Aquaculture for all

Biomarker Detects Brain Injury in Salmon

Salmonids Health Welfare +4 more

US - A protein biomarker under development to detect traumatic brain injury in humans can also reveal the same injuries in salmon that struggle to migrate in freshwater rivers, according to a study by the Department of Energy's Pacific Northwest National Laboratory.

This is the first time that a human biomarker has been used to determine injury risks in wildlife. The findings, from a 2006 study of juvenile Chinook salmon in the Snake River, could provide a way to more accurately examine how hydropower operations impact fish survival.

"This demonstrates a paradigm shift in how we do wildlife assessment," said study co-author Ann Miracle, a PNNL biologist. "It's a completely new tool for us."

Fish biologists can use the biomarker to determine if salmon receive traumatic brain injuries while passing through hydroelectric dams. That conclusion came from Miracle and her co-authors from the University of Florida and a Florida biotech company, whose collective study on salmon is being published in Public Library of Science ONE, also known as PLoS ONE. A biomarker is a naturally occurring substance or process that scientists use to diagnose a biological condition.

Every year, hundreds of thousands of salmon traverse the Northwest's Columbia Basin, where 13 different salmon and steelhead populations are endangered or threatened. There's a significant debate about the role dams might play in the economically and culturally important fish's decline. There are about 2,500 hydropower dams across the country, 15 of which dot the Columbia and Lower Snake rivers. Nationwide, a total of 29 different salmon and steelhead populations are threatened or endangered.

Until now, the only way to measure the trauma that salmon experience has been to count their deaths or look for physical injuries like missing scales or blood-shot eyes. But the biomarker studied can also detect non-lethal brain trauma, which can't always be seen. The study found high levels of the biomarker in up to 20 percent of the fish even though they appeared to be healthy during a visual inspection.

"This biomarker shows great promise," Miracle said. "We're excited to keep investigating it so it can eventually help dam operators scientifically prove how their facilities can aid salmon survival."

Miracle plans to continue her work by examining the connection between salmon biomarker levels and the severity of traumatic brain injuries, as well as determining the long-term outcomes for salmon injured while migrating through various sections of dams.