By ERIC BARKER
Tuesday, July 28, 2015
Warm water in the Snake and Columbia rivers is walloping endangered Snake River sockeye, but Idaho Fish and Game officials are hopeful at least some of the salmon will rest in pockets of cold water and resume their migration when temperatures moderate.
There is some evidence that is happening below Lyons Ferry Hatchery, and the state and Nez Perce Tribe are considering options to trap the fish and truck them to hatcheries or lakes in the Stanley Basin.
According to the National Marine Fisheries Service, the above-average temperatures in the two rivers may eventually kill half of the 500,000 unprotected sockeye bound for the upper Columbia River and most of the listed sockeye headed for the Snake River.
"We think probably 80 to 90 percent of the adult (Snake River) sockeye are going to be lost this year," said Michael Milstein, a spokesman for the federal fisheries agency at Portland, Ore.
Pete Hassemer, salmon and steelhead fisheries manager for the Idaho Department of Fish and Game at Boise, said it was too early to make such a dire prediction.
"It's bad, but it's still early enough in the season, if the temperatures cool and if we stimulate some movement, we can trap them and truck them up to Eagle Fish Hatchery so we can get fish for brood (stock) and release them into the Redfish Lake."
More than 4,000 Snake River sockeye salmon have passed Bonneville Dam on the Columbia River, but only about 350 of those have been counted at Lower Granite Dam on the Snake River. Idaho recently began an emergency effort to intercept sockeye at Lower Granite and truck them to the Eagle Fish Hatchery near Boise. As of Monday, 37 sockeye had been trapped there and loaded on trucks.
That emergency operation could expand to Lyons Ferry Hatchery on the Snake River near Starbuck. The hatchery uses cold spring water to raise steelhead and fall chinook. Hatchery employees have noticed sockeye salmon stacking up in the hatchery's effluent. In a cooperative effort, the trap at Lyons Ferry was opened Monday in hopes sockeye will follow the cold water into the hatchery.
But as of Monday afternoon, no sockeye had entered the trap. If the fish continue to be reluctant to enter the hatchery, seine nets could be used to capture them.
"We told (Idaho officials) we would send down some boats. We have a lot of seine nets we use to sample fall chinook," said Becky Johnson, production manager for Nez Perce Tribal Fisheries Program. "The Nez Perce Tribe would be available to help with a collection effort if there are some adults holding out there in the effluent but not converting into the trap."
Sockeye are Idaho's most endangered salmon species. They teetered on the brink of extinction in the 1990s and the first decade of the 21st century.
But a captive breeding program, where the fish were spawned in a hatchery and some of their offspring were kept there for their entire life cycles and spawned again, eventually boosted the number of sockeye returning from the ocean from the single digits to more than 1,500. Two years ago, Idaho constructed a sockeye hatchery that will eventually produce more than 1 million juvenile fish per year.
While still critically endangered, the species appeared to back away from the brink of extinction this decade and state and federal fisheries officials were hopeful they could continue to build on their success.
This year could be a set back. But even if the adult run turns out to be disastrously low, Mike Peterson, an Idaho sockeye biologist, said the hatchery program would continue at full speed using fish from the still active captive breeding program.
"The fact that we still have the captive brood stock program in place, even though migration conditions are not real good this year in terms of warm water, we are going to be able to make our egg take with the fish we have on hand."
When possible, he said the goal of the sockeye program is to use fish that have migrated to and from the ocean for both hatchery breeding and for wild spawning. However, the hatchery spawning needs can be backfilled with the captive sockeye.
So far, none of the sockeye counted at Lower Granite Dam have arrived at traps in the Stanley Basin of central Idaho. Peterson said he expects that to happen any day. But those fish faced higher-than-average temperatures in the Salmon River.
The heat wave in late June and early July sent river temperatures as high as 78 degrees near White Bird. Temperatures above 72 degrees can be lethal for salmon.
Peterson said he hopes to learn something from the 4,000 or so adult sockeye missing between Bonneville and Lower Granite dams.
"I think mortality is going to be an issue," he said. "What I'm kind of hoping to learn from these fish is whether they will pull into some sort of thermal refuge and, once conditions cool off, whether or not we will see those fish start moving again."
"I kind of think these fish might be holding on and we might see a push later on over Lower Granite Dam. But I don't know if I would expect any of those fish to make it back to the (Stanley) Basin."
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