Population Dynamics and Potential Utility per Recruit of Arctic Grayling in Fielding Lake, Alaska

The population dynamics of Arctic grayling Thymallus arcticus were assessed in Fielding Lake during 1986 through 1992. Estimates of mortality rates were used in a Monte Carlo analysis to assess the potential changes in utility per recruit (satisfaction of the harvest to anglers) if fishing effort or length at first capture were to change, Two formulations of utility were considered: utility based on satisfaction ratings of fish creeled by anglers; and utility based on relative weight (yield) of fish creeled by anglers. Estimates of age and size at age indicate that Arctic grayling in Fielding Lake live longer and grow more slowly than lacustrine stocks in southern Canada, Montana, and Wyoming. Numbers per surface hectare were also less than for stocks at lower latitudes. Total, fishing, and natural mortality rates averaged 0.44, 0.20, and 0.24, respectively, during the study. Utility‐per‐recruit analyses suggest no potential for increasing utility, at the current level of fishing effort, through changes in the length at first capture, Change in utility per recruit could be maximized by increasing fork length at first capture from its present 200 mm to 250–260 mm if fishing effort were to increase 25–150% of current. Results of the yield‐per‐recruit analysis were similar to those of utility per recruit, except that variability in utility at age was greater than that of yield at age. Differences in variability may be due to inherent variability in anglers' attitudes towards the fish they creel.