By Ayano Hayes, Watershed Conservation Manager of Salmon Protection and Watershed Network (SPAWN)

Return of the Salmon

In West Marin, when winter rains come down, everyone looks to the freshwater streams for loud splashing and bright flashes of pink. In the Lagunitas Creek Watershed, one of the southernmost areas in California to have a stronghold of wild salmon returning from the ocean to spawn, this was a miraculous year for their return. This watershed is unique in that it’s home to 5 out of 6 of the Pacific Coast Salmon; Chinook (king), coho (silver), pink (humpy), chum (dog), and steelhead/rainbow trout. Although the native salmon are the endangered Central California Coast (CCC) coho and threatened steelhead, over time, Chinook, pink, and chum salmon have made Lagunitas Creek their home.

This winter, Chinook salmon were spotted all along the coast and in inland streams throughout the Bay Area. The Water District, Marin Water, who monitor mainstem Lagunitas Creek, San Geronimo Creek, and Devil’s Gulch Creek, documented the highest record of live Chinook salmon and Chinook redds (around 120 nests) this year. The good news didn’t end there, because following the Chinook run, the coho salmon began their migration after multiple rain events towards the end of November, throughout December, and into February. Coho were spotted everywhere in the large and small streams within the watershed, harboring excitement and high hopes for a strong salmon return. As rain consistently fell across the lands throughout the spawning season, elevated flows supported the salmon’s migration further upstream than observed in decades, accessing natal spawning grounds high into the headwaters.

SPAWN in the Creeks

The Salmon Protection And Watershed Network (SPAWN) works in collaboration with Marin Water and the National Park Service (NPS) to document spawning throughout the Lagunitas Creek watershed. NPS monitors Olema Creek, a large tributary to Lagunitas Creek, while SPAWN monitors the uppermost tributaries of San Geronimo Creek, the headwaters of the watershed. This year, SPAWN biologists observed salmon spawning in Arroyo, Woodacre, Larsen, Montezuma, and Barranca Creeks (cumulatively 2 miles of stream out of approximately 25 miles monitored by other agencies- within the 108 square mile watershed). Salmon were seen spawning even beyond SPAWN’s monitoring areas shared by word of mouth by local creekside homeowners, providing insight into more habitat salmon accessed and utilized this year.

In years with large salmon returns, access to upstream habitat is hugely beneficial, since it allows for spawning to spread out across the watershed and decreases the risk of superimposition. Salmon enter the system at different times of the season, some laying their nests as early as November, while some finish spawning in February. Superimposition is the result of a nest being built on top of another nest by different females, potentially impacting the egg survival of the first nest. This year, there was a high amount of over 100 records of superimposition…but let’s get into the preliminary coho nest totals for the watershed.

As watershed-wide data is collected, population trends can be analyzed across the three classes of fish. Coho salmon live a three-year life cycle, allowing for comparisons to be made between the current year’s class and the parent generations – 3, 6, 9 years ago, etc. Eric Ettlinger, Aquatic Ecologist with Marin Water shared, “The largest run for this year’s class was in 2003-04 when 492 redds were documented. The largest run on record for the Lagunitas Creek Watershed was in 2004-05 when there were 634 redds.”

Within the San Geronimo tributaries, SPAWN biologists recorded a total of 57 coho nests, 12 unknown nests, and 4 steelhead nests. More coho nests were recorded across the rest of the watershed in Olema, San Geronimo, Devil’s Gulch, and Lagunitas Creeks, bringing the estimated total to over 640 coho redds! As unknown redds get classified and the final count gets solidified, this year’s class could be the largest on record for the Lagunitas Creek watershed in the last 30+ years!

You can keep up to date with the Fisheries Monitoring efforts within the Lagunitas Creek watershed by following SPAWN and through Marin Water’s Fisheries page.

More on fisheries monitoring at seaturtles.org or marinwater.org