Ocean temperatures soared to new 'pretty alarming' highs off Nova Scotia in 2022

Ocean temperatures off Nova Scotia hit record highs last summer, eclipsing the record-breaking temperatures set in the Atlantic a decade earlier.

"It's pretty alarming," said Fisheries and Oceans Canada research scientist Chantelle Layton.

Layton is part of the DFO team analyzing results from the annual Atlantic Ocean monitoring program in eastern Canada.

Canadian scientists are discussing the 2022 data this week.

On the Scotian Shelf, from the Cabot Strait off Cape Breton south to Georges Bank and into the Bay of Fundy, nine of 20 monitoring locations at different depths set records in 2022.

Temperatures were one to two degrees above the 30-year average.

At the greatest depths, temperatures from Halifax to Yarmouth averaged six to seven degrees — and around eight degrees in the Bay of Fundy.

"To see a change in the deep layers was probably the most significant change," said Layton.

"What was most important was the amount of warming that we saw consistently throughout the year, throughout all of our measurements and the fact that there was an absence of colder water at mid-depth."

Cold intermediate layer of water disappeared

Sampling did not detect the "cold intermediate layer," defined as 4 degrees C or less.

It is winter water that is trapped beneath less dense, warmer surface water and above the bottom. It plays a role in nutrient mixing and ecosystem productivity.

Portions of the eastern Scotian Shelf were not sampled. But everywhere that was, scientists did not find the cold intermediate layer.

"That was a first for us," said Layton.

"There was still cold water, but not as cold. It was about one degree warmer than normal."

2012 no longer the litmus

For many, 2012 was a wake-up call for ocean warming, when temperatures off the east coast of Canada were about two to four degrees above normal.

That same year, the National Oceanic Atmospheric Administration in the U.S. reported sea surface temperatures on the northeastern shelf averaged 14 C, the highest temperature recorded in 150 years.

Layton said last year represented another upward shift.

"2022 is another year where you kind of had to take a step back, kind of rethink what is actually happening out there," she told CBC News.

"If we look at the results compared to 2012, 2012 no longer holds any of the high records."

The average ocean temperature for the Scotian Shelf in 2016 was the second-highest on record in 47 years, with 2012 being the highest.

Snow crab and shrimp: how it impacted fishing industry

The fishing industry is watching for the impacts of warming water.

Ginny Boudreau, a veteran inshore fishermen's representative, said snow crab and shrimp industry surveys also detected warming temperatures in 2022.

She blamed it for poor catches of snow crab on the Scotian Shelf south of Halifax, an area known as 4X.

"It was a hard go for the harvesters, especially because crab are one of the more sensitive crustaceans, especially to temperature," said Boudreau.

"The result is they have to go harder. They have to go farther. Fuel cost increased. You have to increase the number of trips to catch your quota."

Warming also resulted in a 25 per cent quota cut in the 2023 eastern Scotian Shelf northern shrimp fishery, she said.

Scotian shelf fishermen

That quota reduction affected Canso fishermen Billy Bond and Ken Snow, who operate shrimp traps inshore.

"We've come really close to catching our quota before, so 25 per cent [less] would put us off the water sooner than we'd like," said Snow.

Both men say they are already seeing the effects of climate change.

"Our catches from the time we did start fishing them years ago to now, we've seen the stocks drop down for sure. The catches have dropped quite a bit," said Bond.

"Some people say global warming is fake news. It's not. The water levels are rising. We've seen that just at our local wharfs," added Snow.  

"Some of our older wharves during storm events would stay above water. Now during storm events and storm surge they are below water. They haven't changed the level, but the water has."

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