Machine gun everyone still in the water, if you don't want to trust hypothermia, and there is nothing left but an oil slick.
It wouldn't be the first mystery of the sea...
Whaling will die with the last of the Japanese whalers. No one in Japan wants whale meat, and it' survival depends on tradition, like manufacturing buggy whips and top hats.
Sea Shepherd has also attacked other fishing vessels as well. This is piracy. We all know what should be due pirates.