For barge lines, check both Samson Tug and Alaska Marine lines. It will go on a flat deck TEU, predictable schedule.
Coastal Transportation might be worth looking into as well. Main terminal is in Ballard. They'll likely be a roll-on/roll-off operation. I've shipped fish with them and they are a good operation.
Alaska Marine Highway allows trailers to be transported on their ferry out of Bellingham, but the cost has gone way up in the last few years and you have to arrange for a live load/unload at the ferry terminals. Sailings have been cut way back as well.
Another option is to find a boat that is heading up to tender the salmon fleet and see if you can have them haul it. I've seen all manner of freight come to from WA on tenders - cars, boats, even a huge load of hay.
Good luck
