How fast walleyes grow depends on the availability of food and the length of the growing season. In southern reservoirs, where shad are super-abundant and the growing season is 8 to 9 months long, walleyes can reach weights exceeding 15 pounds in only 7 years. But in the deep, cold, wonderful lakes of the Canadian Shield, where baitfish are less abundant and the growing season lasts only 3 to 4 months, a walleye reaches a weight of just 2 pounds in the same amount of time.

   Despite this great difference in growth rate, walleyes in northern waters can reach sizes rivaling those in the south. This phenomenon can be explained by a factor that could be called warmwater burnout. Fish in cold northern water grow more slowly, but have a much longer life span than fish in warmer southern waters. Walleyes in the North have been known to live as long as 26 years, although walleyes older than 15 years of age are rare; in the South, a life span of 10 years would be uncommon. So even though walleyes in the North do not grow as fast, their longevity results in an average size not much smaller than that in the South.

   There is evidence to support the theory that a fast growing strain of walleyes exists in rivers and reservoirs in the south-eastern United States. Apparently, this strain spawns exclusively in rivers. When dams were built to create the reservoirs, long stretches of river habitat were lost. In most cases, the walleyes eventually disappeared from the reservoirs.

   Many of these reservoirs were then stocked with northern-strain walleyes. This strain can spawn in rivers or lakes, but evidentally does not grow as fast as the southern strain. In Center Hill Reservoir, Tennessee, souther-strain walleyes sampled in 1964 averaged 30.6 inches (about 10 1/2 pounds) at age seven. They eventually disappeared from the reservoir, so it was stocked with northern-strain walleyes. When the northern fish were sampled in 1976, they averaged only 23.3 inches (about 4 1/2 pounds) at the age of seven.

   Female walleyes grow much faster, live longer and attain much larger sizes than males. In most waters, male walleyes exceeding 4 pounds are unusual.