Orcas attacking yachts off Spanish coast could be doing so 'in revenge'

A group of scientists investigating a spate of attacks by orcas on yachts off the coast of Spain in recent months has said their unprecedented behaviour may be a form of revenge from the whales after being injured by humans.

Members of the international working group for Atlantic orcas say they have been able to confirm that three juvenile orcas from the same pod are responsible for the ramming attacks that have damaged a series of boats.

Of the three orcas, which the scientists have collectively named Gladys, a study of photographs taken over the summer period has revealed that two sustained injuries to their flanks, which is not the kind of habitual damage the animals’ dorsal fins sustain by accidental brushes with fishing lines.

The injuries to white Gladys and black Gladys, named due to differences in their dorsal fin colouration, appeared between June 20 and August 3. The vast majority of the incidents took place after this time, leading researchers to suspect there is a connection and that the orcas are retaliating aggressively to the pain they ensured.

Video: Up-close encounter with Killer Whales caught on camera

“Since that event a series of behaviours have been triggered when the orcas are in the presence of yachts, which culminate in a preventive action to stop it moving by manipulating [the rudder],” the report reads.

The scientists say they do not know when or where the incident took place and how it led to the injuries sustained by the two orcas.

"We are not even certain whether the incident occurred accidentally or intentionally," the report states.

"We cannot rule out that a sailboat could have been involved in the aversive incident or that the orcas identify sailboats as more accessible boats and with larger rudders than others.”

Sailors have reported “coordinated attacks” by a group of orcas sometimes lasting up to an hour, in which the animals take turns to ram the hulls of yachts, bite the rudder and make boats spin around.

In 61 per cent of the 33 reported incidents since late July, the researchers have been able to confIrm that the Gladys trio were involved, leading them to suspect they are always to blame.

Six attacks took place in the Strait of Gibraltar area, five in Portuguese waters and 22 off the coast of the northwestern Spanish region of Galicia, where yachting was banned off a stretch of coastline to avoid further confrontations.