MSU researchers study ways to help iconic fish, agricultural producers

Thursday Oct. 8th, 2020

With a new state-of-the-art facility, Montana State University researchers are starting another chapter in their work to help some of the state's most iconic fish as well as agricultural producers who rely on water diverted from streams.

A recently completed artificial waterway at the U.S. Fish and Wildlife Service's Fish Technology Center on the outskirts of Bozeman will help the MSU team refine their design of small structures that allow grayling and other species to overcome irrigation structures that would otherwise block the fishes' seasonal movements.

"This is really exciting," said Katey Plymesser, assistant professor in the Department of Civil Engineering in MSU's Norm Asbjornson College of Engineering, who is leading the project. "We can test pretty much any fish passage structure here."

The roughly $300,000 facility, funded through the Denver office of USFWS's National Fish Passage Program, consists of a concrete trough with sections of glass that reveal the fish inside, along with pumps and other equipment that allow the researchers to carefully control water temperature and flow rates to simulate a range of stream conditions. In this case, the MSU scientists are interested in whether grayling can use fish passage structures called Denil fishways that have been optimized to work during low water levels.

Grayling inhabit less than 5% of their native range in Montana due to degraded habitat, warming waters and other factors. In the Big Hole River watershed — home of the only remaining population in the Lower 48 of native, river-dwelling grayling — more than 60 full-sized fishways have been installed in recent years as part of a conservation effort involving local landowners, Montana Fish, Wildlife and Parks, the U.S. Fish and Wildlife Service and others. Voluntary adoption of the fishways — metal troughs that span stream obstructions to provide a relatively gentle flow for fish to pass through — has helped to stave off limitations on irrigation withdrawals to protect the fish.

MSU's Fish Passage and Ecohydraulics Research Group, which includes Plymesser, has collaborated on the grayling conservation effort since 2009, including multiple summers of fieldwork that found that grayling were using the fishways as they flocked to cooler waters in the upper watershed. When stream levels were low, however, sometimes there wasn’t enough water flowing through the fishways to allow grayling to use them.

That's where the current project comes in. Backed by a $100,000 grant from the U.S. Geological Survey, the MSU team is redesigning the fishways to use less water while still being big enough for the fish to navigate.

"If we can get the fish to swim through less water, that's a win," said Matt Blank, a member of the study team and a research scientist at MSU's Western Transportation Institute. "We want to find solutions that benefit not only the fish but the irrigators who use the river, and this study is exploring how to do that."

So far the results are promising, he said. When the team visited the Bozeman facility on a clear day in September, civil engineering graduate student Megan Conley reported that eight grayling released into the artificial waterway the night before had all passed through a prototype fishway roughly half the size of those installed in the Big Hole watershed.

"I was super excited," said Conley, who helped design the baffles that slow the water flowing through the fishway's steel trough. "It shows the fish are willing to pass through, which is hopeful."

Conley, along with undergraduate Anthony Bruno, will conduct multiple trials with grayling on at least two scaled-down versions of the fishway this year. Next summer the team will do a similar study with Westslope cutthroat trout, another imperiled species that faces challenges with road culverts and other infrastructure.

"It's been great experience," said Bruno, a sophomore majoring in civil engineering with a minor in water resources. "I feel like I've learned a lot about problem-solving and collaborating with people in different fields."

According to Kevin Kappenman, research fishery biologist at the Bozeman Fish Technology Center, the project is another example of how USFWS and MSU have worked together toward common goals around fish passage research. "Our partnership with MSU allows us to work with some of the top professionals in the hydrology field and tap into expertise outside of our agency," he said.

Other MSU researchers on the project are Joel Cahoon, professor of civil engineering, and Al Zale, professor in the Department of Ecology in MSU's College of Letters and Science.

According to Plymesser, if the study is successful it could lead to swapping out some of the Big Hole fishways to improve passage for grayling while also providing peace of mind for landowners who need water for irrigation but also want to help the fish.

"Our group responds to questions and issues that agencies and other practitioners have," Plymesser said. "That's a big part of our mission, to produce science that helps solve real problems."