Chinook salmon barely stand a chance against climate instability on the Nooksack River


Salmon eggs incubate at the Skookum Creek Hatchery on December 10, 2021.Nathan VanderKlippe / The Globe and Mail

Inside trays stacked 16 depths at the Skookum Creek Hatchery, 740,000 eggs are incubated in spring chinook salmon. They are almost certainly the only fish of their species this year in the South Fork of the Nooksack River, the Washington state waterway that has hosted one of the most successful fish restoration programs in the United States.

Months of severe weather caused a major setback to the program. First, the summer heat killed thousands of fish in the river. Then the November floods devastated the gravel beds where the survivors had laid their eggs. The confluence of disasters has vividly highlighted the toll of rising temperatures on the natural world and demonstrated how climate instability can create a deadly succession of dangers.

“These are two historic events that salmon have gone through in one season,” said Dana Wilson, a fisherman and member of the Lummi Nation, which is now located at the exit of the Nooksack.

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There were times this year that he found himself thinking, “Is this the end of the world? “

“It’s all part of the connections of the natural ways of things,” he said. “What devastation next year – or even this spring? “

For the Lummi, who have struggled to bring back these fish, the double blow to the Spring Chinook is likely to diminish the possibility of continuing a recently restarted harvest of the fish in years to come. It also raises new questions about the river’s ability to support a natural salmon population, a concern for Canadian waterways as well, as the Nooksack flows just 20 kilometers from the Fraser River, which experiences similar climatic conditions.

The Nooksack Chinooks are “very vulnerable right now, and there is a lot of evidence that things aren’t going well for them going forward,” said Tom Chance, salmon enhancement program manager for the Lummi, who oversees the Skookum Creek Hatchery.

The Lummi have long valued the Chinook for its size and its early descents, which traditionally marked the end of the lean season. Fish are also a preferred food source for a small population of killer whales residing in the Puget Strait and the Salish Sea, which are classified as endangered. The effort to care for the Lower Nooksack Spring Chinook was considered significant enough to merit its own funding from Congress. In 2015, only 11 fish returned to the South Fork of the Nooksack. Since then, the number has grown into the hundreds and the hatchery has incubated around 1.9 million eggs in recent years.

This year, however, he was only able to muster less than half. “We lost 2,500 fish in the river before they could even get back to the hatchery,” said Chance. Record-breaking summer heat accelerated the spread of bacterial infections, leaving the Nooksack littered with bodies of blanched white salmon.

Then came the floods in mid-November, which sent torrents down the river (some of its floodwaters poured into the Abbotsford area of ​​British Columbia, submerging farms and drowning animals). Chinook salmon dig their spawning grounds – a depression where they lay their eggs – up to 30 centimeters into the bottom of the river. In part of the Nooksack measured by the US Geological Survey, the river dug nearly two meters from its bottom.

“Anyone who laid eggs, their offspring is gone,” said Kevin Clark, regional hatchery manager for the Washington Department of Fish and Wildlife. For many salmon, the risks of increasingly severe weather conditions mean that “without hatcheries, the habitat is just not there to support it,” he said. Already, researchers have estimated that native salmon runs in the region have declined to less than 8 percent of their size by the late 1800s.

The Skookum Creek Fish Hatchery incubated around 740,000 spring salmon eggs this year, after flooding destroyed the gravel where salmon naturally lay their eggs on December 10, 2021.Nathan VanderKlippe / The Globe and Mail

In the Fraser River system, researchers believe this year’s flooding caused “significant” damage to salmon populations, but it will be years to know exactly how bad it was, biologist Marvin Rosenau said. of Fisheries at the BC Institute of Technology. But the flooding did not only destroy the nests, he noted, as another concern is “the stranding of juvenile and adult fish which strayed into the floodplain during the high flows and then failed. could not find their way back to the main stream. “

Salmon and other fish have the ability to navigate torrential rivers, and Mr. Clark was impressed with the ability of later species, such as chum salmon and rainbow trout, to cross the waters of flood.

At the Kendall Creek State Hatchery, however, the bodies of dead chum salmon were floating in brood ponds on a recent morning. The hatchery is located on a tributary of the Nooksack, and unusually high numbers of fish have returned this year covered in mushrooms. “They are not in good shape,” Mr. Chase said. He believes the sediment washed away at high speed by the floodwaters has abraded their flesh, removing the mucus that normally protects them from pathogens.

“How can we prevent this in the future? We have very few options, ”he said. To help the salmon, “we have to get rid of the dikes.” Restoring rivers to their natural diversion channels would help restore salmon habitat.

People living in these diversion canals called instead, saying it was time to raise the dikes to prevent further flooding.

For some members of the Lummi Nation, however, this year’s death toll on salmon argues for a new approach. “We have to recognize the flood plains and we have to give in to them,” said Troy Olsen, a fisherman from Lummi.

Wilson also pointed to the upper reaches of the Nooksack, part of which flows from the glaciers of the North Cascades Mountains which have lost about 30% of their volume since 1984. Water source flows during the warmer months, scientists warning that lower water levels could affect the ability of salmon to spawn.

The plight of the Nooksack salmon, Wilson said, underscores the immensity of the climate-related problems that are now mounting and the importance of addressing the root causes.

“Are we at a time when we really need to look at climate change and stop thinking it doesn’t exist? he said.

“There is no silver bullet to this.”

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