Killer whales teach fellows to steal fish from fishermen

Scientists have discovered that killer whales begin to eat fish from fishermen's nets and see it as an easy source of food.

The team led by Morgane Amelot, from Deakin University in Australia, tracked the feeding behavior of two groups of killer whales around the Crozet Islands in the southern Indian Ocean from 2003 to 2018.

Killer whale swims in front of a fishing boat.

Killer whales are highly intelligent animals that can adjust their behavior depending on the environment. They eat fish and squid, but also target larger animals such as seals, seabirds, and even whales. Recently, a group of killer whales in South Africa even hunted great white sharks for their livers.

Although fishermen have been accustomed to killer whales using hooks to make easy meals since the mid-1990s, the latest research published on February 2 in the journal Royal Society Biology Letters reveals this new behavior. how quickly it spreads in a population. During the study period, the number of killer whales stealing fish from hooks increased significantly in both groups, from 34 to 94 and 19 to 43, respectively.

According to Amelot, the study shows how killer whales learn new behaviors in response to human activity. Through the expansion of fishing grounds around the world, humans unwittingly provide killer whales with a new source of food.

"There are many mechanisms that need to be explored to understand how killer whales learn behavior and propagate between individuals and swarms," ​​Amelot said. "This mechanism exists not only in killer whale populations but also in other species. This study is a step forward in understanding how the behavior became widespread in cetacean populations."

The development of new behaviors could change the predatory role of killer whales in the ecosystem. It can ease pressure on predators in the short term, and strengthen killer whale populations in the long term as the availability of fish has a positive effect on nursing females.

Killer whales live in all oceans around the world, but they are most common in cold seas like Antarctica, Norway and Alaska. Amelot and colleagues conclude the study reflects how quickly killer whales respond to new food sources and the impact humans have had on the diet of this top predator.