Blob's Travels Win Seals of Approval

Researchers have identified one of the great seducers of the Southern ocean. An elephant seal called Blob travelled 3,200 miles from Macquarie Island in the south Pacific to father at least 19 pups in the Falklands in the south Atlantic.

Elephant seals do nothing by halves. Bull seals can grow to six metres (20ft) in length, weigh in at three tonnes and command a harem or 50 or even 100 wives. They can dive to depths of almost a mile and stay submerged for up to two hours on a single lungful of air. Now scientists from Britain, Italy and Brazil have pinpointed one very long-distance Lothario. The research, published in Science, is a demonstration of the power of genetics.

"We found Blob sort of incidentally. He was on the Falklands breeding grounds and we were doing a paternity study there," said Rus Hoelzel of Durham University.

"We identified him as one of the harem bulls. He had been quite successful, but his mitochondrial DNA told us that he wasn't from around there."

Mitochondrial DNA is inherited only from the mother. It is used to identify maternal descent - forensic scientists sometimes rely on it to identify murder victims, but it can also help conservation biologists read the the connections between animal colonies in unforgiving places. Blob's maternal DNA identified him as coming from Macquarie, south of Australia. The story of his epic voyage emerged entirely from a study of his genes.

"Just imagine if we didn't have genetic markers," Dr Hoelzel said. "You'd have to see the animal born.

"These guys don't reproduce until they are eight, nine, 10 years old: you'd have to follow them until then, and then observe that he had fathered these pups. And even then, you wouldn't be sure."

The research could answer questions about patterns in the southern elephant seal population. Elephant seals feed furiously, store massive amounts of blubber, and then stay hungry during the breeding season while they defend their harems. Nineteenth--century whalers and sealers almost wiped them out, until there were only about 20 seals left in the northern hemisphere and 1,000 in the southern waters. Numbers are probably back over the 500,000 mark.

"The males are quite aggressive to anything that stands upright, so if you stand upright, according to the male you are another male, and want his females," Dr Hoelzel said.

"This meant anybody could approach them with guns or clubs and wipe out whole rookeries, which they did."