Fall test netting and angler surveys indicate how previous year classes are faring. The information helps biologists predict the abundance of various sizes of fish from year to year. Predictions for Rainy are rosy. Its walleye year-class strength increased throughout the 1980s, climbed to a new high in 1991, then skyrocketed in 1994 and '95. The '94 and '95 classes could send catch rates soaring in coming years.
Biologists estimate that a strong year class comes along about every five years or so.
The large year classes in 1994 and '95 may be due to other factors such as good environmental conditions for spawning and young survival. Rainy Lake walleyes reproduce abundantly when springtime water levels rise, as they often did during the 1990s. According to DNR research biologist Paul Radomski, high water in May allows walleyes to spawn on silt-free rock rubble shoals. Unfortunately, spring water levels on Rainy are no longer so favorable for walleye spawning. Since 1996 a Canadian company, Abitibi Consolidated, has operated the water-control structures at the Fort Frances hydropower dam that determine lake elevation.