Continued sea ice loss could alter food web for some Arctic marine predators, says Canadian study

Ringed seal on Ice floes. “We found that by the end of the century, the large, fatty Arctic cod may decline dramatically in terms of biomass and distribution,” said the study’s lead author Katie Florko. “Then smaller fish, like capelin and sand lance, may become much more prevalent.” (Katie Florko)

If sea ice loss continues it could irrevocably alter the food sources for some Arctic marine predators says a Canadian study released this month.

The study, “Predicting how climate change threatens the prey base of Arctic marine predators,” was published this month in the journal Ecology Letters, and used computer modeling to look at different emission scenarios focused the Hudson Bay area between 1950 and 2100.

“All changes were relatively negligible under the low-emission scenario, but under the high-emission scenario, we projected a 50% decline in the abundance of the well-distributed, ice-adapted and energy-rich Arctic cod (Boreogadus saida) and an increase in the abundance of smaller temperate-associated fish in southern and coastal areas,” said the authors in the study’s abstract

“Furthermore, our model predicted that all fish species declined in mean body size, but a 29% increase in total prey biomass. Declines in energy-rich prey and restrictions in their spatial range are likely to have cascading effects on Arctic predators.”

Under the high emission scenario, the study found that changes to fish distribution in the region, as well as their size, would start to pick up in 2025 and continue to accelerate if measures weren’t taken to reduce carbon emissions.

Changes to fish distribution and mass

In a news release, the study’s lead author said small fish like capelin and sand lance could become more common in the region, forcing marine predators like ringed seal to work harder to obtain the same energy they might have gotten before from a species like cod. 

“It costs energy to forage,” said Katie Florko, from the University of British Columbia in Vancouver, and the study’s lead author.

“Does that mean the seals will need to spend more energy to get a larger number of these smaller fish for the same amount of energy as capturing a bigger fish? It’s not unlike how the burgers in fast food restaurants seem to get smaller and smaller every year, and you’re getting less bang for your buck.”

A file photo of a ringed seal. “The number of fish and the biomass will increase, as will the diversity of the fish, but they’ll come in smaller packages,” said the study’s lead author Katie Florko. (Marie Auger-Méthé/University of British Columbia)

However, Florko said the changes may have some benefits. Capelin are a summer staple of the beluga’s diet, so an increase of that species might benefit the whale during that time of year.

Also, since smaller fish store fewer marine contaminants, people who eat seal as a regular part of their diet may also be exposed to less contaminants in their food.

However, the overall changes to the Arctic food web in the face of ongoing climate change, means lowering emissions is still the most desirable scenario for the region say the scientists.

“We’ve never seen such drastic change so quickly,” said Travis Tai, a co-author of the study.

“We’re rolling the dice, and we don’t know what exactly will happen. When we have dramatic shifts in food web structures, we can expect large changes not only to how species such as ringed seals use the oceans, but also how people use the oceans.”

Write to Eilís Quinn at

Related stories from around the North: 

Canada: Seabirds & their vulnerability to a warming climate: Q&A with researcher Emily Choy, Eye on the Arctic

Russia:  Perfectly preserved cave lion cub found in Siberian permafrost, CBC News

Sweden: Sweden to lead major Arctic expedition, Radio Sweden

United States: Climate change is worsening water scarcity in rural Alaska says study, Eye on the Arctic

Eilís Quinn, Eye on the Arctic

Eilís Quinn is an award-winning journalist and manages Radio Canada International’s Eye on the Arctic news cooperation project. Eilís has reported from the Arctic regions of all eight circumpolar countries and has produced numerous documentary and multimedia series about climate change and the issues facing Indigenous peoples in the North.

Her investigative report "Death in the Arctic: A community grieves, a father fights for change," about the murder of Robert Adams, a 19-year-old Inuk man from Arctic Quebec, received the silver medal for “Best Investigative Article or Series” at the 2019 Canadian Online Publishing Awards. The project also received an honourable mention for excellence in reporting on trauma at the 2019 Dart Awards in New York City.

Her report “The Arctic Railway: Building a future or destroying a culture?” on the impact a multi-billion euro infrastructure project would have on Indigenous communities in Arctic Europe was a finalist at the 2019 Canadian Association of Journalists award in the online investigative category.

Her multimedia project on the health challenges in the Canadian Arctic, "Bridging the Divide," was a finalist at the 2012 Webby Awards.

Her work on climate change in the Arctic has also been featured on the TV science program Découverte, as well as Le Téléjournal, the French-Language CBC’s flagship news cast.

Eilís has worked for media organizations in Canada and the United States and as a TV host for the Discovery/BBC Worldwide series "Best in China."

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