Home Sciences Killer whales are learning to ‘steal’ fish from humans

Killer whales are learning to ‘steal’ fish from humans

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The legends of the Spanish sailors of the 18th century led to orcas being known as a ‘killer’ animal, given their cunning, speed and lethality when hunting their prey. Today, science shows that these marine mammals are much more than those fearsome beings from the tales of yesteryear. Their intelligence and resilience have been essential to allow them to adapt to a much more difficult world, where the inclemency and the scarcity of food generated by the human being has forced them to become true experts in looting. The killer whales have learned to steal fish in order to survive.

Your goal in this new skill is focused on deep fishing activities. Without fear and with a polished technique, these cetaceans they are able to get food in the fisheries exploited by man as if it were an ‘open bar’.

This has been shown by a recent investigation, published in the journal Biology Letterswho also discovered that It is not an isolated fact or that it is part of the behavior of a few especially skilled killer whales, since this procedure is beginning to be learned in a habitual way among the pods as another hunting method.

“Our results show how changes in prey availability due to human activities lead to rapid and progressive innovation in killer whales”, point out the scientists, who explain that the new behavior can even “alter the ecological role of this apex predator”. The work involved studying the eating habits of killer whales living off the coast of the Crozet Islands, which are located in the southern Indian Ocean.

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In this archipelago, the commercial fishing of Patagonian black hake, also known as Chilean sea bass, has been highly developed. Since the 1990s, fishing for this animal has gradually increased. Patagonian toothfish are caught with longlines along the ocean floor, usually using large fishing lines with a large number of hooks that catch individual fish.

The environmental impact is very high, as these fish reproduce very infrequently. In fact, they do not reach sexual maturity before 20 months and constitute a vulnerable species in situations of overfishing, for which the Convention for the Conservation of Antarctic Marine Living Resources limits their fishing by setting quotas. For this reason, overfishing can cause great damage to the ecosystem and this is already being reflected in the behavior of its predators.

lose their fear of stealing

Previous research had shown that killer whales residing in this area prefer to feed on toothfish. At the same time, local fishermen and marine scientists had noticed that killer whales they are less and less afraid to swim into human-populated areas to steal fish directly from fishing netsor from eating the remains of discarded fish after they have been gutted.

Noting such incidents were on the rise, the researchers wondered if it was because more killer whales were heading to the area to steal the fish, or if these area mammals were learning how to make such raids. Analyzing data from 2003 to 2018, they noted that cases of killer whales eating fish off hooks were indeed increasing.

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In 1996 it was reported for the first time that an orca, from the populations that scientists studied, had fed on fishing catches. By 2014, 80 of the 100 killer whales in the group had started doing so.

Behind this behavior is overfishing. In the 2000s, as the toothfish population declined, killer whales found it much harder to make a livinguntil one day they realized that the humans had left them a whole ‘free rod’ in the fishing lines.

The scientists were surprised to see that the killer whales had not only managed to adapt to the new food needs in a short period of time (in less than 30 years), but also they were also teaching each other to do it. “Given that a part of the behavior of killer whales is learned through socialization, it can be expected that predation is transmitted from those who have invented it to the rest of the group”, they highlight in the research.

In short, the study shows how these socially complex animals respond to the alteration of their environment by human activity. “The human, by altering the availability of resources in ecosystems, can lead to new behaviors that spread between individuals of species capable of innovating in response to changes in their environment”, they sentence.

They also insist that “fishing can generate feeding opportunities for large marine predators in the form of discards or accessible catches.”

Reference report: https://royalsocietypublishing.org/doi/10.1098/rsbl.2021.0328

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