Sharks vulnerable to over-fishing

Certain shark species migrate much less than previously thought, making them vulnerable to over-fishing, says a study.

The study also highlighted differences in the movements of male and female catsharks.

"It makes a lot of sense, females may want to stay in areas that are good for laying eggs, but males are often the dispersing sex, perhaps taking risks to increase how much they reproduce," said Andrew Griffiths from the University of Bristol in Britain.

The study used genetic techniques to investigate the population structure of the small-spotted shark, Scyliorhinus canicula.

The species is common throughout Europe and has been eaten since ancient times, as documented in Roman mosaics. In Britain, anglers catch it for sport and it can often be seen in rock pools at low tide.

The study found evidence of isolated populations in the Mediterranean Sea but no catshark population division was found around the north-east Atlantic and the British Isles.

The study appeared in the journal Royal Society Open Science.