The Salmon Nursery

a story by David Wolman

Unlocking the habitat secrets of one of the planet’s most important salmon fisheries — and the specter of industrial development that threatens its very existence

What is it about salmon? Their impact on forests, human history, economies, culture, cuisine, and angling is profound. Yet it’s even more than that — a mystique that has to do with home. Much like migratory birds and sea turtles, salmon find their way home. They do so from thousands of miles away and after years after having left, wending their way back to the rivers, small streams, and gravel beds where each first came into the world as a single sphere in a clump of orange roe. (They manage this feat by tapping into a combination of magnetic and chemical signals.) Once they reach their birthplace, the adults reproduce and then die. It’s one of those natural-world phenomena that make evolution sound less like a jumble of adaptations and more like poetry.

“How the fish find their way back has been an obsession” for generations of researchers, says Carr-Harris. And rightly so. Sheer wonderment aside, the study of reproduction — including where it happens and how the fish get there — is, by definition, critical for protecting fish stocks now and into the future.

But while these adult fish get all the attention, the journey of juvenile salmon — the teenagers — is no less astounding. To understand why, start with the inadequacy of the adolescence metaphor. With due respect to junior-high students struggling with all manner of emotional and physical turmoil, the transition from tiny freshwater fish (scientists call them parr) to ocean-going juvenile makes puberty look like a snap. A better analogy Carr-Harris says “is that of a person learning to breathe on Mars.”

Salmon have evolved a delicate regulatory system to ensure that, when in freshwater, they don’t lose too much salt from their tissues, while also not taking on too much water. In the ocean, the challenge is reversed: They must prevent salt poisoning and avoid becoming dehydrated. To go from a world where they must hang on to salt at all costs, to a world where they’re essentially drinking saltwater, the fish undergo a complete systems overhaul. This transformation involves what one group of Norwegian scientists describe as “coordinated developmental changes in biochemistry, physiology, morphology, and behavior…” with alterations “in lipid metabolism, osmoregulation, oxygen transport, buoyancy, growth, color, shape, rheotaxis [holding in position while facing into the current], and schooling behavior…” It’s as if the only thing connecting these freshwater organisms with the ocean-going fish they become is that we call them both salmon.

While a handful of other fish, like sturgeon and striped bass, also undergo this shift in habitat and physiology to match, only salmon transform ahead of time — before they hit salt. Years ago, when Carr-Harris had a job at a hatchery, she sometimes arrived in the morning to find dead juveniles on the floor of the facility. The fish were so completely compelled to get going downriver, or at least somewhere else, that they had jumped out of their tanks.

Scientists today are trying to tease out the underlying genetics — the triggers that control the salmon’s decision to head downstream. “What causes a fish to decide, To hell with freshwater. I’m going to salt!?” asks Jack Stanford, emeritus professor of ecology and director of the University of Montana’s Flathead Lake Biological Station. Attributes of the environment force the decision, but the fish “have to have the genes that allow the environment to push them one way or another.”

Juveniles undergo this transformation ahead of time, explains Stanford, because most big salmon rivers don’t end in broad estuaries where the fish could conceivably ease their way into ocean living. The rivers just empty, with only a small transition zone. That doesn’t mean, however, that out-migrating juveniles in the Skeena are ready for the blue water. They’re “probably freaked out when they encounter saltwater,” says Carr-Harris. The environment is foreign, turbid, and full of unfamiliar predators.

How exactly they respond to all this newness isn’t clear. “In general, we know surprisingly little about how salmon use estuaries,” says Wild Salmon Center’s Sloat. It is reasonable to surmise that young salmon spend some time in the estuary before venturing out into the Pacific, and that mini-habitats within the estuary, like Flora Bank, are especially important, hiding juveniles from predators in the sky and those lurking in deeper water. A 1972 study by Canada Fisheries identified Flora Bank as significant salmon habitat, and indigenous populations have long since touted its significance. But assumptions, no matter how reasonable or grounded in local knowledge, are not as conclusive as data, especially when multi-billion-dollar investments are on the line.

When the LNG proposals began drawing attention to the region, Carr-Harris found herself in the middle of an international smack-down. Born in Victoria, British Columbia, Carr-Harris moved to Prince Rupert when she was twelve. The girl with curly brown hair and wide curious eyes spent much of her childhood exploring the splendor of the region with her father, a seaplane pilot. One of her first summer jobs was counting fish on the docks in Prince Rupert, to earn money for college. Then she fell in love with biology — “Here I am 20 years later, still counting fish,” she says. Now 40, Carr-Harris is in the field most days. When she isn’t studying the estuary and its inhabitants, she’s kayaking or fixing up the tiny cabin that she built in a spot so remote it’s only accessible by water at high tide.

In 2009, Carr-Harris took a research position with the Skeena Fisheries Commission, a quasi-governmental group that advocates for science-based fish policy. She began studying the role the estuary plays in the life cycle of juvenile salmon, looking at basic parameters like salinity, temperature, location, and food availability within small sections of the estuary. Some initial fish counts indicated that there were far more juvenile salmon in the small polygon outlining Flora Bank than in other parts of the estuary, a finding that contradicted reports commissioned by proponents of the LNG project.

Two years later, Jonathan Moore, an associate professor of aquatic ecology at Simon Frasier University, was putting together a research project focused on the Skeena and its estuary. He had learned that historical data on salmon in the region was sparse and felt there was an opportunity to inform the debate with sound science.

He had also experienced the Skeena years before. Moore grew up in Oregon but spent summers during high school driving with his family up the coast to Prince Rupert. From there they would “motor their boat up into Alaska and catch and eat crab, prawns, halibut, and salmon.” When he first saw the Skeena on one of those family trips, Moore was mesmerized. “Unlike where I grew up, there are no dams on the river. Unlike where I grew up, salmon are still an integral part of people’s lives.”

Moore, Carr-Harris, and local researchers have spent four years conducting habitat and population surveys of the Skeena estuary. The goal of the work was straightforward: determine which species of fish are there, where exactly they are, and whether they zip over Flora Bank and nearby spots on their way from the river to deeper water, or whether they stick around for a while.
What they found was an undersea Serengeti. As many as 300 million salmon come down the watershed every year, and many of them stop at — and rely on — Flora Bank to successfully complete their journey to the ocean.
What they found was an undersea Serengeti. As many as 300 million salmon come down the watershed every year, and many of them stop at — and rely on — Flora Bank to successfully complete their journey to the ocean. Their studies determined that juvenile salmon were much more abundant in and around Flora Bank compared with other areas in the estuary. When they compared fish numbers at Flora Bank with other eelgrass habitats in the Skeena estuary, they found that salmon were on average 25 times more plentiful. (The numbers differed depending on the species: sockeye were 72 times more plentiful; coho, 16 times more abundant, Chinook 15 times.)

The diversity on Flora Bank mirrors the diversity of the Skeena watershed as a whole, which is one of its most valued attributes. When people talk about huge salmon runs, they invariably mention Bristol Bay, Alaska. “It is huge,” says University of Montana’s Stanford. “But it’s almost all sockeye. The diversity in the Skeena watershed, of both species and the habitats they live in, adds to the overall resilience of the fish populations.” Summarizing some of these findings in a letter published in Science in August 2015 (“Juvenile Salmon Usage of the Skeena River Estuary”), Moore and his co-authors wrote that the area “supports particularly high abundances of juvenile salmon from more than 40 populations that are harvested in at least 10 First Nations territories throughout the Skeena watershed and beyond.”

To determine how long the juveniles were sticking around, the scientists examined the chemical signatures of their body tissues. Chemical signatures revealed whether the fish had been eating from a freshwater or saltwater menu, and for roughly how long. Although how long the juveniles hang around at Flora Bank varies by species, the scientists found that they typically spend weeks there, sometimes even more than a month, feeding and gaining strength.

Without Flora Bank, it’s unclear where the salmon would go or how well they would fare. This uncertainty is underscored by the fact that the fish go out of their way to get there. Instead of swimming with the current straight out the mouth of the river toward Chatham Sound, the young salmon cut hard right, to the north, through a narrow channel that leads onto Flora Bank. They are expending extra energy to get there, which means this spot doesn’t happen to sit along a migratory superhighway that could conceivably be rerouted. It means the fish have adapted to this particular habitat because of the survival advantages it confers. Picking up on the hourglass image, the fish swim their asses off just to reach a small corner of that already narrow neck between the watershed and the ocean.

Why? Eelgrass is certainly part of the answer. Back out on Flora Bank, the linguine-like grass is the dominant feature underfoot, and Carr-Harris says an estimated 50–60 percent of all the eelgrass in the estuary grows in this one spot. That plant food supports a host of organisms that salmon dine on — periwinkles, baby crabs, micro-crustaceans, marine worms, and more. “And you can smell it, just being here, right?” says Carr-Harris. (It’s not really a question.) “It smells like decomposing animals. That suggests lots of biological activity,” which means great habitat for juvenile salmon. Meanwhile, predators like larger fish, eagles, mergansers, and other diving birds can’t easily see or get at them because they’re hidden in the wavy, dark grass.

Another clue to its significance is that Flora Bank isn’t even a typical sandbar. A veteran sedimentologist named Patrick McLaren recently conducted a study that involved some 2,400 samples of material from the bank. He concluded that this geological feature is a relic from the last ice age. Its large sand grains are not seen in other parts of the estuary, and the bank itself is held in place thanks to a delicate interplay between the tides and the river. The glacial history of the bank is interesting from an academic perspective, says Stanford, but the salient point “is the role it now plays in the productivity and life cycle of the Skeena salmon. It’s there. And the salmon are there!”

OceanEcology.ca | Prince Rupert, BC

In a recent letter to the Lax Kw’alaams tribe, McLaren explained how his data indicate that “Flora Bank and the fish habitat that it supports are highly unlikely to survive the proposed LNG project.” Lose Flora Bank, or even harm it in some unforeseeable way, and the effect on the Skeena watershed — to say nothing of Pacific salmon stocks — could be catastrophic.

At the lab of the Skeena Fisheries Commission, Carr-Harris delicately slices open two juvenile sockeye, each about 3 inches long. After pointing out various organs, she separates the stomachs and places them in a Petri dish. More closely inspecting exactly what the fish have eaten is part of the next wave of Skeena estuary research: Now that scientists know they spend a lot of time on Flora Bank, they want to zero in on just how reliant the fish are on the various foods available in this ecosystem. This so-called food-web study will provide a more refined understanding of the juveniles’ habits and survival needs. Recent data show, for example, that the young salmon here eat lots of terrestrial insects like beetles and mosquitoes. Cutting down the trees on neighboring Lelu Island to make way for the gas-cooling plant could therefore mean lost habitat for the critters that young salmon on Flora Bank depend on for food.

Last year, the Lax Kw’alaams band voted unanimously to reject more than $1 billion from Petronas to consent to the development. (Because sovereignty over these lands and waters remains legally uncertain, companies often seek formal consent from First Nation bands for developments of this sort. The offer was seen by some as a bribe and by others as meager compensation for centuries of mistreatment.)

This past summer, conservationists were further emboldened when the Wall Street Journal reported that Petronas was delaying its play for LNG in Canada, due to unfavorable market conditions. The salmon science was never referenced directly, but local and international NGOs are certainly wielding this data to buttress their defense of Flora Bank and Lelu Island. “For the first time, the presence of all these different species has been empirically documented,” says Stanford. “This exquisite micro-habitat is the difference between hundreds of thousands of adult salmon returning to spawn, versus a few thousands.” A green light for Petronas, Stanford and others assert, would be flouting science, not to mention common sense: Juvenile salmon, not so unlike juvenile humans, need a safe space to adapt and mature.

But the newly elected Lax Kw’alaams band council is pro-development. Last month, following a re-vote that used woefully vague ballot language, the council won approval to pursue “favorable outcomes” during new negotiations with Petronas. Within days of the vote, the council was facing criticism from other members of the community and conservationists for obfuscating the issues at hand in order to gin up support for LNG. The matter could soon come to a climactic head: The Trudeau Administration is reportedly in the process of finalizing its decision about the Petronas proposal and is expected to announce that decision by October. Project opponents see this as an opportunity for Trudeau to live up to his sustainability-themed rhetoric. Yet if he opposes the project while the Lax Kw’alaams support it, the controversy will become that much thornier — and likely end up in court.

Meanwhile, the fall salmon run is well underway. “You don’t have to be here for long to understand how important salmon are to this place,” says Carr-Harris. Communities and cultures up and down the Skeena depend on the salmon, as they have for generations. Will that be the case 25 or 100 years from now? “For all these species of salmon, survival comes down to really slim margins at every stage of life,” she says. “Conserving critical habitat — which is something we can control — that may help salmon populations withstand things that we can’t control, like climate change.”

Even if Petronas quits on British Columbia altogether, there are still a half dozen similar proposals for the area. One of them, on nearby Digby Island, threatens an area called Delusion Bay. Although not as outrageously loaded with juveniles as the Flora Bank nursery, it’s still part of a salmon-rich estuary that has no equivalent on Earth. Tamper too much with such places, and it should come as no surprise when the fish can no longer make it from here to there.


ABOUT THE AUTHOR
David Wolman is a journalist and author. A contributing editor at Wired, he has also written for the New York Times, Wall Street Journal, Outside, Nature, and BusinessWeek. His work has twice been anthologized in the Best American Science and Nature Writing series, and his most recent book is The End of Money. Follow him on Twitter @davidwolman.

This story originally appeared in bioGraphic, an online magazine featuring beautiful and surprising stories about nature and sustainability. Online at biographic.com/posts/sto/the-nursery