In a sign of the times, several warm-water fish species were added to the annual summer research vessel survey off the coast of Eastern Canada in 2020.
The amount of spawning-age blackbelly rosefish is estimated at 4,000 tonnes — the most ever, according to the Department of Fisheries and Oceans.
Scientists say the northward movement into Canadian waters has followed warming ocean temperatures in the Atlantic.
Monitoring for the blackbelly rosefish, john dory, trigger fish, tilefish fish, dusky shark and others was included in the DFO summer trawl survey along the Scotian Shelf and Bay of Fundy for the first time last year.
It was done at the request of the commercial fishing industry, which is capturing them accidentally — called bycatch — but cannot land them because they are not included in any Canadian commercial fish licence conditions.
Stop wasting them, fishing company says
That doesn’t make sense to Alain d’Entremont, president and CEO of Scotia Harvest, a groundfish and scallop company with a fleet of vessels and operations in southwest Nova Scotia.
“I think that if they are groundfish species and we are catching them as part of our regular fishing, then there should be mechanisms for us to be able to land them and extract economic value from them, instead of just wasting them,” d’Entremont told CBC News.
“We’re going to see this as we see changes in the environment. We want to just make sure that there’s a process to manage it, adapt to it and also collect information on certain species and their abundances and their condition.”
‘Oh, look, there’s a weird fish’
Fisheries biologist Don Clark is lead scientist on the Scotian Shelf/Bay of Fundy survey, which has been capturing, counting and helping to estimate commercial fish populations since 1970.
In an abbreviated mission last year, the survey completed 195 trawls.
Based at the St. Andrews, N.B., biological station, Clark has been monitoring marine species in the area for decades.
“I would say over a 10-year period, it’s something that went from being, ‘Oh, look, there’s a weird fish,’ to I now expect to see these fish in this area,” Clark told CBC News.
He has previously reported and photographed non-native fish, including armoured searobin, spotfin dragonet and deep-bodied boarfish, which DFO calls novel warm-water species.
The most common of the newcomers has been around the longest.
Story of blackbelly rosefish
Blackbelly rosefish is a mottled, spiny-finned member of the redfish family — like ocean perch.
The first ones were seen on DFO trawl surveys as far back as 1980 when they were rare and relatively small.
“They started getting bigger over time and we got more of them,” said Clark. “Since they first started showing up in our survey, they’ve spread further north and east but staying in that kind of deep, warmer water.”
In its report on the 2020 summer survey, DFO indicated their abundance is increasing, but Clark said blackbelly rosefish and other arrivals are relatively rare compared to native species.
“But they’re here every year now. That is something that marks a change,” Clark said.
“Some of these things will be coming in on warm water in the summer and disappearing again as waters cool. Ones that are sticking around have found conditions that are conducive to full lifespan. So they’re staying and reproducing, like the blackbelly rosefish.”
What about the other species?
The 2020 survey noted an increased presence of john dory, which have been caught in deeper, warmer water every year since 2014. Distribution is limited but they can be locally abundant, the report said.
Egg-bearing females in spawning condition are being caught.
Clark said Nova Scotia is now probably at the fringe of its range.
Black seabass were not captured during the summer survey, but have been caught in winter surveys on Georges Bank.
The report said the summer survey is unlikely to provide useful information to estimate the abundance of dusky sharks or triggerfish.
Canada must adapt to changing ocean conditions
Clark said fish movement is the biological consequence of oceanographic changes.
Those changes burst into focus in 2012 when the National Oceanic Atmospheric Administration in the United States reported sea-surface temperatures on the northeastern shelf averaged 14 C, the highest temperature recorded in 150 years.
Ocean temperatures off Canada’s East Coast were about two to four degrees above normal in 2012, also setting record highs.
“We shouldn’t be surprised. The fishermen have been seeing these fish for years,” said environmentalist Susanna Fuller, vice-president of operations and projects at Oceans North, which describes itself as a non-profit organization that fosters science- and community-based conservation.
She said it’s time DFO begins to plan for the arrival of warm-water fish.
“These are the kinds of things that we need to be able to pivot on quite quickly as species ranges shift. And it’s going to go the other way, too,” she said, pointing to the disappearance of the lobster fishery off Connecticut and New York.
“I think we need to think about socio-economics as well. I mean, for example, if the Gulf of Maine starts getting too warm for lobster. Well, what does that do to the socio-economics of southwest New Brunswick and southwest Nova Scotia?”
No one from DFO was immediately available for comment.
However, in a 2018 report on Atlantic Ocean conditions, the department explicitly linked northward migration to warming temperatures. Then minister Jonathan Wilkinson said climate change must be factored into all future fisheries management decisions.
More to track …
Bulletin Observer Science and Technology
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