Rain and spawning salmon go together, and the winter season of 2024-25 had a plethora of both! Getting to see these fish, some reaching more than 3 feet in length is an amazing and joyful experience! In Marin, we saw the largest number of endangered coho and threatened chinook salmon in three decades.
I have received calls, photos and video from places where salmon haven’t been seen in the Bay Area. And everyone I run into the San Geronimo Valley has a story to tell— ‘more fish than ever’ — or haven’t seen them in my backyard creek in 30 years.
While there is a general misconception that more rain means more salmon, there are a number of reasons that help explain what’s going on this winter season. It is way more complicated than the amount of water, but includes the right amount of water at the right time that really worked in favor of salmon migration this year.
First, many of the salmon seen during and right after our December atmospheric river were chinook or king salmon. The vast majority of these now begin their lives in hatcheries and do not necessarily return to their natal streams like “wild” salmon do. And for the past two years, the normal fishing season has been shut down due to low returns of chinook salmon, reducing one of their main predators in the ocean, us. That and the juvenile fish released from hatcheries must have experienced good environmental ocean conditions allowing for increasing the survival numbers.
The atmospheric river helped the fish bring lots of sustained rain right at the ideal time allowing the fish to maneuver through or around culverts running under roads that often prevent them from migrating to many historic spawning grounds now blocked. The velocity of water running through many of these undersized culverts is constricted which increases velocity (think putting your thumb at the end of a water hose), and the downstream ends of culverts often erode the stream causing the culverts to be perched high above the creek making passage difficult, if not impossible most of the time.
Federal and State funding for replacing culverts that are migration barriers was massively increased through Biden’s Infrastructure bill, which has helped open up historical spawning grounds to salmon in other locales, but little work has been done locally in the past decade. More is needed to open up more habitat!
The art and science of streamside habitat restoration, also funded by State and federal grants, has also matured over the past two decades, as we have learned from past successes and failures in the young field of restoring functional ecosystems that salmon need to survive and thrive. The decades of hard work by non-profits and agencies may finally be producing results increasing salmon survival in our local creeks and rivers.
Lastly, better understanding of the ecological benefits of a healthy functioning ecosystem for the survival of salmon and other wildlife, and which also protects our homes and the lives from flooding events exacerbated by climate disruption, increases water filtration into underground aquifers, and filters pollution from our recreational sites, leads to better informed regulations to protect our environments. But salmon numbers are up throughout Central California with different areas having various amounts of restoration work. This suggests that as important as restoration is, it cannot completely explain the increased spawning population
While the political will to protect and restore our environment is not always at the forefront of our decision-makers under pressure from developers and corporations, an informed and active citizenry can keep progress moving forward—and increase the chances that we will see even more salmon and wildlife in future years!
Get involved and enjoy our healthier streams and more abundant salmon that brings us joy and makes healthier, happier communities! Join us in Marin County by visiting SPAWN at www.seaturtles.org/spawn.
