EarthFix: Scientists On the Trail of a Potential Salmon Killer

KUOW’s EarthFix features Bruce Stewart, NWIFC’s fish health program manager, in a feature on the risks and safeguards against a potential outbreak of a new virus among Pacific Salmon:

The key to confirming the ISA findings is getting a live sample of the virus in the lab, so scientists can study its intact genome.

That’s part of why Bruce Stewart is here at the Muckleshoot tribal hatchery.

The creek behind the hatchery churns with coho salmon, just returning from two years in the open ocean. While at sea, these hatchery fish have been exposed to the same viruses as wild salmon so they’re a good representation of what might be out there.
Hatchery workers net the salmon from the creek, their dappled red bodies flopping around madly.

A quick thwack on the head with a wooden baton and the salmon lies still. Then hatchery workers cut the eggs out of it’s belly.

Semen from the males is mixed with the eggs taken from the females and then set aside to incubate.

During this process 60 of these fish are set aside for Bruce Stewart. He’s hunched over a long table sticking a syringe into the abdomen of the female cohos and sucking out a clear liquid.

“So what I’m doing is taking ovarian fluid from each of these females,” he explains. “We know that ovarian fluid is a highly sensitive fluid for viruses.”