At least 40 were reported between July and October attacks by groups of killer whales to boats that sailed in different areas along the coasts of Spain and Portugal, both in the Cantabrian Sea – in the north of Spain – and near the Strait of Gibraltar. These episodes, in addition to having frightened those on board, surprised the marine biologists, because it is a rather unusual behavior. Give her searches carried out in recent months, some hypotheses have emerged on which most scientists agree: they would not be attacks made to threaten man, as some newspapers had hypothesized, but a particular form of game.
According to the people who suffered these attacks, the killer whales appeared to have targeted their boats, chasing them and hitting them repeatedly for tens of minutes – especially the sailing ones. In September the boat of a man sailing from Spain to Scotland was approached by an orca which for about 45 minutes hit and bit into the rudder, also breaking through a portion of the side of the hull and spinning the boat on itself. In October an English skipper who was about thirty kilometers from the city of Porto said he had a bad time because he could no longer control the boat: “I don’t get scared easily, but it was terrifying.”
It is not unusual to see killer whales in these parts of the Atlantic Ocean: it is in these waters that they hunt bluefin tuna – one of their favorite prey – and it is by passing through the Strait of Gibraltar, which separates Europe from Africa, that they reach the warmest waters of the Mediterranean, where they reproduce. However, such behavior had never been observed, and although there had been no deaths in various newspapers, there was talk of “killer whales” who were “plotting attacks“; the British tabloid newspaper Sun, for example, had written that the killer whales were “on the hunt for blood” to take revenge on the poachers’ harpoons. In fact, according to scientists there are more rational explanations for these “attacks”.
“Killer whales have always been curious about boats” and that’s why they approach them, he said a BBC killer whale expert Ruth Esteban, who is part of the team of scientists who are analyzing the cases together with the marine biologist Renaud De Stephanis, one of the founders of the organization for the study and conservation of cetaceans CIRCE (Conservation, Information and Study on Cetaceans).
The experts compared the images from the CIRCE archive with the videos of this summer’s episodes and noted that the killer whales mainly aim at the rudder of the boats and attack the hull less frequently. Esteban then hypothesized that the killer whales hit the rudder as a game, because it is a mobile part of the boat that allows them to move the entire boat and therefore to show their strength: something that according to Esteban “perhaps excites them a lot” but that it can obviously do damage to boats and to those on board.
The photos and videos also allowed the researchers to identify the animals thanks to the particular spot behind their dorsal fin, unique to each killer whale, and thus come to another interesting conclusion.
In most cases, in fact, the attacks were carried out by three specimens of young males, who in the official records had been called black Gladis, white Gladis and gray Gladis. As explained by De Stephanis, killer whales are silent and stealthy while hunting, and this allows them to attack even larger animals, such as sperm whales (a sperm whale can weigh up to 45 tons, while killer whales range from 4 to 6). Aggressive behavior and displays of strength towards boats could therefore be part of a kind of training ‘game’.
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Killer whales live, move and hunt in closely related family groups, where the female is in charge. Generally the grandmother teaches the young to hunt, and often the young males migrate, mix and mate with other groups, teaching and learning different hunting techniques and methods of communication. As he explained Michael Weiss, a researcher at the University of Exeter (England) and the Center for Whale Research in Washington state, the game could create “strong social bonds” between the killer whales.
Furthermore, the killer whale brain has several parts similar to the human one and one of them is the sistema limbico, which includes brain structures that involve, for example, emotionality and instinct. From this point of view, according to neuroscientist Lori Marino, who is president of the organization Whale Sanctuary Project, it might be useful to observe the behavior of the killer whales, because if they appear to be angry, happy or in pain “that’s probably what they’re feeling.”
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According to what CIRCE has reconstructed, currently there are about sixty orcas living off the Spanish and Portuguese coasts. In 2011, only 39 were registered, a number that according to the organization was due to the decline in bluefin tuna also due to the increase in fishing in the Mediterranean and Atlantic waters, and which only started to grow again after the introduction of read for the protection of the species.
A further and partly alternative explanation for the attacks had so far been linked precisely to the fact that the area of the Strait of Gibraltar is full of fishing nets and lines, in which killer whales get entangled from time to time: the researcher of the University of Seville, Rocío Espada, had therefore supposed that stress or the idea of danger could also be among the triggering reasons for the orcas attacks.
In the mid-1990s, researchers noted that a small group of killer whales had begun stealing tuna from fishing boats or eating them through fishing nets dragged into the sea; they then observed that the group had expanded and that the “thefts” of fish had increased. According to De Stephanis – who has found no evidence but believes that the three Gladis are part of this group – the killer whales in no way want to take revenge or deliberately harm the boats that follow: the increase in bluefin tuna fishing could however have led to a change in killer whales and a new predatory culture that could help them survive.
De Stephanis said that killer whales “play, play and play”, but that the game is becoming more and more dangerous and is starting to worry even the experts. Meanwhile, the Portuguese and Spanish coast guards have banned the movement of sailboats in some of the areas where attacks have been reported.