Nearly a quarter of a million steelhead have crossed Lower Granite Dam this year, making it one of the biggest runs on record.
But the vast majority of those are A-run fish. The 2009 B-run won't break any records. According to the latest predictions of fisheries managers, about 43,000 B-run steelhead will make it at least as far as Bonneville Dam on the Columbia River. That compares to more than 93,000 last year and 51,000 in 2007.
If historical averages hold true, about 34,000 of this year's returning B-run steelhead will make it back to the Clearwater and Salmon rivers in Idaho. That means the larger-sized B-run steelhead will comprise about 14 percent of the run. That pales in comparison to the record pace the A-run is setting, but it isn't awful either.
"It's not a dismal number by any stretch," said Sam Sharr, a fisheries biologist with the Idaho Department of Fish and Game at Boise. "It's probably going to come in better than the 2003 and 2004 runs did."
In 2003, 38,500 B-run steelhead made it at least as far as Bonneville Dam. In 2004, the number was 37,400. Sharr said in most years about 80 percent of the Bs counted at Bonneville make it all the way to Idaho.
A-run steelhead typically spend just one year in the ocean, are 23 to 26 inches long and weigh 5 to 7 pounds. B-run steelhead generally spend two years in the ocean, are at least 31 to 32 inches long and can weigh between 10 and 20 pounds. Most B-run steelhead return to the Clearwater River and its tributaries, but some hatchery-bred Bs return to the Salmon River.
Fisheries biologists don't know exactly why the A-run is doing so well this year and the B-run is average at best.
Joe Hymer of the Washington Department of Fish and Wildlife in Vancouver said the A-run fish probably experienced both good ocean conditions and good river flows when they migrated to sea last year.
"When they went out, the conditions were better than the previous year when the Bs went out," he said.
Sharr said salmon and steelhead returning this year after just one year in the ocean are all doing well.
Steelhead are the best example, but the spring, summer and fall chinook runs saw huge numbers of jacks return this year.
Most chinook spend two years in the ocean. Chinook that return a year early are known as jacks.
"As one-ocean fish, they obviously encountered some really good conditions in the ocean," he said. "The B-run is composed of a high percentage of two-ocean fish. We are probably just seeing returns off those fish that are not quite as good."