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article imageClimate change is now a fact of life in Atlantic Canada fishery

By Karen Graham     Apr 12, 2019 in Science
A new report by Canada's Department of Fisheries and Oceans says warming sea temperatures off Nova Scotia have led to declines in northern shrimp and snow crab.
The Atlantic Ocean is vital to Canada's economy and culture. The Atlantic Ocean is one of the most productive marine environments in the world, with an abundance of marine organisms from crabs, to lobsters and wild fish stocks, supporting over 55,000 jobs in industries like fishing, aquaculture, and tourism.
On April 10, the Minister of Fisheries, Oceans and the Canadian Coast Guard, the Honourable Jonathan Wilkinson released what is the first Atlantic Ocean status report, called Canada's Oceans Now–Atlantic Ecosystems, 2018.
Grand Manan lobster fishing boats in North Head Harbor in New Brunswick  Canada.
Grand Manan lobster fishing boats in North Head Harbor in New Brunswick, Canada.
Meantimeus
The DFO Report
One of the main takeaways from the report is that Canada will have to factor in climate change impacts in the management of its multi-billion dollar seafood industry.
"That variable of climate change is new, and it's a new variable we didn't have to account for in the past. We're going to have to account for it now," Wilkinson said in an interview with CBC Canada News.
Global warming is affecting Atlantic Ocean ecosystems in Canada, according to the report. The warming ocean waters are causing reduced sea ice, rising sea levels, changes to ocean currents and more acidic water. And the warming waters have caused a shift in marine populations.
Global warming  fishing and growing numbers of tourists who flock to the region for whale watching a...
Global warming, fishing and growing numbers of tourists who flock to the region for whale watching and diving pose a threat
Olivier MORIN, AFP
The melting polar ice will disrupt ocean currents, winds and the growth of plankton, essential to the marine food chain. “Marine ecosystems worldwide will be increasingly starved for nutrients,” according to a study in 2018.
As a matter of fact, in August 2016, WWF Canada released a new assessment of Canadian fisheries in their report Food for All, along with a warning that forage fish are in trouble. WWF Canada studied 27 fisheries against nine criteria, finding three fisheries in Atlantic Canada in critical condition. This includes two herring stocks in the Gulf of St. Lawrence and Atlantic mackerel stocks.
Interestingly, in 2016, CTV News reported that Heather Grant of the Ecology Action Center in Halifax said that the issue of limiting the amount of forage fish taken is very complex because the fish are not only food for predators, but they are also used for bait by lobster and crab fisheries.
WWF Canada releases report on forage fish in Canadian waters.
WWF Canada releases report on forage fish in Canadian waters.
WWF Canada/Twitter
At that time, Grant said, "There's also a lot of uncertainty in the science and there's so much we don't know about what's happening... So there's a lot of reluctance to take a precautionary approach to managing the species because of those economic implications."
Winners and losers are becoming evident
That time has now passed, meaning it is time to take action because the warming ocean is causing physical and biological changes that are having serious impacts on the health of Atlantic Ocean ecosystems including shellfish, fish, marine mammals and seabirds.
The Canadian Atlantic Ocean is divided into three bioregions: the Newfoundland and Labrador Shelves (NL), the Scotian Shelf (SS), and the Gulf of St. Lawrence (GSL) These regions each have their own distinct geographical characteristics and ocean depth and conditions differences. But because there are no physical boundaries, the areas between them are transitional zones.
Three Bioregions of Atlantic Canada – Bioregion locations are based on ocean conditions and depth....
Three Bioregions of Atlantic Canada – Bioregion locations are based on ocean conditions and depth. Northwest Atlantic Fisheries Organization (NAFO) sub-divisions are boundaries used for science and management of various marine resources and are used throughout the report.
DFO
Scientists use a number of different measurements in each of the three zones to determine the health of the ecosystems, measuring temperatures throughout the water column. The also use satellite imagery and data as well as ocean surface temperature measurements.
The research includes looking for stratification in the seasonal changes in sea ice and the layers in the water column. This affects how nutrients are distributed, which has an impact on the productivity of ecosystems. Seasonal changes in sea ice, particularly on the Newfoundland and Labrador Shelves and the Gulf of St. Lawrence, influence freshwater input and the timing of phytoplankton blooms.
Due to these changes, there has been a decline in northern shrimp and snow crab, while at the same time, the warming has helped the lobster populations. Silver Hake have moved into New Foundland - possibly an indication of continuing change in the ocean environment due to climate change.
While we may enjoy the warmer waters  marine heatwaves have 'significant impacts on ecosystems ...
While we may enjoy the warmer waters, marine heatwaves have 'significant impacts on ecosystems, biodiversity, fisheries, tourism and aquaculture'
Tate Drucker, THE NATURE CONSERVANCY/AFP
More exotic warm-water fish are moving into the region. They include John Dory, armored sea robin, and deep-bodied boarfish - which are being caught more often. But perhaps the loss of the smallest of organisms in the ocean food chain is most troubling.
Dalhousie University biologist Boris Worm says, "We see warming waters throughout the region. We see less oxygen as a result of warming waters and increased stratification, and we see lower levels of food in the water, particularly phytoplankton that has decreased over time."
"And these together really show how this place that we call home is shifting away from what it used to be and how it's a different place," he adds.
Wilkinson cautions us not to blame every little thing happening on climate change. Still, he said there's no doubt it's real. "I think it's very serious. Climate change is on us in terms of the impact we are seeing. We already seeing significant changes," he said.
More about atlantic Canada fishery, Climate change, Atlantic ocean, Stratification, Economy
 
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