Thermophilic bacteria kill thousands of Washington salmon
It is estimated that 2,500 chinook salmon died before they could reach their spawning grounds in Whatcom County in September.
Lummi Nation officials say a triple whammy of hot water, low flow rates and bacteria killed 80% or more of Chinooks returning to the South Fork Nooksack River.
Drone photos show their bleached carcasses – the latest victims of the Northwest’s deadly summer heat – litter the bottom of the river.
Tribes and state officials have worked for years to bring the people of South Fork Chinook back from the brink of extinction.
Board member Lisa Wilson of the Lummi Indian Business Council, the governing body of the Lummi Nation, said her stomach sagged when she heard of the September death.
âWe have worked so hard in so many areas to collect fish for our people,â Wilson said. “So it’s devastating for me when we finally get things done in the right direction.”
âFor the Lummi Nation, salmon is as important as the air we breathe,â she said.
Puget Sound Chinook Salmon have been on the Federal Threatened Species List since 1999. They are closer to extinction in the South Fork than in any other river.
In 2013, only 10 Chinooks returned to the river.
Efforts to restore and breed habitat at a South Fork hatchery have seen their numbers rebound, with 1,300 adults returning to spawn by 2018.
“We see columnaris almost every year,” Lummi’s Department of Natural Resources biologist Tom Chance said of the disease causing death. “Of course, in previous years he was far from that scale.”
Vets say Flavobacterium columnare, the bacteria that causes spine disease, is still present in Northwestern waters. It does little harm unless the water gets too hot, as it did with the heat waves and drought this summer.
âWe are seeing more and more columnar diseases and [the parasite known as] Ich everywhere due to climate change, âNorthwest Indian Fisheries Commission veterinarian Nora Hickey said in an email. “It turns out that this year those emerging issues were more apparent in the South Fork Nooksack.”
As luck would have it, the usually rare parasite Ich (short for Ichthyophthirius multifiliis) was found on all fish collected by veterinarians from the river.
âWe also noticed here where we live, in the river, more dead salmon during the summer, just floating around,â said Abby Yates, who lives just downstream on the main course of the Nooksack River near Everson, in Washington State.
âSalmon has always been a way of life for my family, but also for our tribe,â said tribal member Nooksack. âMy dad made the best smoked salmon ever. It’s just a constant as I was growing up and still to this day.
Of course, seeing dead salmon in a river can be a good thing: the carcasses of breeding salmon enrich inland ecosystems by providing nutrients from the sea.
Scientists worry about what they call âpre-spawning mortalities,â fish that die before spawning or even reaching their spawning grounds.
âOver the past two years, there have been a lot,â Yates said.
Chance said most of the Chinooks that died in September returned from the ocean to freshwater in June or July, then took several weeks to ascend the Nooksack River from Bellingham Bay to South Fork.
US Geological Survey river gauges show temperatures in South Fork peak at 72 degrees in August, well above what scientists consider the lethal limit for salmon.
Extreme heat puts stress on all kinds of organisms, from trees to humans. According to the Washington Department of Health, the heat killed 138 people in Washington state this summer.
âWhen you and I go out in hot weather and we’re exhausted, fish have the same metabolic problem,â said veterinary pathologist Kevin Snekvik of the Washington Animal Disease Diagnostic Laboratory at Washington State University.
Fish-killing bacteria proliferate in late summer or fall, when water temperature peaks and water flows reach their annual minimum.
âThe fish get stressed, and then once the fish are stressed, that kind of problem allows this bacteria to cause problems,â he said. “Salmon’s immune system is designed to work in cooler waters, which is why they are native to the Pacific Northwest.”
Biologist Tom Chance says habitat degradation is still the primary driver of the decline of Puget Sound chinooks. But “climate change is exacerbating the existing problems we have in virtually all of the Puget Sound basins,” he said.
The two tribes of the Nooksack Basin strive to keep their shared river cool. Priority works include habitat projects to ensure the river has deep pools of fresh water – âtemperature refuges,â they are called – and a legal fight to leave more water in the river each summer. , for higher and cooler flow rates.
Whatcom County Family Farmers opposes tribal efforts to settle and enforce Nooksack Valley water rights: they expect they may lose access to water that ‘they use to irrigate crops.
Tribal water rights date back to the Point Elliott Treaty of 1855 and surpass those of farmers.
The farmers’ association is in favor of a more collaborative approach to water management.