The Role of Ciscoes as Prey in the Trophy Growth Potential of Walleyes

Abstract

Analysis of the growth characteristics of 215 populations of walleye Sander vitreus across Ontario revealed that female walleyes reached larger asymptotic lengths in lakes in which ciscoes Coregonus artedi provided a relatively large prey species for them. The stomach contents of walleyes from a set of intensively studied lakes revealed that walleyes of all sizes depended on ciscoes but that ciscoes were most important to larger walleyes. In lakes without ciscoes, the walleye diet closely tracked the availability of young‐of‐year yellow perch Perca flavescens; when such prey were in short supply, walleyes consumed invertebrates. The prey size in walleye stomachs was significantly larger in lakes with ciscoes, but the probability of finding empty stomachs was also greater. This suggests that although walleyes in lakes with ciscoes foraged less often, more energy was available for growth. Exceptions to this general pattern occurred when ciscoes were too large to be consumed by walleyes or ciscoes were absent but small prey (i.e., yellow perch) were very abundant. We propose that lakes without ciscoes will provide higher catch rates for anglers, whereas those with ciscoes (particularly small ciscoes) are more likely to provide opportunities for trophy size fish.

Diet of walleye and sauger and morphological characteristics of their prey in Lake Winnipeg

“…Up to 30 walleye and 30 sauger (N200 mm fork length) were randomly subsampled from the available catch at each location. The fork length (mm), round weight (wet weight or fresh weight, g; Kaufman et al, 2009), sex, and maturity were measured immediately and recorded. The gastrointestinal tract was excised from esophagus to anus and preserved in 70% ethanol until further analysis.…”

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

“…Mean length of muskellunge declined significantly with increasing mean cisco length in our dataset, suggesting that gape limitation and preferred prey size of muskellunge may be exceeded in cisco populations dominated by larger individuals. Kaufman et al () observed a similar pattern for walleye in Canadian shield lakes. Further, mean lengths of cisco in CTWI lakes generally ranged from 15 to 30 cm suggesting that gape limitation and exceedance of preferred size was likely occurring (Gaeta et al, ).…”

“…Cisco are a coldwater forage fish native to inland lakes of Wisconsin that have been shown to influence the maximum growth potential of walleye in Canadian shield lakes (Kaufman et al, ). For Canadian shield lake walleye, it was found that cisco were more important determinants of maximum asymptotic female lengths than yellow perch ( Perca flavescens , Mitchill) and that walleye growth efficiencies were higher, and ingestion and activity rates lower in lakes with cisco (Henderson et al, ; Kaufman et al, , ). Cisco are a high energy density prey, therefore it is often assumed that their presence will result in a higher growth potential for piscivores that consume them.…”

“…Cisco are a coregonine, with members of this subfamily having some of the highest energy densities of north temperate freshwater fishes (Pothoven, Bunnell, Madenjian, Gorman, & Roseman, ). Cisco availability has been linked to maximum growth potential of walleye ( Sander vitreus , Mitchill) in lakes of Ontario, Canada (Henderson, Morgan, & Vaillancourt, ; Kaufman, Gunn, Morgan, & Couture, ; Kaufman, Morgan, & Gunn, ). Cisco are native to some Wisconsin lakes, particularly in the Ceded Territory of Wisconsin (CTWI; ~northern third of the state; Figure ); however, about 30% of the cisco populations in Wisconsin have been extirpated over time due to the loss of suitable oxythermal habitat (Lyons, Parks, Minahan, & Ruesch, ; John D. Lyons, Wisconsin Department of Natural Resources, unpublished data).…”

“…Cisco have been shown to influence lake trout ( Salvelinus namaycush , Walbaum) production (Parks & Rypel, ), and the presence/absence of cisco has had variable influences on walleye maximum growth potential (Kaufman et al, ; Noring et al, in press). Anecdotal angler reports have suggested that muskellunge population size structure and maximum size is higher in waters with cisco present.…”