The number of Arctic grayling Thymallus arcticus over 249 mm in FL was estimated at 678 fish (SE = 139) in a 42km section of the Nome River. Arctic grayling captured from the Nome River ranged from 112 to 485 mm in FL and in scale age from 1 to 10 years. Arctic grayling captured from the Eldorado River ranged in FL from 280 to 505 mm, and in scale age from 4 to 13 years. Of 93 Arctic grayling captured from the Eldorado River, six had been marked with OTC and were collected in order to validate aging techniques. Only 16 Arctic grayling were captured or observed in a 25 km section of the Solomon River.