Paulatuk is using acoustic tags to track the whereabouts of Arctic char amid a changing climate

Lawrence Reuben uses an electric auger to drill a hole through about six inches of ice on the Hornaday River east of Paulatuck, NWT.

The machine does its work in four seconds.

As he pulls out the spiral blades, water and powdered snow come to the surface. He steps back, turns to his daughter and says, “It’s the best tool since sliced ​​bread.” They both laugh at the joke before he moves on to the next hole.

The Hornaday River is about a 25-minute ATV-ride from Paulatuck – a distance of eight kilometers as the crow flies. Ruben and his wife Dianne have a built a 16 by 16 foot cabinFar away from your bank. This is a place where they spend a lot of time – to decompress and go fishing for Arctic char.

He will have no luck on this particular trip with his daughter and son-in-law.

Arctic Char in PaulatThe UK area has historically spent the winter in the Hornaday and Brock rivers before returning to Darnley B.Ay and the Arctic Ocean. But Ruben said that Char’s activities have become unpredictable.

“In the fall, they should be up the river,” said Ruben, a member of the Paulatuck Hunters and Trappers Committee. “Based on our fishing efforts recently, we haven’t caught a lot of fish.”

Changes like these are why the community is collaborating with Fisheries and Oceans Canada on a research project: together, they caught and tagged four last July to better understand where and when the fish are spending their time.

38 Arctic char tagged with acoustic monitors

Federal scientists and Paulatuck harvesters spent four weeks capturing 38 Arctic char at four locations around Darnley Bay and placing acoustic transmitter tags inside them.

They also installed 33 receivers in the Arctic Ocean.

The purpose of this system is to paint a picture of where fish are spending their time – or where they aren’t. Tags emit high-frequency sound that is inaudible to the human ear. When the fish passes by the receiver, the receiver picks up the signal and stores the data.

“We’ll open the fish, insert the tag – it’s about the size of a tube of lip balm – and stitch it up. And then the fish goes about its daily life and sends signals from the acoustic tag that will then be collected on receivers that we place underwater,” explained Taji Rodriguez, an aquatics biologist with Winnipeg-based Fisheries and Oceans Canada.

“Next summer, we’ll go out in boats and bring the receivers back to the surface and then we’ll download the files from them. And that will just be a list of every fish that was heard from, and a time stamp.”

Paul Blanchfield, a federal research scientist based in Winnipeg, said the plan was to also install receivers in freshwater lakes associated with Darnley Bay. As of late November, they had not yet been installed – but it was expected that five would be deployed over the winter.

Blanchfield said Fisheries and Oceans Canada has been involved in four monitors in the region for more than 30 years. The aim of the project is to understand which areas of Darnley Bay are most important to the species and when they leave the bay for their wintering grounds, he said.

If they collect enough data, Blanchfield said it could also answer some other questions, such as what triggers their migration.

“The Arctic is changing rapidly, with very noticeable losses in sea ice thickness in the region,” he said. “The timing of ice breakup in the spring and freeze-up in the fall is also changing, both of which have the potential to influence how much time charred spend in the marine environment – ​​and depend on food resources in this area – compared to the freshwater habitats of their annual life cycle.”

Acoustic tags have a lifespan of four years. But there is also the possibility of catching fish before the batteries run out. Scientists expect that to be the case with at least some of them – and each fish has also been fitted with an external tag by its dorsal fin.

If harvesters catch a char that is part of the project, Blanchfield said they can choose to release the fish back into the water or return the transmitter inside the fish to the local hunters and trappers committee for a reward.

Blanchfield said a fish got caught in a net when he and Rodriguez were in the community last summer. “We haven’t heard how many others have been caught yet,” he said.

Warming climate and melting permafrost

Ruben said he and his wife remember 2010 as a “pivotal year” when they saw the impact climate change was having on the region.

Usually in the month of April, he said, people have to take out chisels and augers to make holes in the ice for fishing. That year, the Hornaday River was running on April 25 — a month earlier than normal, Ruben said.

Erosion and landslides are also a factor.

“If you look at the river system, it looks as if someone took a rake to the river banks and pounded them down,” he said. He said silt added to the water was making the rivers “untenable” places to spawn – he and his wife have caught several fish with eggs over the past eight years without spending any time.

Back on the ice of the Hornaday River, Reuben kneels next to one of the holes he dug. He shakes his 1.5-foot-long fishing rod up and down – causing the silver hook and bait at the end of the line to dance in the water. It is a type of fishing fish locally called “jiggling”.

He looks down into the pit and deep water and waits for a glimpse of the species on which his community depends.

“The importance of our char as a life-sustaining resource is enormous to the Paulatuck community,” he says. “You can’t diminish it in any way, shape, or form.”