1. Prepare grill to medium-high heat.
2. Combine first 4 ingredients in a small bowl.
3. Cut 3 diagonal slits on each side of fish; rub rosemary mixture evenly over fish. Place 1 rosemary sprig in cavity of each fish. Place the fish on grill rack coated with cooking spray; grill 4 minutes on each side or until fish flakes easily when tested with a fork or until desired degree of doneness.