The number of Arctic grayling Thymallus arcticus over 239 mm in FL was estimated at 578 fish (SE = 87) in a 12 km index section of the lower Pilgrim River. The density was 48 Arctic grayling/km. Arctic grayling captured from the Pilgrim River ranged from 165 to 475 mm in FL and from 2 to 13 years of age. The majority of Arctic grayling (53%) were in the "preferred" Relative Stock Density category in the lower Pilgrim River. Abundance was not estimated in the upper Pilgrim River during 1995 because an insufficient number of fish were recaptured. Arctic grayling in the Snake River showed greater increases in length during years of high pink salmon Oncorhynchus gorbuscha abundance than during years of low pink salmon abundance. Of 51 Arctic grayling captured and released in the Eldorado River, 41 were injected with OTC for later recapture in order to validate aging techniques; 10 already had been injected during 1994.