Thaw salmon, if frozen. Rinse salmon; pat dry with paper towels. Set aside.
Preheat broiler. Drain canned pears, reserving syrup. Set pears aside. Combine reserved syrup and balsamic vinegar in a small saucepan. Bring to boiling; reduce heat. Simmer, uncovered, for 10 to 15 minutes or until reduced to about 1/4 cup. Set aside.
Place salmon on a greased broiler pan. Season salmon with salt and pepper. Broil 4 inches from the heat for 4 minutes. Turn, brush generously with the balsamic and syrup mixture. Broil for 2 minutes. Turn again and brush with balsamic and syrup mixture, leaving about 2 tablespoon of the mixture in the saucepan. Broil for 2 more minutes or until salmon flakes when tested with a fork.
Meanwhile, add orange juice to the saucepan with the remaining balsamic and syrup. Simmer, uncovered, for 2 to 3 minutes or until reduced by half, remove from heat. Stir in orange zest and pears. To serve, divide lettuce among 4 serving plates. Top with salmon, pear mixture and toasted pecans.