In a large bowl, stir together the parsley, raisins, olives, capers, pine nuts, olive oil, and lemon juice and season with salt and pepper; stir in the couscous to moisten completely and season generously with salt and pepper.
Put the salmon in a single layer in a smallish buttered gratin dish or baking dish (bottom measured 10 by 7 1/4 inches; 2.8 liter); the fillets should not touch one another. Sprinkle with salt and pepper and drizzle with a little olive oil. Now spoon the couscous mixture over the top of the fish so that it completely covers them and fills in the whole dish at the same time. Pour over the water. Drizzle with olive oil. Put the dish in the oven and bake 25 minutes. Use a large spoon to spoon out the salmon and the couscous.
Note: 1 cup couscous plus 1 1/3 cups water is a better quantity to serve 2 if you have a smaller gratin dish or baking dish (remaining quantities are the same).