Studies by two Atlantic Canadian universities on snow crab on Newfoundland and Labrador’s Grand Banks spell trouble for the species in the coming century.
Memorial University of Newfoundland and Dalhousie University recently collaborated as part of a doctoral thesis on a long-term modelling of multiple species on the Grand Banks.
“This study was led by Raquel Ruiz-Diaz, who was a PhD student at the Marine Institute of Memorial University. This study was one chapter of her PhD thesis, and her thesis was more broadly looking at ecosystem-based fisheries management on the Grand Banks,” said Tyler Eddy, a scientist with Marine Institute’s Centre for Fisheries Ecosystems Research.
“We were curious what the climate change projections of temperature would indicate for these species under different greenhouse gas emission scenarios.”
One of the studied species was snow crab, which currently makes up a large percentage of the N.L. fishery. The lucrative species, however, could be seeing a downward trend, with the researchers predicting the stock’s biomass to fall by up to 60 per cent in high-emission scenarios. According to Eddy, the study’s modeling varies from “most pessimistic” to “least pessimistic.”
“Different climate models will give you different projections on how things are expected to change. The most pessimistic climate model we looked at projected a 60 per cent decline from present levels until 2100. However, the least pessimistic model projected about a 20 per cent decline,” said Eddy. “The reason we looked at a range of climate models is to get an idea of what this variability in the projection is. That’s something we consider a lot in climate change science — how well do climate change models agree, and how much variability is there?”
While any forecast for the future of snow crab by MUN and Dalhousie paint a bleak future for the species, another ever-important species for Newfoundland and Labrador is projected to make a comeback in the team’s climate models — Northern cod.
“They’re called snow crab for a reason; they prefer cooler temperatures compared to cod, which prefer warmer temperatures which peaks around five degrees Celsius, whereas snow crab’s high density is around zero or one degrees,” said Eddy.
Given that Eddy and the rest of the research team have 30–40 years of historical data, he said they have a high level of certainty for their predictions, despite how far in the future they are looking to.
“We know with certainty that these are the temperatures in which [snow crab] occur. We also have seen snow crab biomass decline by about 50 per cent in the last 30 years, and this has been related to a period in which the water has been warmer,” said Eddy.
“We’ve also seen a marine heat wave in Alaska and the Bering Sea, and that actually collapsed their stock of snow crab to the point where it’s been under fishing moratorium for two or three years now. So, I would say I have high confidence in our projections. I would say the thing that is less confident is we don’t actually know what our future will be in terms of how much greenhouse gasses we’re putting out there into the environment.”
With a decline heading for snow crab that ranges from 20–60 per cent, Eddy noted that there are steps that can be taken to keep the species biomass as healthy as possible going into 2100. He noted that governmental and organizational efforts like the Paris Agreement, which seeks to keep greenhouse gas emissions at net zero and to keep the global temperature rise below two degrees Celsius, as well as initiatives like the Canadian carbon tax, as good steps to protect species like snow crab.
“Within Newfoundland and Labrador, 98 per cent of our energy is renewable, so we already have this renewable energy at our fingertips,” said Eddy. “The question is, can we transition transportation, home heating and other energy that we use on a daily basis to these renewable systems?”
