Orcas have attacked several boats off the coast of Spain and Portugal over the past few months, leaving experts baffled.

One boater said the attack looked planned as one orca worked the vessel from behind and another from the front. Others reported the killer whales rammed hulls and keels and damaged rudders. One boat was rammed at least 15 times, and after losing steering, two had to be towed into port.

Scientists are baffled by the attacks. Theories range from stress and disorientation to a lack of food caused by competition from commercial fishing vessels. Orcas are highly intelligent creatures, leaving some people to wonder if the animals know boats are taking off with their food supply.

In a video shot by one crew, the Spanish sailors onboard throw some salty language around as the orcas attack their boat’s rudder, and eventually disable it.