Before the advent of whaling there were an estimated 200,000 blue whales across the globe© lionelz.wordpress.com
For the first time since whaling was outlawed in 1965, blue whales—the largest animals to have ever lived—have appeared in the northern Pacific Ocean off the coast of Canada and Alaska. Experts believe that decades of hunting in the northern zones did such damage to blue whale populations that they "forgot" the former feeding ground. "It is feasible that whales lost the cultural memory of the Alaska and British Columbia feeding destinations as a result of the intensive whaling there," says Jay Barlow of the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center in La Jolla, California.
What has brought the whales back, however, is still not entirely known. It may be part of a natural cycle in which the whales are following the cool water zones in the Pacific, as temperatures there fluctuate every 20 to 30 years. It’s also possible that the species" recovery has been so successful that they are heading away from California in search of more krill. But the worry among experts is that the opposite is true—that climate change has reduced the amount of krill available and sent the whales foraging for more. Before the advent of whaling there were an estimated 200,000 blue whales across the globe—now there are just 2,000 off the west coast of North America and anywhere from 5,000 to 12,000 worldwide.
Source: New Scientist