The high seas — the ocean waters that begin 230 miles offshore — cover 43% of the planet’s surface and are home to as many as 10 million species, yet remain one of the least understood places on Earth. Among the region’s many mysteries are how Pacific salmon, one of the West’s most beloved and economically important fish, spend the majority of their lives — and why many populations are plummeting. Combined with how little we know about what climate change is doing out there, such questions make the area an international research and conservation priority.
These sprawling waters, though, are a mostly lawless zone, beyond the reaches of any national authority and governable only by international consensus and treaties. They face tremendous challenges that no nation can address alone: Climate change is causing marine heat waves and acidification, while overfishing and pollution are crippling ecosystems, even as pressure grows from companies and nations eager to drill and mine the ocean depths. In early March, negotiators representing nearly 200 nations came to a historic agreement aimed at protecting the ocean’s creatures and ecosystems. When the new United Nations High Seas Treaty was announced, marine scientists and conservationists around the globe rejoiced.
But what will the treaty actually mean for conservation in a region about which humanity knows less than the moon? When it comes to Pacific salmon, will the new treaty’s tools — and the international symbolism and momentum involved in agreeing to them — aid efforts to manage and protect them? Do the provisions go far enough? Here’s what the experts say.
The treaty’s protective tools may not be what salmon need
The treaty’s top provision establishes a road map for creating marine protected areas (MPAs) in international waters. Like national parks for the ocean, MPAs are zones that typically limit fishing or other activities to preserve ecosystems and species. When adequately enforced, they are widely considered to be a powerful tool for ocean and coastal conservation. They are also seen as key to reaching the U.N.’s goal to protect 30% of the planet’s oceans by 2030 — a goal the world is woefully behind on, with just 3% to 8% currently protected.
But when it comes to Pacific salmon, it is unclear whether MPAs can do anything at all. Salmon fishing in international waters has been banned since the 1990s, so future MPAs there will not reduce fishing. And while boosting enforcement of fishing bans may benefit other species, many believe illegal salmon fishing on the high seas is extremely low.
Still, some salmon experts believe that high seas marine preserves could provide indirect protection: By limiting other fishing, they could prevent salmon from being caught accidentally. They might also help preserve important marine food webs, though such ecosystems are vast, mobile and hard to monitor.
“If salmon used those (protected areas) as part of their migration and ocean habitat, then, yes, it could be beneficial,” said Brian Riddell, retired CEO and current science advisor to the Canadian nonprofit Pacific Salmon Foundation. “But to associate changes in marine survival to (an MPA), I think would be very, very difficult.”
MPAs also don’t address climate change or the marine heat waves that many researchers believe are a key factor in recent salmon declines. Matt Sloat, science director at the Oregon-based Wild Salmon Center, said that limiting global emissions would do more to protect salmon.
Although much remains unknown, recent research suggests that salmon ranges in the ocean are shifting or shrinking because of temperature changes. Salmon are also getting smaller, suggesting there may be more competition for fewer resources. “And then (hatcheries) are putting billions more hungry mouths into that smaller area,” Sloat said, referring to the sometimes-controversial state, federal and tribal hatcheries in the U.S. and other countries that raise and release quotas of juvenile salmon each year to maintain local fisheries. He believes that improving international coordination of the scale of those releases, rather than governing remote ocean habitats, might also improve salmon survival in the ocean.
It may boost collaboration and high seas research
Another section of the treaty bolsters collaborative research in international waters. Although the treaty’s language is directed more at support for developing nations — to ensure that new knowledge reflects the priorities of more than just the wealthiest coastal nations — salmon researchers hope that any overall increase in funding and interest in high seas research could help solve the mystery of what actually happens to salmon there.
While much is known about the environmental factors affecting salmon in their coastal and riverine habitats, scientists call the open ocean a “black box” into which salmon disappear for years. “We don’t even know where our salmon are,” said Laurie Weitkamp, a research biologist at the National Oceanic and Atmospheric Administration. In 2022, seeking answers, she led an expedition that was part of the largest-ever high seas salmon research effort in the North Pacific, during which five vessels and more than 60 international scientists surveyed 2.5 million square kilometers (nearly 1 million square miles) in the Gulf of Alaska.
The open ocean has always been a bottleneck for salmon survival; Weitkamp said that, even historically, “95% of the salmon that enter the ocean never come back.” Once, those numbers were predictable based on coastal and river conditions. Now, she said, scientists’ guesses are often wildly wrong. All known conditions will point to a good return, Weitkamp said, “And then it’s just like, where are they? What happened?”
Researchers have been trying to understand what they’re missing in salmon’s ocean habitats, but work on the high seas is extremely expensive: Expeditions cost tens of thousands of dollars a day, but can collect only small amounts of data because salmon are widely dispersed and hard to find. She said the scale of the information gathered during the 2019-2022 expeditions she was part of was possible only because so many ships and nations worked together. It’s the kind of collaboration the treaty may help to inspire — directly in some cases, and symbolically in others — as nations sign on.
“Collaboration is absolutely essential,” said Riddell, who was also part of the 2019-22 expeditions. “We need a dedicated, ongoing program,” to understand what’s happening to salmon and to strengthen ocean and climate models. He hopes the High Seas Treaty will lead to more support and interest in that work.
Ratification and Indigenous inclusion are not guaranteed
This year, many salmon runs are expected to hit record lows, impacting the ecosystems, economies and communities that depend on them. Chinook returns in Oregon, California and Alaska are forecast to be so low that offshore recreational and commercial fishing this spring has been cancelled in many areas. The Klamath River chinook run, upon which the Yurok Tribe relies for cultural and economic security, is expected to be the lowest in history.
“International effort to preserve and protect ocean habitat is critical to restoring these historic salmon runs,” said Amy Cordalis, an attorney, fisherwoman and Yurok tribal member who has served as the tribe’s general counsel. But “those efforts must accommodate traditional uses of those areas.”
In 2020, during negotiations on what became the High Seas Treaty, a group of scientists published a report calling on the United Nations to better incorporate Indigenous management perspectives, which they said were not adequately represented in discussions at that time. The final treaty, which includes language recognizing Indigenous rights, did better than most to include Indigenous peoples and traditional knowledge, said Marjo Vierros, a coastal policy researcher at the University of British Columbia and lead author of the report. “How that plays out in implementation is of course a different question.”
While the treaty process plays out, salmon scientists are continuing to investigate the mysteries of salmon at sea. Earlier this year, experts from across the North Pacific met in Canada to draft the science plan for another international high seas research program, and leaders in Canada are working to fund an expedition comprised of Indigenous scientists. Researchers are also beginning to use drones and other new technologies to make ocean research less onerous.
Researching at sea, “you gain a whole new understanding for how big (the ocean) really is,” Weitkamp said, and how much of its influence on salmon, climate and humanity remains unknown. “The ocean, especially the North Pacific, is just enormous.”