There's a number of theories. The drop in food along the Portugese/Spanish Atlantic cost. Some of the attacking Orcas also have visible scars caused by boats

There's a number of theories. The drop in food along the Portugese/Spanish Atlantic cost. Some of the attacking Orcas also have visible scars caused by boats and as these attacks increased after the Covid lockdowns it could have realized that the underwater noise before was caused by ships and are angry when shipping started again: https://www.theguardian.com/environment/2020/sep/13/the-tale-of-the-killer-whales https://www.theguardian.com/environment/2020/sep/13/the-tale... "What explains the new behaviour? Was there reduced noise during the Covid lockdown? Selling says yes. “No big game fishing, no whale watching or sailing boats, no fast ferries, fewer merchant ships.” He’s intrigued by the idea that the orca had two months with reduced noise – “Something most of them probably never experienced before” – and considers the possibility they felt angry as the noise restarted"