Population Dynamics and Angler Exploitation of the Unique Muskellunge Population in Shoepack Lake, Voyageurs National Park, Minnesota

Abstract

A unique population of muskellunge Esox masquinongy inhabits Shoepack Lake in Voyageurs National Park, Minnesota. Little is known about its status, dynamics, and angler exploitation, and there is concern for the long-term viability of this population. We used intensive sampling and mark-recapture methods to quantify abundance, survival, growth, condition, age at maturity and fecundity and angler surveys to quantify angler pressure, catch rates, and exploitation. During our study, heavy rain washed out a dam constructed by beavers Castor canadensis which regulates the water level at the lake outlet, resulting in a nearly 50% reduction in surface area. We estimated a population size of 1,120 adult fish at the beginning of the study. No immediate reduction in population size was detected in response to the loss of lake area, although there was a gradual, but significant, decline in population size over the 2-year study. Adults grew less than 50 mm per year, and relative weight (W r ) averaged roughly 80. Anglers were successful in catching, on average, two fish during a full day of angling, but harvest was negligible. Shoepack Lake muskellunge exhibit much slower growth rates and lower condition, but much higher densities and angler catch per unit effort (CPUE), than other muskellunge populations. The unique nature, limited distribution, and location of this population in a national park require special consideration for management. The results of this study provide the basis for assessing the long-term viability of the Shoepack Lake muskellunge population through simulations of long-term population dynamics and genetically effective population size. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Abstract.-A unique population of muskellunge Esox masquinongy inhabits Shoepack Lake in Voyageurs National Park, Minnesota. Little is known about its status, dynamics, and angler exploitation, and there is concern for the long-term viability of this population. We used intensive sampling and mark-recapture methods to quantify abundance, survival, growth, condition, age at maturity and fecundity and angler surveys to quantify angler pressure, catch rates, and exploitation. During our study, heavy rain washed out a dam constructed by beavers Castor canadensis which regulates the water level at the lake outlet, resulting in a nearly 50% reduction in surface area. We estimated a population size of 1,120 adult fish at the beginning of the study. No immediate reduction in population size was detected in response to the loss of lake area, although there was a gradual, but significant, decline in population size over the 2-year study. Adults grew less than 50 mm per year, and relative weight (W r ) averaged roughly 80. Anglers were successful in catching, on average, two fish during a full day of angling, but harvest was negligible. Shoepack Lake muskellunge exhibit much slower growth rates and l...

Evaluation of the physiology, behaviour, and survival of adult muskellunge (Esox masquinongy) captured and released by specialized anglers

“…Moreover, Frohnauer et al (2007) and Strand (1986) observed a 4.1% and 0% mortality rate of angled muskellunge from Shoepack Lake in Voyageurs National Park and Leech Lake, Minnesota, respectively. The C&R mortality rates reported in the present study Frohnauer et al (2007) and Strand (1986) are markedly lower than those reported for other freshwater species (see Muoneke and Childress, 1994;Bartholomew and Bohnsack, 2005), but are consistent with mortality rates in specialized fisheries that are often less than 5% and sometimes below 0.1% (Policansky, 2002). Although no mortalities were observed in this study, it should be acknowledged that zero risk of angling mortality is never achievable in a fishery (Arlinghaus et al, 2007).…”

“…Their estimate, however, was made in a laboratory setting and may have introduced handling and confinement-related stressors resulting in an elevated mortality rate (Pollock and Pine, 2007;Donaldson et al, 2008). Moreover, Frohnauer et al (2007) and Strand (1986) observed a 4.1% and 0% mortality rate of angled muskellunge from Shoepack Lake in Voyageurs National Park and Leech Lake, Minnesota, respectively. The C&R mortality rates reported in the present study Frohnauer et al (2007) and Strand (1986) are markedly lower than those reported for other freshwater species (see Muoneke and Childress, 1994;Bartholomew and Bohnsack, 2005), but are consistent with mortality rates in specialized fisheries that are often less than 5% and sometimes below 0.1% (Policansky, 2002).…”

The Impact of Stocking on the Current Ancestry in Twenty Native and Introduced Muskellunge Populations in Minnesota

“…The apparent inability of the Shoepack strain to attain large sizes (Younk and Strand 1992;Frohnauer et al 2007) was a concern because muskellunge primarily support trophy fisheries (Margenau and AveLallemant 2000;Wingate and Younk 2007). Factors that might affect growth and size structure in muskellunge include prey characteristics (Wahl andStein 1988, 1993), water temperature (Bevelhimer et al 1985;Wahl and Stein 1991;Clapp and Wahl 1996), angling (Margenau and Hanson 1996), and genetics (Margenau and Hanson 1996;Younk and Strand 1992;Clapp and Wahl 1996).…”

The influence of a severe reservoir drawdown on springtime zooplankton and larval fish assemblages in Red Willow Reservoir, Nebraska

“…Similarly, entrainment of adult fish through the dam during drawdown could have resulted in decreased adult population densities (sensu Stober et al 1983;Post et al 2006), thus resulting in decreased production of offspring. Loss of littoral habitat is deleterious to many fishes, particularly when the loss is a consequence of reservoir drawdown (Paller 1997;Frohnauer et al 2007); low water levels can reduce the availability of adequate spawning habitat (Ploskey 1986;Kallemeyn 1987), which could partially explain the changes we observed in the larval fish assemblage.…”