OSOYOOS TIMES-December 2, 2009

By Paul Everest – Osoyoos Times

So far, roughly 70,000 adult sockeye salmon have returned to the South Okanagan this fall.
Howie Wright, the Okanagan Nation Alliance’s fisheries program manager, said between 50,000 to 80,000 salmon were expected to return to spawning grounds near the McIntyre Dam north of Oliver in the past two-and-a-half months.
Although final numbers won’t be known until later this month, Wright said the salmon survival rate for the lower Okanagan River and Osoyoos Lake is “not too bad.”
“(It’s) one of the top three (years) in terms of returns on record,” Wright said.
Last year’s return of 130,000 adult salmon was the highest since officials began keeping records in 1967.
Alliance members carried out “numeration counts” of salmon from the third week of September to the last week of November on a stretch of river from the McIntyre Dam to the 79th Avenue bridge in Oliver, Wright said.
Once the final number of returned salmon is known, he added, the alliance, in partnership with the federal Department of Fisheries and Oceans (DFO), will release a  report on salmon abundance in the area.
Along with counting the salmon, alliance members took a sampling of the returning population to check for disease or other biological problems.
Wright said a sub-sample of the returning population is checked for IHN, or Infectious Hematopoietic Necrosis, a virus which can cause high mortality rates for young salmon.
Test results for the virus won’t be completed until January, Wright said, but so far this year’s return looks healthy.
Wright said there were concerns this summer that high temperatures and the large number of salmon in Osoyoos Lake due to last year’s high return may have been a problem for the health of the local population.
Ideal conditions for salmon in a body of water are when there are four micrograms of oxygen per litre of water and the water temperature is roughly 17 C.
At the end of August, Osoyoos Lake experiences what is called a temperature-oxygen squeeze when water close to the surface gets hotter and deeper water has less oxygen.
Researchers were worried this squeeze would leave the large numbers of fish with a corridor fewer than two metres in height to swim through.
Wright said monitors were constantly checking the lake to see if the squeeze was happening and the alliance, the provincial Water Management Branch and DFO had an agreement in place where fresh water could be released down the river to improve oxygen and temperature conditions for the salmon.
“As it turns out, we didn’t have to,” he said, adding the squeeze never turned out to be a problem.
Salmon spawn in October and the offspring remain in gravel near the dam until spring when they emerge as fry.
The fry stay in Osoyoos Lake for a year, Wright said, and the following spring they head down the Columbia River to the Pacific Ocean as smolts where they will stay for one to two years before returning to the South Okanagan.
Thanks to last year’s high numbers of returning adult salmon, there was an estimated nine million fry in the lake this spring, Wright said.
That means, he added, there will likely be about six million smolts leaving the lake in the spring of 2010.
“Which is more than we’ve ever seen.”
These high numbers of salmon returning to the area suggest the Okanagan basin isn’t having the same kinds of problems as the Fraser River, where fewer than two million salmon returned from the ocean earlier this year.
Scientists had been expecting more than 10 million salmon to return to that river this summer.
A federal judicial inquiry will focus on what happened to those missing salmon.
Wright said the reason local salmon populations haven’t experienced such losses could be due to where the salmon that leave the Okanagan basin go when they reach the ocean.
“In terms of ocean survival, Columbia sockeye follow a lot more of the pattern of the stock on the west coast of Vancouver Island,” he said. “Sockeye, when they go out in the ocean, they don’t all go to the same spot.”
It could be, he added, that the Fraser River salmon encountered some kind of problem in the area of ocean they went to after leaving the river, whereas the Okanagan salmon went to another area and did not encounter the same difficulties.
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