This article was published on: 10/11/14 12:00 AM
The Oregon Department of Fish and Wildlife will lead the efforts scheduled for the week of Oct. 20 to capture and move redband and brown trout, mountain whitefish and sculpin from isolated pools at Lava Island Falls and release them into the main Deschutes River.
“As irrigation season comes to a close, water’s held back into Wickiup Reservoir, and as the flows decrease, eventually that side channel gets dewatered from the main stem, and it’s very porous substrate, a lot of lava,” said Erik Moberly with Fish and Wildlife. “So the water, once it gets cut off from the side channel, disappears pretty fast.”
Fish and Wildlife will have several biologists and technicians on hand during the one- to two-day operation.
“The extent of the one-mile Lava Island side channel fish rescue and relocation is daunting,” said Brett Hodgson, the department’s district fish biologist. “We will capture as many fish as we can with nets, seines and electrofishing units, if necessary, but it is impossible to rescue all of them.”
Some of the areas where fish may be stranded are up to a half mile from where they can be safely released into the Deschutes.
The captured fish will be placed in five-gallon buckets of water equipped with small battery operated aerators to help provide oxygen. The buckets will be hand-carried up or down the Deschutes River trail to the point of release by the cadre of volunteers.
“Our goal is to save as many fish as possible; however, hauling five-gallon buckets filled with water and fish over rough terrain poses a certain amount of risk for all those involved,” Hodgson said.
To minimize that, Moberly said that they plan to set up a form of “bucket brigade” so that each volunteer won’t have to travel the entire distance, but pass the bucket on to another person.
What may help to reduce the numbers of stranded fish is an experimental plan developed by local irrigation districts and the Bureau of Reclamation.
The plan calls for a slower draw-down of water levels in the river over 12 days rather than the usual two to three days in hopes that more fish may be able to find refuge in the main channel before getting stranded in isolated pools.
“While hopeful this experiment will minimize the fish-stranding issue, ODFW stresses the need for a long-term solution to the water-management issues on the upper Deschutes River,” Hodgson said. “We view this as a water-management issue, not a fish-management issue.”
The current water regime results in much higher summer flows and lower winter flows than were historically present.
Natural flows at the Lava Island site were stable at approximately 1,000 cubic feet per second (cfs).
Under current water management, flows fluctuate between 2,000 cfs in summer and 300 cfs in winter.
That limits the river’s ability to support a healthy trout population.
While fish stranded in the side channel are the most visible symptom of low winter flows, the reduced flows impact the trout population in the entire 55-mile reach of the Deschutes River from Wickiup downstream to Bend.
“Until there is a long-term water management strategy that ensures sufficient winter river flows, the fish face more die-offs into the future,” Hodgson said.
The operation is aimed at avoiding a repeat of the 2013 water draw-down that killed hundreds of fish stranded in a side channel of the Deschutes south of Bend. Fish and Wildlife staff also will collect data on the species, size and number of fish that are rescued.
“We hope to safely move as many fish as possible to the river’s main channel and keep mortality to a minimum,” said Hodgson. “That being said, there will be fish that won’t survive these efforts.”
In 2013 approximately 450 redband and brown trout, and hundreds of whitefish and sculpin, died when falling water levels left them stranded in the natural lava side channel that normally has water only during higher flows.
A similar rescue effort then was able to save about 750 trout.
This year’s effort will come just as water levels are minimal.
“We greatly appreciate the number of people and organizations that are offering to put boots on the ground to help protect fish populations in the Deschutes River,” Hodgson said.
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To volunteer
Volunteer efforts are being organized by the U.S. Forest Service, Bend-Fort Rock Ranger District office to learn more about volunteering call Mike Tripp at (541) 375-0552 or the Bend-Fort Rock District office at (541) 383-4000.