Discoveries
03.11.2021

Scales of Reference

Collected at the tail end of British Columbia's "silver fever," hundred-year-old salmon scales are now helping conservation scientists reconstruct and better manage the populations of one of Canada's most important fish.

In late June, 1919, Robert Gibson was feeling optimistic about the salmon. A Scottish veteran of World War I newly arrived in northwest Canada with his wife and infant son, he had recently taken a job as constable and fisheries overseer in the bustling cannery town of Port Essington, on British Columbia’s north coast.

Besides the typical tasks of policing, Gibson was also in charge of tracking the numbers of sockeye salmon that returned from the ocean each summer to spawn in various tributaries of the Skeena River. Each day he would examine 50 or more fish, caught by a flotilla of canoes and wooden skiffs waiting with linen nets at the mouth of the river, which ended its long journey to the Pacific just west of Port Essington. In a black notebook, he’d mark the date of capture, length, weight, and sex of each fish. “Sockeye are surprisingly good for beginning of season,” he wrote on June 23.

After he measured the fish, Gibson also took samples from them, removing a patch of scales with a dull knife and smearing them onto a notebook page, stuck fast in their own slime. At the end of each season, he would ship those notebooks to California, where a Stanford University biologist named Charles Henry Gilbert would examine the scales with a microscope to determine each fish’s age.

Port Essington, which sat on the site of a traditional Indigenous hunting and fishing ground, had been a cannery town for almost half a century by then—the province’s ebbing Gold Rush replaced by “silver fever” as migrants sought profit and livelihood on the backs of the millions of shimmering salmon. In peak season, more than 1,300 skiffs, working six days a week, unloaded hundreds of thousands of silvery fish up an escalator and down a slide into canneries that drew men and women from near and far—from local First Nations communities to China, Japan, and Europe. But in preceding years, sockeye stocks had fallen to a worrisome fraction of what they once were. Gibson’s job was to help fisheries officials understand what was happening.

Gibson continued to collect the scales for nearly a decade, after which he was promoted to sergeant and relocated to nearby Prince Rupert. In 1938, he died there, gunned down at his office typewriter by a disgruntled taxi driver. The records he painstakingly collected, however, survived him—and they have recently found a new life. With the aid of modern technologies, Gibson’s fish scales are shedding fresh light on the past, helping us reevaluate previous assumptions about the health of northwest salmon fisheries and the alarming and overlooked magnitude of their century-long decline.

Dwindling to a trickle

Like most sockeye, those from the Skeena hatch and die in freshwater but spend much of their adult lives at sea. Starting as pea-sized eggs in upstream tributaries, they migrate as fry to a complex of cold-water lakes that dot the river system like bulbous beads on a thread and harbor at least 13 genetically distinct sockeye population groups. Young sockeye grow in these nursery lakes for 18 months to three years before venturing downstream to the food-rich Pacific. There, they mix and compete with other salmon species: Chinook, coho, chum, and pink salmon that migrate from the Skeena and other northwest river systems. It takes several years for sockeye to reach maturity. They will grow up to two feet long and weigh as much as six pounds by the time they swim upstream to the same river where they hatched and will spawn and then die—the same place where their descendants will also hatch, and begin the cycle again.

Sockeye are smaller than the mighty Chinook and larger than the diminutive pinks, but they are commercially prized above all other salmon species for their fat-rich, flavorful crimson flesh. For at least 5,000 years before the first cannery opened on the Skeena in 1877, the Tsimshian, Gitxsan, and Wet’suwet’en First Nations harvested salmon here—especially sockeye—for food, trade, and ceremonial purposes. So important were salmon to Indigenous cultures and economies in the Pacific Northwest that a trading language called Chinook evolved to allow communication among diverse groups.

It is difficult to know exactly how many sockeye swam up the Skeena in the years before European settlement. Relying on historical cannery records, fisheries scientists estimated that an average of 2.5 million sockeye came back each season in the first decade of the 20th century, with as many as 3.6 million in peak years. By 1919, however, when Robert Gibson first arrived in Port Essington, sockeye averages had begun to drop—below a million per year in the 1920s, below 750,000 by the 1940s. After numbers continued to drop to just over half a million by 1955, the province opened a facility just upstream of the river mouth, called the Tyee Test Fishery, using a gillnet to catch a representative sample of passing fish and provide a rough estimate of their abundance.

Numbers rebounded in the 1970s, thanks to favorable oceanic conditions. But another factor also boosted sockeye counts: Canada’s federal fisheries agency, the Department of Fisheries and Oceans (DFO), had launched a rescue effort. In 1965, DFO officials began diverting sockeye returning to breed in streams that fed the Babine, an enormous lake at the headwaters of the Babine River, a major Skeena tributary. Fish returning here were diverted into a labyrinth of concrete, gravel-lined channels where fish could spawn in a protected, flow-controlled environment. Now, when fisheries officials measured sockeye returns, they tallied both wild and enhanced Babine Lake stock in one aggregate number. Enhanced fish are not considered hatchery fish because in these manufactured spawning channels they still mate freely and after the winter, young salmon swim through the gates from channels to nursery lakes where they mature in the wild. So while Skeena sockeye numbers peaked in 1996 at an eye-popping seven million, only a fraction were true “wild” fish.

Soon, both wild and enhanced populations suffered another nosedive. In 2013, only 450,000 sockeye made the journey up the Skeena. Of those, a full 68 percent came from the Babine spawning channels. Such declines have been particularly devastating for First Nations on tributaries besides the Babine, who have seen sockeye returns to their communities dwindle to a trickle. “Many Nations haven’t been able to meet their food fish needs for 10 to 15 years,” says Gitksan First Nation member Stu Barnes, chair of the Skeena Fisheries Commission, which represents three Indigenous nations along the river.

Attributing sockeye declines to any one factor is challenging. Industrialized fishing—using powerboats, nylon gill and seine nets, and mechanized haulers—has enabled harvests that were once inconceivable. Dams, road building, and agricultural water diversions have made salmon migration more difficult, while logging, mining, and development have degraded upstream spawning habitat. In the ocean, sockeye compete amidst warming waters and inconsistent food supplies with a flood of hatchery salmon. “Over the last hundred years or so, we’ve thrown everything we can in their way,” says Greg Knox, executive director of SkeenaWild Conservation Trust, an environmental advocacy group working to protect wild salmon ecosystems and local communities along the river.

In 2005, the Canadian government enacted a new Wild Salmon Policy in hopes of stanching the losses. While the aim is to restore and maintain wild, genetically diverse salmon populations, the policy avoids specific restrictions on commercial and recreational fishing, and is accompanied by little funding or infrastructure for monitoring returning fish numbers. “We can only determine the health of about half of Skeena’s sockeye populations,” says Michael Price, SkeenaWild’s science director and a doctoral candidate studying historical sockeye salmon ecology at Simon Fraser University. “This represents a vast knowledge gap.”

To help the Skeena sockeye, Price argues, we must first understand the extent of its decline. Today, fisheries scientists evaluate the health of modern salmon runs with reference to catch data estimates beginning in the 1960s—more than 80 years after commercial exploitation began. Price believes we need a longer and more specific timeline. Which is where the Port Essington notebooks—and Robert Gibson’s fish scales—come in.

The Holy Grail of salmon data

Sometime in 1948, the collection of data from Port Essington’s canneries ceased. It’s unclear why the program ended, but the last of the notebooks were unceremoniously packed into storage, and over time the experts aware of their existence aged and died. The notebooks languished, whereabouts unknown, for decades.

Then in 1995, a DFO fisheries biologist named Skip McKinnell was trying to compare the condition of sockeye past and present. (Heavier fish, measured as a ratio of weight to length, are considered healthier.) He was using historical averages for his calculations—but, he says, “I’m a data guy,” so he set out in search of the original numbers.

McKinnell had always been intrigued by fisheries of the past. “I used to go into the library at lunchtime and pick out the dustiest book in the stacks,” he says, “to read about what scientists were writing and thinking about a century ago.”

Through that research, McKinnell learned that provincial fisheries officials had hired Charles Henry Gilbert, the Stanford ichthyologist, to conduct a sockeye study that included the data in the Port Essington notebooks. Suspecting that Gilbert—who died in 1928—had taken the notebooks to California, McKinnell began searching, calling Stanford’s archives, federal records centers in Seattle and Anchorage, the Smithsonian Institution, and visiting other government and university archives—all to no avail.

Nearly a year later, McKinnell attended a meeting at the Pacific Salmon Commission’s Vancouver headquarters. He mentioned, in passing, his nerdy and fruitless search for Gilbert’s notebooks, and a fellow ichthyologist told him they were down the hall in a storeroom. “It was like finding treasure,” McKinnell says—boxes and boxes of yellowed books containing the measurements of hundreds of thousands of sockeye from four British Columbian rivers between 1912 and 1946—some 90,000 fish per river. And affixed next to those measurements were the scale samples that Gibson and other fisheries overseers had collected nearly a century earlier. “In my wildest dreams I didn’t imagine that the original scales would be there, too,” McKinnell says.

McKinnell spent some time examining the measurement data, but he lacked the funding and time to dig more deeply, so he set the notebooks aside. They sat in storage for another decade—until, in 2012, Price heard about the notebooks while chatting with fellow salmon biologists. The scale samples affixed to the books could, he realized, open a remarkable window into the past. “Each of these scales provides a snapshot of [a salmon’s] life story,” Price says.

McKinnell, says Price, had found “the Holy Grail of salmon data,” And Price, who was just starting his doctoral research, had the skills, funding, and opportunity to study it.

Shifting baselines

The Skeena notebooks now live in a clear plastic storage box at the DFO Pacific Biological Station in Nanaimo, on Vancouver Island. In May 2019, I visited the station, which sits a stone’s throw from the Pacific, grand but austere and institutionally uninspiring, its long corridors lined with row upon row of black-and-white headshots of fisheries scientists in suits and ties. In a building where scientists study genetic diversity, it was hard not to notice that every portrait was of a middle-aged white man.

Price, who joined me on my visit, is a similar age, though far less starched and decorous than his predecessors: boyish and sinewy, in an untucked plaid shirt and blue jeans, with tanned skin, wispy blonde hair, and the crow’s feet of a man who has spent years outdoors. (He worked for 10 years as a fisheries biologist before returning to graduate school.) He led me down the hallway to the station’s fish-aging lab, where he opened a box and carefully extracted a notebook: Gibson’s, from June, 1919. The edges were warped and tinged in blue, and the pages crackled when opened, the smeared scales rigidly adhering to both sides like shiny dried glue. “Sockeye Data Taken At Port Essington Skeena River No 1,” read Gibson’s careful handwriting, penned in black ink. I felt strangely protective of the notebooks, wondering what fingerprints, moisture, light, and time would do to these irreplaceable artifacts.

Darlene Gillespie, a technician who came out of retirement to work on Price’s project, sat nearby, using tweezers to extract the scales and a microscope to determine the age of a fish by counting the concentric rings within each transluscent disc—growth patterns influenced by fluctuating annual nutrition. Each scale, she said fondly, “is a little treasure trove of information.”

Down the hall, I met molecular genetics program manager John Candy, who led the team that mastered the difficult task of extracting DNA from the scales. The material was “very much older” than typical samples, Candy said, and the fish scales themselves contained no extractable DNA. But the samples also included bits of epithelium—the slimy layer “where the scale attaches to the fish”—which contained sections of genome they could amplify. Borrowing methods and enzyme kits from forensics, Candy’s team harvested enough DNA to make sense of the scales.

Price then set to work analyzing the results, matching the DNA extracted from the historical scales to samples from contemporary fish to determine natal tributaries. (Each population has a distinct genetic signature which has remained relatively stable over time.) Then, using historical cannery records, early commercial harvest numbers, and modern data, he and his colleagues reconstructed overall and individual population-group abundance from 1877 to the present. He published his initial results in the journal Conservation Letters in 2019. Last month, a new paper in the Journal of Applied Ecology expanded the analysis to examine changes in overall population diversity as well.

What Price learned from the scales was troubling. According to his analyses, all 13 of the genetically distinct wild Skeena source populations identified from the scales have declined in abundance by 56 to 99 percent. Those populations with the largest declines were larger-bodied fish most valuable to commercial fisheries, which for many years used mesh nets designed to capture larger fish and let smaller ones through. The Sustut tributary, for instance, saw historical runs of more than 41,000 sockeye. Recent returns are closer to 1,600, representing a decline of 96 percent.

Along with this loss in abundance, Price’s calculations also document an associated loss in diversity. According to his analysis, the Babine population contributed between 48 and 68 percent of all wild sockeye returning to the Skeena between 1913 and 1947. Today, the Babine population represents a full 91 percent of returning fish, nearly three-quarters of which are enhanced stock. So while total sockeye returns are not in themselves dramatically lower now than what they were a century ago, the success of the enhanced Babine population has masked much larger long-term declines of wild fish, both in terms of numbers and variety. “At one time, the Skeena was much more diverse,” Price says—by his calculations, overall population diversity has declined by 70 percent. Diversity spreads out risk and buffers against uncertainty, creating resilience to environmental change. “The risk of a bad year was once spread across many populations. Now, it’s really up to one population. And if it does poorly, the entire system does poorly.”

And Price’s results suggest that the system as a whole has, indeed, suffered. By looking at incomplete records from the past, he says, we have vastly underestimated the magnitude of environmental change along the Skeena.

Conservation scientists call this phenomenon “shifting baseline syndrome”—the downgrading of perceived “normal” environmental conditions over successive generations. We don’t know the full damage we are seeing in the present, because we haven’t looked back far enough into the past.

“[Each scale] is a little treasure trove of information.”

—Darlene Gillespie, lab technician

Swimming upstream

In August 2020, with the summer salmon run heating up and pandemic restrictions easing enough to allow a flight, I don a mask and board a plane, banking over glacier-topped mountains, wild valleys, and the shimmering blue seam of the Skeena that runs through them. After landing in the riverside town of Terrace, I drive two hours upstream to Smithers. Price meets me at the Two Sisters Cafe, a local institution, and we fuel up with coffee for the drive to Witset Canyon, where the exquisite teal-colored Bulkley River races through a gorge on its way to join the Skeena. A natural pinch point where fish leap up the rapids, it’s a traditional fishing spot for the Wet’suwet’en First Nations people who live here.

Walter Joseph, the Nation’s fisheries manager since 1996, meets us at a highway overlook. The traditional fishing has begun, and Joseph points to the raging water below, where Wet’suwet’en men on each side of the river are dipping long nets from precarious rocky perches. An osprey passes overhead, a fish in its talons, as we make our way down to the water.

Joseph, wearing a ball cap over close-cropped gray hair, speaks cautiously and deliberately. “In addition to the food fishery, we do mark and recapture,” he says. This year, half of the sockeye netted from the rapids will be kept for food, the other half tagged for tracking. Sometimes a fish comes every few minutes. Sometimes there are longer gaps; many get away. After a fisherman sweeps a leaping fish into his net, he’ll transfer it to a synthetic sling, thrashing but cradled securely as he carries it across a metal gangplank to a tray of fresh water where two female colleagues weigh, measure, and tag the sockeye, then place it into a plastic sluice pipe that deposits it above the rapids—a free ride upstream for its contribution to science and conservation. Almost every year, the Wet’suwet’en count fewer sockeye. “When I started, there were some good runs,” says Joseph. “One year there were 30,000. Now we might catch a few thousand.”

Hoping to better understand past abundance and find improved strategies for managing a shared and limited resource, the Wet’suwet’en, along with several other Nations, have helped fund Price’s work. Last month, the Wet’suwet’en released a new sockeye management strategy that emphasizes genetic analysis, sophisticated counting techniques, and habitat protection and restoration, using Price’s historical numbers as guidance in setting recovery and harvest targets.

In theory, First Nations fisheries have first priority for harvesting Skeena sockeye. Once an estimated 600,000 sockeye have entered the river from the ocean, regional fisheries managers permit Indigenous groups to catch up to 150,000, across all tributaries, for food and ceremonial purposes. Commercial fishing operations at the river mouth can begin harvesting when the estimated sockeye returns hit 1.05 million—though in 2013 and 2017, numbers were so low that, remarkably, no ocean-based commercial sockeye fishing was allowed. Even in better years, however, upstream First Nations are at a distinct disadvantage. The sockeye arrive at the river mouth first and fishing operations have no way, short of DNA analysis, to determine which fish come from the enhanced Babine population and which are wild fish headed to tributaries such as the Bulkley River. Price’s reconstructions show that, on average, 70,000 fish came back to the Bulkley during the 1940s. An estimated 14,000 now survive the commercial-fishing gauntlet and other hazards to return. “That is nowhere near what the Wet’suwet’en need,” says Joseph. Fewer fish brings a cultural cost, as well, Joseph notes, referring the loss of traditional skills that result where there are few opportunities for Wet’suwet’en fishers to practice traditional methods.

Later, Price takes me to the Kitwanga river, a Skeena tributary west of Witset Canyon, where there has been no sockeye harvest at all for half a century, a result of downstream forces that are out of First Nations’ control. Through habitat restoration and monitoring, the Gitanyow First Nation are working to rebuild the population enough to enable a sockeye harvest. “We haven’t been able to do that for so many years,” says Leslie McLean, a technician at the Kitwanga River Salmon Enumeration Facility, a high-tech fish fence that the Gitanyow, in collaboration with the DFO and other partners, have used to monitor salmon runs over the past 18 years.

McLean, who has long, dark hair peppered with gray and a long mustache and goatee, explains how the fence funnels upstream-bound fish into a channel where a video camera logs every individual’s size and species, relaying the information to laptops in the office that ping as each fish swims by. Price’s analysis suggests the Kitwanga sockeye populations have declined 71 percent since historical times—from an average of 29,000 between 1913 and 1923 to less than 9,000 per year from 2007 to 2014. In all of 2007, the year with the lowest return in the river’s recent history, only 240 sockeye swam past the fence.

Nature’s resilience

Ten miles east of where the Skeena meets the Pacific, the mid-afternoon sky has darkened to a foreboding gray. Baffles of clouds obscure the glacier-rounded mountaintops. Price’s colleague Hup-Wil-Lax-A, also known as Kirby Muldoe, steers a small motorboat along the river. Muldoe, a member of the Tsimshian and Gitxsan Nations, works as SkeenaWild’s Indigenous engagement specialist. He grins in yellow-tinted sunglasses and camouflaged waders, happy to be out on the water, his short hair blowing in the wind.

Though his father was born in Port Essington, Muldoe has never been to see what remains of the former cannery town—now entirely in ruins. He navigates by cell phone map, approaching the river’s southern side, where wood pilings stand like toothpick rows in the mud. Price and SkeenaWild director Greg Knox join us. We pass a wrecked segment of cannery conveyor belt peeking from tall grass, and tie the boat to a rusty ring bolt nearby, clambering ashore.

For a picture of Port Essington’s past, I had spoken over Zoom with Verna Inkster, an 84-year-old Sigidimnak (matriarch) of the Giluts’aaw Tribe of the Tsimshian Nation. She resides in Kitsumkalum now, upriver across the Skeena, but she was born in Port Essington, where her mother worked in the canneries and where the salmon, according to lore, were once so plentiful you could walk across streams on their backs. By the time Inkster was born in 1936, the sockeye were already in decline—as was Port Essington, which found itself on the wrong side of the river after the completion of the Grand Trunk Pacific Railway, isolating the town from easy access to trade. Inkster was about seven when Port Essington’s last cannery was closed and later torn down. Her family moved away, finding work on the opposite shore, and in the 1960s, fire consumed what was left of the town. Inkster still remembers the sound from her childhood of water sloshing under the buildings built on pilings over the water. In her kitchen in Kitsumkalum, she has hung a huge black-and-white photograph of Port Essington’s band hall and hotel. “That’s what I have on the wall because I’m so lonesome for it,” says Inkster. “It was a very good place to live.”

There is little left of Port Essington now: no more canneries, trading posts, hotels, churches, sawmills, saloons, or schools; no town hall or jail; nothing save a smattering of relics and discontinuous strips of decaying boardwalk perched over spongy muskeg shoreline. Port Essington is quiet, still, and otherworldly.

In the town’s heyday, all the trees along the shore were felled, and much of the local wildlife was shot, trapped, or driven away. Now, though, the forest has returned, and I push through low-lying hemlock branches to examine a rusted, moss-wrapped cable and a nylon rope with disintegrating floats. Behind a corroded fuel tank, I find a clump of what I think at first is horse manure. But Knox, once a fishing and bear guide, knows better. It is months-old grizzly scat, he says, full of sedge nibbled in springtime. Wilderness has begun to reclaim this once-denuded shoreline. Can the tide turn for sockeye too?

Price, Knox, and the scientists and First Nations communities along the Skeena hope that is the case, sharing a mix of fear and optimism that has ebbed and flowed along this riverbank since Gibson’s day, when it first became clear that the sockeye might not last forever. “Salmon are incredibly resilient,” says Knox. “They will adapt. We just have to give them a chance.”

Lesley Evans Ogden

Lesley Evans Ogden

Lesley Evans Ogden is a freelance multimedia journalist based in the verdant suburbs of Vancouver, Canada, where she is a settler on the traditional, ancestral and unceded territory of the Sḵwwú7mesh (Squamish), Stó:lō and Səl̓lwətaʔ/Selilwitulh (Tsleil-Waututh) and xʷməθkʷəy̓əm (Musqueam) First Nations. Earning a doctorate in ecology before crossing a career bridge to science communication, Evans Ogden is captivated by the natural world and its stories. She writes about science internationally for print, web, and television, with her words and photography featured by outlets including the New York Times, BBC, ARTE and CBC. Follow her on Twitter @ljevanso

bioGraphic is powered by the California Academy of Sciences, a renowned scientific and educational institution dedicated to exploring, explaining, and sustaining life on Earth.