The aggressive behaviour of Orca towards yachts seems to be increasing with many more instances in 2023 than in the previous yearScientists believe that orca interactions are learnt behaviour, and it is unlikely it will spread to other groups, although not impossible. Credit: Groupo Trabajo Orca Atlantica (GTOA)
Orcas have now sunk three yachts off the Iberian coast in the past 18 months and have attacked over 100 other yachts in increasingly aggressive behaviour, with scientists speculating that juvenile orcas could be imitating the behaviour of adult orcas and that this behaviour has then spread.
Data from the Cruising Association, which works alongside Spanish and Portuguese scientists at the Groupo Trabajo Orca Atlantica (GTOA), shows that the number of orca attacks on yachts has increased in the last few months.
‘In the first three months of this year, there has been a dramatic increase (16 incidents as opposed to 2 last year),’ said John Burbeck, orca project leader at the Cruising Association. ‘In May, with 10 incidents reported, it has already exceeded the total for last year and it doesn’t look like it is going to let up. May has been very, very busy.’
The orca interactions with boats appears to be linked to the migration of tuna exiting the Mediterranean through the Strait of Gibraltar and heading west and north around the Iberian Peninsula into the Bay of Biscay.
‘The behaviour of orcas varies wildly, sometimes it is a single orca that approaches or sometimes they come in a group. Sometimes it appears that adults are standing off and directing juveniles,’ said John Burbeck. ‘Sometimes the orcas come at the yacht with a violent blow and cause significant damage immediately. Sometimes a group of orcas come in and play with the boat for extended period of up to 90 minutes’
Although most encounters between orcas and yachts are harmless, scientists are struggling to explain the orcas’ increasingly aggressive behaviour. Biologist Dr Alfredo López Fernandez from the GTOA told Live Science that a traumatic event may have triggered a change in behaviour of one orca, they have named White Gladis, and that other orcas may be imitating her. They believe that some 15 orcas out of a population of around 50 are responsible for the attacks.
”The orcas are doing this on purpose, of course, we don’t know the origin or the motivation, but defensive behaviour based on trauma, as the origin of all this, gains more strength for us every day,” López Fernandez said in an email to the website.
The scientists believe White Gladis may have suffered a ”critical moment of agony” — a collision with a boat or entrapment during illegal fishing — that changed her behaviour. ”That traumatised orca is the one that started this behaviour of physical contact with the boat,” López Fernandez said.
He added that the scientists do not interpret the data as the older orcas teaching the young, merely that the younger orcas experiment with imitation. Orcas are intelligent, social creatures that can easily learn and reproduce behavioural patterns.
”We do not interpret that the orcas are teaching the young, although the behaviour has spread to the young vertically, simply by imitation, and later horizontally among them, because they consider it something important in their lives,” López Fernandez said.
The behaviour of the orcas peaks between May and October. Credit: Zoe Barlow
In 2022, there were 132 interactions with orca, with 99 yachts damaged and two sinking, data from the CA showed. There were also 256 uneventful passages. Around 25% of the damaged yachts needed to be towed to port.
The latest yacht to be struck was on the night of May 4 when three orcas left the Swiss yacht without a rudder, causing the crew to abandon ship. The Spanish coast guard towed the yacht but it sank before reaching port.
The orcas specifically attack the rudders, bumping them, chewing them and breaking them off. The interactions last between 10–90 minutes and involve between 1–6 orcas. The interactions take place during the day and night, although are slightly more common at dawn and dusk.
The majority of the 2022–23 interactions are down near Gibraltar (69 interactions), with Galicia, northwest Spain, the next most common location (43).
‘Our advice at first is to avoid the orcas,’ said John Burbeck. ‘To avoid interactions, stay less than two miles off shore and navigate in less than 20 metres of water.’
The GTOA operates a traffic light information system on orca sightings. There are also two apps: GT Orca and Orcinus which give information. A Facebook page Orca Attack Reports gives information as does Orca Discussions on Telegram.
The CA this month launched an updated orca information portal. It is urging all sailors to report interactions and safe passages at the portal: www.theca.org.uk/orcas
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The post Adult Orca seem to be passing on yacht attack behaviour to adolescents appeared first on Yachting Monthly.