Orcas like sailing boats

Some Orcas in the Strait of Gibraltar love sailing boats to bits. This is how you could describe their new behaviour since the end of the corona-related lockdown in Spain.

According to the "Guardian" the first interaction between the Orcas and a sailboat occurred between Trafalgar and Barbate on the 23rd of July 2020. "Interaction" is a broader term that the Spanish scientists who have formed a working group (Grupo de Trabajo de Orca Atlántica) prefer to use. On the one hand, sensationalism must be prevented, and on the other, no one knows whether these are attacks or whether they are playing. If you read the reports of the boat crews involved, they perceive the interactions as attacks. Especially when the Orcas tamper with the hull and rudder in the dark of night, many a crew member is afraid of sinking. Modern sailboats with FRP (fiberglass reinforced plastic) and steel hulls are not so easy for the whales to sink, unlike the two wooden ones of which such a thing is known: the boat of the family Robertson near the Galápagos Islands in 1972- and one with an average off Brazil in 1977; in both cases the crews escaped with no more than a fright.

The Orcas have now continued their pranks for a year, targeting sailboats from Gibraltar to Biscaya, the last "attack", after which the rudder blade had to be repaired in Gibraltar because a piece had been bitten off, happened near the Strait of Gibraltar at the end of June. According to the British team, 30 Orcas were involved, but there is no exact information on whether all of them took part in the ramming and biting activities. The method is like the one they use to hunt large whales: ram and bite the fluke (rudder blade). We often watched them looking closely at our stern from below. I assume that they know very well where the weak points of boats are. Nevertheless, according to the work group, there has only been damage in 15% of the cases. According to them, three juvenile Killer Whales are the regular protagonists.
One of the animals had an injury to the head during an attack on the 29th of July 2020. Whether this was the cause, or the consequence of the ramming actions will probably never be clarified. Finding the trigger for this hitherto undescribed series of interactions between Killer Whales and boats is drawing the attention of whale scientists of all stripes to the Orcas of Gibraltar. Will the cause ever be clarified?

In my first article about the events on the 29th of September 2020 I listed some speculations, some new ones have been added:

-An isolated event as a trigger, for example a careless white elderly gentleman with a white beard who, unaware or careless, sailed through a group of resting Orcas during the heavenly lockdown and rammed into a sleeping animal. The description of the perpetrator comes from a "whale whisperer" who approached us, this only as a source reference. If the perpetrator feels addressed, please get in touch, it would help a lot to clear up the mystery.
-General anger among the Orcas that after 2 months of lockdown (during which no harassment from pleasure crafts took place and it was therefore nice and quiet, especially north of the main shipping route in the Strait of Gibraltar) the noise started again and made it difficult for them to locate tuna. Because of the greater risk of injury from motorboats, they specialised in sailing boats for their "vendetta". But they don't spare fishing boats either, as I was told by a befriended fisherman whose ship needed to have its keel repaired at the shipyard; it could, however, have been the result of fighting over some tuna.
-The playful behaviour mentioned above to train to hunt tuna. However, it should not be misinterpreted, the Orcas do not confuse sailboats with tuna!
-Mere playfulness: the three young animals were already particularly curious about ship propellers and rudder blades when they were calves, both those of the whale watchers and those of the CIRCE research boat, whose members are convinced of the theory of " mere play", the increasing size of the growing calves alone leads to the damage, according to them, but they were already up to that nonsense before that. A sailor showed me underwater footage that a sailor friend of his had taken with his GoPro: the Killer Whales seem to be "tenderly" nibbling on the rudder blade. CIRCE suggests just sailing on and pretending nothing is wrong so as not to motivate them. But this would require holding the rudder, with the risk of injury to the skipper if the rudder wheel turns abruptly when the Orcas ram.

The recommendations of the "working group" for sailors are currently as follows:

-A fifth speculation is unlikely but cannot be ruled out: Behavioural change due to toxoplasma. There is
sufficient sewage water coming from the land. On the 15th of May 2014, 5 calves were observed next to the harbour pier of Tarifa in the bay "La Caleta", swimming in circles for a long time and apparently left behind by their mothers. Possibly the mothers wanted to hunt and keep their calves safe. This is exactly where untreated sewage from the old town is discharged, it is sufficient when cat toilets are cleaned, the excrement is flushed into the toilet or washed from the streets so that the pathogens get into the coastal waters. A study showed that mice infected with toxoplasmosis showed a significant decrease in their natural fear of the cat, which is essential for survival. Chimpanzees, large mammals closely related to us, lost their fear of their natural predator leopard after infection with toxoplasmosis, another study shows. From a rich dataset of more than three decades of continuous field research in the Masai Mara National Reserve in Kenya, researchers deduced that hyena cubs infected with Toxoplasma gondii behaved more boldly in the presence of lions than uninfected cubs. This increased the probability of being killed by the predatory cats. The parasite thereby achieves that it can pass from the intermediate host into the intestine of the felines in order to reproduce there. Other studies even transfer this possibility of behavioural change to humans, seeing a connection between toxoplasmosis and aggressive behaviour. However, conclusive proof for humans is still lacking. It could be that the parasite also influences behaviour in marine mammals, with cases of toxoplasma infection already having occurred among those close to the littoral.

Whether the whales are out for revenge (they have plenty of reasons to be stressed), playing, or just victims of parasites does not change the conflict that has arisen in addition to the one with the fishermen, nor the stress caused by the constant noise and lack of prey in their hunting grounds. Unfortunately, the animals usually lose the battle, even though Orcas are protected in Spanish waters.

There are solutions that sound utopian in today's ruined world:

-Reduction of noise from shipping.

-Compliance with the whale watching law, especially the distance of at least 60 metres and the absolute ban on approaching Orcas from the 1st of March to the 31st of August in Spanish waters south of Tarifa to southwest of San Fernando.

-Linking a larger tuna quota for the fishermen of Tarifa to the protection of the Orcas. The abandonment of defensive methods by fishermen should be controlled.

-Prohibition of stunning tuna with electric shocks in the presence of Orcas.

If the Orcas stopped their attacks after that, we would know what the problem was.