Long-Term Mark-Recapture Data to Assess Muskellunge Population Characteristics: Application to Two Illinois Reservoirs

Accurate estimates of growth and mortality are important for management of recreational fisheries. Accurate age estimates often require the sacrifice of fish; thus, assessments of growth and mortality rates of trophy fishes such as Muskellunge Esox masquinongy often lack sufficient data. Mark recapture history can be used as a nonlethal alternative to estimate growth and mortality in fishes. To determine the utility of this approach, we used data from a 17-year Muskellunge mark recapture program conducted on two Illinois reservoirs (Kinkaid Lake and North Spring Lake). Von Bertalanffy parameter estimates by sex, lake, and tag type (passive integrated transponder and T-bar anchor tags) were obtained using a novel modification of the Fabens growth model and compared to von Bertalanffy growth estimates using known- or scale-aged fish. Mortality was calculated using both age- and length-based methods. Fabens growth model estimates of asymptotic length (L-infinity) and growth coefficient (K) were within 6% (<= 62 mm) and 23% (<= 0.11) of corresponding von Bertalanffy growth model parameter estimates from known- or scale-aged fish by lake and sex. Provided that all sizes of fish are sampled, 4 years of mark recapture data with more than 100 recaptures were found to be sufficient to produce reliable parameter estimates. Growth parameters differed between male fish tagged with passive integrated transponder or T-bar anchor tags but did not differ by tag type for females. Differences in Muskellunge growth and mortality rates between the two study lakes suggest that changing from a regionally applied minimum length limit to lake-specific minimum length limits may be warranted. Our results highlight the feasibility of mark recapture data as a nonlethal technique to estimate population-specific growth and mortality rates for Muskellunge and the potential value of this approach in facilitating lake-specific Muskellunge management.