Researchers Test Feasibility of
Researchers have begun testing whether endangered Snake River sockeye salmon spawners can be trapped at southeast Washington's Lower Granite Dam and safely transported via tanker truck to holding facilities at Eagle Hatchery near Boise.
The process would save the fish a swim of more than 400 miles up the tepid lower Snake and Salmon rivers. The idea is to evaluate a strategy that might be used "in years where escapement is low and migration conditions are questionable...," according to the plan.
NOAA Fisheries 2008 Federal Columbia River Power System biological opinion calls for an investigation of the feasibility for ground transportation of the sockeye spawners "because temperatures in the Salmon river during late July and August are probably contributing to the loss of adult sockeye between Lower Granite Dam and the Stanley Basin...."
"If feasible, transport would provide a short-term solution while habitat problems are identified and addressed" to improve conditions in the 462 miles of river between Lower Granite and Redfish Lake in central Idaho's high country.
The Idaho Department of Fish and Game's Jeff Heindel believes the practice will prove feasible.
"We have a lot of experience doing this," Heindel said of the relatively long-standing practice of trapping sockeye spawners after their arrival in the basin at Lake Creek or at nearby Sawtooth Hatchery and transporting them to the holding facilities at Eagle.
He stressed that, if feasible, the transportation strategy would only be employed in years when water conditions were bad and fish numbers are low.
"We really want to let as many fish as we can swim the journey on their own," Heindel said. "We do not intend to incorporate this as a normal practice."
But when flows are low and the river heats up the "conversion rate" -- survival from Lower Granite to the Stanley Basin -- can really dip. It's been as high as 75 percent and as low as less than 7 percent.
In 1992 when only a single fish made it back to the valley, 15 fish had been counted at Lower Granite, Heindel said. And in 2007 53 sockeye launched themselves from Lower Granite but only four made it home.
A relatively large run size in 2000 -- 299 sockeye counted at Lower Granite -- provided an opportunity for a telemetry project to examine the migration behavior and survival of adult Snake River sockeye, according to the BiOp. Researchers found that survival decreased as the season progressed and after July 13, none of the sockeye radio-tagged at Lower Granite Dam survived to the spawning grounds.
"The shift from relatively high survival of migrants that reached Lower Granite before mid-July to 100 percent loss coincided with the date that the Snake River at Anatone, Washington first reached 21 degrees C, indicating that elevated temperatures played an important role," the BiOp says.
The fish are held at Eagle so that researchers can decide which of the fish might be brought into the Snake River Sockeye Salmon Captive Broodstock Program and which will be released into Redfish Lake to spawn. The program was started in 1991 shortly after the sockeye was listed as endangered under the Endangered Species Act. Its initial aim was to prevent species extinction and slow the loss of critical population genetic diversity.
Between 1999 and 2007, 355 hatchery-produced adult sockeye salmon returned to the Sawtooth Valley. Over the previous 14 years, 77 natural-origin sockeye returned.
The program, and apparent favorable conditions outside the Stanley Basin, have in the most recent years fueled a surge in the Snake River sockeye population. In 2008, a total of 907 sockeye were counted at Lower Granite and 650 made it to the Sawtooth Valley, where they were trapped. Last year 1,219 passed the dam and 833 were trapped at Sawtooth Hatchery and Redfish Lake Creek.
Researchers launched what will be a two-year transport study this year in part because of the anticipated large sockeye return. A total of 938 sockeye had been counted at Lower Granite through Thursday.
At present the Lower Granite fish trap is configured to capture about 4 percent of the passing spawners, which also include chinook, steelhead and shad. The fish are captured for a variety of research purposes. In four days of trapping so far on an every-other-day schedule, 11 sockeye have been captured and transported.
All looked to be in great condition as they were pulled from the trap, administered a short-term anesthetic and slipped into a wet carrying sleeve for transport to a tanker truck on-site. And all survived the seven-hour trip to Eagle Hatchery in good shape, according to NOAA Fisheries biologist Darren Ogden, who manages the trapping operation.
"We want to see if they survive the trip down to Eagle Hatchery," he said. The trapping will continue until the water temperature at the trap rises to 70 degrees, at which point handling the fish is considered unhealthy for them.
Once the fish arrive at Eagle biologists there will collect a variety of data such as: the presence of PIT tags, coded wire tag detection, fork length, weight, release group marks and a genetic sample.
The program is showing some progress toward an ultimate goal -- building a self-sustaining population. This spring more than 14,000 naturally produced smolts emerged from Redfish Lake. The previous record over the course of the program was 7,800 in 2008.
"But it was to be expected because they are from the parents of 2008," said IDFG researcher Mike Peterson. That's the year when at long last the anadromous return was large, relatively. The program released the most fish ever into the lake, including 571 of the 650 that returned from the Pacific. That group included 266 females. In all 937 spawners were released in the lake, including captive-reared fish.
The fish are generally released shortly after Labor Day and they spawn from early October to early November
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