Endangered Right Whales Are Shrinking. The researchers used high-resolution aerial photographs to track size and body condition over time of 129 right whales. There are only about 366 North Atlantic right whales in existence now, compared to 481 in 2011, the known high for the population in recent years. The mammals' high fat content and buoyancy after death led to their name: whalers called them the \"right whales\" to kill. North Atlantic right whales typically migrate up and down the Eastern seaboard, from Florida to Canada.