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 blacktip shark in a Virginia aquarium contained no genetic material from a male.
The first documented case of asexual reproduction 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 scientists cautioned that the rare asexual births should not be viewed as a possible solution to declining global shark populations. The aquarium sharks that reproduced without mates each carried only one pup, while some species can produce litters of a dozen or more.
"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 Tidbit, a blacktip shark that had lived for eight years at the Virginia Aquarium & Marine Science Center in Virginia Beach. No male blacktip sharks were present during her eight years.
In May 2007, the 5-foot, 94-pound shark died after it was given a sedative before undergoing a yearly checkup. The 10-inch shark pup was found during a necropsy, surprising aquarium officials. They initially thought the embryonic pup was either the 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.