It's all to track trout in one of the largest Superfund sites in the United States, and "It's awesome," said the Montana State University graduate student in ecology.
Mayfield - the recent recipient of a prestigious Environmental Protection Agency fellowship -- is studying trout numbers, habits and habitat in 120 miles of river and tributaries between the Warm Springs ponds and Missoula.
After two summers on the river and year-round monitoring from Bozeman, Mayfield said she has gotten to know 249 trout so well that she knows the holes they frequent and when they roam. She knows which trout were snatched by bald eagles and carried up to nests. She knows when she's lost trout for other reasons, such as anglers, irrigation ditches, osprey, great blue heron, water quality or heat.
"A big part of our project is looking at the survival of these fish," Mayfield said.
An Ashland, Ore., native who graduated from Ashland High School and Willamette University in Salem, Ore., Mayfield is collecting information for her master's degree and also to assist the Montana Department of Fish, Wildlife and Parks.
MSU ecology professor Tom McMahon -- Mayfield's adviser and co-principal investigator of MSU's study -- said the FWP's fisheries group in Missoula is carrying out a two-phase project to restore native trout populations in the Clark Fork River. Mayfield's field work will guide one phase of the project. Field work conducted by MSU graduate student Joe Naughton will guide the other phase. Naughton's work is overseen by Bob Gresswell, co-principal investigator of MSU's study and an MSU affiliate employed by the U.S. Geological Survey. Naughton's field work focuses on the Silverbow Creek that runs through Butte to the Warm Spring ponds.
"It was basically fishless for 100 years," McMahon said of Naughton's study area.
Mining and smelting in the early 1900s sent arsenic, cadmium, copper, lead and zinc into the Clark Fork River, largely eliminating trout from the river basin. The upper Clark Fork River was designated a distinct part of the Milltown Reservoir Superfund Site in 1992. Mayfield said heavy metal concentrations remain high in the soil, and at different times of the year, those concentrations increase in the water. Copper, for example, still exceeds the levels recommended by the EPA for fish health. Spring runoff carries heavy metals from the soil into the river.
One purpose of her study is to see if fish avoid or select habitat according to those concentrations, Mayfield said.
Most of the trout in her study are brown trout, but others are westslope cutthroat trout, rainbow trout and bull trout, Mayfield said. Some of them seem to have a hard time avoiding predators, maybe because heavy metals have affected their nervous systems, Mayfield noted.
Mayfield's work so far has involved catching trout (100 during 2009 and 149 in 2010), inserting radio transmitters the size of a AA battery, and monitoring the fish from near and far. Assisting in her project are several FWP employees, other MSU graduate students, an undergraduate assistant, and McMahon.
To locate the tagged fish during the summer, Mayfield camps near Warm Springs and moves up and down the river, carrying antennas by hand or on top of a vehicle. McMahon noted that the heavy metals pose a greater danger to the environment than to human health.
"We track the fish every week because we're interested in long-term movement in relationship to different environmental features unique to the area," Mayfield said.
Mayfield recently received the EPA's Science To Achieve Results (STAR) Graduate Fellowship, which will allow her to expand her work. Hers was one of 10 such awards given to master's degree students across the nation and one of 138 given to all graduate students in 2010. It was the sixth STAR award given to an MSU graduate student in the past five years, with the previous winners being Timothy Covino in 2009, Crystal Richards in 2008, Lisa Bithell Kirk in 2007; and Mary Eggers and Kristin Gardner in 2006.
Mayfield's award gives her $37,000 a year for up to two years, which will allow her to collect more water quality data, specifically about heavy metal concentrations, Mayfield said. It will allow her to explore some of the survival aspects of trout. It will send her to Washington, D.C. in the fall of 2011 to present her work to officials from the EPA and other federal agencies.
The work she is doing on the upper Clark Fork River - in spite of mosquitoes, spring snowstorms and radio tags that end up in eagles' nests - is rewarding, Mayfield said.
"Ecology research is really fun," she said. "It's really great to be out in the field and to figure out how things are linked to the environment.
"At the same time, ecology research is really hard," she said. "I'm not in a laboratory. I can't manipulate water quality or what the fish are doing. Instead, I have to wait and observe and see what the fish do."
Mayfield said she knew after earning her undergraduate degree that she wanted to study native trout or salmon restoration. She said she wanted to attend graduate school at MSU because it's one of the top fisheries schools in the Northwest.
"It was a great decision," she said.
Mayfield noted that her research builds on interests that were sparked when she was a 16-year-old fisheries intern with the Bureau of Land Management in southern Oregon. Her MSU project also prepares her for the career she wants after receiving her master's degree in May 2012. Mayfield said she hopes to hopes to work in the Pacific Northwest on native cutthroat trout or salmon restoration or the restoration of their habitat.
For a related story on two previous STAR winners at MSU, see "MSU/Crow project helps diagnose water issues on reservation."
Evelyn Boswell, (406) 994-5135 or email@example.com