After the floods, what’s next for salmon? – High Country News – Knowing the West

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The recently released eggs were probably the most affected by the record rains in the Pacific Northwest.

Standing outside his home in Blanchard, Wash., Thigh-deep water, Kevin Morse watched in wonder at a few salmon – usually found in a nearby cove – swam down his driveway. His son spotted several more later that night as he was carrying friends across the property by canoe.

Morse is just one of thousands of people in western Washington and British Columbia who suffered severe flooding in mid-November. A powerful atmospheric river storm – a long, narrow corridor of tropical water vapor that, when pushed upward by obstacles such as mountain ranges, condenses and wicks away moisture – released quantities massive precipitation, sometimes up to half an inch per hour, over the area. Bellingham, Wash. Received more rain between November 14 and 15 than usual for the entire month. Rivers like the Skagit and Nooksack overflowed onto their banks, and salmon, like those Morse saw in his driveway, were washed away by their streams. Mudslides destroyed roads and three out of four homes in Sumas, Wash. Were damaged by flood waters. At least five people have died.

As communities turn to cleanup efforts and brace for even more rain, experts say the flooding could have both positive and negative ecological impacts on salmon. Salmon, a key species of the Pacific Northwest, are an important food source for 138 other species, including orcas. They are also an essential component of the culture and livelihood of regional tribes, and they support approximately 16,000 commercial and recreational fishing jobs.

Salmon already face many threats, including warmer waters caused by climate change, habitat loss, blocked migration routes, and toxic stormwater runoff. Five species of salmon have made Washington their home: sockeye salmon, coho salmon, and chinook salmon are locally threatened, while chum and pink salmon are not. A 2020 report concluded that Washington salmon “remain on the brink of extinction.” It doesn’t help that this year has already been tough for fish: A record-breaking heat wave in June caused widespread ecological fallout, and in September, hot water, low flows and bacteria killed thousands of people. endangered chinook before they can spawn in the south. Forks the Nooksack River. Treva Coe, fisheries biologist and head of the Nooksack Indian tribe’s watershed restoration program, says heavy rains could lower salmon numbers further. “We know from the data on our populations that years of poor survival are associated with years with high flows and great flooding, so we are very concerned that the survival of this age class will be low or even wiped out.” , Coe said. .

A few days after Morse saw salmon swimming in his driveway, they became food for eagles and raccoons. Salmon are anadromous, which means they are born in rivers, spend most of their lives in the ocean, then return to freshwater to spawn before dying. VSHinook, pink and sockeye salmon were spawning or had spawned before the storm, meaning they were likely the fish that Morse had seen, washed away by a channel, and trapped in shallow water after spawning. Their time was limited, anyway. But what about their descendants?

Salmon embryos are initially buried under gravel so that they do not fly away. “They are very vulnerable at this point,” said George Pess, watershed program manager at the Northwest Fisheries Science Center of the National Oceanic and Atmospheric Administration (NOAA). “Flooding could define the trajectory of this brood year.” Fish in the fry stage are still growing and cannot move for about a month, and even once they emerge as fry, they are only 35 millimeters in size – little more than a quarter of a piece. Females can lay 1,000 to 7,000 eggs, but depending on the severity of the floodwaters at the bottom of the rivers, many of these eggs could have been dug up from their hiding places, carried into the water column and turned into tasty treats for a variety of predators.

“Flooding could define the trajectory of this brood year.”

Flooded farmland near the Nooksack River in Ferndale, Washington.

James MacDonald / Bloomberg via Getty Images

“The key is whether the salmon were able to dig their nests deep enough that they weren’t scoured,” said Thomas Quinn, a salmon researcher at the University of Washington. Egg nests, known as nests, can also be crushed by rocks and sand, or suffocated by silt as it settles. “In general, these floods are not good for them,” Quinn said. “I would expect pink salmon to take a hit, and chinook might take a hit.” But as he anticipates the negative impacts, Quinn said, “I don’t think they will be catastrophic.” And species that haven’t spawned yet, like coho and chum, are likely to do well.

A smolt trap on a lower portion of the Nooksack, designed to capture young fish as they migrate out to sea in the spring, will give the Nooksack tribe their first indication of a dwindling population. Similar traps exist on other rivers in the Puget Sound watershed. In four years – when this cohort of salmon matures in the ocean and returns to spawn – the tribe will know if there has been a decline. George Swanaset Jr., director of the tribe’s natural and cultural resources department, said native people have a duty to protect salmon. The people of Nooksack, he said, have relied on salmon since the beginning of time. “We were fishermen, we lived with these fish,” Swanaset said. “Without salmon, we no longer exist. Swanaset and his colleagues fear that the tribe’s habitat restoration projects, including man-made traffic jams that create pools where salmon can save energy and find cool water during the summer, have been damaged by flooding. They will have a better idea once the flood waters recede and remote travel is safe.

“We were fishermen, we lived with these fish. Without salmon, we no longer exist.

It’s not all bad news: Salmon have adapted to cope with periodic flooding, and landscape remodeling may even create new habitat. High flows are essential to maintaining the complex river systems that salmon need, and flooding is a normal and necessary part of the ecosystem. “While people may be really concerned about these impacts of flooding, it’s important to remember that flooding has been happening for millennia and provides some benefits to salmon, despite what it might look like at the moment. current, ”said Bridget Moran, a conservation associate for American Rivers that focuses on Puget Sound and the Columbia Basin. To the south, atmospheric rivers actually helped salmon back up during years of low flow and high temperatures by providing essential water to watersheds. “We have seen a few different things happening on the Pacific coast, and it has really been a boon for the salmon in California,” said Nate Mantua, fisheries and climate researcher at NOAA in Santa Cruz.

Unfortunately, human alterations to the landscape – dams on rivers, drainage of floodplains for agriculture, narrowing of rivers to a single channel – have changed the way flooding affects ecosystems and salmon, making flooding more damaging than it is. ‘they wouldn’t naturally be. And experts say climate change is accelerating the timeline of many of the challenges salmon face in the Northwest, from warmer waters to severe flooding. Atmospheric rivers are expected to lengthen, widen, and become wetter in a warmer climate. It is still unclear how this will affect the resilience of the salmon. “We take what they’re more or less evolved from,” Quinn said. “And we’re pushing the boundaries a bit.”

Kylie Mohr is a writing intern for High Country News written from Montana. Email him at [email protected] or submit a letter to the editor. See our letters to the political editor.



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