Influence of cisco (Coregonus artedi, Lesueur) on muskellunge (Esox masquinongy, Mitchill) mean length, population size structure, and maximum size in northern Wisconsin lakes

Abstract

Population size structure and maximum size of managed sportfish populations are dictated by abiotic, biotic, ecosystem, and anthropogenic influences. In their native ranges of northern Wisconsin, muskellunge (Esox masquinongy) and cisco (Coregonus artedi) are co‐adapted cool‐ and cold‐water species where cisco presence may influence population size structure and maximum size of muskellunge. We tested whether muskellunge size structure indices (length‐frequency distributions, proportional size distribution), mean length, and mean maximum length of muskellunge differed when cisco were present or absent in Ceded Territory of Wisconsin (CTWI) lakes during 2015–2018. Cisco presence had a positive influence on size structure and mean length of individual muskellunge within populations. In contrast, cisco presence had no influence on the mean maximum length of muskellunge observed in CTWI populations suggesting that other factors may be better predictors of this metric than cisco presence. In cisco lakes, mean muskellunge length was negatively correlated with mean cisco length suggesting that gape limitation may be a factor influencing population size structure and individual growth rates. Therefore, cisco populations with primarily large individuals may be unavailable to muskellunge as forage. Our results suggest that cisco are an important forage species for some aspects of muskellunge population ecology; however, other factors may also contribute to muskellunge population size structure and maximum size outcomes. As such, conservation of remaining cisco populations in Wisconsin is critical because they influence muskellunge population ecology in lakes where the species coexist. Future research is needed to better understand the interactions of cisco, abiotic and biotic factors, and anthropogenic influences on muskellunge growth dynamics.

Using stable isotope data to quantify niche overlap and diets of muskellunge, northern pike and walleye in a deep Minnesota lake

“…Ability to detect the long‐term, integrated importance of prey sources is a major advantage of stable isotope analysis (Grey, 2006), and the dorsal fish muscle tissue we sampled from predators should be time‐integrated over months to years (Hesslein et al., 1993). By comparing lakes with and without cisco, other studies have shown the importance of cisco in boosting the growth potential of northern pike (Jacobson, 1993) and walleye (Kaufman et al., 2009), and increasing mean length and size structure of muskellunge (VanderBloemen et al., 2020). Data from this study support these growth study observations and indicate that cisco are an important energy source for large predators in Elk Lake.…”

“…Possible increased interspecific competition could result in subsequent declines in muskellunge, northern pike or walleye populations in situations where other non‐cisco prey fish were limiting. Additionally, growth potential might be lowered for muskellunge, northern pike and walleye in the absence of a cisco population (Jacobson, 1993; Kaufman et al., 2009), or in combination with abiotic or other factors (Noring et al., 2020; VanderBloemen et al., 2020). Loss of cisco from lakes with just northern pike and walleye could also result in additional potential intra‐ and interspecific competition as cisco form an important prey source for larger individuals in these species.…”

“…Though the interaction of muskellunge with coregonids is poorly documented (Kerr, 2016), cisco have been associated with higher growth potential for northern pike (Jacobson, 1993) and walleye (Kaufman et al., 2009). In northern Wisconsin lakes, muskellunge mean length and relative frequency of larger muskellunge was higher in lakes with cisco populations compared to those without cisco, but no relationship was found for maximum length (VanderBloemen et al., 2020); thus, it would be expected that cisco might be equally important for supporting muskellunge growth. Cisco are threatened by climate change and eutrophication (Honsey et al., 2016; Jacobson et al., 2008, 2012; Jiang et al, 2012; Renik et al, 2020), and their extirpation from individual lakes could alter trophic relationships among their predators.…”

Assessing Minnesota’s Changing Yellow Perch Populations Using Length‐Based Metrics

“…2016; VanderBloemen et al. 2020). The number of largest fish to average for L max was evaluated at multiple increments, and 15 individuals was selected to avoid homogenizing differences between lakes while minimizing the effects of outliers on estimates of L max within individual lakes.…”

Oxythermal habitat as a primary driver of ecological niche and genetic diversity in cisco (Coregonus artedi)

“…Cisco (Coregonus artedi) are a cold-water pelagic fish found in many North American lakes, and provide an important energetic link to pelagic energy sources for gamefish such as walleye (Sander vitreus; Kaufman et al 2009), muskellunge (Esox masquinongy; VanderBloemen et al 2020), lake trout (Salvelinus namaycush), and northern pike (Esox lucius; Kennedy et al 2018). Cisco show a high degree of variability in their morphology, behavior, and diets, allowing them to inhabit diverse aquatic habitats (Turgeon et al 2016;Eshenroder and Jacobson 2020).…”