Evaluating the Ability of Tiger Muskellunge to Eradicate Brook Trout in Idaho Alpine Lakes

Abstract

In western North America, nonnative Brook Trout Salvelinus fontinalis in alpine lakes threaten the persistence of native trout and often offer limited sport fishing opportunity as they are prone to stunting. Stocking tiger muskellunge (Northern Pike Esox lucius × Muskellunge E. masquinongy), which are reproductively sterile, may be an option to eradicate Brook Trout in some alpine lakes. We used floating gill nets to survey 17 alpine lake Brook Trout populations, then stocked 13 lakes with tiger muskellunge, with four additional lakes serving as controls. Tiger muskellunge were stocked at a mean TL of 317 mm and a density of 40 fish/ha. Brook Trout were resampled for 4 or 5 years after stocking to evaluate changes in Brook Trout TL and CPUE (fish/net‐night). Declines in CPUE were substantial for both treatment and control lakes but were significantly greater in treatment lakes. Mean Brook Trout CPUE in treatment lakes declined from 23.1 fish/net‐night to 2.3 fish/net‐night 5 years after stocking tiger muskellunge, whereas in control lakes, CPUE declined from 25.5 fish/net‐night to 7.8 fish/net‐night 5 years later. Complete eradication appeared to occur in two lakes within 2 years, and in two more lakes by year 5. In lakes where tiger muskellunge were stocked, the proportion of Brook Trout ≥250 mm TL in the catch increased significantly in years 1, 2, and 4 after stocking (compared with prestocking data), whereas no increase occurred in control lakes. Tiger muskellunge were most successful in reducing Brook Trout CPUE in lakes with no inlets or outlets, while elevation and lake area may also have played a role. Our results suggest tiger muskellunge can improve the size structure and potentially eradicate Brook Trout populations from some alpine lakes. However, we recommend combining any tiger muskellunge stocking with other conventional removal methods to increase the likelihood of successful eradication. Received October 27, 2014; accepted March 22, 2015

Effects of Turbidity on Prey Selection and Foraging Rate of Hatchery‐Reared Juvenile Tiger Muskellunge

“…Results from this experiment indicate that turbidity could negatively impact the foraging success of and reduce selectivity by tiger muskellunge in turbid systems. Due to 490 their highly piscivorous nature and ability to control populations of undesirable fish species (e.g., White Sucker Catostomus commersonii and Black Crappie Pomoxis nigromaculatus: Siler and Beyerle 1986; Brook Trout Salvelinus fontinalis: Koenig et al 2015), tiger muskellunge are used as a biological control agent, but based on our results, this strategy may be ineffective in lakes where Secchi depths average 26 cm or less. Furthermore, survival and recruitment of stocked tiger muskellunge may be affected, in part, by low food consumption when Secchi depths are 26 cm or less.…”

“…Tiger muskellunge (Northern Pike × Muskellunge) are stocked into aquatic systems throughout North America (Crossman 1986;Wahl et al 2012) to control overabundant or undesirable fish species (Lepak et al 2014;Koenig et al 2015;Sorel et al 2016) or to create sport fisheries (Wahl et al 2012;Sorel et al 2016). Numerous studies have evaluated variables that may affect the survival of tiger muskellunge, including the use of artificial (pellet) versus natural (fish) diets administered prior to stocking (Gillen et al 1981); predation Wahl and Stein 1989); and predator acclimation (Wahl et al 2012).…”

“…However, no evaluations have been conducted to determine the effects of turbidity on tiger muskellunge foraging ability, which could affect fish survival and stocking success. Because turbidity is an environmental condition found in most aquatic systems (Vanlandeghem et al 2011), it is important to understand how turbidity may affect continued stocking efforts to establish tiger muskellunge (Lepak et al 2014;Koenig et al 2015;Sorel et al 2016). The purpose of this study was to test the effects of turbidity at four levels (Secchi depths of >84 [tap water], 53, 26, and 18 cm) on prey selectivity and foraging return of juvenile tiger muskellunge by using three different prey species (Goldfish Carassius auratus [a surrogate for Common Carp Cyprinus carpio], Gizzard Shad Dorosoma cepedianum, and Green Sunfish Lepomis cyanellus) that are commonly found in southern U.S. reservoirs.…”

Survival and Reproductive Success of Hatchery YY Male Brook Trout Stocked in Idaho Streams

“…Most recently, tiger muskellunge (Northern Pike Esox lucius × Muskellunge E. masquinongy ) have been introduced into alpine lakes and have successfully eradicated Brook Trout in some (but not most) of them (Koenig et al. ). The mixed success of these methods identifies the need for additional methods for nonnative fish eradication.…”

Simulated Effects of YY‐Male Stocking and Manual Suppression for Eradicating Nonnative Brook Trout Populations

“…Intensive gillnetting has eradicated Brook Trout populations in a few alpine lakes (e.g., Knapp and Matthews 1998;Parker et al 2001), although this technique may be effective only in lakes smaller than 3 ha in size (Knapp and Matthews 1998). More recently, tiger muskellunge (Northern Pike Esox lucius × Muskellunge E. masquinongy) have been used to eradicate Brook Trout in some alpine lakes, but the technique appears to be ineffective in lakes with inlets or outlets because Brook Trout continue to reside in flowing-water areas not inhabited by tiger muskellunge (Koenig et al 2015). In the most comprehensive study to date on population effects of Brook Trout removal in alpine lakes, Hall (1991) concluded that methods designed to reduce recruitment should be evaluated because massive density reductions alone were not effective in suppressing larger populations.…”