Idaho’s imperiled Snake River sockeye run has nearly matched last year’s return but hasn’t paralleled the surprising performance of sockeye that return to the upper Columbia River Basin.
Fisheries managers from the Idaho Department of Fish and Game expected the Snake River run to be similar in strength to the 2017 return. So far that prediction is right on pace, though it’s still unknown how many sockeye will reach the state’s Stanley Basin.
Through July 24, 223 endangered Snake River sockeye had been counted at Lower Granite Dam on the Snake River, but none had been trapped in the Sawtooth basin where they spawn in big mountain lakes.
A year ago, 228 sockeye were counted at the dam, and by the end of the season 162 of those completed the journey to spawning grounds. The first 2017 sockeye hit the Stanley Basin on July 27.
So far this year, sockeye have experienced relatively good water temperatures.
Paul Kline, assistant fisheries chief for the Idaho Department of Fish and Game at Boise, said water temperatures have been lower than those recorded last year and well below the downright hot temperatures of 2015 that all but wiped out the run.
In the upper Columbia River Basin, sockeye are far exceeding preseason forecasts. Fisheries managers expected about 100,000 sockeye from that run, which is not protected, to return to the upper Columbia.
But by Monday, about 182,000 sockeye had been counted at Priest Rapids Dam on the Columbia River, and fisheries managers expect it could grow to 209,000. The better-than-expected return prompted fisheries officials in Washington and Oregon to open a sockeye fishing season on parts of the Columbia.
Of course no one expected the Snake River run to come remotely close to matching the unlisted upper Columbia run’s numbers. The Snake River fish have been on the brink of extinction for decades. But Idaho officials had expected the new sockeye hatchery at Springfield to be producing modest gains by now. The hatchery came online in 2013 and will eventually produce about 1 million smolts per year. Last year, fisheries managers determined that juvenile sockeye were having trouble adjusting to the relatively hard water at the hatchery and the extremely soft water in Redfish Lake Creek, where they are released to begin their migration to the Pacific Ocean. Survival of the juvenile fish between the release site and the ocean was poor during the hatcheries first few years of operation.
Now, hatchery officials are slowly acclimating the juvenile fish to the softer water of Redfish Lake Creek prior to their release. Paul Kline, assistant fisheries chief for the Idaho Department of Fish and Game at Boise said survival of out-migrating sockeye smolts hit an all-time high this year.
“We had over 70 percent survival from the basin to Lower Granite Dam,” Kline said.
Survival all the way to Bonneville Dam was about 50 percent.
That survival won’t pay dividends until the fish return in 2020. Kline said the hatchery released 700,000 smolts this year. A conservative estimate would dictate a 2020 return of about 1,750 adult sockeye. Kline thinks the 2020 return could be as high as 3,500 adults, and that could grown to 5,000 by the time the hatchery hits its goal of producing 1 million smolts per year.
“In two years, things are going to be exciting if the ocean stays reasonable,” he said. “We predicted on average at least 5,000 hatchery fish would come back to the basin. We are just so anxious to get into the groove to test if our forecasts of we should see back are accurate.”
The sockeye run bottomed out in the late 1980s and early 1990s when adult returns were in the single digits. In some years, no adults returned to spawning grounds. That prompted the listing of the fish under the Endangered Species Act and the start of a captive breeding program that holds some sockeye in hatcheries for their entire life .
Kline said the first adult sockeye of the year is expected to return to the Stanley basin any day.
“We are kind of on pins and needles,” he said. “We are remaining optimistic that we will have good conversion (survival between Lower Granite Dam and spawning grounds) because of the water temperatures.”