The effects of whale hunting include decimation of whale populations, catastrophic declines in populations of seals, sea lions and sea otters, and an increase in the global amount of carbon in the atmosphere. ABC News explains a theory proposed in 2013 that holds that killer whales started feeding on marine mammals after whale populations declined. A 2010 study claims dead whales take tons of atmospheric carbon to the ocean floor.
Nearly half a million great whales were hunted in the north Pacific Ocean after World War II until whaling was banned in 1986. Killer whales, or orcas, changed their eating habits and started to eat more marine mammals, such as seals, sea lions and sea otters. A study claims that sea lion populations have declined by 80 percent in the past 30 years in waters from Alaska to Japan, according to ABC. One reason for this is the changing diet of killer whales. Other reasons for lower marine mammal populations include fewer fish to feed on and global warming.
A 2010 study published in PLoS One claims whales, if returned to pre-exploitation levels, could store 9.1 million tons more carbon. Nearly 160,000 tons of atmospheric carbon could be removed from the atmosphere annually if whales had normal populations. After whales die, this carbon goes to the bottom of the ocean rather than back into the atmosphere, thereby reducing global warming.