Millions and millions of walleye
NEW LONDON -- It takes millions and millions of walleye to improve your odds of landing one. It also requires a lot of hard work by the staff with the Minnesota Department of Natural Resources to nudge Mother Nature along and stock all of those w...
NEW LONDON -- It takes millions and millions of walleye to improve your odds of landing one.
It also requires a lot of hard work by the staff with the Minnesota Department of Natural Resources to nudge Mother Nature along and stock all of those walleye in the state's lakes.
Minnesota operates the country's largest walleye stocking program, and some of that work takes place here.
The DNR fisheries crew in Spicer is one of nine in the state charged with collecting walleye eggs for the state's 12 warm-water hatcheries.
The eggs collected here are raised at the New London hatchery. It has been providing fry and fingerlings for stocking since it began full operations in 1941, first under the authority of the U.S. Fish and Wildlife Service and more recently, the state.
The work of collecting eggs and fertilizing them gets underway just about "when the ice goes out," said Brad Carlson, a fisheries employee with the DNR in Spicer. It was April 8 and he and other fisheries workers had already been stripping walleyes of their eggs and milt for four days.
It's an annual chore that can drag on for weeks, or be over in a matter of days, all depending on the weather each spring.
This year's early warmup meant the spawn started earlier than normal, but also made it likely that the run would be prolonged. "Dibs and dabs," said Spicer fisheries supervisor Bruce Gilbertson to describe how the run of spawning walleye was going at the start.
Each morning during the spawn, two-man crews from Spicer launch boats on Green, Koronis and Rice Lakes. The three lakes are prodigious waters for natural walleye reproduction. The crews set nets on the rock and rubble areas of the waters walleyes use for spawning.
The nets are hoisted, and the males and the females with bulging bellies indicative of their being "ripe" to spawn are placed in oxygenated water tanks in the boats. When a good mix of males and females are taken on a lake, the fertilization can be done at the lake access and the fish quickly returned to the water.
When the mix of males and females isn't sufficient at one lake, the live fish are transported to the fish hatchery. There, the fisheries workers rush about in their own version of a football team's two-minute drill.
That's about the amount of time allowed to strip a couple of female walleyes of their eggs, spray milt from two to three times as many males on the eggs, and add water to initiate the fertilization.
At the same time, the mix is stirred with a feather to maximize the contact between sperm and eggs.
In nature, walleye rely on the wind and their own actions to mix eggs and sperm. Fertilization rates are relatively low.
With human intervention, anywhere from 60-80 percent or more of the eggs in a bowl can be fertilized and raised successfully into fry.
Statewide, over 400 million fry are hatched this way each year.
The local crew collects 160 quarts of eggs each season, not large when compared to the take of Pike River walleyes on Lake Vermillion near Tower. Some 320 quarts of the fertilized, Pike River walleye eggs will be transported to New London, where they will be raised to be fry in racks alongside those collected here to produce millions of fry, according to Gilbertson.
Millions of the fry will be raised in the hatchery's ponds and elsewhere, many to be stocked later as larger, fingerlings.
The egg collection here serves two roles. For one, the collection is a "back up" to assure a good supply of stock in years when weather or other factors may lead to poor results at other sites.
And, the egg collection here serves to provide fry and fingerlings to be stocked in lakes from the South Dakota border to the Iowa border. Some are destined for the prairie lakes in southwestern Minnesota that do not have natural walleye reproduction of their own, but offer fertile waters for walleye to grow.
Others will find their way into lakes where natural reproduction falls short of what the lakes could support. They include lakes known as walleye destinations. Big Stone and Lac qui Parle Lakes are among them, said Gilbertson.
Ten percent of the fry will be returned to Green, Koronis and Rice Lakes. Gilbertson said this is done to assure that the lakes get back at least as much, if not more than was taken from them.
And of course, the parent fish that were netted to provide the eggs and milt are returned to the lake from which they came on the very same day.
A study is currently underway across the state using oxytertracycline to mark the fish raised in hatcheries. The study is looking at the effects of returning 10 percent of the raised fry to the parent lakes. There is the possibility that we could be inadvertently overstocking some of the lakes from which we take the eggs and milt. Putting too many walleyes in a given water body can lead to over-competition for the available food, and possibly stunting growth.
If that's happening here, you wouldn't know it from some of the females collected from Green Lake. It's routine for the fisheries crew to handle true wall hangers, and some of these big mothers come back year after year. Some of the big fish have distinctive colorings, or defects like nicked fins or tails, that the fisheries staff recognize, said Gilbertson.
By all measures, Green Lake seems to produce the largest share of big, female walleyes. Koronis always seems to offer the largest number of males, he said.