Species shift observed off Eastern Canadian coast

Published on
February 15, 2018

Oceana Canada, a scientific research and lobbying group, has reported that 26 fish species on the Scotian Shelf are in critical condition.

The organization came to that determination after auditing the findings of an annual summer survey conducted by Canada’s Department of Fisheries and Oceans’ St. Andrews Biological Station in New Brunswick.

Robert Rangeley, Oceana Canada’s science director, said rebuilding plans are in place for just three of those species, with commitments in place to create rebuilding plans for an additional five. 

Out of its study of 194 species, Rangeley said the audit found that finfish were most at risk. 

“Some of the red fish are down around 15 percent of their lowest reference point and some of the cod stocks are at half of the lower reference point,” he said

Oceana Canada wants to see recovery targets set and measures put in place to reduce mortality for all the species at risk Rangeley said. That may result in “stopping fishing or reducing fishing to an extent that allows growth in the population” of both directed fisheries and bycatch, which Rangeley called unfortunate but potentially necessary.

“We don’t want to see fishing stop. We want to see more fishing. The problem is so many of these stocks are underperforming and some are at risk of never coming back,” he said. “One of the challenges fishermen are always facing – and I’m very sympathetic to – is ‘Who’s going to pay the cost of me not fishing?’ So for many species there’s this dilemma of stopping fishing to help hasten the recovery versus continuing fishing at some level so you can pay the bills. No one wants to see fishermen go out of business, but we do want to see healthy oceans and stocks coming back.”

For Rangeley, the surprise of the audit was “that we can only say that a third of our fish stocks are healthy – 36 percent,” he said. “Another 15 percent are in the cautious zone and 13 percent in the critical zone.”

Don Clark, a fisheries biologist with the St. Andrews Biological Station, conducts the annual summer survey of fish stocks on the Scotian Shelf, which runs from Cape Breton to Georges Bank.  The results, Clark said, could be due to higher water temperatures he’s noticed in recent surveys.

“In the last couple of years we’ve seen temperatures that are roughly two degrees higher than that on average,” he said. “However, there is also a lot of temperature variation over the shelf. So we’ll get bottom temperatures of 10 degrees in some parts and then down to one to two degrees in other parts. The kind of changes we’ve seen in the last few years are fairly broad-spread. Some places have gone up more and other places haven’t changed very much.”

The higher temperatures and their greater variance is worrisome, Clark said.

“It’s not great if it’s getting too warm in some places – then you might start to see local changes in distribution or availability,” he said.

Clark said higher water temperatures on the Scotian Shelf correlate with a growth in species normally found in warmer waters, like John Dory, armored sea robin, black scabbard and blackbelly rosefish. 

“The last several years we’re seeing fish I’ve never seen before or that I’d seen on Georges Bank, but hadn’t seen on the Scotia Shelf,” he said. “Some of these unusual fish might have been found just a little bit south of us, but are now being found on the Scotia Shelf on a consistent basis and in predictable locations.”

One positive from Clark’s research is the consistency of the groundfish he’s found on the western Scotia Shelf in the past seven years. There’s less cod, but more halibut, redfish, and an abundance of silver hake, shrimp, and crab, he said.

“[But] the massive decline in groundfish, which occurred in the early ‘90s from a combination of overfishing and cold water temperatures, hasn’t rebounded,” Clark said.

In contrast, haddock appear to be overabundant, according to Clark. 

“In some places, it looks like there is so much haddock that they’re limiting their own growth because there’s not enough food to provide for all of them,” he said.

Climate change could be playing a role in the anomalies Clark has observed in recent surveys, but the sheer scale of the area he surveys make isolating it as a defining factor difficult, he said.

“We haven’t seen anything that is clearly temperature-driven that would fit in to long-term planning for the fishing industry,” he said. “Obviously, the longer-term projections for climate change have to be concerning for the fishing industry, but I think for the Scotian Shelf they’re difficult to predict because we have so much variation from one end of the shelf to the other and we're influenced by both warm- and cold-water currents, so how they will interact over time is something that stretches the oceanographer’s modeling to try and predict accurately.” 

Reporting from Eastern Canada

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