Dr Eric Shaw’s take on attacks by killer whales documented recently in the Strait of Gibraltar
This summer a number of reports of killer whales (or Orcas) attacking leisure vessels in the Strait of Gibraltar and around the Portuguese coast began emerging. This species of dolphin is typical in this region during the summer months leading into September, however, reports of attacks are rare. Nonetheless, several reports of “deliberate attacks” have been described recently.
Scientists have proposed a number of causes for the interactions such as confusion, defensive behaviours or possibly a newly learned behaviour. These large animals are known to hunt tuna in these areas, and in recent times they have been noted as stealing tuna caught by Spanish or Portuguese fisherman. Obviously, this also results in an increase in interactions between these animals and humans. Dr Eric Shaw has worked with the dolphins in the Strait of Gibraltar for a number of years has proposed a potential explanation for these attacks:
“From what I’ve heard people describe or read in various articles, I think this is protective behaviour that is taking place. The first report was from the coast of Portugal and in the Bay of Biscay. These areas are well known for Tuna following the fish along the continental shelf at this time of year. In the marine world, we know food follows food, and fingerlings of smaller species are moving into deeper water where they become prey to larger species, onwards and upwards to the largest within the ocean.
What was interesting to read in the reports that it was taking place in the Straits also (lots of Fingerlings here too). Two places far apart at the same time, suggests they’re not the same family of Orcas. The reports stated that sailing vessels were being attacked. When a monkey bites you or a dog, we humans always say we have been attacked, but one question that needs to be answered was if the “attack” provoked in some way. There have been cases of sailing boats being sunk or damaged in the open sea by large whales these are in the singular, and all vessel owners state it was unprovoked!
What has not been considered is why these surface-dwelling Dolphins that “attack”, and only target sailing boats would be motivated to do this? We need to contemplate that Orcas have also bred at the same time as the small fish that they follow, there will be young that are being protected by the rest of the family from interlopers, or in our case rubberneckers. A sailing boat moving silently toward a pod of Orcas with young while they are following food would be seen as a threat. This strange animal with a strange tail that needs to be neutralised, finishes up with its tail/rudder damaged and so immobilised it is. So who was attacking who?
In my opinion, people tend to get far too close to wildlife on land and on the sea. Humans forget that they are perceived as a threat and will be “taken care of” by the defenders of the pods if they sail in a threatening manner. Notwithstanding all the above journalists do love a good story”.
It is likely that these Orcas were acting in a defensive manner, likely protecting younger or more vulnerable members of their pods. Interactions between marine life and humans are increasing at an unprecedented rate, the fact lies that humans are encroaching on the habitat of these animals. As such, these orcas feeling insecure because of boats is understandable. This highly intelligent species likely understand that these boats may cause harm and as such, will attack to protect themselves. That almost all reports mention attacks on the rudder of boats is interesting. This is similar to behaviour documented in the wild. As Eric states, by attacking the tail of an animal, Orcas understand that the individual is now immobile and thus no longer a threat. It is possible they are replicating this behaviour on vessels, targeting the same “anatomy” they know well; again highlighting their intelligence.
Recently, CEMMA (Coordination for the study of Marine Mammals) have published a study on a family of Orcas they believe to be responsible for a number of the attacks. Three juveniles known as White Gladis, Grey Gladis and Black Gladis, have been involved in around 61% of the reported incidents over the summer.
These three individuals exhibited a range of wounds caused by fishing lines or interactions with vessels (see CEMMA’s image of Black Gladis left) which are believed to have occurred in early summer before the attacks began. CEMMA scientists have stated that while the attacks may not be directly motivated by revenge, a higher instance of injuries associated with boats, may leave these individuals defensively cautious of vessels approaching them.
Whatever the cause of the interactions, the Orcas are no longer in the Strait but will return next summer. The best course of action would be for any vessel to give all marine mammals a wide berth going forward, at the end of the day we are in their habitat. A bit of respect towards these animals would go a long way.