Ships need to slow down when traveling in the hang-out spots of critically endangered right whales, the National Oceanic and Atmospheric Administration announced Wednesday. Ships 65 feet or longer must slow down to 10 knots (that’s 11.5 miles per hour for landlubbers) within 23 miles of major mid-Atlantic ports. Government scientists had originally suggested a 34-mile radius, but the Bush administration decided that was too extreme. Ship strikes kill one or two whales a year and are the main threat to the species, which has been endangered since 1970. Less than 400 right whales remain in the wild. The new rule will go into effect in December and expire in five years unless renewed.