Washington: Extracting shark DNA posed problems, not the least of which was carrying out biopsies on live and rather uncooperative specimens.

Now, two Macquarie University marine scientists, Heidi Ahonen and Adam Stow, have overcome the difficult procedure by taking samples from old teeth, discarded by wild sharks.

Extracting DNA from sharks is not as simple as with other animals, as they lack the bony skeleton so essential for traditional tooth extraction to work.

But since sharks replace their teeth throughout lifetime, old teeth may be collected from the sea floor in areas where sharks are known to assemble.

Other DNA sources could include trophy jaws and teeth found in museums and private collections.

"Sadly, trophy jaws and teeth from sharks are relatively commonplace, whereas living sharks are becoming increasingly rare," Ahonen said, when interviewed by Nature News.

"This method allows information locked away within the teeth and jaws to be exploited to assist with conservation management."

Ahonen and Stow used a hand drill to extract a small quantity of material from a shark's tooth or jaw. They then combined the material with a mixture of detergents and enzymes in order to release the DNA.

Their research has been published in the Journal of Fish Biology. IANS