Preheat oven to 425 F (220 C). Lightly spray an 11" x 7" (28 cm x 17 cm) baking dish with a non-stick cooking spray. Place salmon fillets in baking dish and season lightly with salt and black pepper.
Bake until fish flakes easily (about 10 minutes per 1" or 2.5 cm thickness of fish fillet) and internal temperature reaches 160 F (70 C)
Meanwhile, in a small bowl,
mix together margarine, tarragon, fennel seed and lemon juice. Spread over salmon and serve at once.