Long-Term Estimation of Population Size and Growth of Muskellunge in a Southern Illinois Reservoir Using Novel Approaches

Understanding population dynamics and growth of fishes is important for fishery management.  Population estimates typically require mark-recapture studies and typical growth metrics use length-at-age data, which often necessitates sacrificing fish to obtain accurate age.  Sacrificing may be undesirable for long-lived species managed as trophy fishes such as muskellunge.  Previous research suggests long-term mark-recapture history (coupled with length data) can estimate both population size and growth.  In this way, we examined long-term trends in muskellunge population size and growth using 12 years of mark-recapture data for muskellunge in a southern Illinois reservoir. Population estimates for each year were obtained using program MARK and von Bertalanffy growth estimates by sex were obtained using a novel modification of Fabens growth model.  Population estimates ranged from 511 to 2255 individuals with a trend of increasing population size through time.  Population size was related to CPUE (r = 0.79), but had no effect on fish condition.  Fabens von Bertalanffy growth estimates of L_∞ and K differed among sexes (P < 0.0001).  Our results suggest CPUE may be a proxy for muskellunge abundance, and our modification to Fabens model resulted in robust von Bertalanffy growth estimates, suggesting our modification could be applied to other fisheries.