Tensions between countries are likely to rise with the global temperature as valuable fish stocks fleeing warmer waters cross into different national boundaries, a new study suggests.

The climate crisis will push 45 per cent of the world's shared fish stocks away from historic habitat ranges and migration routes by 2100, posing a challenge for international co-operation, said senior author William Cheung.

“Fish don’t recognize political boundaries,” said Cheung, associate professor with the University of British Columbia’s Institute for the Oceans and Fisheries.

Fishing allocations, who gets what and how much, are political constructs based on an existing range of conventions and treaties, but these agreements are going to have to adapt to new realities if global emission rates continue, Cheung said.

Overall, climate change is pushing transboundary stocks to fishing grounds closer to the Poles and in many cases, the shift is already happening, he said, adding shifts on the Pacific coast of Central America and West Africa will occur primarily along the equator.

Tropical regions like the Caribbean and South Asia will see the shifts sooner, but northern temperate nations will also be affected.

Ten transboundary fish stocks shared by Canada and the U.S. on the Pacific coast are projected to shift ranges by 2033, according to the study.

The best way to avoid disputes over shifting fish stocks is to craft international agreements that anticipate the changes global warming is going to bring, says UBC researcher William Cheung. Photo by Sylvie Li / UBC

The research team also examined the catch share of the five most-valuable transboundary stocks of Canada and the U.S., said lead author Juliano Palacios-Abrantes.

Ten transboundary fish stocks shared by Canada and the U.S. on the Pacific coast are projected to shift by 2033 due to #ClimateChange, according to a recent @UBCoceans study.

Those catch proportions are expected to move northwest from U.S. states south of the border to B.C., and from Alaska to Russia, said Palacios-Abrantes, who completed the study at UBC, but is now a researcher at the University of Wisconsin-Madison.

Fisheries agreements typically rely on historical data and aren’t necessarily tweaked to deal with the changes to stocks caused by climate change, he said.

“Many of the fisheries management agreements made to regulate shared stocks were established in past decades, with rules that apply to a world situation that is not the same as today,” he said in a press release.

Two valuable stocks shared by Canada and the U.S. on the West Coast are salmon and halibut, Cheung said.

The two countries manage the stocks through the Pacific Salmon Treaty (PST) and International Pacific Halibut Commission regulations, he said, adding the agreements can help handle any potential fishing tensions.

However, the existence of such treaties doesn’t guarantee tensions won’t flare and cause fractures in relations — even between friendly nations.

B.C. and the U.S. states of Alaska, Washington and Oregon got into a dispute in 1992 after the PST expired and agreements couldn’t be reached around new fishing allocations.

Dubbed the Pacific Salmon War, the conflict saw U.S. and Canadian harvesters intentionally target salmon bound for each other's waters. The dispute lasted six years and even saw a flotilla of B.C. fishing boats blockade an Alaskan ferry for three days in the Prince Rupert harbour before a new agreement was crafted in 1999.

The current PST is set to expire in 2028, but conservation groups in a technical report last week say adaptations to fishing allocations in southeast Alaskan districts need changing urgently.

Threatened salmon stocks such as sockeye headed for the Nass and Skeena rivers are being intercepted by Alaskan harvesters at unacceptable numbers, the conservation coalition said.

The best way to avoid potential disputes over shifting stocks across the globe is to craft fishing agreements that anticipate the changes global warming is going to bring, the study suggests.

That might allow fishing fleets to harvest in neighbouring waters if they offer a share of the catch or profit. Or, crafting fishing agreements that are more flexible or nimble when adjusting quota agreements to accommodate climate changes.

The study tracked the shift of 9,132 transboundary fish stocks, representing 80 per cent of the catch of the world's fishing boundaries, starting from 2006 until 2100.

The study is helpful because its climate models suggest where and when stocks will become points of tension, so solutions can be worked out now, said co-author and UBC researcher Gabriel Reygondeau.

“We must accept that climate change is happening, and then move fast enough to adapt fisheries management regulations to account for it.”

Rochelle Baker / Local Journalism Initiative / Canada’s National Observer

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Regardless of anything else, it is essential that the Chinese factory fleet gets restricted to Chinese territorial waters.

Oh, like that's going to happen. Keeping a large nation's ships from entering international waters? I mean, it would only require overturning everything I can think of about maritime and international law. That's even less likely than my pipe dream where Canada just buys the Alaska panhandle.