Factors Affecting Recruitment of Walleyes in Escanaba Lake, Wisconsin, 1958–1996

We modeled recruitment variation of age-0 walleyes Stizostedion vitreum in Escanaba Lake, Vilas County, Wisconsin, to determine factors regulating their abundance. Abundance of age-5 and older walleyes (spawning population), variation in May water temperatures, and abundance of 152.4-mm total length and longer yellow perch Perca flavescens explained 89% of annual variation of age-0 walleye abundance from 1958 through 1995. Abundance of age-5 and older spawners accounted for 32% of the recruitment variation and indicated that maximum numbers of age-0 recruits were produced at low numbers of spawners (fewer than 1,000 individuals). The coefficient of variation of May water temperatures improved the model fit to 56% of recruitment variation and indicated that increased variation of May water temperatures greatly reduced recruitment. The abundance of yellow perch 152.4 mm and longer further improved the model fit to 78% of recruitment variation and also reduced recruitment, though not as much as variation in May water temperatures. The interaction between May temperature variation and yellow perch abundance improved the model to explain 89% of walleye recruitment variation. We interpret the results of the model to mean that walleye recruitment in Escanaba Lake is regulated by competition with or cannibalism by walleyes, variation in May water temperatures, and competition with or predation by adult yellow perch.