Since the early 1990s, scientists up and down the West coast have known about a mysterious killer lurking in the waters of urban creeks wiping out populations of Coho salmon. THE PROBLEM While it is natural to see dead Coho salmon in urban creeks, they are supposed to die after they spawn. In fact, their deaths may have gone unnoticed without the help of park rangers, organizations and citizen scientists who help track Coho salmon populations. It wasn't until the fish was cut open that people realized these salmon were dying before they spawned, causing a ripple effect in our environment. In a healthy ecosystem, salmon provide food for orcas and spawn in urban creeks. Their decomposing corpses also provide nourishment for soil and forests. It's this critical role that led scientists on a journey of searching for the mystery killer and one that ended in western Washington. THE DISCOVERY In 2014, the University of Washington Tacoma Center for Urban Waters brought in researcher and professor Ed Kolodziej to help lead a team of scientists tasked with solving the mystery. With the help of local communities, Kolodziej’s team was able to collect water samples from urban creeks seeing high pre-spawn mortality rates. “We were seeing lots of tire chemical in water for years and by 2017 our investigations pointed to tire,” Kolodziej said. READ THE FULL STORY: https://www.king5.com/article/tech/science/environment/common-tire-chemical-mass-coho-salmon-deaths/281-4845a985-b47e-4dbd-8498-c467f12ddb68