Orca Have Started Eating Fish Caught on Hooks in Buffet-style Meals

Orca have started eating fish caught on hooks, treating fishing lines like a buffet, scientists have said.

Researchers led by Morgane Amelot, from Australia's Deakin University, tracked the feeding behavior of two groups of orca around the Crozet Islands in the southern Indian Ocean between 2003 to 2018 to observe the number of individuals using fishing boats to feed.

Orca are highly intelligent animals and have been known to change their behavior depending on their environment. They feed on fish and squid but will also target larger animals such as seals, sea birds and even whale species far bigger than themselves.

More recently, a group of orca have even been hunting and killing great white sharks.

While orca have been known to take advantage of fishing hooks for an easy meal since the mid-1990s, the latest study, published in the Royal Society Biology Letters, shows how quickly this new behaviour has spread throughout their population.

Over the study period, the number of individual orca snatching fish off hooks had significantly increased in both groups from 34 to 94, and 19 to 43.

Amelot told Newsweek that the study shows how orca have learnt this new behavior in reaction to human activity. By expanding their fisheries around the world, humans have accidentally provided the whales with a new source of food.

Killer whale
A stock image shows a killer whale in front of a fishing boat in the Atlantic Ocean Alessandro De Maddalena/Getty Images

"There are plenty of mechanisms that have to be explored to understand how killer whales learned this behaviour and how it spread between individuals and groups," Amelot said. "This mechanism does not only exist in killer whales population but also other species. This study is a step forward to understand how [the behavior] has spread in the marine mammals population."

The report also said that the development of this new behavior could lead to changes in the role of killer whales as predators in ecosystems.

It could decrease pressure on other prey in the short term, and could also enhance orca populations in the long-term, as fish being so readily available positively influenced females having healthy calves.

Killer whales can be found in all oceans around the world, however they are most common in colder waters like Antarctica, Norway, and Alaska.

Concluding, the team said the study shows how quickly orca can respond to new food sources and how humans are influencing the diets of these top predators. "This study is illustrative of how human activities, by altering the availability of resources in ecosystems, may lead to new behaviours spreading across individuals of species capable of innovating in response to changes in their environment," they wrote.