Columbia, Snake, Willamette Dams
by Anthony Kuipers
Multi-million dollar grant for checking salmon, trout and lamprey migration
University of Idaho researchers want to make it easier for native fish to pass through dams along the Columbia and Snake rivers. This includes not only the precious populations of salmon and steelhead, but also another species that may be most harmed by these structures: Pacific lamprey.
Chris Caudill, assistant professor in the UI Department of Fish and Wildlife Sciences, is leading the effort to study the relationship between dams and the well-being of these fish.
"The primary objective is to understand how adult salmon, steelhead and lamprey are migrating upstream through fish ladders and around dams," said Caudill.
The study, which will take place this summer, is being funded by a $2.7 million grant from the U.S. Army Corps of Engineers.
One major component of the research includes making fish ladders, or passages that allow fish to get through dams, more accommodating to Pacific lamprey.
Caudill said many fish ladders in the area were designed for salmon and steelhead, fish that are able to swim long distances at a high speed. This has hindered the migration patterns for the less-capable lamprey, a species of nocturnal, eel-like fish. Caudill said the lamprey population has declined substantially in recent years due in large part to their inability to navigate past dams.
Last winter, UI grad students designed new fish ladders specifically for lamprey at the Bonneville and John Day dams along the Columbia river. Caudill said lamprey use their sucker mouths to attach to surfaces as they travel along the river bottom, so the new design includes a 45-degree ramp they can latch on to as they ascend upstream. This summer, the researchers will evaluate the success of that design to determine if it should be implemented at other dams.
Caudill said many are concerned about the fate of lamprey because, while they are not as desirable to consumers as salmon or trout, they are just as important to the ecosystem and highly valued by local tribes. The Bonneville Power Administration website said Native Americans historically collected lamprey for medicinal purposes as well as food.
To further understand how the fish are faring as they travel long distances through multiple dams, researchers will tag and monitor Pacific lamprey, steelhead and Chinook salmon using radio signals. Caudill said radio tags will help them track the fish while acoustic monitors, which send out signals much like an ultrasound machine, will let them view the fish as they travel through the fish ladders.
Another part of the study includes catching, tagging and releasing Chinook salmon in the Willamette River in Oregon. Caudill said salmon populations travel to spawning grounds in that area, but often "more than half" die before they are able to reproduce.
The researchers do not know the exact cause of this, but Caudill said it could be related to the numerous high dams along the river that do not have fish ladders . Since the fish cannot get through these dams, Caudill said the fish must be collected and transported around them. This could have an adverse effect on their survival, Caudill said. He also pointed to warming water temperatures and climate change as potential explanations.
(bluefish notes: Caudill provides more detail informing us that "in the Willamette there are several dams in several separate drainages (e.g., Foster, Cougar, Dexter, Fall Creek dams) where fish return to collection facilities at the bottom of the dam and are transported around. In several cases, it is a single dam the fish encounter.")
According to a UI news release, the fieldwork will be conducted this summer and analyses and preliminary findings will be published in 2014. Researchers will be assisted by the UI Echohydraulics Research Laboratory in Boise, the National Marine Fisheries Service, the U.S. Forest Service Rocky Mountain Research Station, the Oregon Department of Fish and Wildlife, and Oregon State University's Cooperative Fish and Wildlife Research Unit.
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