The Free Press, Mankato, MN

Outdoors

March 25, 2012

Cross: DNR Waterville Fish Hatchery helping to create 'green lightning' (w/video)

— A few years ago, while fishing through the ice on Scotch Lake near Cleveland, a fat red line suddenly appeared on the flasher, quickly followed by a solid tap felt through my rod tip.

I set the hook and the drag sang as an unseen fish stripped off yards of line.

After a ten-minute-battle, I had a fat northern pike that stretched a magnificent 37 inches thrashing on the ice, scattering gear throughout my fish shelter.

Standing in the Minnesota Department of Natural Resources Waterville Fish Hatchery the other day, I related the fish tale to Bruce Pittman, a fisheries specialist with the Fisheries Division.

“That fish probably started out as fry right here,” he said, gesturing to a bank of jars filled with fertilized, golden-yellow pike eggs that swirled in a current of fresh, cold well water.

There was a time when the hatchery concentrated mainly on walleye production, capturing wild adult fish from area lakes for egg-stripping operations that would produce millions of fry for stocking programs.

The Waterville facility still hatches some 35 million walleye fry each spring for stocking efforts in southern Minnesota. However, the eggs now come from fish netted elsewhere in the state.

The Waterville site also hatches and raises up to 200,000 muskie fry from eggs taken from brood stock netted in Lake Rebecca in northern Minnesota.

But in recent years, the hatchery has become an important source of northern pike fry as well.

Once upon a time, northern populations replenished themselves quite nicely in southern Minnesota, Pittman said.

 If the pike needed any help, it consisted of Fisheries personnel netting some wild adult northerns and placing them in natural wetland areas adjoining lakes in need of a few more of the toothy predators.

Nature then would take its course and the hatched fry eventually would make their way into the lake system.

But surveys of pike populations in recent years revealed declining numbers of the toothy predators in many south-central Minnesota waters.

Degraded or vanishing quality spawning habitat was largely to blame.

The way it is supposed to work, following ice-out, pike traditionally migrate into ditches and feeder streams and into adjacent seasonal wetlands formed by run-off to spawn.

Immediately after hatching, pike fry attach themselves to a piece of vegetation where they will remain until their yolk sac is absorbed.

At that time, called the swim-up stage, the fry actively begin to feed and grow quickly on small zoo plankton that typically saturate a wetland environment, away from the predatory hazards of other fish.

After 20 days or so, the fry then move from the protective environment of the seasonal wetlands through watersheds and ditch systems eventually into area lakes.

So long as there is enough water.

But tiling and farm drainage systems now mean that many seasonal wetlands have either vanished or no longer hold water long enough for pike fry to hatch, grow and migrate into area lakes.

Pittman said the approach now is to hatch the pike fry under the controlled conditions of the hatchery and then after swim-up, place them at key points in watersheds where they can naturally spread out into available habitat.

It has, he said, proved to be a cost-effective and efficient way of replenishing pike numbers.

For a few weeks every spring, the hatchery is a bustle of urgent activity as fisheries crews roll up to the garage doors with aerated tanks filled with ready-to-spawn pike netted from area lakes — those being Lake Geneva, Duck Lake, Lake Elysian and Horseshoe Lake.

“We begin netting as soon as the ice goes out,” Pitman said. “It has been a good year for netting because the low water has kept the fish in the lakes,” he said, adding during springs when there is high run-off, the fish are able to quickly move into ditches and adjoining flowages where they are difficult to net.

The fat females are stripped by applying pressure to their sagging bellies, their golden eggs flowing in a stream into white porcelain pans.

Then the semen extracted from smaller male pike is carefully mixed with a turkey wing-feather into the eggs to fertilize them. The feather is used partly out of tradition, but also out of necessity because it can mix the fragile eggs and sperm with minimal damage.

After a brief soak in quiet water, the fertilized eggs are transferred to heavy glass jars where carefully metered and monitored water flows through them.

“The eggs will begin to hatch in two to three weeks, depending on the water temperature,” Pittman explained. The estimated 1.5 million fry that will be hatched at Waterville this spring will provide 75 percent of the northern pike stocked annually in Minnesota in coming months.

Walleye remain a focus of the facility. Minnesota is, after all, a place where walleye is king.

And it’s true that some fish snobs sometimes refer to northern pike as snakes, slimers, even snot rockets.

But most uppity anglers would agree that there is something to be said for the slashing attack, the sizzling runs when green lightning suddenly strikes.

The jars of ripening eggs now bubbling away in the jars at the Waterville hatchery are insurance that the lightning strikes will come more frequently.

John Cross is a Free Press staff writer. Contact him at 344-6376 or by e-mail at jcross@mankatofreepress.com.

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