Photo: Rita Mexia

Scientists at loss to explain killer whales “apparent aggressive behaviour”

In the space of two days last week, a group of young killer whales ‘immobilised’ three sailing boats off the Algarve coast by repeatedly ramming their rudders until they had managed to break them.

For the people on board the boats, it was an experience they will never forget: a kind of marine mixture of shock and awe.

Luckily no one was hurt, and the ‘attacks’ (if that is what they were) were relatively short-lived.

The first took place off the coast of Faro on September 4; the other two between Lagos and Sagres last Sunday (September 5).

These are not isolated incidents. They started being recorded in 2020. Experts tracking what they admit is “a nightmare” still have no idea what is causing it.

They believe “the disruptive behaviour” is exclusive to an ‘endangered sub population’ of orcas which depends heavily on an equally endangered prey species: the Atlantic bluefin tuna.

There have been multiple hypotheses for these ‘interactions’ (principally with sailing boats) – but there is no evidence explaining what is causing them.

Giving a webinar on the subject earlier this year, Ruth Esteban – a researcher with a PhD in Marine Sciences, working out of Madeira’s Whale Museum – said the best specialists can do right now is focus on ‘minimising the damage to people and boats’, by giving advice to sailors on how to react when finding themselves in these situations (see box below).

This particular group of orcas is labelled ‘the killer whales of the Strait of Gibraltar’ – although they regularly travel all the way along the southern coast, up to northern Spain, and back again.

A website constructed in the interests of the orcas explains that it is a group made up largely of juveniles, and “distinct from other sub-populations in the northeast Atlantic based on studies of photo-identification data, mitochondrial DNA, microsatellite genetic markers, stable isotope ratios and contaminant loads”.

In lay-speak it’s a group of its own – a kind of Mad Max outfit, in orca terms.

The mammals may be impelled by the fact that bluefin tuna is being heavily fished and as a result has become smaller in size.

Back in 2011, the Spanish Ministry of Environment catalogued these whales as vulnerable; in 2017 they went on a conservation plan; in 2019 they were assessed as Critically Endangered by the IUCN Red List … and in 2020 they displayed the first signs of their ‘disruptive behaviour’.

Could it be that land-based ‘awareness’ of their struggle for survival hasn’t been enough; that they feel they are targeting the enemy? So far “no one knows”, reiterates Ruth Esteban.

So let’s hear first hand what it is like to witness one of these ‘incidents’. (The word ‘attack’ is too strong: it could be the whales are just ‘having fun’.)

Ruth Esteban explains that from the footage that she has seen it looks like at least one adult is present during the interactions with sailing boats. It is a female.

Is she teaching the juveniles? Again, it’s not clear. What is without question is that these incidents are happening mostly to sailing boats; a lot of them end with considerable damage – sometimes running to many thousands of euros. At least one has happened at night. They usually continue for around 20 minutes, sometimes longer.

Rita Mexia was a passenger on one of the sailing boats targeted last weekend. She described over Facebook how “as soon as they saw the boat”, the whales “came to interact, hitting the hull and the rudder heavily for several minutes, which seemed at the time like hours. They were very worrying moments; of panic even. I feared for our lives.”

Luck had it that the skipper radioed for help which arrived swiftly. “They got us out of a real nightmare”, writes Rita Mexia “very much like a horror film…”

The rudder ‘gone’, ISN coastguards ended up towing the boat to Sagres’ port. But once the panic had subsided, the wonder of the experience kicked in. “The contact with those splendid beings really instills a feeling of admiration and respect for these beautiful mammals, for everything in Nature…” wrote Rita Mexia. “This overwhelming, unexpected experience taught us a lot more than respect for the sea and its inhabitants. “It confronted us with how tiny we are as human beings, and elicited the feeling of humility we should always have for all living beings on this planet… It was so good to get to dry land, unharmed. But it was also a great privilege to have met these killer whales…”

Of course, many other sailors can feel otherwise: particularly those who are left helplessly drifting deep offshore (which some have been in the past).

For these, is the ‘go to website’, with advice on what to do during an ‘interaction’, what not to do – and how to help others.

■ “Stop the boat (take down the sails), switch off the autopilot, leave the wheel loose (if sea conditions and location allow it)
■ Contact the authorities (either by calling 112 or radioing channel 16)
■ Take your hands off the wheel and stay away from any part of the boat which could fall or turn sharply.
■ Do not yell at the orca; do not let yourself be seen “excessively”; do not throw things at them; do not try to touch them with anything
■ If you have a camera or smartphone try to take photographs, particularly of their dorsal fins as this will aid identification later
■ Check the rudder turns and works only AFTER “pressure or nudges” to it have stopped
■ If a fault is found, request a tow”.

These are basic rules – the only real advice for now. Researchers also require the name of boats affected, the time and locations (GPS coordinates) of incidents. Their plan is to create a mobile phone app to track these interactions as none of the experts following this rogue pod believes this is an end to the story.

The skipper of one of the boats immobilised last weekend thinks an app is well overdue: “There should be a form of official mariners report whenever the whales are in a particular zone – so that we can make appropriate decisions.

“In our case, we had left anchorage 45 minutes beforehand. Had there been some form of communication on channel 16 for instance, my decision-making would have been different”.

He reiterated that he “felt no aggression” from the whales. “The size and speed of the Orca is enough to sink a boat if they so wish…”

Stop press: Maritime police have advised one sailor whose boat survived an interaction to put a litre of diesel at the stern in future, as this can keep the whales away. There is also a strategy of putting the boat into ‘the aft position’ and going backwards…this seems to protect the rudder from attack.

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Photo: Rita Mexia
Photo: Rita Mexia
Photo: Rita Mexia
Photo: Rita Mexia