April 25, 2023 — 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.
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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.