Study: Shared Fish Stocks on the Move Due to Climate Change Could Prompt Stock Disputes

yelloweye rockfish
The yelloweye rockfish, which dwells in deep waters and lives upward of 140 years. File photo via UC Berkeley.

A University of British Columbia study predicts that climate change will force 45% of fish stocks that cross two or more exclusive economic zones to shift significantly from their historical habitats and migration paths by 2100, possibly leading to stock ownership conflicts.

The report released on Tuesday, Jan. 18, says that by 2030, when United Nations Sustainable Development Goals should be met, 23% of these “transboundary” fish stocks will have changed their historical habitat range.

The UBC modeling study also projects that 78% of exclusive economic zones, where most fishing occurs, will see at least one shifting fish stock. By 2100, this climbs to 45% of stocks, with 81% of EEZs seeing at least one stock shift if nothing is done to halt greenhouse gas emissions.

Lead author Juliano Palacios-Abrantes who conducted the study at UBC’s Institute for the Oceans and Fisheries, said this is not just an issue of stocks leaving or arriving to new EEZs, but of stocks that are shared between countries completely changing their dynamics.

Palacios-Abrantes, now a postdoctoral researcher at the University of Wisconsin-Madison, said the study includes a timeline suggesting that these shifts have been underway since the beginning of the 21st century, with more dramatic changes expected by 2030 and beyond.

The study tracked shifting ranges of 9,132 transboundary fish stocks, which account for 80% of the catch taken from the world’s EEZs, starting in 2006 and projecting to 2100. These changes in stock distribution are expected to affect harvests and raise tensions over which countries can claim majority ownership of certain stocks, particularly given that between 2005 and 2010 fishing of transboundary species in total netted an estimated $76 billion in U.S. dollars in revenue.

The study makes a number of suggestions regarding how to avoid the worst outcomes of potential disputes, such as crafting agreements to allow fishing fleets to fish in neighboring countries’ waters while offering a share of the catch or profit. Study authors said it will also require rebalancing and renegotiating many of the catch quota agreements already in place.

Gabriel Reygondeau, a study co-author, noted that one of the most common effects of climate change on the ocean is a global warming of the sea surface temperature. This effect causes marine species to shift poleward in order to stay in a comfortable environment, since their internal temperature depends on the external water.

Consequently, Reygondeau said, “we expect all marine creatures to move poleward and of course some of them (northern hemisphere species) will reach the pole at some point in time if the ocean gets warmer every year.

“We expect first lower polar species (Alaska gulf, Norwegian coast, Labrador Sea) and then temperate species (located originally in the 30-45° latitude band) to reach the Arctic,” Reygondeau explained. “Yes, there will be a clear displacement of ‘new’ species in the Arctic region. However, we still don’t know how this population will become settled since the environment of the polar biome is extreme in terms of hours of light and new competition between endemic species of the pole and new climate refugee species.”

“If these changes are not addressed, it could lead to disputes between countries, as the Arctic is an ocean with ice on top, as opposed to Antarctica, which is an island with ice on top,” he said. “This increased melting of the ice cap allows more possible fishing ground for the fishing industry combined with potential new stocks arriving due to climate change.”

“Since both the population and the fishing ground are fully new,” he remarked, “existing fisheries management and treaties do not cover these topics and might be the ground for potential debate and evaluation for nations’ cooperation and fisheries management.”