Wascana lake located in Regina, Saskatchewan was in the top fifteen of hundreds lakes tested for greatest oxygen loss. Photo by Darla Ponace

Climate change impacts Saskatchewan lakes

Fish face warmer water, increased organic matter in their habitat

“If you’re not teaching (people) the right methods or the right ways of being environmentally safe and sound, then, you know, it’s just going to carry on to…the next generation.”  – Tony Cote

by Darla Ponace

Climate change is warming the atmosphere, causing warmer water temperatures that are impacting lakes in Saskatchewan.

Peter Leavitt has studied climate change for the past 35 plus years. Recently Leavitt and 50 institutions around the world researched changes in the temperature and the oxygen content of hundreds of lake in North America, Europe and New Zealand.

They found that lakes were losing oxygen at the surface, and at the very bottom. They also found some of the rates of oxygen loss were greatest in Saskatchewan lakes. Wascana Lake in the city centre of Regina and Lake Diefenbaker were in the top fifteen most oxygen-depleted lakes among those studied.

One of the reasons this was happening was due to climate change, and they also found that there was more organic matter in the lakes.  “The organic matter that was degraded was dead and was consumed by microbes of bacteria, and the bacteria were sucking up the oxygen to do it,” said Leavitt.

The lack of oxygen is causing fish to die. Carp can live in waters that have lower oxygen levels, but this past summer carp were seen washing up dead along the shorelines of rivers and lakes around Saskatchewan.

“Systems will become less predictable.”  – Peter Leavitt 

According to Leavitt, carp are actually an exotic species of fish that are non-native to the lakes around Saskatchewan. They come from people’s aquariums as goldfish, and because goldfish can grow as big as the tank they inhabit they can grow quite big in lakes.

“The problem with carp is they dig around or root around in the bottom mud, and they stir up a lot of nutrients in the water column. So that makes the water column more nutrient-rich, which makes it greener, which means there’s more green stuff to sink down and you lose the oxygen.

“So, fish like carp are actually making the effects of climate change worse or at least, they’re doubling down on it. So, losing carp is not necessarily a bad thing for future fish populations,” he said.

But losing carp won’t fully solve the problem, according to Leavitt. “So the problem with global warming is not only are you making the water warmer which is less suitable for fish that like cold water, like lake trout, but you’re also reducing the oxygen that the bigger fish need even more than the small fish,” he said.

“Changing itself isn’t necessarily a bad thing. It’s just that people tend to like consistency. They want to know that they can go to a lake, and catch perch or if they’re up north they can catch bass or walleye or pike,” said Leavitt.

“As climate change is having its effect, systems will become less predictable. And often the species that can survive really poor water quality, are species that are not really desirable. They typically are forage fish or kind of junk feeders.”

Fishers like Tony Cote are also starting to notice a decline in fish populations and water quality issues in lakes around Saskatchewan. Cote says in the winter he fishes three times a week, if not more, and that has been his routine for the past five years.

Cote says he has noticed fewer fish. “Five winters in a row and the numbers have kind of steadily declined. What you normally do is map where the most activity is and then go to exactly to your favourite spots you go to. That hasn’t been really the case as the trend goes since…the last five years,” he said.

“The fish didn’t look healthy.” – Tony Cote 

Corresponding with Leavitt’s findings, Cote noticed there was a buildup of green substance in the Qu’Appelle Valley this past summer. “It’s quite green. It was actually quite noticeable this summer…the water just doesn’t look healthy, he said.

“The fish didn’t look healthy, either….during the winter when catching fish, there might be some aging walleye that we do catch that have noticeable bacteria on them.”

Another change Cote has noticed is ice thickness. “It’s actually taking a little longer in the months for ice to thicken up,” he said. “Like usually the first two weeks in December you should have at least a foot of ice, and it is good for vehicles and you know good for walking on. . . and it’s safe. I’ve noticed it’s taking longer into the winter months for the ice to be safe enough to venture out on.”

People can do their part in climate change action by being environmentally conscious and start living cleaner, according to Cote. “If we’re not going to address climate change and take it seriously, then what’s going to be left for the next generations to enjoy and to experience?”

He said people can help by making sure boats aren’t leaking fluids or oils when fishing, by picking up garbage, and leaving areas clean when they’re finished on the ice.

Cote said it is important to teach each other how to respect the environment, or people won’t understand how much it matters.

“If you’re not teaching them the right methods or the right ways of being environmentally, safe and sound, then, you know, it’s just going to carry on to the next people, and the next generation.”

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