USGS researchers at the Idaho Cooperative Fish and Wildlife Research Unit (Idaho CRU) and graduate students at the University of Idaho are working with Idaho Fish and Game (IDFG) on projects focused on better understanding the dynamics of steelhead fisheries in Idaho. These projects are highly collaborative, with IDFG identifying the most relevant research questions and providing support for public outreach about the projects and the Idaho CRU taking the lead in development of the research tools needed to effectively manage the steelhead fisheries in the state.

Public Domain, Idaho Cooperative Fish and Wildlife Research Unit

A Salty Rainbow Trout

Steelhead are rainbow trout known for their long migrations. Like Pacific salmon, steelhead are born in freshwater and migrate to the ocean where they spend one to three years growing to large sizes before ultimately returning to their home freshwater streams to spawn. In addition to growing large, steelhead become somewhat stubborn after spending time in saltwater. As such, catching a steelhead is the pinnacle angling experience for many anglers.

Popular Sportfish

Given the iconic status of steelhead, it is no surprise that anglers get excited about these fish, and some are particularly passionate about wild steelhead. Steelhead are important from an economic perspective where steelhead fisheries bring in hundreds of millions of dollars annually to Idaho communities. Steelhead also play an important ecological role and are a critical part of the cultural identity of the region.

Delicate Balancing Act

Wild steelhead numbers have declined in many parts of North America; 178 populations were petitioned in 1994 for protection under the Endangered Species Act (ESA). As a result, wild steelhead in Idaho, southeastern Washington, and northeastern Oregon, which comprise the Snake River distinct population segment, were listed as threatened under the ESA. The primary goal of the IDFG and other state agencies such as the Oregon Department of Fish and Wildlife and Washington Department of Fish and Wildlife in managing steelhead is to conserve and restore steelhead runs to the benefit of all users.

Providing angling opportunities while also conserving federally listed wild steelhead might seem like conflicting goals. State agencies are permitted by federal agencies to manage fisheries targeting hatchery steelhead (distinguished by a fin clip) that minimize “impact rates” on wild steelhead. The impact rate is the proportion of the wild steelhead population that dies because of being caught and released in the fishery.

Throughout the northwestern U.S., steelhead, along with Pacific salmon, support incredibly popular sport fisheries. Nowhere is this more apparent than in Idaho where anglers travel from around the world to target trophy steelhead.

Steelhead runs over the last two decades have varied, but reduced runs have heightened concern about the potential negative effects of angling on wild fish. The concerns have culminated in threats of litigation and possible fishery closures, thereby increasing attention and scrutiny on management of recreational steelhead fisheries in the region.

Science Needs

Managers were missing several important pieces of information needed to fully address concerns. First, those challenging recreational fisheries argued that anglers encounter wild steelhead more often than hatchery fish such that impact rates are underestimated. Second, to account for assumed catch-and-release mortality, natural resource agencies apply a 5% mortality rate to wild steelhead that are caught in the fishery, a rate considered too low by wild steelhead advocates. Collectively, the lack of information on real-world encounter and mortality rates, along with increasingly vocal criticism of assumed rates began to cause concern that there would be legal challenges to the management of these fisheries.

Wild Fish, Hatchery Fish, and Anglers

Idaho CRU graduate students used a combination of radiotelemetry techniques and surveys of the distribution of angler effort to evaluate overlap between wild steelhead, hatchery steelhead, and steelhead anglers in the Clearwater River—a primary destination of steelhead anglers in Idaho. Early in the season, wild and hatchery steelhead were found almost exclusively in the lower portion of Clearwater River. Although effort was low during this period, anglers overlapped with both wild and hatchery fish. As the season progressed into fall, angling effort increased dramatically, and anglers followed hatchery fish as they moved upstream. Consequently, anglers focused little effort in the vicinity of wild steelhead, thereby suggesting that impacts to wild fish are minimal. To more directly evaluate possible effects to wild steelhead, an even broader follow-up study was conducted.

Specifically, wild and hatchery steelhead were captured at Lower Granite Dam (Snake River), tagged with an external tag, and released. Reports by anglers of tagged steelhead were used to estimate “encounter rates” (proportion of wild and hatchery fish caught) and catch-and-release mortality of wild steelhead. Across all steelhead fisheries in Idaho, encounter rates of hatchery steelhead were slightly higher than for wild steelhead and catch-and-release mortality was about 1.6%—much lower than the 5% assumed by agencies. The work showed that less than 1% of all the wild steelhead died (impact rate) as a result of the recreational fishery.

Tight Science and Tighter Lines

In light of the threatened status of wild steelhead in Idaho, fisheries for these incredible animals are not legally possible without both the hatchery programs and effective science to ensure that fishing impacts on wild fish are minimal and acceptable. The body of work briefly presented here provided agencies and policymakers with the information needed to respond to concerns and to responsibly manage impacts of recreational angling on federally listed wild steelhead. The success of the effort was a product of close collaboration between the Idaho CRU and IDFG, as well as support from tribal and federal resource agencies. Using science to guide management is paramount for maintaining trust of the public and ensuring that fisheries are sustainable. Using science is especially important when the stakes are as high as they are with steelhead. Fortunately, Idahoans and anglers that visit from around the world continue to have the opportunity to tangle with steelhead.

The ONB features articles from Cooperative Fish and Wildlife Research Units across the country. We believe our readers will appreciate discovering stories about the exciting fish and wildlife research projects that Unit scientists are conducting to solve real-world problems, engage graduate students in experiential learning, and deliver technical assistance to natural resource practitioners. This story was authored by Matthew Corsi, Fisheries Research Manager, Idaho Department of Fish and Game, Michael Quist, Assistant Unit Leader, Idaho Cooperative Fish and Wildlife Research Unit, and edited by Dawn Childs, U.S. Geological Survey Information Specialist, Cooperative Fish and Wildlife Research Units.