There are some available, check SF Bay Craigslist or www.anchoredup.com The problem you will have is the complexity of transferring one as they are not bought and sold, only transferred from a "permitted vessel" to a "replacement vessel" by the owner of the permitted vessel. However, it can be done and there are some available
California Salmon Vessel Permits are transferred on vessel capability, not necessarily the length. Length is just one factor considered. Check anchoredup.com