RICHMOND, Va. - Scientists have confirmed the second case of a "virgin birth" in a shark.

In
a study reported Friday in the Journal of Fish Biology, scientists said
DNA testing proved that a pup carried by a female Atlantic blacktip
shark in the Virginia Aquarium & Marine Science Center contained no
genetic material from a male.

The first
documented case of asexual reproduction, or parthenogenesis, among
sharks involved a pup born to a hammerhead at an Omaha, Neb., zoo.

"This
first case was no fluke," Demian Chapman, a shark scientist and lead
author of the second study, said in a statement. "It is quite possible
that this is something female sharks of many species can do on
occasion."

The aquarium sharks that
reproduced without mates each carried only one pup, while some shark
species can produce litters numbering in the dozen or more. The
scientists cautioned that the rare asexual births should not be viewed
as a possible solution to declining global shark populations.

"It
is very unlikely that a small number of female survivors could build
their numbers up very quickly by undergoing virgin birth," Chapman said.

The
medical mystery began 16 months ago after the death of the Atlantic
blacktip shark named Tidbit at the Virginia Beach aquarium. No male
blacktip sharks were present during her eight years at the aquarium.

In
May 2007, the 5-foot, 94-pound shark died of stress-related
complications related to her unknown pregnancy after undergoing a
yearly checkup. The 10-inch shark pup was found during a necropsy of
Tidbit, surprising aquarium officials. They initially thought the
embryonic pup was either a product of a virgin birth or a cross between
the blacktip and a male of another shark species — which has never been
documented, Chapman said.

Tidbit's pup was
nearly full term, and likely would have been quickly eaten by "really
big sand tiger sharks" that were in the tank, Chapman said in a
telephone interview from Florida.

That is what happened to the tiny hammerhead pup in the Omaha case.

"By
the time they could realize what they were looking at, something
munched the baby," he said of aquarium workers. The remains of the pup
were used for the DNA testing....

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