A detailed assessment of the Arctic grayling Thymallus arcticus population was conducted at Piledriver Slough, near Fairbanks, Alaska during 1992. A mark-recapture experiment was conducted, from which abundance, age and size composition of the Arctic grayling population were estimated. The timing of the investigation corresponded with spring break-up and the onset of a popular spring fishery, similar to past investigations. Fish were captured using pulsed direct current backpack electrofishing gear. An estimated 14,030 (SE = 1,860) Arctic grayling greater than 149 millimeter fork length were present during the May spawning period. The stock was characterized by a high proportion of sub-legal sized Arctic grayling (less than 260 millimeter fork length) and ages 4 and 5 predominated. Preliminary estimates of survival and exploitation indicated the stock of Arctic grayling may have a low survival rate and higher than expected exploitation rates. The results of a concurrent mark-recapture experiment on stocked rainbow trout Oncorhynchus mykiss indicated an overwinter survival of 0.25 percent for the 1991 stocking cohort.