Jan. 15, 2025

Creek Notes: The Coho Keep Coming

Greetings! Eric Ettlinger here from Marin Water's fisheries team.

In recent weeks, anyone looking for salmon in Lagunitas Creek or Devil’s Gulch has seen them – lots of them. 

On our most active day of salmon sightings, Dec. 18, Marin Water surveyors counted 304 coho salmon and 117 coho redds (nests). That is more salmon than we sometimes observe over an entire year, and more coho keep arriving! Last week we observed 270 live coho and 90 new redds. As of Jan. 9, Marin Water surveyors have observed over 1,000 live coho (some fish likely counted twice) and nearly 300 redds. This is already the largest run to return to Lagunitas Creek in 20 years, and the third-largest run in 30 years of monitoring. 

And all of those salmon have made something else unusually visible this year: carcasses. In the last two weeks, Marin Water surveyors have found over 100 salmon carcasses and collected genetic samples and otoliths (tiny bones that are like the fish’s flight data recorder) from many of them. 

Why do salmon die after spawning? 

Anadromous fish (those that migrate from the ocean to freshwater to reproduce) have a “choice,” either to dedicate all their energy to their upstream migration and procreation, or to save some energy for a trip back downstream. 

Pacific salmon have evolved to give everything they have to their offspring and then die. However, these fish continue to give, even in death. Their bodies are eaten by aquatic insects that will, in turn, be eaten by young salmon. The nutrients they transport from the ocean fertilize the forests along salmon-bearing streams. 

So while seeing so many dead salmon may seem sad, we are also witnessing an incredible investment in the next generation of salmon, and in the health of the entire ecosystem. 

New Fish Monitoring Report 

The Adult Salmonid Monitoring Report for 2023-2024 is now available. Dive into the data to see how this spawner class fared.