Response of a Walleye Population to Pulse Fishing in Henderson Lake, Ontario

Abstract

The response of ichthyofauna to the extensive exploitation of walleyes Stizostedion vitreum was measured in Henderson Lake, north-central Ontario. During a period of negligible recruitment, 89% (3,226) of the adult walleye population (1980–1982) was removed with trap and gill nets. Subsequent attempts to estimate adult walleye abundance in 1988 and 1991 were unsuccessful, suggesting the population had collapsed beyond recovery. Additionally, in 1986 the numbers of northern pike Esox lucius and yellow perch Perca flavescens had increased. With the collapse of the walleye population, northern pike and yellow perch densities were expected to increase, with northern pike eventually becoming the sole top predator. However, two large year-classes of age-0 walleyes were produced during 1985–1986. Furthermore, population estimates in 1994, 1995, and 1997 indicated the adult walleye population had recovered to 33% (1,056 fish) of the preexploitation number. Conversely, by 1997 the number of northern pike had declined from its preharvest level (1979). After 1991 the number of yellow perch also declined. Apparently, even if the densities of the dominant predators are severely reduced, boreal fish communities will eventually return to their original configurations.