Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists

Population Estimate of Adult Muskellunge in Lake Bemidji, Minnesota [Abstract]

Anthony J. Kennedy, Andrew L. Thompson, Andrew P. Wiering, and Gary C. Barnard

doi: https://doi.org/10.47886/9781934874462.ch48

Muskellunge Esox masquinongy are native to the upper Mississippi River watershed but were considered extirpated from Lake Bemidji and connected waters prior to restoration efforts that began in 1978. Efforts to re-establish Muskellunge intensified through the 1980s with consistent, alternate-year fingerling stocking that continues to present day. Length- and age-frequency data from Muskellunge assessments conducted in 1998 and 2013 portray an aging population. For example, only one fish greater than 48 in was captured in 1998, whereas 34 fish exceeded this length in 2013. Mean length of fish captured in these two assessments were 39.4 and 45.3 in (1 in = 2.54 cm), respectively. As expected, older fish were achieving maximum growth potential, with the largest females exceeding 55 in. However, despite consistent fingerling stocking, few fish less than 40 in were captured in 2013. Eighty-nine percent of fish captured during 1998 were younger than age 11, whereas these age-classes comprised only 7% of the 2013 sample. Given the length and age distribution of the population in 2013, it appears that recruitment to the adult population has declined. Whether this is due to increased mortality of subadult fish or delayed sexual maturity is uncertain. Mark–recapture population estimates for sexually mature fish were attempted in both years during the spawning period using large-frame trap nets (marking) and boat electrofishing (recapture). In 1998, only one marked fish was recaptured. In 2013, a sufficient number of fish were recaptured to compute a population estimate, but there was concern that model assumptions were violated due to sex-specific fish behavior. Thus, efforts were made to compute two additional population estimates using angler diaries and a follow-up electrofishing assessment in 2014. Our three population estimates for sexually mature Muskellunge in Lake Bemidji during 2013 ranged from 320 to 603 individuals (0.04 to 0.08 Muskellunge/acre [0.016 to 0.032 Muskellunge/ha]).