Killer dolphins baffle marine experts

[Abdul Alhazred]

Killer dolphins baffle marine experts The Telegraph (UK)

New evidence has been compiled by marine scientists that prove the normally placid dolphin is capable of brutal attacks both on innocent fellow marine mammals and, more disturbingly, on its own kind.

Film taken of gangs of dolphins repeatedly ramming baby porpoises, tossing them in the air and pursuing them to the death has solved a long-term mystery of what causes the death of so many of these harmless mammals - but has left animal experts baffled as to the motive.

Another mystery is that the animal 'murders' have only been reported in two parts of the world - along Scotland's East Coast and in America off the beaches of Virginia, where even more alarmingly, the victims were scores of the dolphins' own young.

The first clues to solving the riddle came in 1997 when, by coincidence, marine biologists in Virginia were finding young, dead dolphins with horrific internal injuries at the same time as young porpoises were washing up on Scotland's north-east coast with identical causes of death. The body count was growing in both locations.

The two groups of biologists pooled information and, at first, it was believed the mammals had died through 'blast trauma'. In American cases, this was supposedly from exercises by the US Navy, and in Scotland from air guns used by oil rig technicians to detect undersea caverns.

This theory was dismissed after further examination of the mammals' bodies revealed the injuries - broken ribs, imploding lungs, damaged livers and massive internal bleeding - could only have come from prolonged, focused attacks.
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When tell-tale teeth-marks were identified, the dolphin - the mammal classified as one of the world's most intelligent, sensitive and sociable creatures - became the official suspect.

Confirmation of the murders came by way of two shocking films shot by holidaymakers.

...

I don't see why marine experts are baffled, just because they never witnessed it before.

Or is that just a case of headline-writer's disease?

 

[latent aaaack]

It could be something akin to what's happening to many elephants in Africa and Asia. They're family/hierarchical structure is being disrupted by human activity causing social problems among newer generations.

Or dolphins could just be like humans and there are always some bad apples.

Or it's those jumping and fish catching games so many young dolphins play all day nowadays, corrupting them.

 

[robinson]

Whenever I see the words "scientist are baffled" I mentally change them to "scientist make new discovery, but can't explain why".

 

[CFLarsen]

Those dolphins must have bad auras.

 

[Cainkane1]

maybe theres a food shortage and they don't want the competition?

 

[Madalch]

It's all those cruise ships playing rap music at them.

 

[godless dave]

Or is that just a case of headline-writer's disease?

That's what I suspect. None of this behavior seems new. More like "scientists observe typical dolphin behavior in wild; journalist who watches too many cartoons and not enough nature documentaries confused"

 

[robinson]

I suppose you could read the report from the scientist, instead of the news article.

 

[Garrette]

I suppose you could read the report from the scientist, instead of the news article.

Good lord, man! What is wrong with you? Think of the widespread panic!*


*Amongst the media

 

[MWare]

Every once in a while ya just gotta flex that pimp snout.

 

[Abdul Alhazred]

That's what I suspect. None of this behavior seems new. More like "scientists observe typical dolphin behavior in wild; journalist who watches too many cartoons and not enough nature documentaries confused"

 

[Molinaro]

Didn't the US military train dolphins for stuff?
Could this be a Rambo like post traumatic stress suffering group of ex GI's?

 

[AK-Dave]

I think the scientists were truly baffled by this one. Initially, it was believed that humans were using baseball bats or similar blunt weapons to kill the young dolphins. It was several years before they realized what was really causing the deaths. I think the initial public belief that humans were the cause probably tainted the scientific investigation. I saw a show on this investigation a year or so ago, so my details may be a bit fuzzy. I remember when this was on the news and in the papers as they were finding the corpses.

-David

 

[Floyt]

If there was a tad more evidence for actual social transmission and the like among dolphins, this really would sound like an evil cult, or a civil war, or an extremist movement

 

[Big Les]

"The Dolphin Murders", indeed. What's next - The Chimp Rapes?

 

[INRM]

Well I guess when you get a carnivorous animal with nearly the intelligence we have, I guess you're going to have room for barbarism and brutality.

After all, humans are pretty much world renown for having the capability being barbaric, brutal and cruel, even to our own species (capability being the key word, most of us do not excercize this capability).


INRM

 

[George]

It's just the're way of saying 'thanks for all the fish'.

 

[robinson]

Dolphins have been reported raping females. Gang rape. I wonder if it is like lions who kill all the young when they take over a pride. Kill the young so they can breed.

Nature is mysterious. Baffled, they shouldn't use that word. It doesn't mean "we had no idea this was happening", it means baffled.

 

[kellyb]

I wonder if it is like lions who kill all the young when they take over a pride. Kill the young so they can breed.

That was my first thought, too. I don't know much about their social structure, though.

 

[m_huber]

From the article in the OP:

Theories abound on the reason behind the mammal murders. These have included territorial clashes and feuds over food resources. But food is not in short supply and the victims are not just chased away but pursued to the death.

Another belief is that dolphin attacks on their young may be down to mating instincts, because when her calf dies the female dolphin is ready for mating again. But the experts are still not positive that it is only males who do the attacking.

And, incredibly, they can only guess that the attacks by bottle-nosed dolphins on Scotland's harbour porpoises is some kind of bizarre 'target practice.'

I found articles about dolphin infanticide dating back to 98 and 99.
Here's one:
http://www.sciencenews.org/pages/sn_arc98/7_18_98/fob1.htm

The attacks on dolphins less than a year old have spawned numerous theories. "Probably my favorite is male infanticide," notes coauthor Paul Thompson from Aberdeen. If a new suitor approaches a female that already has a youngster, "there's no point in hanging around for two years with the wrong male's calf," he says. Killing the calf might bring the female into a receptive state much sooner.

From dolphin studies in Shark Bay, Australia, Richard C. Connor of the University of Massachusetts at Dartmouth and his colleagues predicted killer males. Although they observed no infanticide, they noted that females become fertile within 1 to 2 weeks of losing an infant.

Murderous stepfathers are certainly a possibility, agrees Susan Barco of the Virginia Marine Science Museum in Virginia Beach, who collaborated with Dunn. "We're still very baffled about what is going on," she says.

In 1997, she found more than four times as many dead young dolphins as she did in 1994, raising the possibility of a boom in infanticide. "I have the feeling that in the past year, it probably became acute," Barco says.

Marine mammal specialist John Harwood from University of St. Andrews in Scotland notes that "these results are remarkably similar to those for large terrestrial carnivores like lions." Young males sometimes jump-start their dynasties by killing off another's offspring, he says. "It suggests that the evolutionary pressures in the marine environment are not so different from those on land."