For years, scientists at Pacific Northwest National Laboratory have worked on fish tags to monitor salmon. Those original tags weighed around 2 grams, less than what a penny weighs.

Now, new technology has helped to make those tags incredibly small, about the size of a grain of rice. They clock in at about 1/20 of a gram. It’s the latest improvement to help scientists study smaller fish.

“There (are) some species that we want to study but have never studied before. So I call them ‘untaggable,’” said Daniel Deng, a lab fellow who helped develop the tags.

The tags were first designed for American shad, but scientists said it could also open up all sorts of avenues for scientists to study “untaggable fish.”

Shad are invasive in the Northwest. In recent years, shad have jammed up fish passage systems at dams.

But they’ve been hard to study.

“In the fisheries biology field, they joke about American shad,” Deng said. “They say, ‘When you look at them wrong, they die.’”

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The fish are so delicate that scientists at PNNL had to design a new way to transport them from McNary Dam, downriver from the Tri-Cities. Scientists also had to figure out a way to inject the tiny tags into the fragile shad.

“Shad are biologically adapted to be extremely sensitive to sound and movement in the water to avoid predators,” Kate Deters said in a news release. She’s an Earth scientist at PNNL and the lead author on the peer-reviewed publication that details new tagging protocol for juvenile shad.

These tiny tags have tiny microbatteries. The batteries transmit information every five seconds for 50 days. That could help scientists to see how fish migrate through an entire river system before the battery dies, Deng said.

In addition to the microbatteries, the SHAD-TAGS+ can measure water temperature, Deng said. An interdisciplinary team worked for about three years to create these newest tags. They also designed an AI model to help speed up the process, he said.

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With the new ways of handling the shad and tagging them, scientists found tagged and untagged shad had similar survival rates.

" If you asked me to predict 10 years ago, I wouldn’t (have) predicted that we can get (a tag) that small,” Deng said.

Decades of designing smaller and more effective fish and lamprey tags also helped, he said.

“Basically, the new one is significantly smaller without sacrifice,” Deng said.

Researchers have reached out to see if they can use the tags for “untaggable fish” in other areas as well, like the Great Lakes, Deng said.

Next, the PNNL team hopes to find ways to scale up manufacturing.

“By providing scientific information for species in early life stages, we can understand more about them, and then of course develop better strategies to manage them,” Deng said.

Courtney Flatt is a reporter with Northwest Public Broadcasting. This story comes to you from the Northwest News Network, a collaboration between public media organizations in Oregon and Washington.

It is part of OPB’s broader effort to ensure that everyone in our region has access to quality journalism that informs, entertains and enriches their lives. To learn more, visit our journalism partnerships page.

News Source : https://www.opb.org/article/2025/09/28/tiny-tag-salmon-northwest-dams/