Watch: Salmon are back in Sonoma Creek

The news from the Sonoma Ecology Center was clear: “We all feel like celebrating over this news: Sonoma Creek has salmon again!”

Research program manager and aquatic scientist Steven Lee assembled showcased the return in video of the Chinook (King salmon) as they made their journey upstream and began settling into their spawning habitats.

The abundant rainfall that Sonoma County received in late October created ideal conditions for Chinook to make their way back to the local creek. Chinook salmon spawn in Pacific streams from California to Alaska, and their numbers have been in serious decline for decades.

Chinook were known to have successfully spawned in Sonoma Creek a few years ago, and it’s possible some of these are their offspring are returning to spawn. The Sonoma Ecology Center has conducted studies of young fish migrating out of Sonoma Creek and found, in addition to steelhead, a surprising number of young Chinook are heading out to the bay and ocean. It’s hard to know for sure if these fish originate from Sonoma Creek – there are many salmon released from hatcheries in the Central Valley who could be making their way up local waterways. Some of the fish we observed do have clipped adipose fins – an indication that they were raised in a hatchery. However, many of the fish in Sonoma Creek right now lack this indicator and their size suggests that they are the right age to have come from the last run here.

The video shows both male (bucks) and female (hens) – males present as redder in color and with a hooked snout while females tend to be smaller and more torpedo-shaped. Both must go through significant changes in making the transition from ocean dwelling to freshwater fish, and to prepare to reproduce. Both male and female Chinook show up to spawn about the same time in our streams, as water starts to drop after a larger, late-fall storm.

Females seek out a pool to lay their eggs, typically in deeper water with larger gravels than our other resident salmonid–steelhead. A female will defend her nest, or redd, until she can no longer maintain her strength and dies, about 8-12 days after spawning. Males compete for spawning females, and dominant, generally larger males spawn more successfully than smaller males, but several males will often attend a spawning female, who can lay eggs several times in her redd.

A dominant male will often leave right after spawning to court another female, so less dominant “satellite” males that wait are often also successful in reproducing. Both male and female Chinook decline and die within a few weeks of arrival at their spawning location. There’s been a lot of territorial sparring going on, which can be seen in the video.

The ecology center adds, “If you choose to try to spot Chinook during their time here please take proper precautions to not disturb the fish in Sonoma Creek. Stick to established trails in an effort to prevent erosion and try not to walk into the water to see the salmon. These fish are on the lookout for predators and we can do our best to not frighten them while they are spawning."

Much of the research SEC conducts is focused on streamflow and aims to ensure there is adequate water for fish, such as these Chinook, year-round in our watershed.