By Paul Withers, CBC News, Aug 25, 2017
Temperatures on Scotian Shelf were up by 2 or 3 C in some places
Ocean temperatures in the Scotian Shelf and the Gulf of St. Lawrence reached record or near-record highs in 2016, according to a Fisheries and Oceans Canada report on Atlantic Canada’s marine ecosystem.
Federal fisheries scientist Dave Hebert said temperatures on Nova Scotia’s Scotian Shelf were up by 2 or 3 C in some places.
“Most were well above normal. Some were record highs,” said Hebert, who works out of the Bedford Institute of Oceanography in Halifax.
One of those records was set last October, 32 kilometres off Halifax where the ocean bottom exceeded 11 C.
He said the average ocean temperature for the Scotian Shelf in 2016 was the second highest on record in 47 years, with 2012 being the highest.
The Gulf of St. Lawrence set a 102-year record for temperature in deep water with a depth of 200 to 300 metres.
“This is more concerning than the variations of temperature on the surface of the water,” said Peter Galbraith, a researcher at the Maurice Lamontagne federal fisheries institute in Mont-Joli, Que.
He said this is because these deep water temperatures have not been seen before, it’s not known what the impact will be.
Newfoundland bucks the trend
In Newfoundland and Labrador, ocean temperatures were normal or just above normal.
Elsewhere, higher ocean temperatures in the Bay of Fundy, Scotian Shelf and the Gulf of St. Lawrence are part of an upward trend that started earlier in the decade.
The warming water coincides with a shift in where zooplankton are residing. Known as copepods, this food source is eaten by the endangered North Atlantic right whale.
More of the whales are moving from their traditional Canadian feeding grounds in the Roseway Basin off southern Nova Scotia and the Bay of Fundy in search of food.
“Those zooplankton are now in the Gulf of St. Lawrence. That’s probably the reason the whales are going to where they are going because the temperatures aren’t quite as warm as they are in the Scotian Shelf,” said Hebert.
The question is whether the zooplankton are leading the whales into a shipping lane super highway.
Since June, at least 10 right whales have been found dead in the gulf. Several deaths have been attributed to ship collisions or fishing gear entanglements.
What about 2017?
Hebert said readings taken this spring showed temperatures returning to normal on the Scotian Shelf. He said it also happened in 2016, before the onset of higher temperatures later in the year.
The deeper water Bedford Basin inside Halifax Harbour is considered a proxy for what happens off the Scotian Shelf. In July, the Bedford Basin temperature at 10 metres was 16 C, well above normal variability.
“It only normally gets up to 12 C. That’s quite warm,” said Hebert.
Still, Hebert is not ready to blame warmer water on climate change. Ocean temperatures can vary over the decades, he said.
Better data coming soon
Ocean temperatures are gathered several times a year in surveys as part of a monitoring program.
Thanks to an infusion of money from the federal government, Fisheries and Oceans Canada will soon receive ocean temperatures and much more data on a continuous basis.
The department is in the process of deploying up to eight new gliders — costing about $250,000 each — into the Atlantic and Pacific oceans. Several of the new gliders are at the Bedford Institute of Oceanography.
Two of them will be dedicated to collecting ocean data from Halifax to the shelf break more than 120 kilometres off the coast.
“What we have been getting is a snapshot. We don’t know if it’s an anomaly. Now, we we will get real-time data every six hours,” said Hebert.
Data from the gliders will also go to Environment Canada to help with weather forecasting.
Source : CBC