It may be a shot in the dark, but freezing sperm is one of the last chances to save the hellbender, North America's biggest salamander, conservationists say. Hellbenders—also known as snot otters and devil dogs—have dwindled throughout their range, which once encompassed streams from northeastern Arkansas to New York. The 2.5-foot-long (0.7-meter-long) amphibians have declined by 80 to 90 percent in most of their traditional watersheds in recent decades, and healthy populations now haunt only isolated pockets of southern Appalachia (see map) and Pennsylvania, said Dale McGinnity, curator of reptiles at Nashville Zoo. All of the states in the hellbender's...