Monday November 3, 2025
The Lewiston Tribune —
An annual report on wild steelhead and wild spring and summer chinook from the Idaho Department of Fish and Game shows the fish continue to be in trouble but there are a few positive signs.
Tim Copeland, a fisheries biologist for the department, likens the report to an annual visit to the doctor’s office where humans get an assessment of their health and progress, or lack thereof, toward goals.
“This seems to show they may not be getting sicker but they are not back to full health yet,” Copeland said.
The recently published Wild Adult Steelhead and Chinook Salmon Abundance and Composition at Lower Granite Dam, Spawn Year 2024 is focused on the return of adult fish in 2024. It measures their overall abundance of the fish and traces how they performed based on when they were hatched, known as a brood year, and when they migrated to the ocean, or migration year.
Brood year is used to calculate adult-to-adult productivity or how many fish returned from a given number of adults. Migration year is used to calculate smolt-to-adult productivity — how many adults return from a given migration year. The numbers are different because fish from a specific brood year don’t necessarily migrate to the ocean at the same age.
Steelhead
The 2024 Spawn Year included a total return of 70,117 steelhead, of which 15,327, or 22%, were wild. The return included the last of the adult steelhead from Brood Year 2016, which were hatched from 33,936 parents. But those parents begat only 15,810 adult steelhead, or 0.47 recruits per spawner.
A recruit-per-spawner rate of less than one means the fish are not replacing themselves.
“If you get one spawner back for every spawner that started that generation, then the population stands still,” Copeland said. “We are at the point where the populations are low. You don’t want to stay there. You want to grow the population. You want the number to be greater than one.”
According to the department’s work, wild steelhead returning above Lower Granite Dam on the Snake River haven’t had a recruitment rate greater than 1 since 2010. Brood Year 2017 won’t be complete until the adult return from this year is tallied. But the department calculated an initial adult-to-adult productivity rate of 0.65 recruits per spawner.
Fisheries managers also calculate smolt-to-adult productivity. This metric measures how many adults come back from a specific migration year, which includes fish from multiple brood years.
The COVID-19 pandemic shut down juvenile fish monitoring activities in 2020, so fisheries officials don’t have a solid estimate of how many smolts migrated to the ocean that year. That makes a smolt-to-adult rate impossible to calculate for migration year 2020.
In 2021, an estimated 294,392 wild steelhead smolts left the Snake River upstream of Lower Granite Dam for the ocean. So far, 7,276 adults have returned. The produces a preliminary smolt-to-adult return rate of 2.47%. That rate will change slightly when wild adults from this year are added.
The longtime regional goal is to have a smolt-to-adult rate from 2% to 6%.
“We are getting fish back at a greater rate but it is still not where it needs to be,” Copeland said. “A 2% SAR keeps you from sliding further. It needs to be north of 2 for a couple of years in a row to build it back up.”
Spring and summer chinook
The 2024 spawn year included 61,251 spring/summer chinook that returned above Lower Granite Dam. That includes 9,803 wild fish, about 16% of the total run.
The run completed the return of fish from Brood Year 2018, which produced an adult-to-adult productivity of 2.61. In 2018, there were just 7,382 spawners but they produced 19,287 adult fish. The department calculated a preliminary adult-to-adult productivity estimate of 1.4 for Brood Year 2019. The number will be finalized in next year’s report when adults from 2025 are added.
Because of the COVID-induced shutdown of the trap at Lower Granite Dam, there is not a smolt-to-adult calculation for migration year 2020. The preliminary estimate for Brood Year 2021, which will be completed next year, shows a smolt-to-adult return rate of 4.82, or 7,715, adults from 160,082 smolts.
Wild spring chinook have replaced themselves for the previous two years after a five-year run in which the replacement level was less than one.
“We have been down so long, anything looks up,” Copeland said. “We have had a number of bad years in a row and the wild fish numbers are down. We would like to build them back up. This shows we are starting to build them back up but we are not at a place we want to declare victory.”
Wild Snake River steelhead and wild Snake River spring/summer chinook are both listed as threatened under the Endangered Species Act and their numbers remain below objectives.
John Cassinelli, anadromous fish program manager for Fish and Game at Boise, said the performance of both runs remains below objectives.
“We are not trying to paint a rosier picture than what is going on,” he said. “These fish are not doing great. We are paying attention and doing a lot of studies to help but it’s not great right now.”