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Fish populations are shifting around the planet and 'someone is going to lose out,' says UBC researcher

By 2100, nearly half of the world’s shared fish stocks are expected to shift to neighbouring countries or international waters, says a new UBC study
Salmon fishing Alaska
Commercial purse seine fishers haul their net while fishing for pink and chum salmon, Chatham Strait, Admiralty Island, Alaska

A shift in the planet’s global climate system is already prompting an untold number of people to leave their homes in search of a better life. Could fish be next? 

According to new research out the University of British Columbia examining over 9,100 species around the world, the answer is yes. 

By 2100, nearly half of the world’s shared fish stocks are expected to shift in a relocation that could affect four out of every five exclusive economic zones on the planet, according to a study published Tuesday in the journal Global Change Biology.

And that, in turn, will inevitably spark conflict in some parts of the world, says lead author Juliano Palacios-Abrantes, who conducted the study while at UBC’s Institute for the Oceans and Fisheries (IOF) and is now a postdoctoral researcher at the University of Wisconsin-Madison.

“The data behind our research shows that climate change is shifting the distribution of marine fisheries around the globe. It's projected to continue and we have evidence that this is happening,” Palacios-Abrantes said. 

“This is a key moment.” 

Part of the problem is the way countries measure fish abundance in what's known as an Exclusive Economic Zone (EEZ).

Extending 200 nautical miles (370 kilometres) from a nation’s shoreline, EEZs chart where a country has special rights over marine resources like fishing, oil and gas, and the production of green energy. Where these zones overlap, the division of resources is worked out between the countries involved, or in the case of disputes, can land in the hands of the nearest state.

In Europe, where disputes have worsened in recent years, the region’s Atlantic herring stocks are divided based on the number of fish landed in the 1970s, says Palacios-Abrantes. But those baselines have already shifted, and as the sea warms, fish are likely to move even more, leaving some countries with dwindling stocks. 

It’s also a problem of geography. Fish don’t respect international borders, and there’s a serious misalignment between where fish live and where humans have decided, arbitrarily, to define exclusive fishing grounds off their shores.

Any dispute puts at risk shared resource that between 2005 and 2010, brought in roughly US $76 billion in revenue.

To understand how fish stocks are moving across international borders Palacios-Abrantes and his colleagues used the latest forecasts showing global climate emissions under a worst-case scenario. 

Those results were then layered on top of species distribution maps showing where fish would live based on a number of environmental variables, like salinity and water temperature. 

Then they ran everything through a model several times to adjust for natural climate cycles over the coming decades.

“In one run, maybe it was an El Niño year, so things were like very, very warm. Then, the next run it was actually a La Niña year,” he said. 

What they found was a new normal in where fish are expected to live and what countries will have access to them. 

Some of the areas expected to face the earliest rejigging of fish stocks are in the Pacific islands of Polynesia and Micronesia, where relatively small EEZs are expected to lead to a “messy” situation, says Palacios-Abrantes.

Along both the Atlantic and Pacific coasts of North and South America, as well as the Atlantic coast of Southern Africa, shifts in stocks are expected to benefit fishing grounds closer to the poles.

The Caribbean, as well as the Pacific coast of North America are also among the areas expected to see early shifts in fish stocks. 

The Pacific coast of Canada, the U.S. and Mexico should prepare for the start of a big shift in where fish live starting in 2030, when 10 shared stocks are projected to shift, says Palacios-Abrantes.

“Our results suggest that Mexico in the Pacific will lose on average to the U.S., which will lose to B.C.,” he said, noting more work needs to be done to understand the impact of local ocean currents. 

Counter-intuitively, the researcher says those countries expected to gain stocks might have the most to lose. That’s because a country forecast to lose fish might be tempted to overfish migrating populations and threaten stocks on both sides of the border. 

“Agreements need to be made so that those who are losing can ensure that they can have some type of security,” he said. 

While B.C. may come out as an overall winner in the coming decades, many species of fish could be increasingly vulnerable to American fishing fleets, including iconic species of salmon.

The study comes less than a week after a technical report found Alaskan fishers caught over a half-million sockeye salmon bound for B.C. rivers. That triggered outrage among both Indigenous and non-Indigenous fishers in B.C., who in 2021, were effectively shut out of fishing as a sacrifice to help rebuild salmon stocks.

Salmon don’t like warm water, so as the ocean warms, they are expected to take an increasingly northerly route as they return to their home rivers. 

Experts say that will make them vulnerable to interception as more B.C.-bound salmon crash into the Alaskan coast before making their way south to spawn. 

Canadian critics say the federal government has failed to pressure the U.S. side and has allowed the interceptions to continue for years. The Canada-U.S. Pacific Salmon Treaty is meant to settle such imbalances, but it isn’t up for renewal until 2028.

The ongoing dispute offers a glimpse of how future conflict between countries could be made worse by a changing climate. 

But some nations have already found ways to work together. Palacios-Abrantes points to neighbours like Argentina and Uruguay, which have set up a shared buffer zone where fishers from both countries can bring in a catch. And in the North Atlantic, Russia and Norway have set up a successful trade quota system.

Palacios-Abrantes says his group’s findings offer a clear call for governments to strengthen their transboundary agreements and consider side payments to share both the benefits and responsibilities of maintaining fish stocks. 

“Definitely someone is going to lose out,” he said. “What we are saying here is like, look, this is the baseline.”

“There are things that we can do now, if we can make policy work with faster than climate change.”