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Redfish Sockeye Run Numbers Down

by Barry Espenson
Columbia Basin Bulletin - July 27, 2001

The number of endangered sockeye salmon swimming toward central Idaho's Stanley Basin is a trickle compared to the relative gusher of adults that made the trip up the Columbia, Snake and Salmon rivers last year.

But researchers involved in the captive broodstock program -- attempting to revive a population that counted zero returning adults in 1997 and one in 1998 -- remain optimistic. The first returns from the 9-year-old captive brood program were in 1999 -- seven sockeye. Then last summer 257 sockeye made the 900-mile trip from the mouth of the Columbia River to either Sawtooth Hatchery or Redfish Lake Creek, which feeds from Redfish Lake.

The count through Wednesday had 31 sockeye passing the Snake River's Lower Granite Dam, the last hydro impediment on the fishes' journey but still more than 400 river from the Stanley Basin.

"If you add video in, I think we're up to 48," Paul Kline said Tuesday. The Idaho Department of Fish and Game biologist was referring to fish captured on film at night or during the fish counters' regular breaks.

"That's an expected lower number," Kline said of the 2001 run compared to last year when nearly 10 times that number were counted at Lower Granite. Given the program's relative youth, researchers are using variety of approaches, particularly for the release of fish, to try to find methods that best "bring adults back to Idaho."

Release strategies vary with some mix of at least four different methods. In 1999, three of the seven returning fish were released in Redfish Lake and were allowed to try to spawn naturally. Four of the fish were added to the captive brood genetic stock. Last year nearly 200 of the returning fish were released into Redfish, Alturas and Petit lakes.

The program also includes the release of hatchery produced pre-smolts, young fish that then overwinter in the lakes with survivors making their migration the following year. The planting of eyed eggs -- fertilized eggs that have developed to the point they can be transported safely -- is also employed with hopes that they will hatch, grow and migrate.

"It is an experimental program," Kline said. Inconsistencies in the maturation of adults captured for broodstock, egg survival rates and other factors can also limit production.

Seventy percent of last year's adult return came from a smolt release program in which fish are reared to the point that they are ready to begin their downstream migration almost immediately. Some 143,000 smolts left the basin in 1998 and came back in force in 2000. All but 10 of the 257 returning fish were marked, meaning they had either been released as smolts or pre-smolts. The 10 unmarked fish were likely either from eyed eggs or adults that spawned naturally.

"We are starting to see an increase in unmarked fish," Kline said. The products of the eyed egg outplants and from natural spawners seem to be having the best success in terms of smolt-to-adult returns but their numbers remain low in comparison to hatchery-produced smolts and pre-smolts.

"The bottom line is what left the basin in 1998" Kline said of what helped produce the largest adult return since 1977. Only 49,879 smolts left the basin in 1999, the basis for much of this year's return. The 2002 return could be even smaller. Only 13,405 smolts were produced because of a low fertilization rate in the hatchery.

The technical committee that determines each year's strategy is leaning toward a plan that more heavily emphasizes smolt releases, given last year's strong return. But unfortunately, implementing change takes time, Kline says. The smolts produced from last year's adult return would be released next year, and return as adults in 2004.

The 200 adults allowed to spawn naturally last year did well with 30 redds observed at Redfish and 15 at Alturas. Redds are too deep in the water to be detected at Petit.

Only two of the sockeye counted at Lower Granite this year have made that long, last leg to the Stanley Basin, one to Sawtooth Hatchery and one of Redfish Lake Creek. The first was likely from a smolt release at the hatchery; the second from a pre-smolt release in Redfish Lake, Kline said. On average, roughly half of the sockeye that pass Lower Granite survive that final leg. Severe drought conditions that include low river flows and warmer than normal water temperatures may make that journey tougher.

"From my perspective, as a human, I wouldn't want to swim in it," Kline said of deteriorating environmental conditions.

Counts in recent days have dwindled so Kline holds little how that the numbers will swell.

The captive broodstock program is co-managed by the IDFG and Shoshone-Bannock Tribes with research assistance from the National Marine Fisheries Service 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.

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.

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.

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.

Since the inception of the program in 1991, approximately 1,000,000 progeny -- eggs, adults, and juveniles in combination -- had been supplemented to Stanley Basin waters through early 2000.

This year's Columbia Basin sockeye return was, overall, abundant. Through July 19, 114,021 had passed the first dam on the Columbia, Bonneville. That is 1.2 times the previous year's count through that date and 2.5 times the recent 10-year average count.

About 100,000 of those sockeye had been counted at Priest Rapids Dam with most continuing up the Columbia River to the Lake Wenatchee and Lake Osoyoos basins. The upper Columbia sockeye runs are largely naturally produced and are not listed under the Endangered Species Act.

Barry Espenson
Redfish Sockeye Run Numbers Down
Columbia Basin Bulletin, July 27, 2001

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