Make salsa:

Cut peel and any white pith from oranges with a sharp knife, then cut sections free from membranes, letting them drop into a bowl. Stir in remaining salsa ingredients.

Prepare salmon:

Preheat broiler.

Season salmon with salt on all sides. Arrange on rack of a broiler pan, skin sides down, and broil about 4 inches from heat 4 minutes. Spoon glaze on top and spread onto sides, then sprinkle with fennel seeds and cracked pepper. Broil until glaze is bubbly and fish is just cooked through, 2 to 3 minutes more.

Serve salmon with salsa.