– Monday morning, Forrest Overby was the only angler at the mouth of the French River toting a woven trapper’s basket on his back. Conditions were ideal for fishing. The sun bore a faint hole through a hazy sky. The wind was calm. And in the near distance, just offshore, anglers in small boats, including two kayaks, dragged spoons and other lures, trolling mostly for coho salmon.

Not Overby, 54, of Duluth. Like a few score other anglers scattered along the North Shore on Monday morning, he was fishing for Kamloops rainbows — Loopers, as they’re called — a sport he undertook relatively late in life. His dad was into it, he said, and would stand for hours at the mouth of the French River casting waxies or spawn bags into the big lake.

Sometimes a Looper would take his bait, sometimes a coho salmon. Regardless, it was a great way to pass the time.

“Then when I got into it, it was like warfare down here,’’ Overby said. “There were a lot of fishermen.’’

First stocked in Lake Superior in 1976, Kamloops rainbows were intended to provide a put-and-take fishery for shore anglers, generally between Two Harbors and Duluth. Loopers couldn’t reproduce, or so it was thought, and the fishery would depend on continual stocking.

Another rainbow species — steelhead — had been introduced to Lake Superior more than a century earlier. Generally described as migratory rainbows, they were planted in the Canadian side of Lake Superior as early as the 1880s, followed by introductions a few years later into Minnesota’s St. Louis, Lester and Poplar rivers.

Today, wild reproducing steelhead swim up streams between Duluth and the Canadian border, usually beginning in early April.

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Like Forrest Overby, Blake Twyford also chased Loopers along the North Shore on Monday morning. But rather than fishing near the French River, Twyford was settled into a lawn chair near the mouth of the Lester River, not far distant.

Twyford has fished Loopers since moving to Duluth in 1998, when he worked for Northwest Airlines as a mechanic.

“When I catch a Looper, I like to fillet it, lay the fillets on tin foil along with onions and carrots, and drizzle butter on them,’’ Twyford said. “If I have a little apple-smoked bacon, I’ll lay that on top, too, and cook them for 25 minutes.’’

A tasty treat, and one that’s available to Shore anglers in winter as well as in spring, when Kamloops (and steelhead) return to the rivers of their births — or what they believe are the rivers of their births.

Yet in what numbers Kamloops will be available in coming years to North Shore anglers is uncertain.

One reason is that the Department of Natural Resources (DNR) announced last year that its French River hatchery will close. The facility needs about $8 million in repairs, the agency said, and consumes too much energy warming the Lake Superior water necessary to produce Kamloops rainbows, as it has in the past.

Looper production will instead move entirely to the DNR’s Spire Valley hatchery, where fry, or baby fish, will be raised to about 4 or 5 inches long.

Some Loopers have been raised at Spire Valley since 2010. But they were always returned to the French River hatchery at about 4 or 5 inches to grow a few additional months and imprint to that North Shore stream before being stocked as yearlings there and in the Lester.

Now the 4- or 5-inch Kamloops produced at Spire Valley will be planted at that size upstream in the French and Lester rivers, where the DNR hopes they imprint, assuming they are big enough to survive.

If they survive but don’t imprint proportionate to their stocking numbers, some will scatter throughout Lake Superior, rather than returning to the French or Lester rivers in their third years, diminishing the North Shore Looper fishery.

“We want those fish to come back to the Lester and the French,’’ said Cory Goldsworthy, DNR Lake Superior area fisheries supervisor stationed at French River.

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While Overby and Twyford fished Monday morning, Goldsworthy and other DNR staff seined a few hundred Kamloops from the French River, along with a relative handful of steelhead. Eggs would be stripped from some of these fish and fertilized.

Except that hatchery-reared Kamloops have a fin clipped to identify them, these fish are virtually indistinguishable from steelhead — in more ways than one.

“What we’ve learned,’’ Goldsworthy said, “is that some Kamloops rainbows are naturally reproducing in Lake Superior, and some are interbreeding with steelhead.’’

This discovery, made possible by recent developments in genetic testing, raises concerns that Lake Superior’s “wild’’ steelhead — which have their own well-organized constituency — might not be entirely that.

Fisheries experts worry that hybridization might also compromise the steelhead brood stock the DNR keeps for egg collection and fertilization. To avoid this, they’re testing scale samples of these fish to determine strain purity.

All of which, Goldsworthy said, is part of a constantly changing complex web of Lake Superior life that includes not only Kamloops and steelhead rainbows, “but herring, whitefish, lake trout and sea lamprey,’’ among other species.

As Goldsworthy spoke, not far away, Overby and Twyford fished.

Like scores of other anglers on the North Shore on Monday morning, they cast waxies, spawn bags and other baits into Lake Superior, wanting only to feel a strike — and to catch a Looper.