In southeastern B.C., rivers might be getting too hot for local fish

B.C. has ordered anglers to stop fishing on some rivers and lakes in the afternoon to protect local fish from the latest threat to their health — the heat.

At the end of July, the province asked anglers in southeast B.C. to stop fishing in several waterways each day between 2 p.m. and midnight when water temperatures could reach about 20 C. In an email to Canada’s National Observer, a spokesperson for the provincial Ministry of Forests said angling at that temperature could be harmful to the fish or even kill them. They said the restrictions would help protect local fish populations.

William Cheung, a marine ecology professor at the University of British Columbia, said more frequent restrictions are evidence that waterways might be getting too hot for local fish.

“Climate change is increasingly a challenge to them because the number of times in a year that the temperatures exceed preferred temperatures is increasing,” Cheung said. “And the effectiveness of the (fishing) limitations will also become increasingly limited with frequent, intense temperature rises.”

After catching a fish in the warm water, former fishing guide Brian Hamagami said it can take a while for the fish to recover. When it’s released back into the water, at first, it will sit by the boat and seem sluggish, he said.

“You have to nurse it along and make sure it's right-side up,” Hamagami said. “And when it's ready to go, it’ll — boom — go.”

Every year, local angler Shane Westle said tourists head to southeastern B.C. to fish the waterways that run around Kootenay Lake. Often, they don’t know when or how to nurse the fish back to health.

“There's only so many of them big fish, and when you see pictures of people holding them in the air, you know that that fish could possibly be hurt,” Westle said. “They get hit pretty hard. Last year, they got nailed.”

Hamagami said local anglers are now familiar with the restrictions — the last time they went into effect was in 2021. But that wasn’t always the case.

“Twenty-plus years ago, we didn't see those restrictions because the water flow tended to be more normal,” Hamagami said. “That's not to say we didn't have very low water years — we did. But the trend tended to be more normal.”

It’s not the only change anglers have seen. When he first moved to the Kootenays region 35 years ago, Westle said Kootenay Lake was filled with Gerrard rainbow trout.

“It was the best fishing. They grew big and kids could catch them off the wharf — these big, huge fish,” Westle said. Now, it’s hard to catch fish the same size around the area anymore.

While a report from the province says rainbow trout still exist in abundance, they grow slower. According to the report, that may be because the trout’s food source, kokanee salmon, saw a steep decline in population nearly a decade ago in the “perfect storm of climate events.”

As the planet sees more extreme heat, Cheung said anglers can expect heat-related restrictions to happen more often.

“Fish generally like to be in an area that’s within their typical temperature,” Cheung said. “Fish evolved around their environments and their body functions (rely on) the environmental temperature.”

He said most fish have a range of temperatures they prefer in which they are healthiest. Bass, for example, often prefer warmer temperatures than salmon.

Living in temperatures too warm, Cheung said, could affect how the fish reproduce and the rate at which they die. Cheung said it could also decrease stocks of their food sources.

He said heat is now the latest challenge freshwater fish face with climate change — including pollution, development and drought.

“The challenge with freshwater fish is that (heat) also coincides with other climate-related changes,” Cheung said. “There is a really urgent need to intervene with climate actions to reduce global warming that’s the root cause of these changes.”