The Freshness Gate: When Water Still Remembers a Salmon's Age
Every fall, Issaquah Creek in Washington State turns into a maternity ward for thousands of salmon. The fish swim in, spawn, and die, and the water carries away their molecular traces: fragments of DNA, short-lived RNA, chemical marks on the genetic text. From September through November 2024, researchers collected a liter of water every week and ran it through a filter to catch those traces.