Early Warming. Nancy Lord
They not only survived the winters that had previously kept them in check with cold temperatures, but were able to complete their life cycle in a single year instead of two. They loved the hot summers that enticed them from their galleries beneath the bark and propelled them to new trees. The infestation, which eventually killed thirty million trees (decimating four million acres of spruce forest—that is, a land area larger than all of Connecticut)—was the largest insect infestation ever documented in North America. (It was recently overtaken by an even larger attack of pine beetles in British Columbia, also linked to climate warming.)
Spruce bark beetles (Dendroctonus rufipennis), like the Ichthyophonus salmon parasite, are a natural part of the ecosystem in our region—thought perhaps to be the instrument of forest succession, rather than fire—but their success in attacking and killing nearly every adult spruce tree across an entire landscape is unprecedented in either historic or prehistoric (judged by tree-ring evidence) times.5 I well remember the summer “flights” in the 1990s, when a series of overly warm days would release swarms of beetles, like a biblical plague, that would, literally, drive people to the shelters of their closed homes. And I remember the march of death across the landscape—the forest turning red as needles died, then gray, then splintered as the dried-out trunks shattered in winter winds.
Parts of the peninsula were logged, the dead trees turned to chips and shipped to Asia, while others were left “natural” as habitat for insect-eating birds, for building new soil, for eventual regrowth. In both cases, our woods were being replaced with grasslands; it’s thought that the tall native grasses may, for a long time, keep any trees from gaining a foothold.
The changed landscape can, of course, have profound effects on water resources and salmon. Trees provide shade, which can help cool rivers. Trees also provide woody debris, beneficial to salmon streams for breaking up the flow and providing resting and hiding spots for fish.
Mauger waded into the raging stream to take another water sample. She pointed out, against the far bank, a pole and instrument she uses, when she can reach it, to measure stream height. A dead tree had fallen against it, and next visit, when she hoped to be able to wade across, she’d bring a chainsaw to clear the area.
All around us, grasses and other debris were hung in the willows, showing how high the water had been earlier. Mauger surveyed the banks, alert to another climate change threat: invasive species. Two that had devastated habitats elsewhere on the peninsula were northern pike—a toothy, predatory fish that can take down ducks and muskrats while also gobbling up young salmon—and exotic grasses. Neither had moved in naturally, as some species did, mile by mile, as the climate changed. They had been introduced—pike by people who valued them as a sport fish, and exotic grasses by being mixed with grass seed, seed packets, or imported hay. Still, in a hospitable climate, they can flourish. Such “weedy” species can outcompete native ones.
Reed canary grass (Phalaris arundinacea)—“a huge deal,” Mauger said—grows into mats that turn flowing streams into marshes. It’s been used for revegetation of roadsides precisely because it spreads rapidly and builds sod that helps with erosion. All along the West Coast, from California to British Columbia, it’s destroyed wetlands and salmon habitat. Plant specialists once thought that in Alaska’s cold the grass wouldn’t produce viable seed, but recent surveys had found infestations in at least 259 locations on the Kenai Peninsula, including along salmon streams.
“It’s all additive,” Mauger said, capping her water sample. Warmer temperatures, more flooding, greater drying, less shade and debris, human alterations to the river corridor and uplands, invasive species—“the system is getting hammered.”
We made our way back along the river, past the fallen forest and the eroded muddy banks, to the highway. We drove back toward Homer through more dreary rain, and I asked Mauger whether, with all that she knew about consequences, she considered herself an optimist or pessimist about the future.
She hesitated a few seconds before drawing a breath. “I do have optimism that some of the repercussions of climate change can be minimized. We’re going to do that with having better information. That’s what this project is about—getting the information that we need so that we don’t have a collapse in fisheries with no warning.”
She paused again and then added that she was also hopeful that, after so much delay and denial from our political leaders, our national politics would change enough, soon enough. “To make the transitions that we need to make, I think it will be a painful ten years. But we have to start now.”
That summer, the stream temperature work Mauger had pioneered on the four Kenai Peninsula rivers was being extended, with state funding, to the rest of the Cook Inlet watershed—forty-eight sites in all. Mauger had worked all winter on the protocols so that data would be collected in a consistent, reliable manner. “We want to try to identify what types of streams are likely to warm fastest, and what types of systems are likely to remain coolest, so we can make some decisions about where to study more about the habitats and the fish. This is really a first cut at looking at different stream sizes and types, the role of wetlands, the role of lakes.” The plan was, after that, for the same monitoring system to be employed by partners and volunteers in the major salmon streams of Bristol Bay (the location of the most valuable salmon runs) and elsewhere in the state.
In this way climate data would be broken out of the broad models and brought down to a local, real-time, and real-place level, to empower communities with the tools and data they need to protect salmon habitat and watershed health. Biologists and land use planners, it’s hoped, will use the data to identify streams most vulnerable to change, then apply it to decisions about further research, habitat protection, water use, and restoration activities. In that ideal world, fishery managers will incorporate temperature information into their modeling of run strengths and escapements (the numbers of fish allowed upstream to spawn). They will also use everything they know about stock structures and life histories to maintain genetic diversity within Alaska’s salmon, knowing that such diversity is critical to the ability of salmon populations to respond to climate change; elsewhere in the world, where individual stocks have disappeared due to overfishing or habitat loss, there’s been little left for filling voids. (This need for genetic diversity, of course, applies to all species.)
We drove along and then across the swollen Anchor River, and Mauger offered up an example of practical application, one way that stream temperature data had already been used in decision making. She’d worked with a university student to identify and map “temperature refugia” along the Anchor. Areas of cool water—shaded by banks with overhanging vegetation—would be most essential to maintaining the river for salmon, and the local land trust added that information to their conservation priorities for working with willing land owners on maintaining vegetative cover in those key areas.
I was listening and making notes, but I was thinking about that eagle in the nest we’d passed, in the cottonwood tree right beside the highway. We used to think that eagles were shy birds that needed plenty of undisturbed space around them; now we know they don’t—or that some have adapted to our busy presence.
Eagles—like bears, belugas, other large and small birds, trout, microbes, even the trees enriched by the spawned-out salmon carcasses that are carried into the forest by the birds and the bears—depend on the salmon. So, of course, do we. I can hardly imagine my home place without them. How would we live?
Salmon are adaptive; we know this. The five Alaska species have managed to survive in this part of the world for six million years, through periods of warmth and cold. Over the course of time, individual stocks have been challenged by change—whether it came from glaciers and ice sheets that overran streams or tied up water in ice, from volcanoes that buried streams in ash or mud, from rock slides, floods, earthquakes that raised or lowered the land and its streambeds. Some stocks perished, while others survived, adapting to conditions and colonizing new habitat.
The challenge, this time, looks to come from climate change that modifies both freshwater and marine conditions on a large scale, and rapidly. Despite all of Alaska’s bragging about our sustainable salmon management, we may find ourselves up the proverbial creek. This time, the degree and speed of change may be