Humpback whales are returning to the waters of Rio de Janeiro. They migrate here annually from Antarctica to breed. About 40 years ago there were 2,000 of them. Now more than 30,000 individuals swim. Humpback whales almost went extinct due to whaling. It is estimated that the population originally consisted of 150,000 individuals. In the 18th century, active commercial hunting of humpback whales began....
