Monday, January 24, 2011

Whales eating whales

Aptly-named killer whales in Alaska seem to be quite fond of eating baby grey whales.

The babies are separated from their mothers and held underwater until they drown. Then, after a good feed, the killer whales store the carcases in shallow water and come back days later to eat again.

These hunting methods are unique and carried out by a group of perhaps 150 killer whales, with the result of nearly 1/3 of eastern Pacific grey whale calves being eaten each year, from a total grey whale population of around 20,000.

Sharks and brown bears benefit by eating the scraps underwater or the carcases that wash up on the shore. One baby whale carcas quickly attracted a group of 19 brown bears. In this way, healthy grey whale populations provide an important food resource for ocean and land animals.

All of this happens around Unimak Island in Alaska, a group of killer whales specialize in grey whale calves, even though their prey is close to their own size and their protective mothers are much larger than the killer whales.

Here's an unrelated video of a killer whale attack on a baby grey whale. Yikes.

2 comments: said...

It is a pretty amazing life cycle. Thanks for the video as well. I do appreciate your reporting as it paints a more correct picture about these creatures and that they are endangered.

People are prone to think that it is only whaling that is the issue. Well it is, but with the current research going on around the world, the attrition of these giant gentle mammoths is also due to predation from other species.

So when you add Man into the equation and his technology, you have a real situation.

And then there is the issue of krill. Only in the past few years medical science has discovered a use for the oil from krill. Now krill are harvested in the millions by fisherman. That means less of a food source for whales. And krill populations are diminishing.

They are diminishing for a very interesting reason, in addition to over fishing. Whale feces. You see, whale feces is highly nitrogen enriched. Plankton feed on the feces and multiply. Small sea crustaceans feed on plankton, including krill. And where the whale population numbered in the millions, well it is in the tens of thousands now due to whaling.

And guess what? The population of the krill is diminishing at the same rate. Hmmmmmmmmmm....

So when you double the killing rate, I guess you really affect the marine ecosystem.

Thanks again for your post.

mountain bikes said...

is grey whales bigger than killer whales when they grow up?