Pre-heat oven to 200 C, 400 F, Gas mark 6. Drain the salmon and break the fish into large pieces. Set aside. Place the pizza bases on two silicone paper lined baking trays. Spread equal amounts of the drained tomatoes over the pizza bases and arrange the salmon on top. Decorate with the mushrooms and olives then cover with the cheese. Bake for 15-20 minutes or until the cheese is melted and golden. Serve with salad. Serves 4-6. Approx. 430 kcals per serving