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When a trout’s not a trout

SHADY COVE — While fly-fishing for cuttroat trout on the upper Rogue River, angler Chris Glogtson hooked and landed a fish that defied an easy definition.

It had a clipped adipose fin, so it was definitely a product of Cole Rivers Hatchery. But it was 11 inches long, with broad shoulders and the markings of a steelhead.

Too big for a steelhed smolt headed to the ocean, and too small for a halfpounder steelead. And fin-clipped trout are not stocked in the mainstem Rogue, so what could it be?

“There are definitely some fin-clipped trout in the river,” Clogston says. “The mystery is where they came from?”

State fish biologists are hoping Clogston and other upper Rogue anglers can help determine where these hatchery rainbow trout are coming from, but it’s not to make more of them.

It’s to reduce their numbers, because these fish are most likely steelhead smolts released from Cole Rivers Hatchery that for some reason didn’t head to the ocean and instead reverted to resident river trout.

The official term for these trout is “residualized,” and the agency charged with growing more steelhead wants to learn why these former steelhead didn’t live up to their piscatorial expectations.

Oregon Department of Fish and Wildlife biologist Ryan Battleson is embarking on a genetic study to determine the origin of these steelhead-turned-trout. Specifically whether they are part of steelhead smolt releases as either summer-run or winter-run steelhead from Cole Rivers Hatchery on the Rogue near Trail.

Learning their origin can help biologists and hatchery technicians perhaps determine why hatchery fish raised to be steelhead are reverting to trout status on the Rogue.

“Our goal is to figure out what fish are residualizing,” Battleson says. “We want to make more steelhead, not residual trout.”

Battleson is in the early stages of a three-year study to figure out what turns a steelhead into a trout, using angler-collected fish for sampling.

Anglers can keep five fin-clipped rainbow trout a day on the Rogue, and Battleson has the authority to extend that limit for specific anglers helping out on the project.

Learning their origin could lead to changes in how hatchery technicians grade and release steelhead smolts, Battleson says.

Already hatchery technicians cull the smaller “grunt” steelhead smolts and larger males for release in local reservoirs.

Figuring out which hatchery-released steeelhead are residualizing is one of the goals of a new draft plan for managing wild and hatchery steelhead in southwest Oregon streams.

The logic is simple. Cole Rivers Hatchery spawns, rears and releases steelhead smolts under the intention of creating returning adult steelhead for anglers to catch and keep in a river-wide, multimillion dollar fishery once made popular by Zane Grey.

Those smolts generally are raised up to two years at the hatchery and released to the Rogue to join their wild brethren in a run to the ocean called “smolting.”

Research shows that steelhead smolts physically change during the process, growing longer and leaner in their rush to salt water.

Researchers also know that those young steelhead that are either too big or too small don’t always make that smolting process, triggering the residualized rainbows caught by anglers like Clogston.

“We obviously have reports of anglers catching fin-clipped rainbow trout in the upper Rogue,” Battleson says. “We just want to know what they are.”

Identifying their origin will give biologists an idea on how to reduce that funky life-history.

Possibilities are sorting young steelhead earlier to get larger fish into the river sooner or perhaps keeping undersized fish longer at the hatchery before release.

Either way, biologists want Glogston and other anglers to catch that hatchery fish as a larger adult steelhead than a smaller legal rainbow.

“Our goal is to make steelhead, not residualized trout,” Battleson says.

Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or mfreeman@rosebudmedia.com. Follow him on Twitter at www.twitter.com/MTwriterFreeman.