New Method Offers Direct Detection of Salmon Brain Injury
by Henry Fountain
New York Times, February 13, 2009
The journey of an adult salmon upstream on its way to spawn is not an easy one, but the downstream swim for the juvenile fish is no picnic, either. On rivers with flood-control and hydroelectric dams, like many in the Pacific Northwest, the young salmon are buffeted, subject to sharp pressure changes and otherwise knocked around as they pass through spillways, tunnels and power-generating turbines.
Scientists have studied the effects of this rough treatment for years, with the goal of designing dams and equipment that go easier on the fish. To detect the forces at work, they have used dummy fish containing accelerometers and other devices and have even embedded sensors in live fish.
Now they have a new tool. Ann Miracle, a researcher at the Pacific Northwest National Laboratory in Richland, Wash., and colleagues have shown that it's possible to directly detect brain injury in salmon.
Dr. Miracle said the work had grown out of a discussion with Nancy D. Denslow of the University of Florida, who told her about efforts to quickly detect traumatic brain injury in soldiers by testing for the presence of breakdown products of a protein found in cell membranes. Cell damage releases enzymes that break this protein into smaller compounds. "It struck me that using a physical injury biomarker could be very useful," Dr. Miracle said. But first she had to determine that the same cell-membrane protein and breakdown products occur in salmon. Once that was confirmed, she and her colleagues tested the method on brain tissue from juvenile Chinook salmon that had been through a dam on the Snake River.
They found that by comparing amounts of intact protein with amounts of breakdown products, an assessment of brain damage could be made. This assessment correlated well with sensor data on conditions the fish encountered going through the dam. Their findings are published in the online open-access journal PLoS One.
Dr. Miracle said the goal was to create a nonlethal test that would work the same way it would in humans, by testing spinal fluid for evidence of the breakdown products. "That's a little more challenging in fish," she said, "but we think we can do it."
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