Dramatic decline in genetic diversity of Northwest salmon

ScienceDaily | 1/10/2018 | Staff
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Preserving genetic diversity is a central goal of the Endangered Species Act, in part because it helps a species adapt to changing environments. Yet it is rarely measured to this degree. Writing in the journal PLOS One, the researchers say their analysis "provides the first direct measure of reduced genetic diversity for Chinook salmon from the ancient to the contemporary period." In effect, they look beyond the four H's of fisheries management -- habitat, harvest, hatcheries and hydropower -- to consider a fifth H, history.

The researchers found no specific cause for the decline. Possible impacts include heavy native fishing pressures at falls along the Columbia, intensive fishing in the wake of European settlement and the arrival of dams. "The big question is: Is it the dams or was it this huge fishing pressure when Europeans arrived?" said Bobbi Johnson, who did the study as part of her WSU doctorate in biological sciences. "That diversity could have been gone before they put the dams in."

Johnson - Co-authors - Gary - Thorgaard - WSU

Johnson's co-authors are Gary Thorgaard, a WSU emeritus professor of biological sciences, and Brian Kemp, a former WSU molecular anthropologist and ancient DNA expert now at the University of Oklahoma. The researchers also worked closely with the Spokane and Colville tribes, associated agencies and Stan Gough, director of Archaeological and Historical Services at Eastern Washington University.

The researchers started with a trove of 346 vertebrae drawn largely from ancient garbage piles, or middens. Wearing not one but two layers of medical gloves to avoid contaminating samples with their own DNA, the researchers gleaned sequences of mitochondrial DNA from a region shared by 84 of the ancient fish.

Snapshot - Family - Lineage - Johnson

"It's like a little snapshot that tells you who's who, who's in what family or what lineage," said Johnson.

She then compared these with the same identifying regions on 379 contemporary samples. "We...
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