Sharks inhabit less than a third of the world's oceans, a British study reveals.
Marine scientists believe the fearsome fish thrive only near the surface and cannot be found below 3000m where there is not enough food to allow them to survive.
The finding is a blow to researchers who
have spent years scouring deep, uncharted waters hoping to find new species.
The study was carried out by an international team.
A member, Professor Monty Priede, said all shark populations were in reach of human fisheries.
"As far as we can see, there is no hidden reserve of sharks in the deep sea.
"All we see is all there is and it is highly unlikely we are going to find any more.
"They are already threatened worldwide by the intensity of fishing activity, but our finding suggests they may be more vulnerable to overexploitation than was previously thought."
The deepest confirmed sighting of a shark was at 3670m.
- NZPA
