© 2024 | Jefferson Public Radio
Southern Oregon University
1250 Siskiyou Blvd.
Ashland, OR 97520
541.552.6301 | 800.782.6191
a service of Southern Oregon University
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Drought Allows A Salmon-Killing Parasite To Thrive In The Klamath

Two technicians balance on a floating fish trap about the size of a double bed. They dip nets into the water and scoop out small fish and mats of vegetation. The fish are carefully placed in five-gallon buckets and the weed is casually tossed back into to river.

The U.S. Fish and Wildlife techs are recording their catch from shallow side channel of the middle Klamath River. They're observing variety, inspecting the fish for signs of trouble, and packing up hatchery for disease testing at a lab.

“We’ve got a number of dead fish. Some of them are from disease. Some of them look like they’ve been ravaged by lamprey,” says USFWS fish biologist Steve Gough, who has been overseeing fish sampling on the Klamath.

It’s the disease biologists are worried about. More than half of the 3-inch long chinook in the trap are either dead or showing signs of a serious parasitic infection called of Ceratanova, or “C” shasta. Gough says the fish likely picked up the parasite at a hot spot just a little ways upstream from the trap.

“They were most likely infected and on there last fin floating in,” he says.

C. shasta is naturally present in major river systems throughout the Northwest, from the Cowlitz to the Columbia, Willamette and Deschutes, and all the way down into central California.

But this year, the Klamath River has been like a tropical resort for the parasite. It’s warm and lazy with a steady buffet of the two hosts it needs to complete its life cycle: the tiny, nearly invisible polychaete worm and the chinook salmon.

Klamath River water tests have shown parasite levels there more than 10 times greater than the level known to cause fish death. And nearly 100 percent of chinook caught in this fish trap in early May were infected.

Biologists warn that a fish kill is likely to occur. June is a critical time for the young fish.

“What we really want is for them to get out of the river before it gets too warm, but some fish aren’t growing quickly enough for that to work out,” says Alex Corum, a biologists with the Karuk tribe.

And the fish keep coming. Over the past few weeks, the Iron Gate Hatchery in Northern California released more than five million juvenile chinook, the backbone of the Klamath salmon fishery.

Biologists believe few will escape infection. Infection does not always cause death, but the warm, low river flow means fish are weaker and they’ll remain in the kill zones longer. Many young chinook will die.

“Any increase in flow in a drought year is going to be beneficial to the situation,” USFWS’s Gough says.

But aside from rain, the only place that water could come from far upstream – the Link River Dam.

Bureau of Reclamation Klamath District Manager Therese O’Rourke Bradford walks along the Link River Dam, which controls water flow out of Upper Klamath Lake in Oregon. A nutria scurries out of the way, disappearing over the side.

“Water is extremely restricted. It’s restricted for the fish, whether that be the suckers or the salmon. It’s extremely restricted for the irrigators,” O’Rourke Bradford says.

The dam is there to serve Klamath Project irrigators. Because there’s no snowpack, the farmers are only slated to get about half the water they need.

A 2013 joint biological opinion requires Reclamation to release a minimum average flow to keep the fish alive. But when scientists with the Klamath Fish Health Assessment Team – or KFHAT- requested an additional pulse flow to help disperse the parasite and get the fish downstream, Reclamation said “no,” they didn’t have enough.

“It’s not something that we make a decision and put it on the shelf. We are literally meeting every single day, talking about fish, talking about irrigation, talking about the needs. Every single day,” O’Rourke Bradford says.

She adds that the Bureau of Reclamation will consider future requests for additional water releases as they come.

In the event Reclamation’s daily decisions don’t lead to the release of enough water for salmon, agencies downstream are planning for the worst.

On the breezy bank of the Salmon River, a tributary of the Klamath, field technicians from a multitude of state, federal, non-profit and tribal agencies are being trained on how to respond to mass die-off of fish.

At this point, not only are the trainees concerned about the juvenile fish that are dying from the C. Shasta parasite, they’re worried about the adults returning this fall.

Weighing on everyone’s mind is the death of tens of thousands of adult chinook in 2002. Craig Tucker is the Natural Resources Policy Advocate for the Karuk tribe.

“September is when the Yurok and Karuk people are doing World Renewal ceremonies, and it’s when the active fishery is going on. And to see 70,000 adult salmon to go belly up in the river was a traumatic experience, to say the least, for people,” he says.

Tucker says one way to prevent this from happening again is to implement the Klamath Restoration agreements, which would lead to the removal of several dams on the river.

But for now fish scientists are struggling deal with the present situation – making sure no one is blindsided by a mass fish kill. Aside from requesting more water releases from Upper Klamath Lake, technicians on the river can do little to prevent a kill.

But at least this time around, California Fish and Wildlife Biologist Sara Borok says they’re much better prepared to respond.

“Now we can see it building from now. We have an idea, if we don’t get water this year, we could be in a world of hurt again.”

Copyright 2020 EarthFix. To see more, visit .

<p>A juvenile chinook salmon from the Klamath River shows signs of parasitic infection and disease.</p>

Jes Burns, OPB/EarthFix


A juvenile chinook salmon from the Klamath River shows signs of parasitic infection and disease.

A number of dead fish floated to the surface of the murky Klamath river.

Jes Burns, OPB/EarthFix


Fish biologists and technicians gather on the Salmon River in California for a Fish Kill Response training.

<p><span style="font-size: 12.0pt; font-family: Cambria; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 'MS 明朝'; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi; background: white; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">Bureau of Reclamation Klamath District Manager Therese O&rsquo;Rourke Bradford at the Link River Dam, which controls water flow out of Upper Klamath Lake in Oregon.</span></p>

Jes Burns, OPB/EarthFix


Bureau of Reclamation Klamath District Manager Therese O’Rourke Bradford at the Link River Dam, which controls water flow out of Upper Klamath Lake in Oregon.

Jes Burns is a reporter for OPB's Science & Environment unit. Jes has a degree in English literature from Duke University and a master's degree from the University of Oregon's School of Journalism and Communications.