It's a problem if your transporting the salmon back to a Washington port and you haven't cleared customs. The WDFW will then contend that you have no proof the fish weren't caught in Washington waters since many of the banks in the Straits are divided between American and Canadian waters. If you want no problem then get a Canpass and you can call in to the Canadian Customs and get cleared on the phone and then clear in San Juan on the way back.