The annual return of A-run steelhead to the Snake River and its tributaries, normally the most reliable of Idaho’s anadromous fish runs, won’t tickle the record books this year.
Just like the spring chinook run that preceded it, the steelhead return is showing signs of not living up to preseason predictions. A regional group of salmon and steelhead managers recently downgraded the run forecast by 27 percent.
Before the run started, the technical advisory group predicted about 291,000 A-run steelhead would pass Bonneville Dam this year. Of those, about 83,500 were expected to be wild fish.
On Aug. 19, the group reduced the estimate to 212,000, with the biggest reduction coming out of the pool of hatchery fish that can be kept by anglers.
“We didn’t do an official breakdown (of wild vs. hatchery fish),” said Alan Byrne, an Idaho Department of Fish and Game biologist at Boise. “Right now it looks like the wild fish are going to be very close to the preseason forecast. The shortfall is due to the hatchery fish not showing up as expected.”
A-run fish return to several river basins above Bonneville Dam, including the Snake River and its tributaries. Byrne said it is typical for about 50 percent of the fish counted at Bonneville to pass Lower Granite Dam on the Snake River. Based on that conversion rate, the total A-run at Granite should be about 106,000. If the wild run holds up to its preseason forecast, about 41,000 steelhead with intact adipose fins will swim past Lower Granite, leaving 65,000 hatchery fish for anglers.
“You would like to see the wild fish come back, but if you are an angler who wants to keep some steelhead, you want some of the clipped hatchery fish to come back too,” Byrne said.
So far, the run is ahead of last year’s pace, with 100-200 steelhead climbing the Lower Granite Dam fish ladder daily last week.
Byrne said warm water in the Snake River continues to delay the run.
“We just have to wait for the water to cool off and we should see some fish moving into the Snake River,” he said.
The A-run group of fish, as measured at Bonneville Dam, should be a little more than 50 percent complete, he said.
The larger B-run fish, which return largely to the Clearwater River, are just starting to show up at Bonneville, the first dam on the Columbia River.
Since the B-run was just starting to ramp up, the technical advisory group wasn’t able to update its forecast.
The preseason forecast called for 31,600 B-run fish to return at least as far as Bonneville Dam. Of those, about 7,900 are predicted to be wild fish.
Typically, 71 percent of B-run fish that pass Bonneville Dam make it at least as far as Lower Granite, Byrne said. Based on that conversion rate, the preseason forecast calls for 22,436 to return past Granite.