Warm water killing half of Columbia River sockeye salmon

584
Thousands of tiny winter steelhead are released from an Oregon Fish and Wildlife truck for the start of their journey that starts in Carberry Creek above the Applegate Dam in southern Oregon. The Northwest has been going through a record-setting hot spell that's stressing out not just humans but also causing worry about fish in rivers with temperatures that are higher than normal for this time of year. Hatcheries are releasing fish as much as a month earlier for their trip to the ocean to try to protect them from diseases that can occur in warm water. (Bob Pennell/The Mail Tribune via AP, File)
Thousands of tiny winter steelhead are released from an Oregon Fish and Wildlife truck for the start of their journey that starts in Carberry Creek above the Applegate Dam in southern Oregon. The Northwest has been going through a record-setting hot spell that’s stressing out not just humans but also causing worry about fish in rivers with temperatures that are higher than normal for this time of year. Hatcheries are releasing fish as much as a month earlier for their trip to the ocean to try to protect them from diseases that can occur in warm water. (Bob Pennell/The Mail Tribune via AP, File)

More than a quarter million sockeye salmon returning from the ocean to spawn are either dead or dying in the Columbia River and its tributaries due to warming water temperatures.

Federal and state fisheries biologists say the warm water is lethal for the cold-water species and is wiping out at least half of this year’s return of 500,000 fish.

“We had a really big migration of sockeye,” said Ritchie Graves of the National Oceanic and Atmospheric Administration. “The thing that really hurts is we’re going to lose a majority of those fish.”

He said up to 80 percent of the population could ultimately perish.

Elsewhere in the region, state fisheries biologists in Oregon say more than 100 spring chinook died earlier this month in the Middle Fork of the John Day River when water temperatures hit the mid-70s. Oregon and Washington state have both enacted sport fishing closures due to warm water, and sturgeon fishing in the Columbia River upstream of Bonneville Dam has been halted after some of the large, bottom dwelling fish started turning up dead.

Efforts by management teams to cool flows below 70 degrees by releasing cold water from selected reservoirs are continuing in an attempt to prevent similar fish kills among chinook salmon and steelhead, which migrate later in the summer from the Pacific Ocean.

The fish become stressed at temperatures above 68 degrees and stop migrating at 74 degrees. Much of the basin is at or over 70 degrees due to a combination that experts attribute to drought and record heat in June.

“The tributaries are running hot,” Graves said. “A lot of those are in the 76-degree range.”

In Idaho, an emergency declaration earlier this month allowed state fisheries managers to capture endangered Snake River sockeye destined for central Idaho and take them to a hatchery to recover in cooler water. Of the 4,000 fish that passed Bonneville Dam on the Columbia River, less than a fourth made it to Ice Harbor Dam on the Snake River. An average year is 70 percent.

Commercial fisherman Les Clark pulls a sockeye or blueback salmon from his net while fishing on the Columbia River near Skamania, Wash. More than a quarter million sockeye salmon returning from the ocean to spawn are either dead or dying in the Columbia River and its tributaries due to warming water temperatures. Federal and state fisheries biologists say the warm water is lethal for the cold-water species and is wiping out at least half of the 2015 return of 500,000 fish. (Gordon King/Yakima Herald-Republic via AP)
Commercial fisherman Les Clark pulls a sockeye or blueback salmon from his net while fishing on the Columbia River near Skamania, Wash. More than a quarter million sockeye salmon returning from the ocean to spawn are either dead or dying in the Columbia River and its tributaries due to warming water temperatures.(Gordon King/Yakima Herald-Republic via AP)

“Right now it’s grim for adult sockeye,” said Russ Kiefer of the Idaho Department of Fish and Game. He said sockeye will often pull into tributary rivers in search of cooler water, but aren’t finding much relief.

“They’re running out of energy reserves, and we’re getting a lot of reports of fish dead and dying,” he said.

Thirteen species of salmon and steelhead are listed as endangered or threatened in the Columbia River basin.

Don Campton of the U.S. Fish and Wildlife Service said fish congregating in confined areas trying to find cool water makes them a target for pathogens.

“When temperatures get warm, it does stress the fish out and they become susceptible to disease,” he said.

Graves said that this year’s flow in the Columbia River is among the lowest in the last 60 years. But he said the system has experienced similar low flows without the lethal water temperatures. He said the difference this year has been prolonged hot temperatures, sometimes more than 100 degrees, in the interior part of the basin.

“The flow is abnormally low, but on top of that we’ve had super hot temperatures for a really long time,” he said.

Print Friendly, PDF & Email