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On a clear and cold November night, a team of Port of Tacoma employees volunteered to place cages of mussels in Commencement Bay precisely at zero tide, which arrived around 10. 

The mussels were deployed to check for contaminants.

But at two of the three Port sites, volunteers ran into challenges. 

At the mouth of the Milwaukee Waterway, Port biologist Kristin Evered’s group slogged through knee-deep mud.  

At least it wasn’t raining. 

“People were still smiling after,” Evered said. “I don’t know how happy we would have been wet and cold because it was a really cold night.” 

On the Blair Waterway, the team deploying mussels had to improvise to secure a cage over a slope of riprap, where pounding the supplied rebar stakes vertically into the solid surface wasn’t possible.  

Instead, they figured out a way to install the rebar horizontally and weigh the cage down with rocks.  

“It was really impressive that they were able to problem-solve like that at 10 p.m. on a dark slope covered in riprap,” Evered said. 

The deployment was part of an effort led by the Washington Department of Fish and Wildlife (WDFW) to use transplanted mussels to monitor the nearshore environment for various contaminants. 

Scientists will check for industrial compounds once used as coolants and lubricants in electrical devices and various building materials (PCBs), fossil fuel byproducts (PAHs), metals, pharmaceuticals, and chemicals used to make non-stick cookware and flame retardants. 

According to WDFW, the same week as the Port deployment, 108 cages were placed at sites around Puget Sound and along the outer coast — a total of 9,000 mussels. 

The mussels were obtained from an aquaculture source on Whidbey Island and were considered relatively uncontaminated for use at monitoring sites.   

They will be retrieved in February, so scientists can check their tissue for signs of contamination. 

“We’re using them basically as filter-feeder tools that we can deploy,” said Mariko Langness, senior biologist at WDFW’s Toxics Biological Observation System in the Salish Sea. 

Mussels filter the water for tiny organisms to eat but in the process also filter contaminants which build up in their tissue over time. 

The state’s mussel program began in 2012 with deployments completed every other year.  

Because it’s a long-term effort, Langness said it’s too early to report on contaminant trends identified by mussel monitoring, but she said Commencement Bay is not meeting recovery targets established for two main reporting contaminants (PCBs and PAHs), nor are most areas being monitored in Puget Sound.  

Only the eastern Strait of Juan de Fuca, the San Juan Islands, and Hood Canal are currently meeting the targets established for PCBs. 

For several years, the Port of Tacoma has been a local site sponsor for the mussel program, which is seeing growing interest. 

WDFW is getting inquiries from more organizations, including homeowners’ associations, wanting to deploy additional mussel cages and help scientists track contaminants across the Salish Sea. 


Video above produced by Washington Department of Fish and Wildlife.