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[Lee Borgersen]

  Study: Steelhead, Kamloops rainbows interbreeding on North Shore

 
By Sam Cook on Apr 1, 2017

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First-year results from a steelhead genetics study on Minnesota's North Shore streams confirm that hybridization between steelhead and stocked Kamloops rainbow trout is occurring, said fisheries officials with the Minnesota Department of Natural Resources.

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"We found that Kamloops ancestry was pretty much widespread in both juvenile and adult populations (of steelhead)," said Nick Peterson, DNR anadromous fish specialist at French River. "That being said, still the majority of fish we caught were pure steelhead. That's important to anglers."

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Steelhead anglers have long held concerns that the two strains of Lake Superior rainbows are interbreeding in North Shore streams and negatively influencing steelhead numbers. The Kamloops fishery, almost entirely dependent upon stocking, is considered by some anglers a less hardy rainbow trout strain. That stocking began in 1976. Four previous studies by fisheries biologists at French River have shown that hybridization between the two species reduces the potential survival of young, Peterson said.

 
The genetics research project is a cooperative effort between the DNR, the Minnesota Steelheader group, Minnesota Trout Unlimited and the Lake Superior Steelhead Association. The project will continue for two more years.

 
The genetics study, conducted at the University of Minnesota, analyzes scale samples that anglers have contributed as well as scale samples taken by DNR biologists. In all, more than 2,000 samples from steelhead in 27 North Shore streams have been analyzed.

 
About 80 percent of those fish turned out to be "pure" steelhead, Peterson said. The others had Kamloops genetics present. And some fish that appeared to be steelhead — that is, lacking the fin-clip of hatchery-reared Kamloops rainbows — were in fact pure Kamloops rainbows from natural reproduction, Peterson said.

Concern over results:

Groups such as Minnesota Trout Unlimited have long been opposed to Kamloops rainbow stocking because they fear it will dilute the wild steelhead strain, first introduced to Minnesota waters of Lake Superior in 1895.

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"I've been telling the DNR for 20 years they're playing roulette here," said John Lenczewski, executive director of Minnesota Trout Unlimited. "I wasn't surprised. We're not happy about it, of course. Now that the handwriting is on the wall, the only responsible thing the DNR can do is stop stocking Kamloops."

Otherwise, he said, the consequences to the steelhead fishery could be extreme.

"It will essentially destroy the steelhead population over time," Lenczewski said.

About 92,500 Kamloops rainbows are stocked each year by the Minnesota DNR, some in the Lester River and some at the mouth of the French River.

The Lake Superior Steelhead Association based in Duluth also found the study's results troubling.

"At this point the LSSA is concerned with the genetic hybridization between steelhead and Kamloops and the discovery that Kamloops rainbows appear to be reproducing and surviving in the wild," said Craig Wilson, president of the group.

Neil Fredericks of Centerville, Minn., vice president of Minnesota Steelheader, said the first-year results of the genetics study were "certainly an eye-opener."

"Clearly, the DNR recognized that hybridization was possible," Fredericks said. "The results are what they are. We feel our next best option is to continue the (genetics study) to gather more results. One year of sampling is not enough."

Duluth's Ross Pearson of Kamloops Advocates called the results "irrelevant." He said he believes that with the eventual closure of the DNR's French River Coldwater Hatchery, the Kamloops stocking program eventually will fail. With a shift in Kamloops rainbow rearing to another hatchery, he said, the fish will be stocked at a smaller size and far fewer will return as adults to be caught by anglers — or breed with steelhead.

"There will be much less potential for hybridization in the future because of the closing of the French River Hatchery," Pearson said. "It's a planned failure. They (DNR officials) won't acknowledge that."

Long comeback:

Minnesota's steelhead population flourished through the 1960s and 1970s, then began to decline. In an effort to bring the population back, the DNR imposed a no-kill regulation in 1997 that remains in place today.

"The DNR's goal is to rehabilitate the steelhead population to a point where we can allow a limited angler harvest," said Cory Goldsworthy, DNR Lake Superior area fisheries supervisor at French River. "We've gone 20-plus years with the same goal."

             
 
In recent years, steelhead catch rates have begun to increase, but not to the point that the DNR would consider lifting the no-kill requirement. A majority of steelhead anglers support that regulation.

Goldsworthy said he was surprised the genetics project showed that interbreeding among steelhead and Kamloops strains was geographically widespread up and down the North Shore. Since Kamloops rainbow stocking began, it has been limited to streams from Duluth to the French River, mainly to decrease their chances of interbreeding with steelhead. But steelhead anglers say they've seen Kamloops rainbows in rivers all along the shore and into Ontario.

The study revealed that naturally-produced pure Kamloops adults were found in four rivers and that naturally-produced pure Kamloops juveniles were sampled in five rivers. Those Kamloops rainbows were indistinguishable from steelhead.

"To see wild Kamloops being caught that we can't distinguish from wild steelhead — that's concerning," Goldsworthy said.

That's an issue for DNR biologists because each year they take eggs from fish that are presumably steelhead and use the eggs to raise young fish to supplement natural steelhead reproduction.

Goldsworthy said the DNR will discuss the study's first-year results with interested parties at some point.

"We do plan on sitting down and figuring out what this all means," he said. "We'll definitely be having those conversations."