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Rising sea temperatures projected to cause global fish oil shortages

U of T scientists warn that shortages may negatively impact human fetal development
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Fish oil, an essential fat for human development, is projected to fall drastically over the next few decades due to rising sea surface temperatures.

The finding was reported by a study co-authored by U of T researchers which analyzed the relationship between temperature and the amount of DHA. This is an omega-3 fatty acid that is found chiefly in cold-water fish and is produced by algae.

Fish, like humans, cannot make their own DHA in significant amounts. They must get it from algae, which is the base of most aquatic food chains.

Algae typically produce more DHA at lower temperatures to maintain the fluidity of their cell walls. When temperatures are higher, the cell walls are more flexible, so the algae need to produce less DHA. This reduction means fish on the upper echelons of the food chain are consuming less DHA as well — in turn, humans have a shortage of this essential nutrient.

Omega-3 fatty acids are often supplemented as fish oil capsules, and are necessary for heart health, neurological function, and fetal development in the third trimester.

Medical professionals recommend that pregnant people consume about 250 milligrams of DHA per day. To date, there are no commercially-available sources for omega-3 fatty acids besides fish.

This puts us in a dire situation as, according to the paper, 96 per cent of the world’s population will be in a shortage of DHA by 2100.

“Although [low-income countries] will be impacted, so will rich countries, [which] brings home the [wide impact] of climate change,” said PhD candidate Tim Rodgers, who co-authored the paper, in an interview with The Varsity.

“Our generation’s children might have these shortages, and especially pregnant women.”

The most vulnerable countries are located in sub-Saharan Africa. When accounting for trade, said Rodgers, which wasn’t included in the model the paper projected. North America and Europe are net importers of fish, and Africa and Asia are net exporters.

If these trends continue, the situation is much more critical than the paper suggests in regions where people are subsistence fishers, said Rodgers.

A deeper look reveals an even grimmer picture. According to the model, it is inevitable that these shortages will eventually occur, even in the best-case scenario where world leaders congregate and limit greenhouse gas emissions and the climate crisis. The damage is already done, and by 2100, shortages will be severe — at an approximate 10 to 58 per cent global loss of DHA. Alternative technologies for DHA production are being explored, though none are on the market.

Even if we managed to produce DHA from other sources, its distribution would be unequal. Low-income individuals who cannot access international markets would be left most vulnerable, noted Rodgers. The gap between those who stand a fighting chance against the climate crisis and those who don’t will become more obvious with time.

“One of the worries I have in the face of climate change, is that we have this fortress mentality,” said Rodgers, “where as resources become more scarce, we all try to protect ourselves at the expense of everyone else in the world. That’s not going to solve the problem.”

Discussing solutions to mitigate the impact of the climate crisis, Rodgers emphasized the need for alternative energy sources to produce clean electrical power. “Conceptually, we know what to do to keep global warming below 1.5 degrees Celsius,” he said.

“It’d be great if people just realize that these impacts will be felt by them, by their children, by their grandchildren, by everyone around the world — and that we need to act now.”