Acoustic Tagging to Prepare for the Return of Klamath Spring-Run Chinook Salmon

For more than a century, four large dams on the Upper Klamath River have blocked spring-run Chinook salmon, steelhead trout, Pacific lamprey, and other species from their native spawning grounds. The absence of those species has affected the biology of the river and the culture of the communities along it in Northern California and Southern Oregon.

Thanks to decades of advocacy, led largely by the Yurok, Klamath, and Karuk Tribes and a wide range of partner organizations, those dams are set to be removed to restore historic fish passage, revive cultural fishing rights, and rebuild a healthy ecosystem. The first of the four dams is expected to come down in 2023.

Researchers are now pushing to capture as much quality data as possible before the dams are removed – it’s their last shot at the “before photo” against which outcomes can be measured.

On an early spring morning in southern Oregon, with temperatures barely above freezing, Rachelle Tallman was moving quickly. A graduate student at UC Davis, Tallman was orchestrating the outdoor set-up of five portable surgical stations at the Oregon Department of Fish and Wildlife (ODFW) Klamath Fish Hatchery. Over five days, she and a rotating team would surgically insert acoustic tags in more than a thousand spring-run Chinook salmon.

The acoustic tags will help researchers better understand how the salmon may traverse the waters of the upper Klamath basin, once they regain access to it. The basin’s many spring-fed creeks keep the upper Klamath’s tributaries cold year-round and are the reason this region was so hospitable to spring-run Chinook, which once raced upstream to find cold water refuge in advance of hot summers and falls.

Aside from the cold, what I noticed right away was the masking tape. Sharpie lettering on torn strips of different colored tape noted the source of each piece of equipment used in the surgical stations. Scales, scalpels, buckets, aeration pumps, boxes of tags, tents, coolers, laptops – each piece had the name of the contributing state or federal agency, university, Tribe, or nonprofit organization to help with sorting when the task was done. It was physical evidence of stellar cooperation and organization. As one participant noted: “It’s a stone soup – everyone is bringing something to the pot.”

On this first day of tagging, 15 people from seven different entities performed or supported the surgical procedures – Tallman having previously trained several of them.

The tagged salmon, all of them roughly one year old and between four and nine inches long, were from eggs collected at a California Department of Fish and Wildlife (CDFW) hatchery on the Trinity River. This stock was chosen because the Trinity flows into the lower Klamath, and the Tribes and agencies involved sought the historical genetic connection to the river.

The surgical procedure involves anesthetizing a fish, weighing and measuring it, making an incision in a fatty area on the underside, inserting the acoustic tag (about the size of an aspirin tablet), and using a suture to close the wound with two stitches. Throughout the procedure, cold creek water is dripped across the fish. The cold water, cold air, and small size of the fish made for a slow start for some of the surgeons.

“I relaxed after the first hour. I got in a flow,” said Faryn Case, a biologist for the Klamath Tribe who performed 145 surgeries. “Later in the day I could do the surgery in a minute.”

“Half of it is confidence,” said Tallman. “We do trainings throughout the year. And we try to do 20 reps every time we do a practice. With some of the grad students, we’ve met four or five times – they’ve done a lot of surgeries.”

One week after the tagging started, the fish were moved from the hatchery in a truck-borne transport tank. Again, 15 people were there to help with, and celebrate, the release into the Wood and Williamson Rivers, tributaries to Upper Klamath Lake in Southern Oregon. A heavy rain fell, which many interpreted as a good omen: The fish would have rain and cloud cover, reducing the immediate risk of predation as they were placed in the stream.

In all, 1,138 fish were released – half in each river. This is not a reintroduction of the species but is instead an experimental release to see how Chinook salmon may again use the upper basin.

“It was exciting to see them swim out of the buckets. And we all got to cheer when Rachelle released the last fish” said the Klamath Tribe’s Case. “It felt like a big deal. There are so many uncertainties, but it would give us a lot more peace of mind to see the salmon ultimately survive in this environment.”

ODFW’s Mark Hereford, principal investigator on the project, is eager to see how the salmon respond.

“How will they migrate within and out of the system?” he asked. “Will they linger in the creeks or rivers, will they stay in the lake for an extended period, or will they move swiftly out of the basin as they try to make it to the ocean? They can show us how wild, juvenile salmon might migrate in and out of the system.”

Trout Unlimited played an important role in ensuring an accurate “before photo,” working with landowners, lining up staff and volunteers to help with tagging and release, and collaborating closely with representatives from multiple agencies and Tribes to ensure consistent data capture and protocol.

California Trout has also played a key role. While their focus has tended to be the Lower Klamath, all of which is in California, they helped design this current study to ensure a consistent monitoring approach from headwaters to the sea.

ODFW’s Hereford raved about the scale and quality of the collaboration on this project. He cited the Klamath Tribe, ODFW, CDFW, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, US Fish & Wildlife Service, Bureau of Reclamation, Bureau of Land Management, US Geological Survey, UC Davis Center for Watershed Sciences, Cal State Humboldt, and others.


Faryn Case, biologist with the Klamath Tribe, about to place an acoustic tag in a juvenile Chinook salmon.
Two stitches seal the wound and enclose the acoustic tag.
When many agencies pitch in, masking tape is the reliable post-event sorting tool.