The importance of colder streams in a warming world
Molly Kemp (left) and Nick Olmsted (right) retrieving a stream thermometer. (Photo: Author)
The five of us are wading upriver. It’s a bright blue, mid-May morning in Southeast Alaska. We’re on Chichagof Island, in a bay off Tenakee Inlet called Long Bay. The small river winds ahead of us, meandering through another mile or so of tidal flats before reaching the forest. The Endeavour is anchored behind us in deeper water.
The river is up to our waists in places. Everyone has chest-high waders on except me. We were a pair short. I’m in soaked jeans, bringing up the rear. Patsy, my wife, is just ahead of me. Noah, our high school intern from California, is next. In the lead are Molly Kemp and Nick Olmstead. Molly is carrying a long walking stick with an orange can of bear spray dangling on the front of her waders. Nick is a few steps ahead wearing a backpack and holding his lever-action rifle at shoulder height to keep it out of the water. As we get closer to the trees, we see there is still snow on the ground in the shade.
We’re here to collect data. Molly and Nick used to collect salmon otoliths – ear bones – for the Alaska Department of Fish and Game and the Sitka Science Center. The composition of the otoliths gave clues to the fish migration patterns and their general health. In 2007, before the spawn, Molly and Nick saw a massive die-off of salmon. Those fish missed their chance to reproduce, threatening the population. Molly and Nick thought the cause might have been warming streams. Salmon can’t tolerate warmer water because it holds less oxygen. The fish suffocate.
To test the theory, they planted recording thermometers in the streams off Tenakee Inlet, streams that flowed into Trap Bay, Kadashan Bay, Saltery Bay, and others. These thermometers record the water temperature on an hourly basis for more than a year. So, every year, Molly and Nick revisit these thermometers, download the data, and change the batteries. They send the data to government researchers.
This is harder work than I had guessed. The thermometers have to be planted above the tide line to get the stream temperature unaffected by salt water. This means going far upstream, well past the open tidal flats and into the dense forest, climbing over and under fallen logs and around rocks. The water is too swift for a canoe, and too narrow and log-filled for even a small skiff with a jet outboard (I had to leave ours a mile back). You have to wade, and the water is cold. You also have to watch out for bears. There are brown bears here – coastal grizzlies – that grow big on the salmon. A large adult male can stand 10 feet tall, weigh 1,200 pounds, and outsprint a racehorse.
Molly and Nick have been tending to their thermometers for 15 years, with almost zero financial support.
We reach the thermometer. It’s tied with a steel cable to a huge log about five feet in diameter, lying at a 30-degree angle into the river. Nick uses Molly’s stick to retrieve the device while Molly pulls herself up and over the log, disappearing on the far side. The cable has rusted, and it takes Nick some time to replace the cable and the clamps. While he’s doing that, Molly climbs back over the log, takes the thermometer from Nick, and comes over to where I’m standing (uselessly) on a sandbar and downloads the data to a hand-held computer. When she’s done, she wades out into the middle of the stream to check for the temperature differential between the eddy where the thermometer has been sitting and the more free-flowing water. Today, it’s negligible.
What their long series of data show is that in the Tenakee watershed some streams are indeed colder than others: the source of a colder stream may be higher, or the rivulets and brooks that feed the stream may be better shielded from the sun by the forest canopy. It also shows that the healthier salmon populations are in the colder streams.
Their conclusion is, if you want to protect salmon in Tenakee Inlet as the climate warms, focus on protecting the colder streams. Mostly, this means not logging their watersheds. Several streams in the lower inlet – and the Sitkoh River, around the corner in Peril Strait – have already had their canopies logged off with the trees sold at bargain prices to pulp mills to be turned into newsprint and disposable diapers, says Molly. Molly and Nick’s data shows there is still a chance to protect the upper streams: Seal Bay, Long Bay, Goose Flats, Saltery Bay, and the head of the inlet.
We got back to the Endeavour late in the afternoon and stayed there at anchor for the night. In the morning, with the windows still steamed up from breakfast, I asked Molly what drove her and Nick to keep collecting this data, year after year, without getting paid.
She was quiet for a moment, then said, “The salmon reflect the integrity of the world we live in. There are still some pockets of interconnected ecosystems that are functioning, healthy, and vibrant in a way that nothing compares to. There is overwhelming life and abundance that pours out of these streams and either we preserve it, or we hand over a planet that’s denuded of everything we value.”
She looked out the window, back up the river, and added, “The other part is emotional. When you fall in love with a place, you have no choice in the matter; you have to protect what you love.”
Molly and Nick coordinate their work with two volunteer groups, the Chichagof Conservation Council and the Southeast Alaska Watershed Coalition.
— William Urschel