Klamath trout journey toward the future

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.

[caption caption="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.)"] [/caption]

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?

[caption caption="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.)"] [/caption]

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.