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Nearly half of the wild populations of spring chinook in the Snake River basin have crossed a critical threshold, signaling they are on the verge of extinction and without intervention they may not persist, according to a tribe analysis Pierced nose.
The rainbow trout populations of the river, while doing better, also face alarming threats to their existence, according to the work.
Modeling conducted by tribal fisheries scientists and shared with other state, federal and tribal fisheries managers in the Columbia Basin, indicates that if current trends continue, 77% of the spring chinook populations in the Snake River and 44% of the rainbow trout populations will be in a similar situation. post within four years.
Tribal fisheries officials say a wide range of short- and long-term measures, such as new conservation hatcheries, predator control, increased discharges at the Snake and Columbia River dams, and the adoption of the plan of Representative Mike Simpson to break down the four dams of the Lower Snake River, are urgently needed.
Oregon and Washington fisheries officials agree that dam removal should be considered and that other actions beyond current salmon and rainbow trout recovery efforts should be continued .
The tribe found that 42% of Snake River spring chinooks and 19% of rainbow trout had reached near-extinction threshold – an analytical tool used by the federal government to assess the risk of extinction or measure the viability of fish populations. The threshold is triggered when a naturally occurring fish population has 50 or fewer spawners returning to native streams for four consecutive years.
“It’s a comeback, a series of feedbacks, that shows that you had better do something or you’re going to lose your ability to do a lot of anything,” said David Johnson, director of the management department. fishery resources of the Nez Percé tribe.
Further tribal modeling shows that populations of Snake River spring chinooks that are protected as threatened under the Endangered Species Act have declined at a rate of 19% over the past 10 years. and rainbow trout fell at a rate of 18% over the same period.
Jay Hesse, director of biological services for Nez Perce Tribal Fisheries, looked at data from 31 of 32 native populations of the basin’s spring chinook returning to places like the Middle Fork of the Salmon River, Loon Creek, the Grande River Round and the Imnaha river. Of these, 13 are already reaching the threshold and more will follow soon, according to the analysis.
“If you take that 19% decline rate and say going into the future, where does that take us, and look at five years, you end up with 24 of the 31 populations below 50 spawners. natural origin by 2025, ”he said.
Hesse analyzed 16 of the wild rainbow trout populations in the basin. The sea rainbow trout also listed as threatened by ESA are doing better than chinook, but have declined rapidly over the past five years or so due to poor ocean conditions. The fish showed a declining trend of 18% over 10 years, almost identical to that of the spring and summer chinook.
This projected forward trend places seven of the 16 native rainbow trout populations analyzed by the tribe, or 44%, below the threshold of near extinction by 2025. The large rainbow trout slide rainbow cherished by fishermen is steeper – more like 23%.
“Look at the population names all the way down,” Hesse said, pointing to a graph showing the expected decline in rainbow trout. “South Fork Salmon, South Fork Clearwater, Lolo Creek, Secesh River – these are all populations that are the life cycle of Descent B.”
Representatives of other agencies that manage salmon and rainbow trout in the basin praised the tribe’s work and said it signals the need for more conservation measures.
“If that’s not a wake-up call, I’m not sure what people are looking for,” said Tucker Jones, director of the ocean and salmon program for the Department of Fisheries and Wildlife. Oregon.
“We think their analysis is concerning,” said Bill Tweit, special assistant to the fish program at the Washington Department of Fisheries and Wildlife.
“Anytime you have a total abundance of spawners of less than 50 fish, it really puts you in a bad spot,” said Lance Hebdon, anadromous fish manager for the Idaho Department of Fish and Game.
The National Marine Fisheries Service, also known as NOAA Fisheries, is conducting five-year reviews of the status of endangered species mandated by the Endangered Species Act for Chinook. spring and rainbow trout. Chris Jordan, a scientist at the agency’s Northwest Fisheries Science Center, said the tribe’s work largely reflected an assessment of viability his workshop is working on. While it’s not uncommon for populations to fluctuate, he said the latest downturn was concerning.
“What is becoming more and more worrying over time is if these populations do not rebound from changes in the ocean.”
Michael Tehan, deputy regional administrator of NOAA Fisheries, said that while the data is concerning, the fish have shown a remarkable ability to rebound from previous low abundance. He also said the agency was looking for additional measures to help the fish.
Earlier this year, scientists at the agency’s Northwest Fisheries Science Center published an article that said climate change could cause the already low survival rates of the Snake River spring chinook to drop 90% and that the fish could face extinction by 2060. The study, led by Lisa Crozier, said urgent action is needed to counter the fish-destroying effects of warming oceans and reduced river flows caused by climate change.
The tribe’s analysis included a graph of the downtrend predicted by federal scientists with the addition of actual chinook returns in spring from 2019 for reference.
“As grim as his (de Crozier’s) projections sound, we’re saying we’re already starting this decline and we’re already here on the verge of near extinction,” Hesse said. “I think it is urgent that this continue.”