Glacier Salmon: Lessons for an Uncertain Future
It was high summer in Glacier Bay National Park. Lofty serrated peaks were visible above the leafy alders, but I couldn’t see a trace of the ice that gave Glacier Bay its name. It was hard to imagine that just two centuries ago, Captain George Vancouver reported a solid wall of ice at the present mouth of the bay, with a vast glacier spreading away toward the north. Amazingly, thanks to the world’s fastest glacial retreat, this has now become a massive complex of open waterways more than 60 miles long.
I’d come here with my friend Hank Lentfer, to meet Dr. Alexander “Sandy” Milner, a biologist from Birmingham University in England. Each summer for 35 years Sandy has worked in Glacier Bay, where he studies the development of salmon runs in streams that emerge as the ice retreats.
Now Hank and I stood beside one of those streams — Wolf Point Creek — along with Sandy and two of his graduate students, Leoni and Jessica. Rounding out the group was Todd Bruno, skipper of the park service boat Caplin that ferries researchers to their remote study sites in Glacier Bay. We all peered into the whirl and thrash of clear water…and my heart jumped when we picked out shadows weaving through the fretwork of multicolored rocks. Salmon!
Every wild salmon is a creature worth celebrating, but we would soon learn that these fish were very special indeed.
To understand why, let’s consider the first thing everybody learns about salmon: They hatch from eggs in a river or stream, spend their adulthood at sea, and then flawlessly migrate back to spawn in the same stream where they were born.
Countless scientific studies prove that salmon possess this amazing ability. But here’s the kicker. Research also shows that a small percentage of salmon don’t come back home. Instead, they stray and end up spawning in streams other than their birthplace.
This fact is more than simply interesting…it’s also vital for understanding the history of salmon and their future in a changing world. Few people know this better than Sandy Milner.
WOLF POINT CREEK
Dense thickets crowded the stream banks, so we walked mainly in the rushing creek and along the stony gravel bars, occasionally startling more schools of pink and chum salmon.
We also came across brown bear tracks, scats, and half-eaten fish; but our seasoned crew hardly flinched, even when a young bruin rambled directly toward us, earnest and unfazed, then begrudgingly faded into the underbrush.
Sandy hustled ahead, quiet but obviously excited, guiding us to the spot where he had first begun studies of the creek more than three decades earlier. I imagined him working in this same place when he was a much younger man, and importantly, when this was a much younger stream.
Everyone helped to set a couple dozen baited minnow traps in the stream, and then Sandy had a few moments to reflect. He explained that Wolf Point Creek is about 45 miles from the mouth of Glacier Bay, and sometime in the 1940s or 50s this very spot was still covered by an immense glacial face. But by 1977 — when Sandy’s research began — the rapidly shrinking ice had drawn back about a mile.
At that time the whole surrounding area — where the crushing ice once stood — was mostly bare ground except for small, scattered plants like fireweed. The creek itself was a torrent of murky 35 degree water. Today it’s far slower, shallower and clear, with summer water temperatures up to 62 degrees.
In fact, a bit later we all hiked to a deep pool farther upstream, cool enough for salmon yet warm enough for humans to take a dip. The endlessly energetic crew dove in and swam amid the circling schools of fish. It was a joy to watch the scientists momentarily abandon their serious pursuits for a refreshing folic with their subjects.
At the same time, I tried to envision the ice, several hundred feet thick, where we now had this idyllic swimming hole amid a green alder jungle, where thrushes and warblers chorus in the luxurious summer dawns.
The swim was a short break in a very long and concentrated workday. Back at their research site, Sandy and his crew emptied dozens of silvery “minnows” into a tray of water laced with a mild anesthetic. Next they noted the species for every fish, recorded its length and weight, gently extracted its stomach contents into a vial for later analysis, then returned it to the stream unharmed.
Months later in the lab, every tiny bit of food from thousands of trapped fish would be identified under a microscope to understand the diet for young pink, chum, and sockeye salmon, as well as dolly varden char that share the same waters. Modern biological research is remarkable for its focus on examining the meticulous details of living nature and converting these details into numbers for analysis, assuring strict objectivity and accurate conclusions.
If this sometimes gets tedious, you wouldn’t know it by the animated energy of these scientists, who obviously loved their work and had completely saturated themselves with the wild beauty of Glacier Bay.
BIRTH OF A SALMON STREAM
In the late 1970s, still early in Sandy’s studies of Glacier Bay, another retreating glacier revealed the nub of a stream that became known as Stonefly Creek. Sandy Milner jumped on this rare chance to study a stream from the start of its existence, when it was totally devoid of life.
What he learned from his long-term study is truly remarkable.
Within ten years, Stonefly Creek had runs of pink salmon and dolly varden; and soon afterward there were also spawning coho and sockeye salmon. By 2001, up to 5,000 pink salmon were spawning in Stonefly Creek, and in Wolf Point Creek as many as 12,000 pinks had returned.
Genetic studies reveal that each new stream is colonized by salmon from nearby waterways, so in the early years of Glacier Bay’s ice retreat strays came from outside the bay. In more recent times, streams like Stonefly and Wolf Point Creek are colonized by strays originating inside the bay. And as the ice continues to recede, these fish might themselves colonize new streams farther up the bay.
Life has blossomed and diversified, so that by 2002 Stonefly Creek also had more than 80 species of freshwater invertebrates, mostly insect larvae and tiny shrimplike creatures, which are essential food for young salmon. Analysis of the water chemistry also revealed that salmon carcasses were helping to fertilize Stonefly Creek with nutrients brought in from the Pacific Ocean.
Sandy Milner’s research documents a process that’s been repeated countless times since Glacier Bay’s ice started retreating two centuries ago. In an astonishingly short time, rich communities of life have developed in these Glacier Bay streams, bringing brand new salmon runs to the Pacific Coast of North America.
WHY IT MATTERS — A LOOK AT THE PAST
For 35 years, Sandy Milner has carefully documented the progression of streams — from torrents of icy water, devoid of all life, to the home waters for thousands of spawning salmon. When I asked Sandy about the significance of his work, he smiled self-consciously, then said he’s published at least 25 scientific articles based on his studies, and that nine of his students have done related PhD research on Glacier Bay streams. More young scientists like Leoni and Jessica keep adding to this remarkable accumulation of knowledge.
The combined result is a powerful and important exploration of how salmon streams develop, from the very moment of their birth.
During the last continental glaciation, which ended about 12,000 years ago, much of North America was covered by an immense sheet of ice extending all the way to the north Pacific Coast. As the climate warmed (very slowly compared to the rate of warming today) the glaciers retreated, and this gave rise to thousands of new creeks, streams, and rivers, some as large as the Columbia and Frazer. Eventually salmon colonized these waters in such abundance that salmon have come to define the entire Pacific Coast ecosystem.
Today in Glacier Bay, scientists like Sandy Milner can witness and document the same process on a much smaller scale. In this sense, Glacier Bay’s salmon streams are a natural scientific laboratory and a window into the history of North America’s great salmon runs.
WHY IT MATTERS — A LOOK AT THE FUTURE
The rapid colonizing of Glacier Bay by straying salmon demonstrates the resilience and adaptability of these remarkable fish. This is important in a time when thousands of salmon runs in the Lower 48 and Canada have been depleted or completely extinguished by human activities. Studying the biological development of newly born streams in Alaska may help us learn how to rebuild these damaged or lost salmon runs.
Recently, we’ve seen this process happening in places like the Elwha River on the coast of Washington, where a major dam was removed and salmon (all five Pacific species spawn here) are quickly returning to their upstream spawning grounds after a 100 year absence.
Climate change is a more daunting problem for some salmon runs, especially in places like California, where warming streams threaten the survival of spawning and hatching fish. On the other hand, Glacier Bay shows us how receding ice creates new, cold streams where adult and young salmon thrive. Similar processes seem to be happening farther north, as straying salmon are appearing in arctic streams where they were not previously known.
THE SCIENCE OF HOPE
On our last afternoon together, Sandy Milner guided us along yet another new and developing salmon stream. Going through a now-familiar routine, the crew weighed, measured, and tallied the catch of young salmon. Sandy pitched himself into the work alongside Leoni and Jessica, and I couldn’t help noticing how tenderly he handled every fish.
Then Sandy led us farther upstream, to a broad sweep of gravelly outwash and braided river channels, backed by a long, steep, formidable ridge. Once again, he explained how the glacier that once buried this land had retreated and how salmon followed in its wake.
To me, this place was exquisitely wild and glorious. To Sandy, I’m certain it was all this, plus a lot more. He seemed utterly contented to be in a place that he so obviously loved, delighted with the work at hand, grateful for the good company, and certain about what this place — and its living community — had taught him.
Sandy Milner’s studies show us the remarkable adaptability and resilience of salmon — when they’re given a suitable home. And they remind us, yet again, that where there are salmon, there is always hope.
A special note of thanks. To my friend and colleague Hank Lentfer, who introduced me to Sandy Milner, brought us together in Glacier Bay, and brought his own wealth of knowledge, intelligence, and humor, to the experience.
By Richard Nelson for SalmonWorld