Opener Minnesota Fishing Here’s a look at the life cycle of a stocked walleye fish, so it’s essential to a healthy population of state fish.
As one of the best walleye fishing states in the country, Minnesota is blessed with up to 260 large lakes where fish grow wild. This water naturally produces 85% of our annual yield of more than 3 million springs. But to satisfy our collective craving for more walleye, state fisheries managers sweetened the pot in other lakes with stacked cows more than 120 years ago.
If you caught a light gray fish this season in one of the approximately 1,000 hatchery-bred fry or fingerling lakes, there is a good chance that it was born in a jar. Here’s a look at the walleye life cycle:
Each April, when the wild states gather to spawn, the Department of Natural Resources (DNR) intercepts them at 12 sites as south as Sarah Lake in Murray County and as far north as the Pike River in Lake Vermillion. Cut Foot Lake Sioux north of the Deer River and Pine River near Brainerd are two other well-known sites.
Work crews at stripping stations carry male and female walrus by hand, squeezing gallons of eggs and millions of yellowish eggs into plastic bowls. Workers spin the gametes together and transfer them to an insulated storage tank for trucking to one of 11 warm-water hatcheries across the state. The jars are designed with supply lines that distribute water evenly to keep fish eggs moving quietly, mimicking the conditions of a lake’s breeding bed.
In hatcheries, the fertilized eggs are transferred to calibrated jars where they are left to incubate for about two weeks. Once hatched, mosquito-sized bodies are loaded into modified 5-gallon camp jugs – 100,000 fry per container. Pitchers are trucked to selected lakes and are most often released at a rate of 1,000 fry per coastal acre (the surface area of a lake where the water depth is less than 15 feet). Generally, managed lakes are stocked every two years, or less frequently depending on individual lake plans.
A third of the larvae do not go directly to the lakes. At an additional cost, they are transferred to 250 DNR breeding ponds for retrieval in the fall. By this time, young walleyes are 4 to 6 inches long “fingerlings” – better suited to stocking in lakes where large numbers of sunfish and bass devour the fry very easily.
Even in lakes fairly hospitable to light gray fry, only about 2% of brooding babies live longer than 18 months. Hungry minnows, baby perch and baby sunfish stand in their way. By 18 months, walleye have matured into a fast swimmer and are too large to accommodate within the hiatus of small predators.
It takes several years for a stocked eyeball to reach 1 pound, or about 14 inches. Warmer southern lakes have longer growing seasons, so gray lakes grow to a large size in those lakes within three to four years. On the northern border, the same growth takes five to six years. Of the approximately 3.5 million fish eyes that fishermen harvest each year, about half a million are stocked.
Sources: Minnesota DNR and “Walleye, A Beautiful Fish of the Dark” by Paul Radomsky.