SPRINGFIELD, Mass. — A poaching ring that involved the slaughter of more than 400 black bears in the Northeast was broken Tuesday with the arrests of 11 people, officials said. The bears were killed for their gall bladders, which are prized as aphrodisiacs in the Far East. The arrests were the culmination of a 2 1/2-year investigation by wildlife officials from Massachusetts, Connecticut, New York and the U.S. Fish and Wildlife Service.