For many Minnesota anglers, the walleyes they seek today began years earlier in jars of fertilized walleye eggs at 11 state fish hatcheries.

This spring, the Department of Natural Resources collected 582 million walleye eggs that produced about 411 million mosquito-size walleye fry. Nearly 300 million were dumped into 272 lakes; the rest went into DNR rearing ponds, where they will grow to 4- to 6-inch fingerlings before they are stocked into other lakes this fall.

“Everyone says the bigger the fish the better it will survive, but we stock fingerlings only where it works,” said Neal Vanderbosch, DNR fisheries program consultant. “It’s expensive. Fry are cheap and give you a good bang for your buck.”

Those tiny walleye babies, or fry, produced in April now are 1 to 2 inches long, and their survival still is perilous. Weather and larger fish take their toll, and only a fraction will grow to adulthood.

But that fraction can make the difference between good fishing and fair fishing on some lakes.

So if stocking helps boost a lake’s walleye population, why not dump even more fry into lakes? Because lakes can only support a certain amount of biomass.

“We’ve learned fry densities can be too high,” said Vanderbosch, which affects survival. “There’s an optimal amount. We used to stock from 500 to 1,000 fry per littoral acre. Now we think maybe 300 to 500 per acre might be better. Less might be more.”

Lakes generally aren’t stocked every year. All told, about 1,050 lakes are stocked with walleyes. Still, officials believe about 85 percent of the state’s walleye harvest come from the 260 lakes with natural walleye production, including Lake of the Woods, Upper Red, Winnibigoshish, Vermilion and Mille Lacs.

Without walleye stocking, those 260 lakes would be the only ones in Minnesota where anglers could catch walleyes, Vanderbosch said.

The DNR also rears and stocks catfish, muskies, lake sturgeon and northern pike. Stream trout, lake trout and splake are produced in five cold-water hatcheries.

Stocking fish isn’t cheap. The entire program costs around $7.5 million annually. Walleye stocking accounts for $3.7 million of that — about 10 percent of the DNR fisheries budget. Anglers pay for it through their license fees. The $5 walleye stamp, which anglers aren’t required to purchase, raises about $100,000 yearly for stocking. But sales have been declining.

Trout face threats

Wild trout populations in North America face serious threats and now occupy only 25 percent of their native waters, according to a Trout Unlimited report issued Tuesday. The report, “State of the Trout,” cites many threats to trout, including nonnative species, climate change, loss and degradation of habitat and an increased demand for water.

“If future generations of Americans are to continue to reap the recreational and economic benefits of abundant trout populations, we must chart a new path forward,” the report says.

Said Jack Williams, a Trout Unlimited senior scientist: “The scope of the problem is huge and spans the whole nation.”

The report (available at www.tu.org) says frack sand mining, which is occurring in Wisconsin and Minnesota, threatens trout streams. And it says Wisconsin scientists predict brook trout habitat will decrease by nearly 50 percent even under limited climate warming.

 

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