These are the gill plumes of a nudibranch (sea slug).
Below is a view of the entire nudibranch:
Matt let us know that Kelly had spotted a few Polycera hedgpethi at Spud Point Marina. I took a look on 14 November 2015 and found a few individuals.
On the West Coast, Polycera hedgpethi is generally a more southern species — most books list Marin County as the northern limit. Although it has been noted in Bodega Harbor before, it might not be that common here. It's another species that could be responding to warmer water temperatures.
This species has bright yellow markings, but it blends in well with the background of colorful marine invertebrates (in this case, tunicates, bryozoans and tubeworms) living on the docks:
Polycera hedgpethi eats Bugula — the purple, branched bryozoan in these photos. Searching among patches of Bugula is a good way to find this nudibranch. I'd love to hear about it if you spot any!