The Pacific Northwest National Laboratory has developed a new "super small" battery and acoustic tag to track fish so biologists can study younger fish and smaller species.

The Eel/Lamprey Acoustic Tag, or ELAT, is the size of a grain of rice but with twice as much energy as a AAA battery, according to PNNL.

The new tag was developed over the past decade in part to study Pacific lamprey, a sensitive species in the Columbia Basin that has experienced significant declines.

"Pacific lamprey are difficult to research and are, therefore, understudied," PNNL Earth scientist Stephanie Liss said in a news release. "There's a lot we still don't know about them, and this tag opens the door to learning more about their behavior."

In addition to lamprey, the tags have been tested on Chinook salmon migrating to the ocean in the Columbia River. Scientists determined that fish as small as 2.3 inches can be tagged without impacting their ability to swim. Previously, only fish larger than 3.7 inches could be tagged without affecting their mobility.

The smaller battery and tag will allow scientists to tag and study the downstream survival rates for lamprey, and smaller or younger salmon and steelhead.

In studies, the tags worked in a variety of settings, from shallow water to tailraces at hydroelectric projects. Nearly all of the fish studied retained their tags, survived and had the same growth rate as untagged fish, PNNL says.

The smaller battery with more energy lasts 30 days and provides an acoustic signal that pulses every five seconds over the length of a football field. Costs of the tag are similar to other acoustic tags, which were also originally developed by PNNL.

"This tag opens up possibilities to track movement of a variety of species and life stages that we were previously unable to study," said Daniel Deng, PNNL fellow and mechanical engineer who led development of the new device.

PNNL says the information gained from studying lamprey and younger salmon will help support sustainable hydropower by informing future design and operations.

Work to develop the new tag was funded by the U.S. Army Corps of Engineers and the U.S. Department of Energy's Water Power Technologies Office. PNNL's Laboratory Directed Research and Development program funded the study on its use in Chinook salmon.

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K.C. Mehaffey covers fish issues for Clearing Up, and is editor of the NW Fishletter. She joined the NewsData writing team in February 2018. From lawsuits to scientific studies, she is enjoying the deep dive into the Columbia Basin's many fish topics.