Preheat oven to 400°.
Place bread in a food processor; process until crumbs are fine. Add pine nuts; pulse just until pine nuts are finely chopped. Place breadcrumb mixture in a shallow dish. Place egg white in a shallow bowl; beat with a whisk. Sprinkle salt and pepper over fish. Dip fish in egg white; dredge in breadcrumb mixture.
Place fish fillets on a baking sheet coated with cooking spray, and drizzle margarine over fish. Bake fish at 400° for 15 minutes or until outside is crispy and browned and fish flakes easily when tested with a fork. Serve fish with lime wedges.