In the mid-80's, Pike Place Market and a restaurant were advertising/selling wild steelhead. One of the sport fishing groups got a few letters written to them, explaining the "game fish" status and special need to conserve this resource. Lo and behold, they listened, and stopped buying wild ones! Maybe a reminder is in order. (I realize the tribes don't have to honor the game fish rules, but the letters still worked.)
Similar success in the Spokane area a few years ago, when some non-Tribal folks were selling largemouth bass to fish markets.