North Atlantic right whales are one of the world’s most critically endangered large whales, but if you’re lucky, you can still see them: a mother nursing her newborn in the warm waters off the Georgia or Florida coast, their only known calving grounds; right whales socializing and feeding in the fertile waters of Cape Cod Bay, sometimes within sight of shore; whales — black, 50 feet long, and weighing some 100,000 pounds — rising through the water in the Bay of Fundy or the Gulf of St. Lawrence, the northern end of their thousand-mile-plus migration route.