NOAA scientists find killer whales in Antarctic waters prefer weddell seals over other prey

Mar 30, 2011
Killer whales generate a wave designed to knock the resting Weddell off an ice floe near the western Antarctic Peninsula. Credit: Robert Pitman/NOAA

NOAA's Fisheries Service scientists studying the cooperative hunting behavior of killer whales in Antarctic waters observed the animals favoring one type of seal over all other available food sources, according to a study published in the journal Marine Mammal Science.

Researchers Robert Pitman and John Durban from NOAA's Southwest Fisheries Science Center in La Jolla, Calif., observed hunting in ice floes, off the western during January of 2009. While documenting the whales' behavior of deliberately creating waves to wash seals off ice floes, the researchers noticed Weddell seals as their primary target, despite the availability of other , particularly the more abundant crabeater seals.

"These killer whales would identify and then attack Weddell seals almost exclusively, even though they made up only about 15 percent of the available ," said Pitman.

Killer whales creating waves to wash seals off ice floes in Antarctica had previously been observed only a handful of times. The whales, sometimes as many as seven abreast, charge the ice floe creating a wave that either washes the seal off the ice or breaks the ice into smaller pieces and more vulnerable to another attack. A previous study involving the authors suggested that this very distinctive killer whale population, which they refer to as "pack ice killer whales," is a separate species.

Once the seal was washed off the ice, the killer whales worked as a group to keep it away from hauling onto the safety of another ice floe. The whales seemed to try and confuse the seal by causing turbulence in the water with their flukes and blowing bubbles under the water through their blowholes.

Away from the ice, the whales attempt to tire and eventually drown the animal by pulling it under water by its hind flippers. Eventually the seal succumbs to exhaustion and is usually divided up among the pod members underwater. In most cases, little of the seal's remains float to the surface, but in one instance the carcass rose to the surface and appeared to have been methodically skinned and dismembered before being eaten.

Explore further: Science casts light on sex in the orchard

add to favorites email to friend print save as pdf

Related Stories

Activists, Japan whalers clash in Southern Ocean

Jan 01, 2011

Militant anti-whalers Saturday said they had clashed with Japanese harpoonists in the Southern Ocean, chasing them through ice packs, throwing stink bombs at them and being hit with water cannon.

Recommended for you

'Divide and rule'—raven politics

5 hours ago

Mythology has attributed many supernatural features to ravens. Studies on the cognitive abilities of ravens have indeed revealed that they are exceptionally intelligent. Ravens live in complex social groups ...

Science casts light on sex in the orchard

Oct 30, 2014

Persimmons are among the small club of plants with separate sexes—individual trees are either male or female. Now scientists at the University of California, Davis, and Kyoto University in Japan have discovered ...

Four new dragon millipedes found in China

Oct 30, 2014

A team of speleobiologists from the South China Agriculture University and the Russian Academy of Sciences have described four new species of the dragon millipedes from southern China, two of which seem to ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.