A COMPARISON OF WHOLE AND THIN-SECTIONED OTOLITH AGING TECHNIQUES ANDVALIDATION OF ANNULI FOR ARCTIC GRAYLING

Information on age and growth is essential for the conservation and ma nagement of fish species, Age is often estimated using the banding str ucture 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 a rcticus) otoliths from the Kuparuk River, Alaska, gave similar age est imates. Age estimates from whole otoliths were less variable, particul arly for older age groups, and were much easier to prepare and read th an thin-sections. Comparison of growth of individual tagged fish to a von Bertalanffy growth model revealed that the translucent rings are t rue annuli. This approach to validation may be most useful in northern latitudes where other techniques are impractical. Our study shows tha t whole otoliths provide a fast, reliable, cost-effective technique fo r age estimation of this long-lived, slow-growing fish species common to the North American Arctic.