Ecosystems 101: Hard lessons from the mighty salmon runs of Alaska’s Bristol Bay
The world’s longest ongoing salmon research reveals the astounding complexity of wild ecosystems.
Wood-Tikchik State Park, Alaska
When Daniel Schindler was 6 months old, his parents took him on an adventure: They moved into a tent at a research camp in the Canadian backwoods, surrounded by dozens of lakes. His father, limnologist David Schindler, was measuring how those lakes were harmed by phosphate detergent runoff and acid rain; the work he did would help lead to the reduction of those pollutants across North America. The family spent four months at the camp every year, abandoning tents for cabins once they were built. Young Schindler did a lot of fishing and swimming, and around age 14 he got interested in the science.
Now, 44 years after that first adventure started, Schindler has become the kind of scientist who can pilot a 90-horsepower jetboat across a huge lake and into a shallow meandering river, goosing the throttle while standing up to read the riffles ahead of him, zooming from bank to bank, finding the least-risky course through barely submerged rocks and snags as the waves buck the boat into the air and a cold rain pelts him the whole way.
I saw Schindler enjoying this experience in August, when I visited his research camp here on Lake Nerka, in southwestern Alaska, in an area managed as Wood-Tikchik State Park and Togiak National Wildlife Refuge. The camp is a cluster of cabins far off the grid, reachable only by boat or floatplane. The landscape feels prehistoric – more than 6 million acres of wilderness with hundreds of streams and lakes. Lush peaks, never entirely snow-free, rise steeply from the shores. It's the kind of natural setting that encourages you to breathe in more deeply than usual.
Schindler makes his living as a professor of aquatic and fish sciences at the University of Washington in Seattle, but he still embraces the rhythm of his childhood; this was the 17th summer he's spent researching this nearly pristine Alaska ecosystem. Reflecting on the path he's taken, he said, "I like being outdoors. I wanted an interesting life."
That commitment and eccentricity were shared by the outdoorsy grad students on Schindler's research team, as well by as his wife, Laura Payne, a bird biologist, and their pink-booted 9-year-old daughter, Luna, who's been their companion in this camp since she was an infant. Fellow UW professor Lorenz Hauser, an Austrian-born population geneticist, was on his 10th summer of research here, speaking English with an Arnold Schwarzenegger accent that even he finds amusing. And he'd brought along his girlfriend, Ronel Nel, a South African sea turtle biologist, who eagerly pitched in even though there are no sea turtles in this ecosystem.
Sockeye salmon are the keystone species here. The scientists study how salmon live, and how other creatures depend on them, including predators such as grizzly bears, which occur in densities 10 or 20 times higher than in Glacier and Yellowstone national parks, and seagulls, bald eagles, osprey, foxes and otters. They also study the insects and plants and water chemistry – all the factors that determine the ecosystem. "This isn't rocket science," Schindler likes to say. "It's a lot more complicated."
Until I met Schindler, I thought I was up to speed on salmon ecosystems from my decades of work as an environmental journalist in the Lower 48's version of wildness. There are six salmon species, and all of them are in trouble in the Lower 48. I've interviewed people involved in salmon recovery and visited hatcheries and dams. I'll never forget my first glimpse of sockeye back in the 1980s, when I watched a few big ones thrashing up an Idaho stream, completing their 900-mile migration from the ocean back to their spawning sites around Redfish Lake. I have since tracked the dwindling of that run, but like many conservation-minded folks, I still considered the Lower 48's millions of acres of habitat a good place for salmon to make a comeback.
Schindler had shaken up my thinking in February when he visited Montana State University, a few miles from my house, to show slides about his Alaska research. Watching his presentation, I began to see that the restoration efforts I'd reported on were kind of desperate, almost pathetic. The Lower 48 will never regain the kind of wildness that survives in Alaska. Joining his research team for several days, I experienced how Alaska is what the rest of the West used to be. And I was struck by the purity of the human endeavor itself, the scientific quest for knowledge that is such a contrast to the quest for money that dominates the civilized world.
Clad in waders and armed with bear spray, besieged by mosquitoes and yelling, "Hey, bear! Hey, bear!" to warn any lurking bruins that I was coming, I slogged with the scientists up cobble-bottomed creeks where thousands of big mature sockeye glowed psychedelically red. They turn that color for their final days, as if they're flaming out at the end of their exhausting migration from the ocean back to their home waters, intent on spawning where they were born years ago. Some of the streams were so shallow and narrow, they seemed to contain more fish than water.
We counted salmon, not only in the creeks but also in areas along the lake shores where some preferred to spawn. We netted and measured and tagged them as they thrashed in our hands, and recorded their eventual deaths from predators or exhaustion. A typical narration to the note-taker, by a scientist examining a single female carcass left on a streambank: "AW" ... "K2" ... "BK" ... "belly 10 percent!" (Translation: AW is the tracking number on the plastic tag they'd attached to this salmon the previous day, when it was alive; K2 indicates the creek segment where the carcass was found; BK means "bear kill," as shown by teeth marks. And check it out: The bear chomped out only the eggs, the richest nutrition, and discarded 90 percent of the fish.)
We also netted different species of fish and recorded their basic data, including stomach contents. The method for that: Grab the slippery fish, stick the tube from a squeeze-bottle of water into its mouth and flush the stomach contents into a pan; then release the fish back into the stream. "Grayling" ... "182" ... "62" (species, length and weight) ... "17 black fly adults, 10 caddis fly larvae, one stone fly nymph, 10 midge pupae, and salmon eggs" (what this particular grayling had eaten lately).
The scientists climbed trees to retrieve memory cards from cameras positioned to shoot photos and video of predators gorging on the salmon (when reviewing the images, scroll past the vegetarian moose that wandered through the frame). They clipped fins off fish so the DNA could be recorded, to track not only individual fish, but also generations of offspring over the years. They used tweezers to extract otoliths – the tiny stones in a salmon's skull cavity, formed by the minerals it swims through – which can show not only where a salmon traveled in fresh- and saltwater, but also the timing of its movements.
This kind of science is incredibly laborious, requiring high tolerance for immersion in cold water, hours in the rain punctuated by blasts of sunburn, swarms of stinging and biting insects, and the constant risk of irritating a bear, even in camp. (One evening we watched a bear swim across the bay and pad ashore into the brush on our side; a few weeks earlier, within sight of our camp, a bear killed a moose calf while the mother moose circled helplessly.) You also have to put up with fragrant outhouses and the lack of electricity, as a generator and solar panels provide only a few hours of juice per day. The fieldwork is less Herculean than Sisyphean; day after day, the scientists push the boulder up the hill, gathering precious data for later analysis and re-analysis and re-re-analysis.
All this work reveals an underlying truth: The sheer complexity of inter-related species and habitat is essential for an ecosystem's health, particularly for resilience to stresses like climate change. And the inverse is also true: When you "coarsen" an ecosystem (Schindler's term) by introducing roads that carve up the habitat, channeling streams, erasing wetlands, and bringing in mining projects, new transmission lines, more buildings, more traffic and so on – as we've already done in most of the West, and as is proposed for the headwaters of part of this area – the ecosystem weakens and may even collapse.
The University of Washington's Alaska Salmon Program is billed as "the world's longest-running effort to monitor salmon and their ecosystems." UW scientists began working here back in 1946, and generations of them have returned every year since. They have six camps in the area, concentrating on the Wood River, which they consider a proxy for the eight other major rivers that also flow into the saltwater of Bristol Bay – a megasystem collectively hosting the world's best sockeye runs.
The only system comparable in the Lower 48 is the Columbia River and its tributaries, stretching from the Oregon coast to headwaters in Idaho and Canada. Coarsened by more than a hundred big dams and vast modifications to floodplains and wetlands, the Columbia supports roughly 1 to 2 million migrating salmon in a good year – 10 percent of the number it used to support – and most of them are raised in hatcheries and injected into the system like a shot of methamphetamine. In Alaska, most salmon runs are still near the historical highs. The Wood River system alone – an area less than one-one-hundredth the size of the Columbia – averages 2 to 3 million sockeye per year, and sometimes hits 10 million. And they're all wild.
Commercial fishing boats hovering near the Wood River's mouth capture 60 percent of the migrating sockeye, on average, yet enough make it past the fishermen to form "the Red Wave" – a huge pulse of sockeye in the river and associated streams and lakes that supports the abundance of predators, from bears down to the blowflies that lay eggs in salmon carcasses so their maggots can feast. Scientists have found that a single carcass can support 50,000 maggots, which, in turn, are consumed by other insects, birds and fish.
The first scientists here "developed an integrated view – what we would call 'ecosystem science' today," Schindler told me. "The strength of our program is the long-term measurements," with the continuous studies generating "immense data sets."
The program's current luminaries include gray-haired Thomas Quinn, the author of a definitive textbook, The Behavior and Ecology of Pacific Salmon and Trout. He helped establish how salmon navigate far out in the ocean and then return to their home streams: They sense geomagnetic fields in the ocean and smell distinctive odors in freshwater, which lead them back to the exact spot where they hatched. Some of this information is genetically passed to offspring, Quinn believes.
The salmon face very long odds. The average spawning female lays 3,000 eggs. To maintain a healthy population, at least two of those offspring need to grow up and return to spawn a new generation. That doesn't always happen: Bears kill an astounding number of the Wood River sockeye that make it past the fishermen, ranging from 5 percent on the river itself to as much as 90 percent on the tiniest creeks. Once the bears' initial hunger is sated, they become connoisseurs, often chomping out only the brains of the males and the females' eggs. Scientists calculate that salmon flesh provides a respectable 2 kilojoules of energy per gram, while the eggs and the brains provide 10 kilojoules per gram. "Bears are omnivorous," Quinn said, "but nothing is as predictable and rich as salmon."
As the ripples of the Red Wave spread, the predators transport the dead salmon and their eggs around the ecosystem: Bears carry the carcasses a short distance, spreading nutrients in the riparian area, while gulls take fragments and salmon eggs longer distances to their nesting places, where they enrich little islands and lakes, providing food for snails and Alaska blackfish. Scientists have even found "salmon signatures" embedded in the feathers of songbirds, because nutrients derived from salmon feed the plants that produce berries the birds eat.
Jonny Armstrong, a post-doc working with Schindler, dispensed this expert advice about how it all fits together, pointing to a salmon carcass: "When you find a dead salmon that still has its eyes, you know you're tight on a bear." Translation: Gulls quickly discover salmon carcasses left by bears, and they peck out the fishes' eyes, so if you find a carcass punctured by big teeth marks and its eyes are still intact, you know that you just scared off the bear. It's probably hiding in the bushes waiting for you to move on. The gulls will arrive any second.
The complexity of this wild ecosystem begins with the water in the hundreds of creeks that form the rivers of Bristol Bay. Each creek draws from a different ratio of snowmelt, summer rains and fall rains. When some creeks are low due to a dry summer, others will likely be normal or high, which means the average is more consistent than you would expect looking at just one or two of them. The same goes for the nine rivers: Their average total flow is more reliable than any individual river.
The natural topography and geology are also complex. Some creeks rush down super-steep mountain valleys, while others dawdle down gentler grades from little spring-fed lakes; some drain volcanic soil and others don't; some are colder and some are warmer. This provides a varied habitat for salmon to exploit.
Hiking up Lynx Creek one day, above Lake Nerka, Schindler explained the "hydrological complexity" of just this single creek. It has a cold tributary (roughly 44 degrees Fahrenheit) fed by groundwater, a warm tributary (65 degrees) originating in a small headwaters lake, and a general mosaic of relatively warm pools and cold rapid segments, plus much warmer pools off the main channel, where young fish get stranded in low flows. This complexity provides "refugia" during varying weather and flow conditions, Schindler said. When a tributary floods with rains, for instance, the juvenile salmon attempting to feed in it leave, hanging out in the main channel just above the confluence – "a velocity refuge" – until the flood subsides. If the whole main channel floods, they seek sanctuary in the side pools that are barely connected to the main.
I sat on a bank at the confluence of Lynx Creek and its cold tributary, where bears had flattened the grass and left portions of carcasses, and watched sockeye swim up to me. In many places, the water was so shallow that it didn't even cover their humped backs and dorsal fins. In brief stretches that were merely soggy gravel, the fish wriggled, rather than swam, uphill. Some turned left at the confluence to go up the cold tributary and spawn there, while others kept going up the main channel, heading for higher segments or the headwaters lake, to spawn in warmer water. Those spawning in the cold tributary are genetically distinct from those spawning in the main channel – one data set that supports the conclusion that the locator information is passed on to offspring. "We're discovering the genetic diversity of salmon also benefits the consumers (predators)," Schindler said. If salmon can't spawn in one segment of the creek for some reason, the other segments might be OK, so the predators can find salmon pretty consistently during the run in this creek.
Even the timing of salmon runs is complex. Some creeks have early runs, in June and early July, some have middle-of-the-season runs, and some have late runs, in August. Runs on the spawning sites in the river itself last into September, and runs on the lakeshores, where some fish spawn, last into October. Each run hits its peak for two to three weeks, but because the timing is staggered, the run for the whole Wood River system lasts eight weeks or longer. The predators have learned to roam around the fenceless, roadless miles, hitting each creek, river segment and lake at its peak, Schindler said.
The salmon's varying life cycles also lend resilience to the system. Of the offspring from a single batch of sockeye eggs, some will stay in the freshwater for a year, while others linger for two years. Once they migrate out, some spend two years in the ocean, some three. So one batch of eggs can produce salmon that return to that exact spawning site three years later, four years later, and five years later, providing multiple opportunities to successfully reproduce at that site. Schindler made this point tangible on Berm Creek, which has a persistent sandbar where it meets Lake Nerka. A few years ago, a flood deposited so much sediment on the sandbar that it completely closed off the creek to spawning salmon. No problem for the ecosystem: Other creeks did well that year, and the next spring's runoff was strong enough to blow an opening in the sandbar, allowing the next run to return to every spawning site in Berm Creek. Ultimately, the one-year disaster didn't matter.
And don't overlook the strays. A small percentage of the migrating salmon don't return to the place they were born. Instead, they appear in other spawning sites, breeding with other distinct populations or re-colonizing creeks whose runs have been wiped out.
Other ecosystems operate with similar fundamentals derived from complexity. Wyoming deer and elk, for instance, ride a "Green Wave," roaming to feed where grasses and other forage are best at certain times of year, according to Armstrong, who's now based at the University of Wyoming.
Sea turtles, Nel informed me, are born on South African beaches and then swim through the waters of at least nine nations, navigating through threats like fishing nets. The turtles feast on jellyfish, but selectively, just nipping off the tentacles, much the way bears and gulls high-grade the best parts of salmon. Then the turtles return to lay eggs on the beaches where they began, following subtle cues including magnetic fields and smells –– "almost the same blueprint" and "ecological infrastructure" as the salmon, Nel said.
Any change that reduces complexity can threaten an ecosystem. Fragment the land here, with new roads and fences and other obstacles, and the bears can't roam freely enough to hit the brief peak runs on each creek, river segment and lake. The same goes for the water. In our walk along Lynx Creek, Schindler told me, "If a road went along here, it would constrain the stream and turn it into a rain gutter." The complexity of many varying temperatures and velocities in this single natural creek would be reduced, resulting in fewer options for salmon, and likely fewer salmon for predators, fewer nutrients derived from decaying salmon, and so on.
"An industry might say there's little or no impact from degrading or eliminating just one small salmon run, a few hundred salmon at one spot," Schindler said, "but it even reduces the complexity of time." Meaning, in such a strongly seasonal environment, if you subtract a few days from the peak run in this creek, you leave predators noticeably less time to fatten up enough to get through the rest of the year. Repeat that on enough creeks, and the bear population here would be winnowed down to the remnants in the Lower 48.
On another creek, Armstrong discovered one of the small complexities that would be easy to erase without noticing. He placed PIT tags (metal pins that can be detected by antennae) in juvenile coho salmon that spend most of their time in the headwaters, which on that creek are warm due to meanders and beaver ponds. Turns out, the tiny coho dash down to the creek's lower reaches to gobble the eggs of sockeye spawning near cold groundwater springs. Then they dash back up to the headwaters, because they need warm water to digest their meal. If a culvert or any other manmade obstacle is installed on a creek like that, it would cut off that feeding pattern – potentially causing a reduction in coho salmon, with who knows what ripple effects.
These are not hypotheticals. Scientists, fishermen and conservationists are alarmed about a proposal to construct the Pebble Mine on a high divide between two nearby watersheds, the Kvichak River/Iliamna Lake complex and the Nushagak River (for more info on the Pebble Mine, check the sidebar and the infographic/map). The rock bodies contain copper, gold and molybdenum, and are very porous and high in sulfides, so any runoff would be extremely acidic. And if the Pebble Mine is developed, more than a dozen other proposed mines would follow, Schindler said, using the roads and infrastructure built for Pebble.
Schindler is not an alarmist. He thinks that environmentalists often exaggerate when they talk about "fragile" ecosystems being threatened. Ecosystems in general are "resilient," he told me, in that their organisms and plants and inter-relationships can adjust to insults, "as long as we don't pave them over." But he's concluded that large-scale mining like that proposed for Pebble is incompatible with healthy watersheds and the fisheries and wildlife they support.
That's why Schindler and a few other scientists traveled to Washington, D.C., in early May 2013, as the federal Environmental Protection Agency revised its assessment of the Pebble Mine's potential impacts on the watershed. He met with EPA and congressional staff, urging the agency to scrupulously analyze the impacts. The EPA is under intense political pressure from congressional Republicans who are skeptical about a great deal of its science and heavily influenced by industry lobbyists. "The mining industry began promoting the Pebble Mine by saying a few years ago there will be no impacts," Schindler told me. "Now they admit there will be impacts, but they say they can mitigate it with hatcheries and buffering the impacted streams with limestone, and opening up new streams. In some cases they are talking about knocking down beaver dams. In other cases it is really not clear what they are talking about – possibly diverting water from non-salmon streams or digging spawning channels. It is all extremely vague. They have a list of consultants a mile long lining up to tell them what they want to hear."
The mine's backers, of course, tout its many human benefits – jobs, economic multipliers, more civilization for highly rural communities. But in any "manipulated landscapes," Schindler said, "we make them simpler by getting rid of variation we don't want or think we don't need." And then, when the ecosystem is damaged, "restoration" efforts are very difficult or impossible, because the complexity has been so reduced. "We also need to think about this complexity," he added, "when we talk about 'restoration' in the Lower 48."
Restoration has become a buzzword in the Lower 48. We dig up toxic mine sediments from riverbanks and haul them away, re-engineer meanders and pools on channelized streams, yank out culverts, install screens on irrigation diversions to block fish from straying into farmfields. On the land, we pull down fences or make them "wildlife-friendly" by tuning the arrangement of wires. We replant native vegetation where it was wiped out, tune up forests and wetlands that were mismanaged, bring in a toupee of topsoil to cover mine tailings and grow plants on roads carved for industry. In Alaska, I learned that we don't even understand the full extent of what was lost, and we probably never will.
The scientists here will never complete their research, because there is always more to learn about how this ecosystem works. Hauser, for instance, through surveying two creeks and the lakeshore spawning site between them, day after day for 10 years, has discovered that a single male sockeye that spawned with two females in 2004 had about 34 offspring that returned in 2008-'09 – about 10 percent of the run. That's amazing, he said, because more than half the spawning sockeye have no offspring that make it back. He doesn't know why that particular male's spawning was so successful, but thinks more research might provide an answer.
Hauser also hopes to answer a question about the salmon's anti-bear strategies: "No one really knows why" the salmon generally gather at the mouths of creeks and then rush up all at once to their spawning sites, he said, but it's probably because, by running with a crowd, each one has a slightly better chance of surviving the gantlet of bears long enough to spawn. Some of the salmon even go back and forth, entering and leaving the creeks repeatedly at certain times of day, avoiding the bears' most active feeding times around sunrise and sunset. Hauser wonders whether this is "risk-sensitive breeding" – are these particular fish just better at dodging bears and thus more successful in having offspring?
Connectivity is one of the main questions. If salmon are wiped out in one creek, how long does it take for other salmon to re-colonize it? And where do they come from? The answer matters to more than salmon; already, climate change is causing many species to re-locate in response to the upheaval in conditions.
"We have a really lame ability to predict the future," especially how ecosystems will evolve with climate change, Schindler said. "But what we can do is spread the risk around," by maintaining the complexity and diversity as "an investment strategy." There's already evidence that colonizing and re-colonizing can happen very quickly if the ecosystem is still complex and diverse. "Let's keep our options open for animals and species we value."
In his "continuous game" of attempting to keep all this research going, Schindler sat at the kitchen table in the main cabin one morning, sipping coffee made with lake water, surrounded by shelves of high-energy food brought in by boat – M&Ms, peanut butter, blocks of cheese – and fired up his computer. He was writing the annual progress report to the National Science Foundation, which provides roughly 50 percent of the program's current budget. The team needs at least a half-million dollars per year just for the core activities, not including their university salaries. "We lose sleep over funding this program," Schindler said.
Salmon canneries initially funded the research, hoping to determine how to maintain healthy runs, but since cheaper farmed salmon has flooded the market, their business has declined; they now provide just 10 to 15 percent of the program's budget. The rest is raised in bits and pieces from many sources, including the U.S. Fish and Wildlife Service and commercial fishermen who want to help ensure stable runs. The largest support in recent years has come from the Gordon and Betty Moore Foundation, based in Palo Alto, Calif. – Gordon Moore, the founder of Intel, is an avid fisherman – but the foundation is shifting away from supporting basic research.
"Our program's strength is long-term data, and that's the hardest thing to get funding for," Schindler said. The University of Washington itself doesn't provide much funding for this program; even though universities build their reputations on research, they usually just house it and skim off a percentage of the grants for overhead. "The longevity of the program depends on the energy and passions of a couple of faculty," Schindler said, citing Tom Quinn and Ray Hilborn, another veteran in UW's School of Aquatic and Fishery Sciences. "It's not the institutions."
Schindler himself puts in the most time at the camp, staying into autumn after the others leave, sometimes walking the creeks alone with a shotgun because the bears get frantic before hibernation. He and Armstrong even came here last winter, driving snowmobiles across the frozen lake to sample the chemistry of snow that would end up in streams in the summer. Tim Cline, one of the grad students, told me that Schindler can count salmon simply by walking up creeks to see what's there; at a glance, he can estimate hundreds accurately and even do the gender breakdown.
In many respects, Schindler is carrying on his father's legacy. David Schindler was in constant hot water in Canada due to his outspoken advocacy for the science on acid rain and phosphate detergents. More recently, he's been raising hell about the oil sands mining in Alberta. Says Daniel, "He's influential because he's not scared of anyone."
About 10 years ago, on the bank of Washington's Snohomish River, surrounded by roads and farms and cities, I met a guy who put on a snorkeling mask and swam with the remnants of the salmon run there – just for the love of it. I put it on my bucket list: Someday, somewhere, before I die, swim with salmon.
One afternoon here, on Sam Creek, I got my chance. First, Armstrong donned his snorkeling gear and a dry suit and slipped into the cold, clear water to take close-up photos of the vivid red sockeye in a pool where the creek meets Lake Nerka. Hundreds of salmon hovered side-by-side, facing upstream, getting ready to make their run, and they tolerated Armstrong slowly easing into their formation.
Then we walked up the creek through a litter of salmon carcasses, past fresh bear and gull prints in the sand, finding smaller pools where more sockeye hovered. I wrestled into the rubber suit, adjusted the facemask, and lay down in a pool. Almost instantly, it seemed, I was surrounded by the big reds.
As they undulated to keep themselves in formation, some brushed against me with their bodies, and some swiped their tails against exposed portions of my face. A few even wriggled under me, one by one forcing their way between my chest and the sandy bottom.
Shifting slightly upstream, I turned to look at them head-on. Dozens faced me, just a few inches away, their jagged teeth exposed through gaping, elongated jaws – another physical change that occurs as they spawn, as if they're reverting to a completely primitive form that matches the landscape. Their gills flexed water in and out, extracting oxygen, and their eyes, eerie golden circles, gazed at me implacably, as if nothing else mattered except their instinct to spawn. I reached out, touched one, and then another, and another.
Ray Ring, writer of this story, is an HCN senior editor based in Bozeman, Montana.
Jonny Armstrong, the photographer, was born and raised in Ashland, Oregon, and just finished his University of Washington doctorate, working with Daniel Schindler. He's now a 2013 Smith Postdoctoral Research Fellow based at the University of Wyoming, working to evaluate the effects of resource development on wide-ranging consumers in Alaska watersheds.
This coverage is supported by contributors to the High Country News Enterprise Journalism Fund.