1. For charmoula, in a bowl, mix lemon juice, olive oil, cilantro, paprika, cumin, coriander, cayenne, garlic, salt, and pepper.
2. Rinse zucchini and trim off ends; cut into 1-inch lengths. Rinse, stem, and seed bell peppers; cut into 1-inch squares. In a bowl, mix the vegetables with 2/3 cup charmoula. Thread onto metal or soaked wooden skewers, alternating zucchini and peppers.
3. Rinse salmon and pat dry. With tweezers or needlenose pliers, remove and discard pin bones. Lay a double sheet of heavy-duty foil slightly larger than salmon on a 12- by 15-inch baking sheet. Set fish, skin side down, on foil. Trim foil to within about an inch around fillet; fold edges over, then up, to form a slight rim. Spread remaining charmoula evenly over salmon.
4. Prepare barbecue: If using gas, turn all burners to high and close lid for 10 minutes, then adjust burners for indirect cooking (no heat down the center) and keep on high. If using charcoal, mound and ignite 60 briquets on the firegrate of a barbecue with a lid. When they're dotted with gray ash, in 15 to 20 minutes, push equal amounts to opposite sides of firegrate. Set a drip pan on the grate between coals. Set grill in place.
5. Slide salmon on foil off baking sheet onto grill, not directly over heat. Set vegetable skewers directly over heat. Cover barbecue. Cook vegetables, turning once, until they are browned and tender when pierced, 10 to 15 minutes total. Remove from grill, cover barbecue again, and continue cooking fish until opaque but still moist-looking in center of thickest part (cut to test), 20 to 30 minutes total.
6. Slide a large, rimless baking sheet or several wide spatulas under foil and fish to transfer to a platter or board. Tuck edges of foil under fish. Set vegetable skewers alongside and garnish with lemon wedges.