What higher temperatures could mean for fish farming in Ontario

Warming waters in Lake Huron are creating stress for fish — and that has one farmer considering a new site in Lake Superior
By John Michael McGrath - Published on Sep 17, 2019
Some in the province’s aquaculture industry are looking to move their operations to Lake Superior. (iStock.com/LawrenceSawyer)



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For decades, Ontario fish farms have been clustered in Lake Huron — mostly in the North Channel, near Manitoulin Island — but there’s a growing problem: the water is getting too warm, likely as a result of climate change. And that has some in the industry casting their eyes farther north, to the shores of Lake Superior.

“We’ve had high temperatures in the summer in the past; that’s nothing new,” says Tanya Hughson, a manager with Cole-Munro Foods, which owns net-pen fish farms around Manitoulin Island and a fish-processing plant in St. Thomas. “What’s new is that the high temperatures are sustaining for longer periods of time.”

Warmer water holds less dissolved oxygen. Fish may live underwater, but they still need oxygen to live, and less dissolved oxygen in the water leads to more stress for the fish. Stressed fish grow more slowly, which means longer wait times until they’re marketable — and less money for farmers.

And when warmer temperatures last longer, farm operators spend more of their year trying to cope with stressed fish. They can sink their cages somewhat to give the fish some respite from the heat, but there are limits to how deep they can go.

So Hughson and Cole-Munro are looking at the waters near the town of Marathon, 300 kilometres east of Thunder Bay on the north shore of Lake Superior.

“They’re much farther north, obviously, and they have cooler air temperatures in the summer. So what we’re looking for is a more optimal growing period,” Hughson says. “Lake Superior warms up slower and cools off a lot slower. So we would have that sweet spot a lot longer.”

The company has collected water and sediment samples from the lake and is conducting an ecological survey of the area. Hughson says it would be years before Cole-Munro could put actual fish in the water — getting to that point would require provincial permits and collaboration with the municipality and local First Nations.

Marathon is interested in hearing more.

“We were really looking at sustainable natural-resource industries as part of our economic development strategy,” says Daryl Skworchinski, the town’s chief administrative officer. “I think more communities are looking at these opportunities — agriculture and aquaculture, in our case.”

Like much of the northwest, Marathon has been hit hard by the decline in such traditional industries as forestry. In Marathon’s case, however, the cloud has a silver lining. The Tembec pulp mill went bankrupt in 2009, costing the community 250 jobs, but the town expects to inherit the 100-acre site after a lengthy court process comes to an end, likely later this fall. The mill itself was demolished in 2015, which would allow the town to repurpose the site as an industrial park for many different possible users — including some who could use the waterfront access.

Marathon isn’t the only town looking into the economic possibilities of farmed seafood. Manitouwadge, an hour’s drive northeast of Marathon, considered the business case for farmed shrimp in a report earlier this year.

In theory, agriculture and aquaculture could provide more stable jobs for northern communities that have traditionally lived and died by the boom-bust cycle of resource industries. But nobody has tried to site a fish farm in Lake Superior before. The first step will involve putting an empty cage in the water to see how it holds up to the rigours of a northern winter.

Skworchinski doesn’t expect aquaculture to replace the hundreds of lost pulp-mill jobs, nor does he expect it to replace the nearby Hemlo gold mine as the town’s primary employer. But the addition of dozens of jobs could be meaningful in the town of 3,300. And he sees the potential for fish farms in Lake Superior as a sign that, whatever climate change means for the rest of Canada, it could bring real benefits for communities such as Marathon.

“I think we’d be lying if we didn’t say that,” Skworchinski says. “It’s one of the natural benefits of being located where we are. We don’t get a lot of the extreme weather events that other communities do. It gets cold in the winter, but it’s predictably cold, so we work with that.”

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