1. In a medium size skillet, heat 2 tablespoons of the oil over medium high heat. Add the breadcrumbs and saute for about 5 minutes, or until the breadcrumbs are toasted. Transfer to a small bowl and stir in the parsley, garlic, lemon zest, orange zest, 1/2 teaspoon of the salt, and 1/2 teaspoon of the pepper. Set aside.
2. Preheat the grill over very hot charcoal and brush with oil.
3. Brush the salmon with the remaining 1 tablespoon oil and sprinkle with the remaining 1/2 teaspoon each salt and pepper. Place the salmon skin side down on the grill. Grill for 4 to 5 minutes on each side, or until just cooked through. Transfer to serving plates, sprinkle with gremolata, and serve.