# Gene Study: Minn. Brook Trout Thriving



## dinoday (Feb 22, 2004)

Gene Study: Minn. Brook Trout Thriving
By Associated Press
Mon Feb 6, 6:33 PM

ZUMBRO FALLS, Minn. - Brook trout are thriving again in Cold Spring Brook and other streams in southeastern Minnesota, thanks to a secret locked in their genes.

Brook trout are the only trout native to this corner of the state. Beginning in the 1840s, they were nearly wiped out by overfishing and destruction of their stream habitats.

Restocking of the streams with East Coast strains of brookies began early in the 20th century. Water conditions also improved, and today, brook trout swim in 26 of Minnesota's 67 chilly, spring-fed southeast streams.

Scientists had feared that stocking transplanted trout from the East would nearly finish off Minnesota's native brookies _ a unique strain that evolved here during the past 10,000 years. That didn't happen.

University of Minnesota scientist Loren Miller has used genetic fingerprinting to establish that native brook trout have repopulated many southeast streams, while the stocked East Coast strains faded away.

Genetic fingerprinting of fish is raising many questions about the cost and effectiveness of stocking fish in Minnesota, particularly if their genes don't match those of native fish.

Stockings of East Coast strains ended decades ago, so the trout now inhabiting southeastern waters would have to be the descendants of either the transplanted easterners or the native Minnesota fish.

The professor compared the DNA of native brookies from southeast Minnesota with strains from hatcheries and streams in Maryland, New Hampshire and other eastern sources. He concluded that in 16 of 19 streams, including Cold Spring Brook, native Minnesota fish rule the waters.

The discovery was a revelation for Department of Natural Resources biologists, who have hung a new name on the native fish: "heritage trout."

"We understand better today that species that evolve in a system have a genetic advantage," said Jason Moeckel, the DNR's southeast trout manager. "We've learned that just because you stocked East Coast fish, it doesn't mean they took."

Here are some examples of how the new science of stocking is likely to affect anglers:

_Anglers and business interests in Walker want the DNR to nearly quadruple the stocking of walleyes in Leech Lake, which had been one of the state's premier walleye fisheries but is slumping. DNR officials say the only place they could get that many eggs would be from Cut Foot Sioux, a lake 75 miles north of Leech Lake. That strain of walleyes may not match those in Leech Lake, so there's a risk that mixing the strains won't work.

_Wisconsin is debating stocking muskies that originated in Minnesota's Leech Lake because the Leech Lake strains of muskie grow fast and get big. While Leech Lake muskies have thrived in Lake Mille Lacs and Lake Vermilion in Minnesota, Wisconsin officials are wary of stocking them because they might not survive there.

_On the North Shore of Lake Superior, managers worry a newly introduced rainbow trout, the Kamloops, could interbreed with steelhead, a rainbow species first stocked in the 1890s. The two fish are very different genetically, and interbreeding appears to hurt the steelhead more than the Kamloops.

_In Red Lake, which opens to walleye fishing this spring after an eight-year closure for restocking, managers picked a strain of walleyes from the Pike River near Lake Vermilion because their genes closely resembled those of fish native to Red Lake.

Identifying fish strains isn't new science, but DNA fingerprinting has given it a sophistication that sheds light on fish origins, Miller said.

The brook trout study was such an example.

"It's not earth-shattering news, actually," Miller said of the discovery. "It's not the first case where there has been a species in a region where a fair amount of stocking went on and the native genetics remained."

To the untrained observer, native Minnesota brookies and East Coast brook trout look the same. And both are aggressive feeders, relatively easy to catch and good-tasting. But something in the genes of the East Coast fish made them less adaptable to southeast Minnesota streams.

No one knows whether it was the streams' unique chemistry, climate or other factors, but the East Coast fish never reproduced to perpetuate their genetics today, Miller said.

The survival of native brook trout says a lot about the importance of stocking native fish in Minnesota streams and rivers, said Jack Wingate, DNR fish and wildlife research manager.

On a recent trip to Cold Spring Brook, DNR biologist Jeff Weiss and two colleagues looked for native brookies. Using an electrical device that momentarily stuns fish, they found many hiding under banks and vegetation.

"It turns out these native fish have done pretty well," Weiss said. "It makes you feel good they're still around."

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