Injection Tagging Makes Salmon Studies Safer

Understanding salmon and other fish migrations has always been very important to conservationists, especially for species whose treks may be made harder by hydroelectric dams. Now a new tiny and injectable device may help experts better understand how these dams stress these fish, providing data that could lead to more fish-friendly systems in the near-future.

That's at least according to a study recently published in the journal Scientific Reports, which details how this novel fish tracker could help improve the accuracy of essential data and make life easier even for test subjects.

This, of course, is not exactly the first tracking device that helps researcher gather data on migrating salmon. Researcher from the Pacific Northwest National Laboratory (PNNL) in the United States have been using "sensor fish" for years. These fish-sized devices are regularly released upstream of hydro electric dams in order to help researchers determine what kind of trauma newly spawned salmon and other migrating fish might experience when passing around turbines and other unnatural obstacles. The original sensor fish even looked like a fish!

However, there is only so much researchers can learn by tossing a "dead" rubber fish through tumbling water. After all, real fish swim, and may actions that might help them survive the trip, or endanger them further.

To better understand what this behavior could entail, researchers in the past used to slit open the bellies of some salmon and insert a tiny tag, called a Juvenile Salmon Acoustic Telemetry System (JSATS). The US Army Corps of Engineers, which operates dams in the Pacific Northwest has used data from these tags to help craft modern "salmon friendly" turbines since 2001, but researchers have long been concerned that this data wasn't exactly accurate.

After all, a subject may not swim like your average salmon after having a heavy foreign device surgically implanted in his body.

That's where the latest injectable JSATS comes in,  being three times lighter and significantly smaller than the tags used in 2007. (Scroll to read on...)

"This is the first acoustic transmitter that can be inserted with a simple needle injection," Zhiqun "Daniel" Deng, a scientist at the Department of Energy's PNNL explained in a statement.

He added that the new tag already proved its usefulness in 2013, when about 700 juvenile salmon boasting the tag were released in the Snake River in Washington state. Initial results showed survival was higher in fish carrying the injectable tag than those with the older tag, indicating that it has less of an impact on fish behavior and thus can lead to more accurate data.

Research is still ongoing to fully evaluate how the tags affect fish and to determine the smallest fish that is suitable for safe injection tagging.

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