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A Game of Tagging Fish - Hakai Institute

A Game of Tagging Fish

Campers get an impromptu science lesson on the beach.

Koeye campers Thea Wilson, Danica Windsor, and Everette Johnson help transfer Dolly Varden trout from the net to a holding bin before they are tagged. Photo by Raina Delisle

As six researchers pull in a seine net at the mouth of the Koeye River, one of the most ecologically complex watersheds on BC’s coast, a dozen children from the Koeye Camp come running out of the woods and onto the beach. “I want a dolly,” a nine-year-old girl says as she splashes into the shallow water. But she’s not looking for a doll to play with; she wants to catch a Dolly Varden trout.

“These kids are the future of science on Koeye,” says Will Atlas, a Hakai scholar and PhD candidate at Simon Fraser University. The affable biologist, who also works for the Qqs Projects Society that runs the Heiltsuk youth science and cultural summer camp, encourages the keen campers to catch fish with a net or their bare hands and toss them in a bucket.

The children giggle as the fish slip and slide between their fingers and Atlas dramatically tosses by-catch back into the river. The nine-year-old triumphantly scoops up a dolly and promptly names it Num-num-num. When all of the Dolly Varden are pulled from the net, the scientists move to their makeshift workstation in the sand, with the junior scientists in tow.

As Atlas mixes fish anesthetic into a blue bin of water, he explains to his mentees that he’s going to put the fish to sleep for a while so he doesn’t hurt them when he pokes them with a small needle and inserts a rice-sized tracking tag under their dorsal fin. Once the fish have conked out, Atlas grabs one and runs a scanner over its limp body, telling the kids they will hear a beep if it has been captured before and carries a tag.

Will Atlas measures a Dolly Varden trout before placing a rice-sized tracking tag under its dorsal fin. The trout’s movements can then be tracked along the coast. Photo by Raina Delisle

After the fish are tagged and measured (“Num-num-num’s num-num-number is 236000872130,” Atlas jokes), they are placed in a bin to sober up before being released. The girl who caught Num-num-num returns him to the river and waves goodbye.

The researchers drop the net for the third and final haul of the day. The day’s tally is 69 Dolly Varden, seven of which had been captured before, either earlier this year or last year. The work is part of a long-term monitoring program—now in its second year—that seeks to understand Dolly Varden life history and general population biology.

“There’s not a lot known about the Dolly Varden compared to salmon,” says Atlas, who also runs a sockeye monitoring program in the area. “They have a huge amount of life-history diversity. There are populations that stay in the lake and ones that go to sea, and sometimes they don’t even mix. Individuals can go out to sea for three years and then all of a sudden—boom!—they’re spawning each year. They integrate the environment in a really neat way because they’re so locally associated.”

From where we are standing at the river mouth, the Dolly Varden may go out to sea or up the river to the lake, crossing radio-frequency identification readers—electrified cables that lie under the river—and sending data back to Atlas and his colleagues.

Radio-frequency identification readers are set up in the Koeye River. These electrified cables lie under the water and record every tagged fish that swims past and sends the data back to Atlas and his colleagues. Photos by Shawn Hateley

Fish that reach the weir (a fish trap built through a Qqs Projects Society-Hakai collaboration in 2013) will again be caught, scanned, and measured, giving researchers valuable data on their movements and how much time they spend in the estuary. Coastal watersheds are one of Hakai’s core research axes and this work, along with the salmon monitoring, is a long-term initiative.

With thousands of Dolly Varden in the local population, tagging and recapturing as many as possible is key to understanding abundance and life history, Atlas says. “In a couple of years, we’re going to have a really nice data set.”

Raina Delisle is an associate editor at Hakai Magazine, which is also funded by the Tula Foundation. She was visiting the Calvert Island Field Station to learn more about Hakai Institute research. Hakai Magazine is an editorially independent publication covering science and society on the world’s coasts.