Biomarker reveals brain injuries in salmon

What's good for human kind is also good for endangered salmon.

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.

Miracle's study evaluated a biomarker called the alpha-II spectrin protein. That particular protein supports cell structure and is broken down when cells are damaged. Miracle's study found higher levels of the protein fragments in cells collected from salmon that experienced traumatic events while passing through a dam.

The biomarker was also used in two studies that examined salmon passage at McNary Dam on the Columbia River and Lower Monumental Dam on the Snake River. The U.S. Army Corps of Engineers' report on the Lower Monumental study can be found online.

Both the Lower Monumental and McNary studies used a PNNL-developed technology called the Sensor Fish, a 3.6-inch sensor that helps evaluate the potentially dangerous conditions fish experience when passing through dam turbines and spillways encountered while migrating to the ocean. The Lower Monumental study found the biomarker was more prevalent in live fish when Sensor Fish recorded collisions with dam structures and intersections of fast-moving water.

"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.

Beyond evaluating salmon dam passage, Miracle also envisions the biomarker being used to assess traumatic brain injuries in marine mammals like whales and dolphins. Some have linked the premature deaths of both animals to underwater sonar testing.

The study was inspired by the work of Banyan Biomarkers, Inc., a Florida biotech firm that is investigating the same biomarker's use in humans. The firm announced a Department of Defense-funded international clinical study of alpha-II spectrin in 2007. The U.S. military is looking at biomarkers as a way to quickly detect traumatic brain injuries on the battlefield. Banyan has a worldwide exclusive license agreement with the University of Florida to use the biomarker. The firm plans to submit an application to the Food and Drug Administration for a rapid blood test to be used by physicians to detect traumatic brain injuries.

The salmon study was published at 5 p.m. Pacific time Feb. 12 in PLoS ONE, an online journal of peer-reviewed scientific research. PNNL Laboratory-Directed Research and Development funds paid for the initial research.