The Columbia River adult fall chinook return is decent this year for the most part, based on passage numbers at Bonneville Dam, but warm water temperatures are making it hard on the fish moving toward the lower Snake River and Upper Columbia.
Last week Columbia River harvest managers (the two-state Columbia River Compact) approved four more days of salmon fishing (Thursday to Sunday) from Buoy 10 at the mouth to Pasco, Wa. Though the run forecast was downgraded a bit, Washington and Oregon allowed more fishing since further harvest during this period would not exceed limits under the Endangered Species Act aimed at protecting natural spawning, ESA-listed salmon and steelhead.
The Compact’s Technical Advisory Committee Wednesday provided the first in-season update to the 2025 upriver bright and tule stock fall Chinook Bonneville Dam passage expectation. “Based on passage to date, assumptions of passage timing at Bonneville Dam, and harvest below Bonneville Dam, TAC expects the Columbia River mouth return of adult-aged fall Chinook to total 637,870 adult fish (13% lower than preseason forecast).”
Through September 16 a total of 341,725 adult and 60,022 jack fall chinook have passed Bonneville Dam. The adult count is the 5th highest count to date in the last 10-years, according to the Compact’s fact sheet. https://wdfw.wa.gov/fishing/management/columbia-river/compact/notices
Upriver, in contrast, through September 16, a total of 33,466 adult and 4,308 jack fall chinook have passed McNary Dam. The adult count is the lowest count to date in the last 10 years. At Lower Granite Dam a total of 11,106 adult and 1,507 jack fall chinook have been counted through September 16. The adult count is the fourth lowest count to date in the last 10 years.
In a Sept. 12 blog post for Idaho Fish and Game, fisheries manager Joe Dupont noted, “Fall Chinook Salmon passage over Bonneville Dam is nearing completion (about 90% complete), and as such, we have a good understanding of how many fish bound for the Snake River basin will return from the ocean this year. It looks like this year’s return past Bonneville Dam will be about 36,000 adult fish which is lower than the preseason forecast (about 47,000 fish). Regardless, this size of return is large enough to provide some exciting fishing opportunities.
“A troubling issue we are seeing this year is the fall Chinook Salmon are taking longer to migrate to Lower Granite Dam than has occurred in the past. This is troubling because the slower these fish migrate the fewer that tend to make it to Idaho. Most suspect this slow migration is due to the warm water temperatures occurring in the Columbia and Snake rivers. At this point, we don’t know how many fall Chinook Salmon will make it to Idaho, but in years when we saw slower travel times, survival rates during their migration from Bonneville Dam to Lower Granite Dam approached 50%.
“This year the migration rates are the slowest we have seen since we started PIT tagging these fish. As such, we fear their survival rate could even be less than 50%. If we assume the survival rate this year will be 48%, about 24,000 adult fall Chinook Salmon would make it to Lower Granite. If this survival rate is accurate, it would come in considerably below the 10-year average (34,000 adult fish). Additionally, the adult wild return to Lower Granite Dam would be around 4,700 fish which is the lowest we have seen since 2009.”
Dupont explained that the “the number of adult wild fall Chinook Salmon that can be killed during our sport fisheries (through harvest and catch-and-release fishing) is determine by the number of fish that pass over Lower Granite Dam. A sliding scale was developed in coordination with NOAA fisheries that limits harvest of wild fish on down run years and provides more harvest when the wild run is better.
“One of the important points on this sliding scale is 5,040 adult wild fish. When more than 5,040 adult wild fish pass over Lower Granite Dam, the sport fisheries can kill over 10% of the run. When the adult wild return is less than 5,040 fish, the sport fisheries can only kill 6% of them. In the past, when the adult wild returns over Lower Granite Dam were greater than 5,040 fish, the sport fishery did not reach its allowable wild fish impacts and no changes to the fishing seasons were required. When the return was below 5,040 fish, it was necessary to shut down harvest of adult fish with an adipose fin to protect the wild fish. If survival rates come in similar to what we are projecting, the number of wild fish that pass over Lower Granite Dam will be less than 5,040 fish, and it is highly likely that changes to the fishing regulations will occur that would prevent the harvest of adult fish with an adipose fin.”
At the end of last week, IDFG announced it was closing harvest of unclipped adult fall Chinook salmon statewide beginning Friday, Sept. 19 through Friday, Sept. 26. During this period, fisheries for adipose-clipped fall chinook will remain open, but all unclipped adult fall Chinook salmon must be released.
“Warm water in the Columbia and Snake rivers has led to longer travel times and fewer fish making it to Idaho than expected under normal conditions. Closing harvest on unclipped adult fall Chinook reduces overall mortality of wild chinook; ensures the fishery stays within the agreed upon harvest shares; and helps ensure sufficient chinook available for spawning. This closure will also reduce the need to shut down the entire fishery for the rest of the year,” said IDFG in a press release.
“Fisheries managers will review harvest through the rest of this week and continue to track fish passage through the Columbia and Snake rivers. If there are enough wild fish impacts left after next week, we may be able to reopen harvest of unclipped adult fall Chinook.”
Some Columbia River fall chinook passage numbers:
At Bonneville Dam as of Sept. 17, 351,076 fish. Last year on same day, 413,856. 10-year average on same date, 342,817.
At McNary Dam as of Sept. 17, 37,938. Last year on same day, 100,616. 10-Year average, 99,414.
At Lower Granite Dam as of Sept. 17, 11,664 fish. Last year on same day, 24,910. 10-year average, 18,446.
At the Upper Columbia’s Priest Rapids Dam as of Sept. 17, 4,100. Last year on same day, 12,078. 10-year average, 14,597