Continued loss of sea ice could alter the food web of some arctic marine predators, Canadian study finds

Ringed seal on the ice floe. “We found that by the turn of the century, the big fat Arctic cod could decline dramatically in terms of biomass and distribution,” said lead author Katie Florko. “Then the smaller fish, like capelin and sand lance, could become much more prevalent. “(Katie Florko)

If sea ice loss continues, it could irrevocably alter the food sources of some Arctic marine predators, according to 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 examine different emission scenarios focused on the Hudson Bay region between 1950 and 2100.

“All of the changes were relatively negligible in the low-emission scenario, but in the high-emission scenario we predicted a 50% decline in abundance of well-distributed, ice-adapted, and energy-rich Arctic cod (Boréogadus dita) and an increase in the abundance of small fish associated with temperate zones in southern and coastal areas, ”the authors said in the study summary.

“Additionally, our model predicted that all fish species decreased in average body size, but a 29% increase in total prey biomass. Declines in energy-rich prey and restrictions on their range are likely to have cascading effects on arctic predators.

In the high emissions scenario, the study found that changes in the distribution of fish in the region, as well as their size, would begin to accelerate in 2025 and continue to accelerate if measures were not taken. not taken to reduce carbon emissions.

Changes in the distribution and mass of fish

In a press release, the lead author of the study said that small fish like capelin and sand lance could become more common in the region, forcing marine predators like the ringed seal to work harder to get the same energy they could have previously obtained from a species like cod.

“Forage costs energy,” said Katie Florko, University of British Columbia in Vancouver, and lead author of the study.

“Does this mean that the seals will have to expend more energy to get more of these small fish for the same amount of energy as to catch a bigger fish?” It’s not unlike how burgers in fast food restaurants seem to get smaller and smaller each year, and you’re getting less for your money.

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

However, Florko said the changes could have some benefits. VSApelin is a summer staple of the beluga’s diet, so an increase in this species could benefit the whale during this time of year.

Additionally, since small fish store less marine contaminants, people who consume seals on a regular basis may also be exposed to fewer contaminants in their food.

However, global changes in the Arctic food chain in the face of ongoing climate change mean that reducing emissions remains the most desirable scenario for the region, scientists say.

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

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

Write to Eilís Quinn at [email protected]

Related stories from the north:

Canada: Seabirds and Their Vulnerability to Global Warming: Q&A with Researcher Emily Choy, Eye on the Arctic

Russia: Perfectly preserved cave lion 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 Eye on the Arctic

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