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Thursday, September 22, 2016

23/09/2016: Successful salmon trucking

Could spring Chinook salmon offspring survive the passage over the dam and subsequent ocean migration to eventually return as adults some 3-5 years after technicians transported them by truck?


According to a written article written by Mark Floyd onPhys.org, for the past several years, technicians have been trucking spring Chinook salmon above Foster Dam in Sweet Home to see if they would spawn, and then eventually migrate to the ocean.

A new study examining the genetic origin of adult spring Chinook returning to Foster Dam offers definitive proof that the offspring survived, potentially opening up miles of spawning habitat on the upper South Santiam and other river systems.

Results of the study have been published in the Canadian Journal of Fisheries and Aquatic Sciences.
 
Image: Richard Fraley

"With a little human assistance, it is now clear that we can restore natural production to areas above some dams and there is prime habitat on some river systems, such as the North Santiam above Detroit Dam," said Kathleen O'Malley, an Oregon State University geneticist and principal investigator on the project.

"This could really contribute to the long-term population viability in some river systems."

Some past studies have explored whether salmon that spawned above dams could survive as juveniles going back through the dams, but this new study is one of the first to assess whether those fish successfully would return years later as adults.

Beginning in 2007, technicians from Oregon Department of Fish and Wildlife and the US Army Corps of Engineers took genetic samples of adult salmon trucked above the dam.

During the first two years, most of those adult salmon were reared in hatcheries and released as juveniles, but in 2009 they began using only wild-born fish, hoping to give a boost to that population. Since then, researchers have taken genetic samples from returning adult salmon to see if their parents were among those released above the dam.

The key is the "cohort replacement rate," Ms O'Malley said.

If you release 100 female salmon above the dam, will you get at least 100 females from that population returning as adults to the dam for a rate of 1.0? The researchers have to sample for several years to determine the success rate of one cohort, since spring Chinook can return as 3-, 4- or 5-year olds.


Read more HERE.

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