DULUTH—Fisheries officials with the Minnesota Department of Natural Resources expect to make a decision soon about future management of rainbow trout in Lake Superior.
The agency is considering four management options after a recent genetics study confirmed interbreeding between stocked Kamloops rainbow trout and a different rainbow strain called steelhead, which reproduce in the wild but are supplemented with fry stocking. Fry are tiny, recently hatched fish.
Anglers and fisheries officials have long suspected that interbreeding of Kamloops rainbows and steelhead might be occurring. That hadn't been confirmed until recent genetics studies were completed.
"We've found it in juvenile fish and at the adult life stage. It's geographically widespread on the North Shore, as well as in Michigan rivers and in the Brule River in Wisconsin," said Cory Goldsworthy, DNR Lake Superior area fisheries supervisor at French River. "Everywhere we've looked for it, we've found it."
Earlier studies of fish in captivity showed survival was low among the progeny of steelhead that interbred with Kamloops rainbows.
"We do know that when they interbreed, fewer fish are produced," Goldsworthy said. "So, if our goal is to rehabilitate wild steelhead and they interbreed with Kamloops, fewer are produced. It's not a steelhead anymore. It's a hybrid."
The DNR's long-term goal has been to rehabilitate the steelhead population to the point that anglers could be allowed to harvest some of them, Goldsworthy said. When steelhead numbers plummeted in the 1980s and 1990s, a no-kill regulation was imposed in 1997. Catch rates have improved in recent years.
The DNR recently convened its Lake Superior Advisory Group, a citizens' panel, and presented it with four options for future rainbow trout management. Those options included:
• No change
• "Wait and see": Cease stocking of Kamloops rainbows and steelhead fry, evaluate natural reproduction of steelhead, and reconsider steelhead harvest/stocking options during next management plan revision process in 2024, or sooner if needed.
• Limited wild steelhead harvest: End Kamloops rainbow stocking but continue steelhead fry stocking and allow a limited harvest of wild steelhead (for example, perhaps a one-over-28-inch limit on certain rivers).
• An alternative hatchery product for harvest: End both Kamloops rainbow stocking and steelhead fry stocking, and replace that with stocking of genetically screened, adipose-fin-clipped, pre-smolt steelhead.
Recent surveys of rainbow trout anglers on Lake Superior indicate that it's important to about 50 percent of them to be able to keep some fish they catch, Goldsworthy said.
Currently, the DNR is experimentally raising about 120,000 genetically-pure steelhead rainbow trout at the French River Coldwater Hatchery. If all goes well, those fish could be available for stocking in April. Any stocking would be done in the upper reaches of the French and Lester rivers, Goldsworthy said.
Like the Kamloops rainbows stocked now, those hatchery-reared steelhead would have clipped adipose fins to distinguish them from naturally produced steelhead. Anglers would be permitted to keep stocked steelhead with clipped adipose fins, Goldsworthy said.
Advisory group members' opinions vary on the DNR's options. Ending Kamloops rainbow stocking would eventually mean the end of that fishery, which is popular with many North Shore anglers. The fish grow large and can be caught from shore in every season except summer.
"Cessation of the Kamloops program is not acceptable to the group," reads a statement on the website of Kamloops Advocates, headed by Duluth's Ross Pearson. "Recreational and harvest opportunities would become nearly nonexistent from shore without the Kamloops program."
The group supports the "no change" option among those offered, but also proposes eliminating steelhead fry stocking because "it is the costliest program (requires a captive brood-stock population) and is of questionable value."
John Lenczewski of Minnesota Trout Unlimited said his membership has long been opposed to the stocking of Kamloops rainbows.
"We've been concerned for going on 20 years that we had a dangerous situation with a domesticated fish that was not fit and might bring down the whole steelhead population," he said. "We don't take any joy in seeing them (DNR officials) cease the Kamloops program ... but it's too dangerous to continue."
He's less enthusiastic about the possibility of ending the steelhead fry-stocking program.
"We've put a lot of effort into restoring some (steelhead nursery) habitat above the barrier falls, with the (DNR's) intent to continue stocking fry for another 10 years," he said.
Mike Pitan, president of the Lake Superior Steelhead Association based in Duluth, said the evidence of interbreeding among Kamloops rainbows and steelhead is "a big concern." The group supports the DNR's second option, ending the stocking of both strains and a "wait and see" stance.
The association does not favor any potential harvest of steelhead. Instead, it proposes the DNR begin stocking Seeforellen brown trout and Atlantic salmon that anglers could keep.
The DNR has offered no timetable about when a decision might be reached on the rainbow trout issue.
Ultimately, Goldsworthy said, Lake Superior, with its robust population of lake trout and salmon that prey on smaller fish, might make the final decision about any rainbow trout management efforts.
"Lake Superior is the big equalizer in everything we do," he said.