You asked: Why can’t I harvest bull trout when they’re plentiful in Idaho?

This story is part of our Curious Idaho series, where you vote on questions submitted by readers, and then we investigate the winning question for a story. Recently, we asked what questions you had about Idaho’s outdoors.

Justin Jones, of Boise, asked this: How did bull trout become endangered? Who sets the recovery goals? At what point would they be considered to come off endangered species?

Justin Jones has been fishing Idaho’s waters for years, long enough to know that there’s one sport fish you can’t keep: the bull trout.

In 1999, the U.S. Fish and Wildlife Service listed the fish as “threatened” — not quite endangered, but well on the way to it. So Jones was surprised when his fishing trips to mountain streams and along the South Fork of the Boise River yielded fewer of the rainbow trout he’d become accustomed to and more bull trout that must be tossed back into the water.

“Recently, I have noticed a large increase in the bull trout population and decrease in the rainbow trout population,” Jones said in an email to the Statesman. “The last few years in particular, there were days where the only fish we caught were bull trout, including some really nice fish up to 30 inches in length.”

Does this mean the fish are finally making a comeback? The answer is complicated, according to Jeff Dillon, state fisheries research manager for the Idaho Department of Fish and Game.

Threatened or thriving?

When the fish were first listed, it was due to threatened populations along the Puget Sound, the St. Mary-Belly River area of the Montana-Canada border, the Jarbidge River in Nevada, the Klamath River in Oregon, and the Columbia River in Washington and Oregon.

Bull trout, a type of char, are very sensitive to habitat change. They prefer much colder water than many fish species and require clean streams for spawning, as well as well-connected waters for migration.

“Habitat alteration, primarily through construction of impoundments, dams and water diversions, has fragmented habitats, eliminated migratory corridors and isolated bull trout,” the Fish and Wildlife Service wrote in 1999.

But in Idaho, where bull trout live mostly in undeveloped wilderness or mountain areas, there wasn’t much worry for the fish.

“We did not have good information on bull trout [in the ‘90s],” Dillon said. “We weren’t concerned, but we didn’t know much about them.”

The Fish and Wildlife report didn’t prove that Idaho’s bull trout populations were in trouble — but with little data, Idaho couldn’t prove the fish weren’t in trouble. It was enough to allow Fish and Wildlife to declare the species threatened across the entirety of its range.

For the next 15 years, U.S. Fish and Wildlife researched and proposed recovery plans for the species, finally settling on a strategy that was approved in 2015. Dillon said the delay is a testament to the complexity of the bull trout conundrum.

It also served as an opportunity for Idaho Fish and Game to collect valuable information about the bull trout populations in the Gem State. Dillon said he hopes the agency’s findings will be a step toward delisting some of the fish, allowing anglers to harvest some of their catches.

“Idaho’s argument is that most Idaho bull trout populations are secure,” Dillon said. “As we’ve learned more about bull trout in Idaho, our populations are doing well. We don’t believe they’re in danger of going extinct at all. But the weakest link keeps them on the list.”

The road to recovery

The Fish and Wildlife recovery plan is threat-based, Dillon said. That means threats are identified for each population unit where bull trout live so unique factors can be addressed. Bull trout will be eligible to come off the threatened species list when Fish and Wildlife feels the threats for each population have been appropriately mitigated — which is no easy task, considering the threats include everything from dams to warming trends in waterways.

According to Dillon, Idaho’s population units show thriving bull trout populations — and, in some places, such as the Snake River and Salmon Basin areas where Jones fishes, increasing numbers. He attributes much of that to an ideal habitat that includes cold mountain streams and vast, well-connected waterways.

But that doesn’t solve the issue for other habitats.

“There are fewer bull trout now than 100 years ago,” Dillon said. “Those smaller, isolated populations remain at risk.”

The solution, he said, is not to declare all bull trout stable but to look at the 600 nationwide population groups individually.

“We feel our portion of bull trout distribution is in good shape,” he said. “We’d like to find a way to delist the populations that are doing well.”

That’s easier said than done thanks to the way the species was originally listed: as a contiguous unit rather than separate threatened populations.

“Unringing that bell is the hard part,” Dillon said. “Once they’ve been listed contiguously, it’s hard to break that up.”

What delisting might look like

In spite of the potential challenges, Dillon is optimistic.

“Our recent talks with Fish and Wildlife have been encouraging,” he said. “They really want to move the ball forward.”

He believes the several years’ data on the fish can prove what Idaho officials couldn’t in the 1990s.

“Within the next five years, we will hopefully have made progress in demonstrating most of the bull trout populations in Idaho are recovered and will be here in the future,” Dillon said.

It will be good news not just for the fish but to anglers like Jones, too.

“Anglers do wonder, when they’re fishing in places where these fish are abundant, why they can’t harvest [bull trout],” Dillon said. “It’s not just saving bull trout for the sake of the fish. It has recreational value, too.”

Even if their threatened status is revoked, bull trout would remain under protections, such as harvest limits, similar to other Idaho sportfish.

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Nicole Blanchard is the Idaho Statesman’s outdoors reporter. She grew up in Idaho, graduated from Idaho State University and Northwestern University and frequents the trails around Boise as much as she can.