Fisheries Team Update - July 24, 2023

Creek Notes: 2023 Smolt Monitoring Update

Every spring, all along the northern California coast, young salmon and steelhead make their way from their natal streams to the ocean. In comparison, Chinook Salmon leave when they’re about six months old, Coho Salmon wait until they’re older than a year, and Steelhead generally migrate at two years of age. Their migrations are timed to take advantage of an annual bloom of plankton just offshore, where they need to grow fast before they’re eaten by birds. Only a tiny fraction of these fish will ever see their natal streams again.

Lagunitas Creek is just one of many coastal California streams, but it’s known for sending thousands of young Coho Salmon to the ocean every year. Marin Water biologists, along with our colleagues at the National Park Service, count these “smolts” to better understand how they survive in the face of significant habitat degradation. The good news is that the Coho Class of 2023 did extraordinarily well! A record 50,000 coho smolts left Lagunitas Creek this year, which was 270% above average. Over nine weeks, our team handled more than 7,500 Coho Salmon smolts, including 900 in a single day.

So when can we expect to see these fish again? While some male smolts will return to Lagunitas Creek as “jacks” later this year, most Coho Salmon wait to spawn until they’re three years old. If these smolts can survive the gauntlet of seabirds, seals, sharks, and everything else that wants to eat them, we may even see a record salmon run in the fall of 2024. Mark your calendars!

-Eric Ettlinger
Aquatic Ecologist