There are too many pink salmon in the Pacific
June 03, 2022
Evidence is mounting that pink salmon, pumped by the billions into the North Pacific from fish hatcheries, are upending marine ecosystems. Climate change is making this worse.
By Miranda Weiss
This story is available in full at The Pacific is overrun by pink salmon | Popular Science (popsci.com)The Tutka Bay Lagoon Hatchery is located at the edge of an isolated estuary off southcentral Alaska’s Kachemak Bay. Accessible only by boat from the closest hub community of Homer, the hatchery is one of 30 constructed by the state to boost commercial salmon fisheries that were struggling in the 1970s. On the last day of April, I board a water taxi in the Homer harbor to visit the facility. A raging westerly wind careens across the bay as the 10-meter landing craft slams into swells the skipper describes as “sporty.”
I’m visiting during the hatchery’s ponding process—the transfer of pink salmon fry from freshwater incubators on land to floating saltwater pens in the lagoon. This is the first step before the hatchery releases about 60 million paper clip–sized pink salmon into the ocean where they’ll disperse to feed and mature by next summer.
Fish farms, which are illegal in Alaska, raise salmon until they’re marketable size. But hatcheries take advantage of a salmon’s innate homing instinct, unleashing juvenile fish to feed and complete the growing process at sea, after which they’ll return to the waterbody near the hatchery to provide fish for commercial and recreational harvests. This practice is known sometimes as salmon ranching, and seafood marketers often label hatchery fish as “wild caught.” My goal is to get a feel for the scope of the industry, which is mostly run by NGOs funded by the sale of hatchery fish. I want to put into perspective mounting scientific evidence that these industrially produced fish are flooding marine ecosystems where they can impact everything from plankton to whales.
The tide is too low for the skipper to bring the boat through the narrow channel that leads to the lagoon, so she drops me on a nearby beach where I climb five flights of old wooden stairs up a rocky cliff into a forest of towering spruce that surrounds the facility. These tall trees provide protection from the raging conditions at sea, allowing the fluty song of a kinglet, a tiny songbird with a big voice, to fill the air from a bough high above my head.
Josh Sawlsville, the manager of the operation at the time, meets me at the hatchery office. A hefty guy with sandy blond hair, Sawlsville got into the industry on a lark over eight years ago when he was a biology undergrad in Wisconsin and took a semester off to work as a cook at a hatchery in the heart of Alaska’s pink salmon production, Prince William Sound, about 300 kilometers northeast of Tutka. He returned after graduating, shifting from the kitchen to the fish operation, and has been working in the industry ever since. During the summer months, Sawlsville manages a staff of more than a dozen, but the hatchery is just coming out of the winter season, when the work slows down and no more than five souls keep the place running in the winter gloom: tucked back among the trees, the hatchery loses direct sunlight for months.
Sawlsville and I put on rain gear and he hands me a red-bulbed headlamp to enter the dark incubation room, a cold, damp warehouse with what sounds like 100 faucets going full blast. Here, we meander among the incubators, shallow tanks stacked in rows like shelves lining grocery aisles. Water piped in from a nearby stream gushes through the incubators, filled with salmon fry that hatched in late fall and are now about the length of a matchstick. Overhead lights are kept off to keep the young fish calm so they use up less oxygen. The red light Sawlsville loaned me doesn’t bother the fish, he explains, but it does pick up flashes of silver everywhere I look: in the incubators; in the chest-high trough where the fry, about five months old, are dumped before being flushed out to pens in the lagoon through an underground pipe; and underfoot where the little fish have splashed out of their tanks to die on the wet concrete floor. The scope of the effort is dazzling. If all of these fish survived to maturity, there’d be six salmon dinners for all of the residents of Canada and Alaska put together.
Hatcheries have been under increased scrutiny in the Pacific Northwest for damaging wild salmon runs, as hatchery fish—which are less successful spawners compared with wild salmon—stray into far-off streams where they can interbreed with wild populations, producing wild offspring that aren’t as fertile. Meanwhile, Alaska’s love affair with industrial production of salmon fry continues. Hatcheries contribute one-quarter of the value of the state’s salmon harvests, boosting commercial fisheries, propping up large-scale fish processors, and generating US $600-million in the process. And they produce fish that fill the dinner plates and freezers of Alaskans. In addition to pink salmon, the Tutka facility, which is owned by the state and operated by a private organization governed primarily by commercial fishermen, annually releases around 420,000 sockeye smolts (representing less than one percent of the pink fry released). Sockeye salmon, though valued more than pink for their flavor and because they hold up well to frozen storage, are more expensive to raise in hatcheries because they require a longer rearing time in freshwater tanks. In July, when the tide allows, the lagoon fills with pleasure boats, and fishermen lob hooks to snag the mature sockeye—heftier than the pinks and still gleaming silver—returning to the facility. At a nearby whitewater creek that the hatchery also stocks with sockeye, locals plunge wide-mouth dip nets into the current to catch enough sockeye to put up for the winter.
Despite these benefits, some people are questioning whether it makes sense to keep pumping salmon into the Pacific with seeming abandon. In the decades since Alaska rushed to construct hatcheries to fill the gaps in ailing salmon runs, especially pink populations hit hard by tectonic shifts caused by a massive earthquake in Alaska in 1964, ocean conditions across the North Pacific have been a boon to pink salmon. Today, Tutka’s pink salmon fry are swimming into a very different ocean than when the facility was first built in 1978, an ocean that appears to be favoring pinks.
It’s a heyday for pink salmon in the North Pacific. Across the region, there are three times more pink salmon in the ocean than there were about 50 years ago. Nearly three out of every four salmon in the North Pacific are pinks. Hatcheries are piling onto that bounty.
Since the 1970s, industrial production of pink salmon has exploded, and today, hatcheries in the United States, Canada, Russia, and Japan pump about 1.3 billion pink salmon fry into the Pacific each year, leading to the production of roughly 82 million adults. About 15 percent of all pinks in the ocean originate from hatcheries, topping off a population that is already at a record level of abundance. This means there are about as many hatchery pink salmon as there are wild sockeye and more hatchery pinks than each of wild chum, chinook, and coho. The bulk of this production comes from Alaska.
Despite being the smallest of the Pacific salmon at less than two and a half kilos, pinks are the darlings of the hatchery industry in part because of their rapid life cycle. These fish are voracious feeders and fast growers, quickly bulking up to market size by increasing their weight 500 percent at sea over four months. And unlike other salmon species that spend a variable number of years in salt water—up to five years for chinook—pinks return for harvest predictably after about 18 months at sea.
This short life cycle is one reason why wild pink salmon are thriving in today’s changing ocean conditions. As waters warm, their ability to reproduce at breakneck speed enables pinks to quickly colonize new areas and recover from population drops, prospering like rats where other species might fail. Warming conditions are also altering the food chain in ways that appear to favor wild and hatchery pinks alike.
But pinks aren’t the only salmon species that is booming. In recent years, there have been more salmon in the North Pacific than there have been at any point in the last century. And while this has been a blessing in some places—the Bristol Bay sockeye run hit a historic high last summer at more than 66 million fish—more fish in the ocean means greater competition for the next meal. As throngs of hungry salmon chase similar prey—including zooplankton, squid, and small fish—salmon are getting smaller.
Nancy Hillstrand has seen this firsthand. She is the owner of Coal Point Seafood Company, a seafood processing and retail outlet at the edge of the Homer harbor, where I caught the water taxi to the hatchery. On a typical summer day, the place buzzes with activity—workers on the slime line deftly fillet salmon and halibut delivered by commercial boats and recreational fishermen; high-end seafood—king crab legs, scallops, smoked salmon—sells for a premium at the front counter.
Hillstrand has lived on the bay for close to 50 years. She’s watched as lucrative crab and shrimp fisheries disappeared, and now, salmon delivered to her processing plant are shrinking. “I didn’t realize what was happening until everyone was asking for scissors,” she says. The nearly arm-length bags she had always ordered for vacuum-packing salmon fillets needed to be trimmed to fit fish that were coming in smaller.More than a half century of data has confirmed what Hillstrand has seen on her processing line. While the number of salmon has shot up, the size of fish is going down: in Alaska, chinooks have shrunk the most at eight percent compared with pre-1990 sizes, and elsewhere, such as on the Columbia River where the “June hogs”—chinooks that weigh more than 35 kilograms—used to spawn each summer, mighty chinooks are a thing of the past. This means a loss to commercial fishermen and other fish harvesters as well as a new paradigm for fish processors, restaurants, and markets.
Now Hillstrand orders 46-centimeter bags, and she believes hatcheries are partly to blame. For nearly a decade, Hillstrand has pressed for reform in an industry she knows well. She spent 21 years working at salmon hatcheries across the state and estimates that she single-handedly released more than one billion young salmon into the ocean. At the time, she loved the work and those years of living in some of Alaska’s most remote and beautiful places. But when she thinks back on it all, she cringes. “I never thought about what it was doing to the wild fish,” she says.
Researchers have long known that salmon in lakes and streams compete with each other for food. But understanding what is happening in the open ocean is a different story. All natural systems are difficult to study, but marine habitats—which are largely out of sight, are often frustratingly remote, and extend over vast distances—may be some of the trickiest. Salmon scientist Greg Ruggerone thinks he’s found a workaround.In the late 1970s, Ruggerone was a young graduate student at the University of Washington, starting what would become a long career immersed in salmon and their environments. At the time, a fellow graduate student, Art Gallagher, was completing his master’s thesis, a study of chum and pink salmon in Puget Sound. Gallagher wanted to understand how one species affected the other, and to do so, he took advantage of the fact that in odd years, millions of pinks return to the region to spawn, while during even years, hardly any do. By looking at how chum salmon fared as pink numbers rose and fell, Gallagher could see that, when there were a lot of pinks around, fewer chum survived.
Ruggerone found this biennial pattern in pink populations intriguing. No one knows the definitive reason for the pattern’s origin, which is most extreme at the northern and southern ends of the fish’s range, traditionally spanning from Washington State to just below the Arctic. Ruggerone spent summer after summer studying salmon on the Alaska Peninsula, seining fish from the beach for his research and living in an old cabin with plywood walls that brown bears would claw through periodically at the end of the field season. The unusual pattern in pink salmon populations stayed at the back of his mind as he went on to become project leader of the University of Washington’s Alaska Salmon Program for nearly a decade.
In 2000, Ruggerone was studying scales of sockeye salmon from Bristol Bay. Like tree rings, fish scales hold marks that reveal the fish’s growth rate and age. While analyzing the data, Ruggerone noticed a pattern in sockeye growth that seesawed with the rise and fall of pinks he’d first learned about two decades before. “Sure enough, it just stood out,” he says. The growth in Bristol Bay sockeye dropped when pinks were abundant, just as populations of Puget Sound chum fell in Gallagher’s study.
Years before, tagged fish had shown that far out at sea, Bristol Bay sockeye swim into the same waters as pinks from Japan and Russia, which, as in other areas, are far more abundant during odd years than even. The scales suggested that competition with odd-year pinks spelled lean times for Bristol Bay sockeye. And survival data showed that young sockeye died at higher rates when more pinks were around. Pink salmon from faraway Japan and Russia had left their mark—like a fingerprint—on sockeye headed back to Alaska.
“This biennial pattern is really unique,” Ruggerone says. In essence, this reliable up-and-down pattern in pink populations creates a natural experimental control in the North Pacific, an ideal tool, Ruggerone says, for seeing the extent of the pink fingerprint across the ocean.
The fingerprint has appeared on salmon runs across the Pacific. Chinook from British Columbia fare poorly when pink numbers are high. Coho in southeast Alaska are smaller when pinks abound. Chum from Puget Sound to Russia’s Kuril Islands eat less when crowded by pinks. Steelhead in the central North Pacific go hungry in pink boom years, and on the Fraser River in British Columbia, fewer young chum survive in years crowded with juvenile pinks.
These are disturbing trends, but when Ruggerone and biological oceanographer Sonia Batten from the North Pacific Marine Science Organization compared 15 years of plankton data with pink salmon abundances, a more alarming pattern emerged. For more than two decades, Batten and her team have been gathering data about the North Pacific’s smallest creatures using a meter-long torpedo-shaped sampling device called a continuous plankton recorder that is towed behind tankers and cargo ships. During odd years, when there could be as many as 40 times more pink salmon as during even years in the waters she was studying, large zooplankton such as copepods declined, while levels of phytoplankton—food for copepods and other kinds of zooplankton—went up. Pink salmon, it appeared, were wiping out the highest value food, large zooplankton, essentially eating the steaks and leaving only celery.
“It was a really clear effect of the top of the food chain affecting the bottom,” Batten says. She had never before seen a single predator species controlling the abundance of plankton. Pinks, Batten and Ruggerone concluded, were triggering a trophic cascade, where hungry fish were completely altering the food chain.
This food chain effect might be why researchers have seen the impacts of pink salmon on mackerel and herring, which feed on zooplankton and are the targets of lucrative commercial harvests. The well-being of seabirds that prey on small fish that, in turn, gorge on the same zooplankton targeted by pinks also hinges on the seesawing abundance of these fish. Ocean researcher Alan Springer has seen how seabirds produce fewer chicks in years with abundant pinks, and he is confident that pink salmon booms are linked to a succession of seabird wrecks that have alarmed coastal communities and puzzled scientists in recent years. “They’re intimately connected,” he says.
The pink fingerprint is showing up elsewhere, as well. Within a minute of looking at a graph, shared by a colleague, that showed the mortality of endangered killer whales off British Columbia and Washington, Ruggerone recognized the pink effect. “It’s still mind-boggling for a lot of people,” he says. These killer whales rarely eat pink salmon, and the decline of chinook salmon, the preferred prey for these marine mammals, cannot explain why there’s a biennial pattern in whale deaths. Researchers believe that the sheer number of pink salmon—which, in this southerly part of the fish’s range, can be 45 times more numerous in odd years—could be disrupting killer whales as they hunt for dwindling chinook.
But what, specifically, is the ecological fallout of the billions of pink salmon released into the North Pacific by hatcheries? Brendan Connors, a fisheries scientist at Fisheries and Oceans Canada, wanted to tease out the effects of industrially produced pinks from wild ones. Connors put himself through university as a fishing guide on Haida Gwaii, taking clients out with single-action reels for coho and chinook. He dove into researching salmon interactions at sea after the Fraser River sockeye run collapsed catastrophically in 2009.
Connors and his team zeroed in on the question of how hatchery pinks affect sockeye runs. They reviewed data from 47 sockeye populations that enter the ocean from waterways in British Columbia to the Bering Sea, which represent nearly all of the North American sockeye runs. In the northern part of the sockeye’s range—such as in Bristol Bay—warming temperatures have boosted wild sockeye populations, so much so that negative effects from competition with pinks are offset. But in the southern part of their range, hatchery pinks alone have reduced sockeye survival by about 15 percent. If the gushing tap of pink salmon hatchery production were shut off, Connors explains, sockeye runs on the Fraser—some of which are at risk of extinction—would have a better shot at recovery.
“We often think of the ocean as this big place, as limitless,” Connor says. “This work really challenges those simple assumptions.” Ruggerone and others are concerned that, at least in parts of the North Pacific during high pink years, the ocean may have met its production limit, and any new fish added only take away other parts of the biological pie.
Hillstrand is sure of this. A few years ago, she and a state biologist sliced open a pink salmon belly and found seven sidestripe shrimp inside. The shrimp were worth $7, the fish less than a buck. “We’re replacing our fisheries, and everyone is kind of in denial,” she says.
Ruggerone, Connors, Hillstrand, and others say that it’s time to talk about the big picture. But especially here in Alaska, going up against hatcheries can mean swimming against a raging tide. Leon Shaul, a retired state biologist, knows this. During nearly four decades of research on coho salmon in southeast Alaska, Shaul discovered that competition with pinks was leaving coho—the target of valuable sport and commercial fisheries—smaller. But his concerns gained no traction among managers. “Almost nobody is willing to look at the policy level,” he says. Hatchery culture is infused into state decision-making at the highest levels, including Alaska’s recently appointed director of commercial fishing, Sam Rabung, who has spent the bulk of his career in the hatchery industry working his way up from technician to numerous leadership positions. And hatcheries are backed by deep-pocketed seafood processors, such as Peter Pan Seafood Company and Trident Seafoods, which rely on hatcheries for one-third of the value they get from pinks. These hatchery fish are processed into canned salmon and roe, as well as frozen headed-and-gutted fish that is exported to China and elsewhere and sold back to US markets as vacuum-sealed fillets, burgers, and other products. The politically powerful processing sector has openly urged for a boost in hatchery production. Questioning the industrial production of salmon fry in Alaska, Shaul says, is like disparaging corn in Iowa.
In the coming years, with climate change, Connors says, as pinks migrate northward and lay claim to new streams, the North Pacific will continue to change rapidly, making conditions harder to predict. Last year, as runs of other species of salmon failed in many regions, Alaska and Russia recorded the largest harvest of pink salmon in nearly a century. In Norton Sound, off Alaska’s northwest coast, fishermen saw the lowest chum harvest in nearly two decades, while processing companies—including one from outside the region—stepped in to profit from a burgeoning run of pinks. And last summer, pinks that likely are descendants of fish from Russian hatcheries in the Barents Sea flooded waterways in Norway, Scotland, and Ireland. Those countries are viewing them as an invasive species that could threaten native Atlantic salmon runs.
Connors, Ruggerone, and others believe it will take international conversations between Pacific salmon–producing nations to address the issue. But who will host—and then act upon—such conversations is uncertain. Most scientists concerned about production of hatchery pinks are looking to the North Pacific Anadromous Fish Commission (NPAFC)—an organization made up of the United States, Canada, Russia, Japan, and Korea—to take on the issue. But while the commission, which was formed to regulate high-seas fishing, has the authority to enforce the ban on drift netting more than 370 kilometers from any shore, it has no formal role in setting policy for other activities—such as hatchery production—that might threaten salmon runs. Not all scientists agree that the North Pacific has too many fish. And even as other scientists have been raising red flags for decades, only now are discussions about the issue starting to develop at the NPAFC.
On the last part of the hatchery tour, I follow Sawlsville across the rocky beach to where a small aluminum dinghy with a light-duty outboard has been pulled up onto the gravel. We’ll take the boat over to the floating net pens where millions of fish are being fed until they’re released next month during a series of high tides that will flush them out of the lagoon. It’s possible that these pinks, like others, are already feeling the pressure of a crowded ocean: the average weight of pink salmon across the Pacific declined by as much as 22 percent from the early part of the 1900s to more recent years. As we navigate the rocky footings beneath us, I ask Sawlsville about the idea that the Pacific might already have too many salmon in it. He says that he believes the ocean has limits, but asks, “Are our fish really messing with the ocean’s carrying capacity? I don’t think so.” Just as it’s hard, from this sheltered spot, to imagine the big swells and stiff wind at sea, it’s difficult to comprehend how events in this little lagoon could have an impact across the entire North Pacific. But they likely are.
This article is part of “The Paradox of Salmon Hatcheries” series.
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