Why did World War II temporarily reduce whale hunting?

World War II caused a temporary reduction in whale hunting primarily because the whaling industry's infrastructure was diverted or destroyed during the conflict. Specifically, 27 factory ships—the essential vessels used for processing whales at sea—were sunk during the war.1

The loss of these specialized vessels significantly hampered the industry's ability to conduct large-scale pelagic whaling operations. Following the war, the importance of whale oil for European fat rations and the demand for meat in countries like Japan and Russia led to a rapid rebuilding of the fleet with newer, larger factories and more efficient diesel-powered catchers.1