CALL it the myth of industrial sin. It seems fish stocks were declining due to human exploitation long before the arrival of giant trawlers and factory ships, according to marine scientists at a conference being held this week in Canada.

“We are discovering that human pressure on marine life was much earlier, much larger and much more significant than previously thought,” says Poul Holm, an environmental historian at Trinity College Dublin in Ireland. “We now know that there was major commercial exploitation of fisheries, doing huge damage to fish populations, back in medieval times and even before. The idea …