Sockeye Surge Toward Hatchery, Idaho Mountain Lakesby Barry Espenson
Columbia Basin Bulletin - August 23, 2002
Researchers are taking stock as the latest batch of Snake River sockeye salmon begins to trickle back into Idaho's Stanley Basin where a captive broodstock program aims to perpetuate a still-flickering genetic line.
As of early this week, 52 sockeye had been counted passing Lower Granite Dam with few, if any, more expected this year. So far 11 of the adult sockeye had made it from Lower Granite -- the eighth and final hydro project the fish pass during their 900-mile swim up the Columbia, Snake and then Salmon rivers from the Pacific -- to the state's Sawtooth hatchery.
Redfish Lake sockeye salmon were listed as endangered in November of 1991 -- the first Idaho fish to be listed. Redfish Lake sockeye are unique in that they travel to the highest elevation, run the longest distance, and travel the farthest south of any North American sockeye population, according to information provided by the state of Idaho.
Of the 11 that completed their trip, six have been captured --three at a hatchery trap and three in Redfish Lake Creek. Five of the bright red fish could be seen early this week biding their time nearby in the Salmon River.
"They're easy to see but they haven't descended the fish ladder down into the fish trap," said Paul Kline, program manager for the Idaho Department of Fish and Game. Two of the six captured fish are unmarked (have no fin clips).
"We could still potentially see a non-program fish," Kline said of the unmarked fish. Those fish without fin clips could be the product of hatchery reared adult fish that were released into the wild to spawn or from fertilized eggs that were outplanted in Redfish or other nearby lakes. Or they could be the progeny of native sockeye that had residualized -- spent their entire life cycle in the lake instead of spawning to the ocean and back.
A tissue analysis will determine if the fish have the genetic types that can bolster the program's broodstock. Decisions about which returning fish to bring back into the hatchery and which to release will be made by a multi-agency management group after the genetic analysis, and after the run has ended. An additional 120 hatchery produced adults will also be released in the coming weeks with the hope they will spawn in the wild.
"We have another two weeks of high hopes," Kline said of the wait for returning fish. On average, about half of the sockeye that pass Lower Granite survive that final 400-mile swim to the hatchery.
Researchers feel the captive broodstock program has done well in its goal to preserve the genetic diversity of a sockeye a population that has severely dwindled. No returning adults were counted in 1997 and only one returned to the central Idaho basin in 1998. A total of only 16 adults made the spawning trek during the period from 1990 through 1998.
The program was initiated in 1991 when outgoing juveniles were trapped and brought into the hatchery to be raised and used as broodstock. The first returns from the captive brood program were in 1999 -- seven sockeye. Then in 2000, 257 sockeye made the trip from the mouth of the Columbia River to either Sawtooth Hatchery or Redfish Lake Creek, which feeds from Redfish Lake. More than 400 sockeye were counted at Lower Granite that year, the most since 1977.
Fish and wildlife officials were able to capture 243 of the adults. Of those 43 were held as broodstock and 200 were released into Redfish, Pettit and Alturas lakes to spawn.
That huge 2000 return was the result of numerous forces, according to Kline. A total of 67,000 smolts -- fish more than a year old that are ready immediately to begin their journey to the Pacific Ocean -- were released in 1998. They made up much of 2000's banner return. Those smolts, among about 143,000 total outmigrants that year, encountered favorable river conditions on their outmigration and the Pacific had begun a cycle of favorable conditions for the growing salmon.
Only 49,879 smolts left the basin in 1999, the basis for much of the 2001 return. Researchers captured 23 returning sockeye last year of which 18 were released to spawn naturally. Only 13,405 smolts were produced in 2000 because of a low fertilization rate in the hatchery.
The Redfish smolt release program -- one of four strategies being tested in the program --suffered a setback in early June when the Oregon Department of Fish and Wildlife was forced to euthanize more than 43,000 sockeye salmon smolts that had been reared at Bonneville Hatchery for the IDFG. The fish had become infected with an incurable virus -- infectious hematopoietic necrosis.
The National Marine Fisheries Service directed ODFW to take the action after IDFG requested the fish be euthanized to prevent other fish from contracting the non-treatable disease. ODFW operates the sockeye rearing program as an agent for NMFS.
The cooperative captive brood program is in place to enhance the wild populations using conservation hatcheries in Idaho, Oregon and Washington. Although the loss of the sockeye smolts will likely reduce the number of adults returning from the ocean in 2004, the Bonneville-reared fish comprised only one component of the sockeye restoration program.
Out-migrating smolts this year included 38,000 fish reared at Idaho's Sawtooth hatchery and released, and about 40,000 from Redfish and other central Idaho lakes. The lake production comes from fish released as pre-smolts last year that "over-wintered" in the basin, as well as from the fertilized eggs planted in the lakes, and from natural spawning by the outplanted and "residualized" adult sockeye.
"The smolts are the most tantalizing and they give you the most numbers back," NMFS' Tom Flagg said of that particular strategy. The smolts are released in prime shape and tend to begin their migration within days. The pre-smolts spend all fall and winter in what was their ancestors natural environment, but as few as 30 to 40 percent survive to become smolts. Only about 5 percent of the outplanted eggs actually yield smolts.
"The crux of the program is more about maintaining genetic diversity, rather than just pure numbers," Flagg said.
"We've retain the majority of what's important there," he said of the stocks' genetic diversity.
Of concern is the overall fitness of hatchery-raised smolts-- the possibility of "hatchery effects" or influences that might lessen their ability to survive in the wild and reproduce. NMFS is hesitant to become too reliant on the smolt portion of the program. But the loss of the smolts at Bonneville was vexing.
"It was a setback for our evaluation of how to proceed," Flagg said of the search for the best mix of production strategies.
The immediate goals of the program are to prevent the species from going extinct, to hopefully increase the number of naturally spawning fish and to maintain the genetic variability that would eventually allow the sockeye to sustain populations over time, Kline said.
"We can't afford to take a hands-off approach," Kline said of the captive brood production and research effort.
The captive broodstock program is co-managed by the IDFG and Shoshone-Bannock Tribes with research assistance from the NMFS and University of Idaho. The research is funded in large part by the Bonneville Power Administration through the Northwest Power Planning Council's fish and wildlife program at a total cost of about $1.75 million per year.
The program has four primary elements: 1) the captive broodstock program, 2) habitat evaluations, 3) genetics monitoring, and 4) monitoring and evaluation of fish supplemented back to the system. IDFG is involved with captive broodstock efforts and monitoring and evaluation efforts. NMFS shares captive broodstock responsibilities. The Shoshone-Bannock Tribes conduct habitat and lake fertilization work, while the University of Idaho assists with genetic evaluations.
"It's an absolutely intense effort," Flagg said.
The captive broodstock element that IDFG is responsible for has two primary objectives: 1) to produce genetically prudent broodstocks for future spawning purposes and 2) to produce eggs, and fish for supplementation back to the Stanley Basin.
Testing for pathogens and disease at the Bonneville facility occurs regularly in the captive brood rearing cycle from egg to release as smolts. About 70,000 disease-free eggs were transferred to Bonneville Hatchery for rearing in January 2001 from NMFS's Manchester Research Station in Washington's Puget Sound area and from IDFG's Eagle Hatchery near Boise. Testing at Bonneville detected IHN infection in late April, 2002 just before the smolts were scheduled for transport to Idaho for release. Daily losses since early May reduced the number euthanized Tuesday to about 43,000 smolts.
According to Oregon fish pathologists familiar with IHN, it is likely that 80 to 90 percent of the remaining fish would have died within the next six weeks. IHN initially attacks the blood-forming tissues of the kidney. External symptoms include lethargy, darkening of the skin and hemorrhaging at the base of the fins. The most likely source of the disease was from adult steelhead carrying IHN that entered Tanner Creek from the Columbia River and swam above the hatchery water intake. Tanner Creek supplies water to the hatchery rearing ponds. Testing found that no other juvenile salmon or steelhead species currently being reared at the Bonneville facility have contracted the virus.
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