By Lynda V. Mapes

The Seattle Times

Salmon and steelhead are in hot water — a problem scientists warn is going to get worse because of climate change.

Steelhead returning this year to the Columbia and Snake rivers migrated out of the river during horrendous conditions in 2015, which included record low flows and high water temperatures.

Those steelhead also were at sea during the so-called “blob” — a mass of warm water that began forming off the West Coast in 2013 and wreaked havoc in the ocean, including depressed food supplies for marine animals of all sorts.

Now those steelhead are migrating back through reservoirs where water temperatures at some Columbia and Lower Snake River dams, thanks to a record Northwest heat wave, have been stuck this summer above 70 degrees for days on end — potentially lethal for salmon and steelhead.

“They are just getting creamed everywhere they turn; conditions in the Columbia and Snake are the worst I have ever seen them,” said Steve Petit, a steelhead biologist with Idaho Fish and Game for 32 years before retiring, he hoped, to fish the Clearwater River that runs past his home.

But not this year. The state of Idaho closed all rivers for sport harvest of steelhead this week because there are so few fish. Only about 400 steelhead had crossed Lower Granite Dam on the Snake River when the agency announced a fall steelhead season closure, a precipitous drop from the 10-year average of more than 6,000 steelhead over the dam near Lewiston, Idaho.

Steelheaders all over the region are reeling — just not the good kind of reeling.

“Until this year, I had a narcoticlike steelhead fishing habit,” Petit said. But this year he’s fishing in the Kamchatka region of Russia for a last hurrah. “Then I’m probably going to just put all of my gear on eBay and sell it. I just don’t see any future for our fish. And I am not alone. All my friends that are in our 70s have just given it up, they don’t fish anymore. It’s too painful.”

It’s an echo of the sockeye slaughter on the Columbia in 2015, when fish died in the superheated lower river before ever making it back to their home tributaries to spawn.

Hopes were high for a better year in 2017, with fat snowpack everywhere, and high runoff to start the season. But roasting heat dashed the optimism as reservoir temperatures rose with day after day of the Northwest heat wave that set records all over the region.

Salmon are tough beasts that since the Pleistocene have radiated over a wide geography, with brilliant adaptive capacity and an adventuresome proclivity to stray to colonize new habitats. But the Northwest salmon and steelhead nonetheless have genetics tuned for cold water, noted Jack Stanford, an emeritus professor of ecology with the University of Montana, affiliated with the Flathead Lake Biological Station.

In water warmer than 70 degrees, Stanford said, Pacific salmon and steelhead tend to slow down, or stop migrating altogether. Their susceptibility to disease goes way up.

And Michele DeHart of the Fish Passage Center in Portland noted that while warm water is a chronic problem, not a new one, on both the Columbia and Snake rivers, climate change is exacerbating it.

“What we see is since 2012 we have had a gradual increase in temperature,” DeHart said of the two rivers. But what is different now is how much earlier in the summer the heat sets in — and how long it lasts, she said.

“Before the dams, the river would get hotter for a few days. This is different, 30, 40 days, and that is where it really takes a toll. It has always been a problem but climate change is making it worse.”

Climate change affects the future of salmon in the Northwest in several ways. More precipitation is predicted in the Northwest, in the form of rain, rather than snow, reducing snowpack. And melt-out is predicted to come earlier, extending periods of lower flows.

A 2016 scientific literature review of climate change and its effects on Pacific Northwest salmon notes extreme heat events, among other problematic conditions for salmon, are more likely in the future. An Environmental Protection Agency review of effects of climate change on the Northwest — posted on the agency’s website until the DTrump administration removed it — found that by the year 2100, one-third of current habitat for Northwest salmon and other cold-water fish will be too warm for salmon to tolerate.

A federal judge in a court order last year demanded that managers of the federal hydropower system start fresh on crafting a plan for running the system that won’t jeopardize salmon and steelhead.