Why volunteers scoop thousands of fish out of Alberta irrigation canals each year

Throughout the warmer months, Alberta's irrigation networks play a crucial role in the province.

They transfer water from rivers and reservoirs, delivering it to rural communities, to farmers and to recreational areas, supporting some wildlife along the way.

But along with the water comes the fish. And in the fall, when the irrigation networks shut down, thousands of them become stranded.

"It's absolutely a recurring problem," said Lesley Peterson, a Calgary biologist with Trout Unlimited Canada. 

"There's no need to divert water throughout the winter. So as the canals drain … the fish are vulnerable right now to birds and predators and just desiccation [drying out] and freezing." 

That's why Trout Unlimited, an organization working to conserve freshwater ecosystems across the country, runs fish rescues every fall. Already this month, they've gathered volunteers to conduct three rescues on canals that divert water from the Bow River, the Waterton Reservoir and the Oldman River.

The group has run the programs every fall since 1998, using electrofishing to temporarily stun and capture the fish and collect data. The fish are then brought back to the river or reservoir where they came from.

The group has managed to rescue more than one million fish.

Members of the Piikani Nation have been at it even longer.

They started in 1990, removing fish stuck in irrigation canals along the Oldman River — which runs through the reserve just west of Fort Macleod.

Harley Bastien is a founding member of the group and the organizer of the annual rescue. 

LISTEN | Harley Bastien describes how the annual fish rescues work:

Each year, dozens of volunteers herd the stranded fish — which range from mountain whitefish to cutthroat trout to northern pike — scoop them up in nets and place them in oxygenated holding tanks. 

At the end of the day, they're hauled back to the Oldman River and released.

"The fish don't get siphoned off the Oldman's River by natural order. It's an endeavour that was man-made, and so they get the fish off their natural habitat and home and basically are doomed to a certain short lifespan," he said in an interview on the Calgary Eyeopener.

"In my Blackfoot way, you know, we have to step up and try and help."

Bastien says they've managed to relocate about 250,000 fish since they started 32 years ago, including about 4,000 this month.

Still, both groups realize it's a cyclical issue: fish are returned to their original waterway only to risk the same fate the following year.

'No real silver bullet'

There's multiple reasons why that's a problem, Peterson says.

Species-at-risk, such as bull trout, are ending up in the irrigation canals, she says. Those fish are listed both federally and provincially as threatened.

She also points to the Bow River, which is known as an important sport fishery.

"There are concerns about declining rainbow trout populations in the Bow River. And so there are multiple threats likely causing those declines, and one of those may be that fish are getting stuck in irrigation canals," she said.

"We're hopeful that … people become concerned and the issue becomes more front of mind so that maybe we can look to some permanent solutions in Alberta."

The provincial government says it has added fish exclusion devices, such as screens, to some reservoirs, but they've had limited success, according to Carla Jones with the Ministry of Environment and Parks.

"A canal system is too large to effectively exclude fish while also meeting water delivery needs," she said, adding the screens can also get clogged with debris. "We've had some success minimizing fish entrainment and mortality through operational changes, such as reducing the diversion amount during times when species of fish are moving to or from spawning."

Jones says they're continuing to look at how different devices might help, but they need to make sure they don't stop the infrastructure from properly functioning.

In the meantime, the province says it offers staff and equipment to help with both the Trout Unlimited and Piikani Nation fish rescues during the fall.

Trout Unlimited will hold another rescue this weekend in Carseland, Alta., about 40 kilometres southeast of Calgary.

For now, it's the only thing they can do — a temporary solution to a decades-old conundrum.

"There is no real silver bullet fix for the issue," Peterson said.