New ‘ichthyograph’ offers deep dive into links between fish and their environment

CORVALLIS, Ore. – A new technique that enabled scientists to display large amounts of data related to fish migration on the North Umpqua River offers a deeper look into the links between migrating fish and their environment.

A research team comprised of researchers in Oregon and California are calling the results of their method the “ichthyograph.” The ichthyographs are color-coded charts that depict stream flow, water temperatures and the timing of upstream migration of fishes using 20 years’ worth of fish counts at the Winchester Dam in southern Oregon.

The team published its results in the journal PLOS ONE: Linking Hydroclimate to Fish Phenology and Habitat Use with Ichthyographs.

“An ichthyograph allows us to understand how multiple fishes use streams as upstream migration corridors,” said Ivan Arismendi, an aquatic ecologist at Oregon State University’s College of Agricultural Sciences and collaborator on the project. “An analogy would be like knowing how drivers merge onto highways without crashing.”

The ichthyographs show the general patterns in upstream migration of six fish species native to the Pacific Northwest – steelhead, sucker, chinook salmon, lamprey, cutthroat trout and coho salmon.

A fish ladder was installed at the dam in 1945 with a viewing window to monitor the upstream passage of all fish past the dam. The Oregon Department of Fish and Wildlife monitored the ladder 24 hours a day from the fall of 1991 to the spring of 2015.

Of particular interest to the researchers was an ichthyograph for the threatened coho salmon, which has declined in southern Oregon and northern California to a population of fewer than 10,000 reproducing adults.

The researchers would like to see similar ichthyographs that could be used in rivers in Oregon and beyond to help fisheries managers track the timing and trends in fish migration. Knowing when the fish are migrating is critical for fisheries regulators when they set rules for commercial and recreational fishing.

“It does not replace counting fish, but instead uses counting fish in an environmental context,” Arismendi said.

The ichthyograph will be useful for fisheries managers as they assess the impacts of climate change or human-related activity such as water control and diversion, floodplain stabilization and road construction, said Rebecca L. Flitcroft, a scientist at the U.S. Forest Service Pacific Northwest Research Station and lead author of the study.

“One of the critical challenges facing fisheries and land managers is assessing the ability of populations to persist in a changing climate,” Flitcroft said. “Climate change is likely to influence both streamflow and water temperature, thereby increasing the potential for physiological stress in fish populations, but climate change is one of many human-related disturbances that may cause changes in river flow and temperature.”

They key life stages of fish, including spawning, are being altered by changes in regional climate patterns and human activities, so it is important to understand how fish respond to hydrologic conditions at different points in their life. The conditions they require at key life stages will help biologists and managers mitigate the effects of future climate change or management actions on aquatic systems.

Flitcroft is a fish biologist with the USDA Forest Service Pacific Northwest Research Station in Corvallis and holds a graduate faculty appointment in the Water Resources Graduate Program and Department of Fisheries and Wildlife at Oregon State.

Collaborators on the project included Sarah L. Lewis and Mary V. Santelmann of the College of Earth, Ocean, and Atmospheric Sciences at Oregon State; Rachel LovellFord of the Oregon Water Resources Department; Gordon Grant of the Pacific Northwest Research Station and Mohammad Safeeq of the Sierra Nevada Research Institute at the University of California, Merced.

The research was funded by the USDA Forest Service Pacific Northwest Research Station.