Spring Salmon Counts Up, Exceeding Biologists’ Expectations

For Immediate Release: April 21, 2023

Contact: Preston Brown, preston@tirn.net

Spring Salmon Counts Up, Exceeding Biologists’ Expectations

Olema, CA—As juvenile salmon migrate to the ocean to mature into adults, early reports look very promising.  

SPAWN, the Salmon Protection And Watershed Network, monitors out-migrating “smolts” that are migrating to the sea from San Geronimo Creek in Marin County. Smolts are defined as 1.5 year old juveniles. The fish hatched from salmon nests, called redds, as 1.25 inch fish approximately 18 months ago, and have grown to about 6 inches long as they start their migration to the ocean.

SPAWN recently installed their annual spring monitoring station to count juvenile salmon headed to the ocean in the Lagunitas Watershed in Marin County, part of an annual research study conducted by biologists to learn how many fish survived the winter and are making it into the Pacific Ocean. These 1.5 year-old fish are then called “smolts”.  

This study allows better understanding of survival rates of juvenile salmon in their fresh-water habitat when compared to the number of nests laid by their parent generation and the impacts of drought, floods, and habitat quality these baby fish experienced in the past 1.5 years.

“We were concerned with survival rates following the 10 atmospheric rivers these tiny fish had to survive this winter. However, the counts so far look great, with one of the largest coho smolt out-migrations we’ve ever seen happening now”, said Preston Brown, Conservation Director for SPAWN. 

“The large amount of adult spawning in 2022, coupled with good streamflow in 2023, has made for a larger than expected juvenile population of coho salmon. The habitat restoration projects in the watershed, such as Roy’s Riffles Restoration on the former San Geronimo Golf Course, have created slow moving floodplains and back channels that give juvenile salmon a place to survive giant storm flows, such as the ones these fish faced this winter,” said Brown.

Adult salmon spawn in the winter when streamflows allow fish to access small creeks and headwater streams. The rains of December 2021 and January 2022 created ample opportunity for coho salmon to swim to optimal spawning habitats in the San Geronimo Creek Watershed, where they spawned in small streams where some residents claimed they hadn’t seen spawning in 20 years. 

There is a growing understanding by scientists, regulatory agencies, and even the public, that coho salmon need complex habitats to survive. Recent habitat restoration work within the watershed has created additional complex habitats for young fish to survive heavy storms. 

“Although the streamflows were strong, habitats like floodplains and large woody debris jams create areas where young fish can survive heavy flows”, says Brown. “With enough habitat where fish can find refuge, the strong currents deliver a great deal of food for fish to eat that gets washed into the stream from upland areas. These conditions create the best nurseries for young fish.”

The predictions for the coho salmon smolt outmigration this spring was high, but recent counts have exceeded biologists’ expectations. “We have seen some of the highest single day counts in recent years”, says Ayano Hayes, Watershed Biologist for SPAWN. “We’ve recently seen nearly 80 coho salmon smolts each day moving down from the San Geronimo Creek Watershed into Lagunitas Creek.”

The San Geronimo Creek smolts account for a portion of the total coho salmon leaving the watershed as many fish that come from other creeks like Devils Gulch, Olema Creek, and mainstem Lagunitas Creek are all contributing to the total coho salmon out-migration into Tomales Bay.

“We’re thrilled with the results of the spring smolt counts so far,” says Hayes. “The Lagunitas Creek Watershed continues to show us how critical this salmon population is for the survival of the entire Central California Coast Coho Salmon.”

The Lagunitas Creek Watershed represents roughly one-fifth of all wild coho salmon within the range of Central California Coast Coho. 


The Salmon Protection and Watershed Network (SPAWN) is a program of the global ocean conservation non-profit Turtle Island Restoration Network that protects endangered, wild coho salmon and the forests and watersheds they need to survive in West Marin County, California. Learn more at www.seaturtles.org/salmon.