Climate change makes winners and losers out of cod and snow crab, says scientist

New research out of Memorial University's Marine Institute shows that species like cod fish could be the winners of climate change and a warming ocean, but the opposite could be expected for snow crab, says one research scientist.

A team of scientists used modelling to look into the effects of climate change on three Grand Banks fish species. They anticipate that warmer waters could lead to biomass declines for snow crab and yellowtail flounder but gains for Atlantic cod.

"That's one thing that we see when we're looking at the impacts of climate change on marine ecosystems and oceans, is that there are winners and losers. So it's not as though everything is going to be negatively impacted," said Tyler Eddy, a scientist with Marine Institute's Centre for Fisheries Ecosystems Research.

Species that thrive or struggle in these scenarios will depend on the their thermal preferences and changes in a region, he said, adding a specific species might also leave a region to follow their preferred temperature.

Eddy is part of an eight-member team, which includes scientists from Dalhousie University and the Department of Fisheries and Oceans. Their research was recently published in a paper that Eddy co-authored.

Snow crab decline

Eddy said snow crab like cooler water temperatures and in the best case scenario, with low carbon emissions, the modelling predicted there wouldn't be much change in the biomass.

However, in the worst case scenario where emissions aren't reduced, it could result in a biomass decline between 20 per cent to 60 per cent by 2100.

"There's quite a wide range in the decline depending on, you know, which sort of climate model or weather forecast equivalent you look at," he said.

The consequences could be drastic. Eddy said that in the last few decades there has been a similar decline in the snow crab biomass.

"The fishery is already sort of having to adapt to the changing abundance of snow crab," he said. "We would prefer to not have another 60 per cent decline beyond, you know, what we are working with at the moment."

Some like it hot

But not all species will be negatively affected by warming temperatures, said Eddy.

The modelling found the cod biomass could increase if water temperatures increase.

If emissions remain low and water temperatures don't increase, he said the cod biomass could remain stable or increase up to 10 per cent.

"If we do have increased warming in our high emission scenario, we're expecting cod to increase anywhere between 15 and 30 per cent in biomass," said Eddy.

However, Eddy stressed that warming water isn't something to cheer on. 

As a climate scientist, he said, the risks of unmitigated carbon emissions far outweigh any benefit and there are more losers than winners.

He said scientists are already seeing the negative impacts, citing heat waves, wildfires, more frequent hurricanes and flooding.

"I think from a fisheries perspective and from a marine ecosystem management perspective, you would want to minimize the amount of carbon emissions and try to minimize the amount of warming as much as possible," Eddy said.

Banner year for some

In another area of the province, fishermen have been feeling similar concerns.

Mary's Harbour Mayor Alton Rumbolt — who's also a fish harvester — told CBC News he's noticed that the cod fishery has been booming lately, but warns that it's coming at the expense of the crab and shrimp harvests.

"We don't have the crab now because the cod has overtaken the grounds," he said.

"When you've got a lot of cod, you're not getting so much shrimp, crab."

He believes climate change is having an impact in the changing populations.

Eddy said climate change is the most pressing issue scientists are currently facing in the natural world.

They already know the waters of Newfoundland are naturally dynamic, he said, pointing to the collapse of the cod fishery and subsequent increase in the snow crab and shrimp fisheries, which are also impacted by the Gulf Stream and Labrador current.

"We have seen these changes through time. And I think the lesson that we're learning from the study is that we're expecting to see even more changes in the future," said Eddy.

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