave similar age estimates. Age estimates from whole otoliths were less variable, particularly for older age groups, and were much easier to prepare and read than thin-sections. Comparison of growth of individual tagged fish to a von Bertalanffy growth model revealed that the translucent rings are true annuli. This approach to validation may be most useful in northern latitudes where other techniques are impractical. Our study shows that whole otoliths provide a fast, reliable, cost-effective technique for age estimation of this long-lived, slow-growing fish species common to the North American Arctic