Humans have been piloting boats across the Atlantic for around 800 years (beginning with Greenland), and the great cod collapse happened on the quincentennial of Columbus's voyage. Each of your explanations has a "why now?" caveat. Fads fit in the gap, unless they've recently developed weapons.
Increasing water temp, climate change, food scarcity, environmental pollution, desperation, habitat loss, new audible or physical disturbances caused by these boats. I mean, there's probably 100 different reasons you could think of for why now.
"Fads" answer nothing aside from simply removing the need for further explanation. Why are they doing that? I don't know, they're bored! It's a fad. Great research.
