To make ahead: Place brine ingredients in quart-sized freezer bag. Freeze fish in store packaging. Tape brine bag to fish container.
To serve: Thaw salmon and place in a 13x9 pan. One hour before cooing, mix brine ingredients with with 3 1/2 c. water and pour over salmon. Float 1 c. ice cubes over fish, making sure whole fish is under brine. Turn once. Remove from brine, wash under cool water, and barbecue intil done.
Serve with: Spicy Grilled Pineapple, Four-Bean Salad