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Mike Follows
Sutton Coldfield, West Midlands, UK
Orcas are among the ocean’s top predators, yet there is only one well-documented attack on a human in the wild: in 1972, a surfer was bitten – probably because he was mistaken for a seal – but survived. Humans simply do not feature on the orca menu and this can be explained by diet, culture and context.
Different orca populations have different specialisms. In the North Pacific, residents mainly eat fish, transients hunt marine mammals, such as seals and porpoises, and offshore groups appear to focus on sharks.
Predators – and orcas in particular – pursue what they know, and humans are neither familiar nor nutritious. Calves acquire hunting skills culturally, observing mothers and podmates over several years. Humans, being unpredictable and relatively small, do not appear in these learned traditions. In the wild, encounters usually involve curiosity – a nudge or an inspection of a boat hull – rather than predation.
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Predators – and orcas in particular – will pursue what they know, and humans are neither familiar nor nutritious
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Captivity presents a different scenario. Orcas are wide-ranging, social and intelligent. In the wild, they travel tens of kilometres daily, hunt cooperatively and live in stable family pods. Captivity removes space, social structure and stimulation, often producing stress, frustration and boredom, which can manifest as aggression towards humans.
Since 2020, however, Iberian orcas have been damaging the rudders of yachts, occasionally sinking them. One explanation is that a matriarch known as White Gladis initiated the behaviour, perhaps in retribution for a prior injury, and others copied her. Another idea is that the rudders resemble the tails of Atlantic bluefin tuna – the orcas’ prey – and were used to train juveniles, but this seems unlikely as vessels moving quickly in water shallower than 30 metres are usually avoided.
Other factors may contribute. A rise in prey abundance may leave orcas with more time and energy for play. Meanwhile, more whale-watching excursions perhaps encouraged bolder behaviour around boats, and bored juveniles seeking stimulation may have started the fad of interacting with rudders. During the covid-19 pandemic, shipping traffic and noise declined sharply in the “anthropause”, although levels have since risen. Alongside this, the bioaccumulation of toxic polychlorinated biphenyls in orcas’ bodies and changes in other stressors, including shifts in prey availability, may influence orcas in ways that are poorly understood.
Sam Edge
Ringwood, Hampshire, UK
Orcas are social mammals and don’t generally eat other marine mammal predators such as dolphins – indeed various reports in Â鶹´«Ã½ detail orcas and dolphins cooperating during hunts. They may see us the same way. (They do hunt larger whales of course – the name “killer whale” may be a reversal of “whale killer”.)
Another possibility is that they are intelligent enough to realise that killing humans would make them more likely to be hunted down as a threat by the vastly larger number of humans than orcas that they observe.
Yet another possibility is that they do eat humans, but are smart enough to do it only when there are no human witnesses!
Heidi van Someren
Bottisham, Cambridgeshire, UK
My personal, not very scientific answer is that orcas usually feed in pods on large schools of fish. Humans swimming in small numbers could hardly be much more than a snack for one orca. Not worth the trouble.
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