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Klamath trout journey toward the future

Klamath trout journey toward the future
How they cope in an unlikely environment

In the Klamath Basin, we can study the future, here and now. And that’s exactly what Jonny Armstrong is doing, as he tracks the movements of Klamath’s legendary redband trout as they navigate through a remarkably transformed basin.

Trout are cold-water fish, related to salmon. Klamath Lake in the summer—with low dissolved oxygen, high alkalinity, and temperatures approaching 80 degrees—would seem to be an unlikely place to find redbands, which are among the world’s largest rainbow trout. “These trout are living in a system now that resembles conditions that might be more common in the future, with climate change,” Armstrong said.

Bill Tinniswood with redband trout

Bill Tinniswood, a biologist with Oregon Department of Fish and Wildlife, tags a hefty Klamath redband trout for a study he’s conducting with OSU biologist Jonny Armstrong. (Photo by Jonny Armstrong.)

Armstrong is tracking these remarkable trout (some are up to 28 inches long) to see where they go and how they cope with the challenges of living in this huge, shallow lake, cut off from the sea. As a new assistant professor in the College of Agricultural Sciences, Armstrong is in his first year of research, working with collaborators in the Oregon Department of Fish and Wildlife. His previous research was in Alaska, where sea-run salmon are ubiquitous in cold, clear rivers. Redband trout in the Upper Klamath Basin grow as big as their sea-run cousins, but how?

Williamson River

The Williamson River, a groundwater-dominated tributary of Klamath Lake, is where most of the tagged fish were found to spend their summers. (Photo by Jonny Armstrong.)

Tagging trout in late spring, Armstrong’s team has mapped fish moving across the lake and up into crystal-clear streams on the shoulders of the Crater Lake volcano. There they remained until early autumn. “These fish take a summer vacation,” Armstrong said, “but they need to work the the rest of the year to pay for that vacation.” It appears that redband trout feed voraciously in the lake in spring and fall, growing fast and putting on the fat they will need to survive on a much leaner summertime diet in the tributaries.

“In the future, much more of our state could look like the Klamath, with river stretches that are completely unusable for fish during parts of the year,” Armstrong said. “To survive, fish will need to be migratory. And the basins in which they live will need to have cold-water refugia where fish can escape summer heat, as well as highly productive areas where fish can fatten up during the spring and fall.”

Armstrong’s study challenges the long-held notion that salmon and trout habitat is all about cold water. “Places that are lethally hot during summer may be critically important because of the role they play in other seasons,” he said.

Published in: Ecosystems, Water