6PPD – What is it? And Why Does FISH Care?!?

6PPD – What is it, and Why Does FISH Care?!?

The Issaquah Salmon Hatchery (ISH) is lucky in that the returning salmon are counted as they exit the saltwater at the Ballard Locks.  However, many of the coho and chinook do not survive the mere 45 miles of freshwater passage to the ISH.  For the last 20 years or so, those losses were referred to as “Urban Runoff Mortality Syndrome”.  In December 2020 a more detailed understanding of this loss was identified in Science magazine:  a nasty component of stormwater runoff, a complex chemical referred to as 6PPD-quinone.  It turns out that this compound is created by the UV breakdown of an additive to virtually all car and truck tires, and carried into our salmon streams by rainwater.  It is incredibly toxic to coho salmon in particular:  a fraction of a teaspoon of this in an Olympic-sized pool will kill coho in a matter of hours.  There are two strategies evolving to mitigate this hazard:  campaigns at the State and Federal level to get this additive out of tires, and improvements in stormwater treatment to remove the 6PPD-q before it kills our favorite fish.  The City of Issaquah is very active on the mitigation side, testing various filtering strategies.  If you want to help protect coho, please let your elected representatives know you care, and ask them to take action!

Submitted by Larry Franks