Swordfish isn't on the menu where it usually is. Hammersley's Bistro in Boston is one of more than 25 restaurants along the East Coast and Texas that are taking swordfish off their menus for the next year. Chef m says it's an effort to restore the fish whose stocks in the North Atlantic have dropped close to commercial extinction. Steve Curwood reports from the kitchen of one of Boston's finest bistros, which has joined the boycott.