Since you mentioned you've never caught a salmon before, this may be helpful in identifying what species you are catching. This is in the regulation book as well.
http://wdfw.wa.gov/fishing/pac_salmon_id.pdf

Every pink run people end up keeping fish they think are pinks but turn out to be species they can't legally retain.

The San Juans are in Marine Area 7 in the regulation booklet.

Have a good trip.
SF