The Puyallup Tribe is conducting a genetic study to determine how many distinct populations of chum salmon there are in the Puyallup watershed system.

At the Diru Creek Hatchery genetic samples are collected to compare hatchery-raised chum with their wild cousins spawning elsewhere in the watershed.

“This has pretty big implications in terms of how we deal with Puyallup River chum,” said Blake Smith, enhancement manager for the Puyallup Tribe. “Are populations from these tributary streams independent of each other, or do they interbreed? That’s a question we need to answer if we want to protect and enhance Puyallup chum.”

Much of the Puyallup chum’s historic habitat has been degraded in the past century and is still disappearing. Chum spawn in the lower reaches of river systems, sticking to low gradient areas with shallow water.

“Many of the streams that we would consider ‘chum streams’ don’t exist anymore or have been severely altered,” Smith said. “Industrial and urban development in the lower watershed has put limits on where chum can go to spawn. By learning more about the populations that use what is remaining of the Puyallup River’s habitat, we can be smarter about protecting it.”

Even though Puget Sound chum stocks this year are expected to come back in numbers not seen since records were first kept in 1913, Smith believes the Puyallup River once supported a much larger chum population that it does now.

“On the White River [a tributary to the Puyallup], historic catches used to be in the thousands,” he said. “Now, we only see escapements in the hundreds.”

The Hatchery Scientific Review Group, an independent science panel, is reviewing hatchery practices in the Puyallup watershed to determine how hatcheries can help recover and conserve wild salmon populations and support sustainable fisheries.