This method of fishing kills huge numbers of sharks and other sea animals.
VOA: special.2009.04.03
They act as grazers on the ocean floor (manatees are the only otheranimals that do this), helping keep a balance under the sea for other creatures to live and breed.
Organizations like Sea Shepherd, Greenpeace, The International Fund for Animal Welfare, the Humane Society and -- yes -- People for the Ethical Treatment of Animals all campaign in various ways to stop the decimation of whales and other intelligent creatures of the sea.