In a small bowl whisk together soy sauce, pineapple juice, ginger, brown sugar, garlic and 1/4 cup water. Pour into a baking dish and add salmon fillets, turning to coat. Cover and refrigerate 30 minutes, turning fillets occasionally.
Coat grill rack with nonstick cooking spray and preheat to medium-high heat.
Remove fillets from marinade and discard marinade. Grill fillets 4 to 5 minutes per side or until fish flakes easily with a fork and the center is still translucent.
Transfer fillets to a platter. Sprinkle with sesame seeds and serve.