The first great white shark seen to cross from one side of the Atlantic to the other may be pregnant, says the head of the expedition tracking her.
At the weekend, the satellite-tagged fish, called Lydia, crossed the Mid-Atlantic Ridge, which marks a rough boundary line between east and west.
She has now turned towards the UK, but it is unclear where she will go next.
Chris Fischer told the BBC he thought she was pregnant and heading for birthing grounds in the Mediterranean.
Mr Fischer, who is expedition leader and founding chairman of the Ocearch shark tagging venture, said that if Lydia continued on to Europe or Africa, she was likely to become "more coastal".
He told BBC News: "I certainly think that it's possible for Lydia to make it to the UK." But he said that he could not know if that was where she was heading.
Mr Fischer said there had been sightings of great white sharks in UK waters before, but added: "I think these were anecdotal versus a documented presence. So hopefully we'll be able to help with that."
On Sunday (GMT) , Ocearch announced that Lydia had crossed the ridge into the eastern Atlantic. And although it is often argued that the waters of these isles are too cold for the sharks, Mr Fischer cast doubt on this.
"One thing we have learnt just in the last year with sharks in the Atlantic is what we used to think was too cold simply is not," he said.
"Lydia has come over from Nova Scotia [in eastern Canada]… These sharks have the capacity to deal with very cold water temperatures for long periods."
But he said: "If I had to guess, I would guess that Lydia is pregnant, and that she has been out in the open ocean gestating her babies, and that this spring she will lead us to where those baby white sharks are born – the nursery."
Mr Fischer, who has led numerous ocean expeditions, added: "If you forced me to guess where that was, I'd say it was over in the Mediterranean, near Turkey… but that's longball I'm playing. She could turn around right now and head back to Florida."
He said that small white sharks had been observed in the Aegean Sea before, but scientists working on the team did not share his view. This was because preliminary analysis of blood samples from Lydia suggested she was not pregnant at the time of her tagging.
But Mr Fischer defended his theory, saying there were still uncertainties over the way that white sharks become pregnant, adding: "The sperm from the male comes in a packet with a shell on it. They can carry it around for a while until a special organ inside them breaks down the shell and they get pregnant.
"We know it's 18 months from when we discover the breeding aggregation to when they lead us to the nursery… What we don't know is how long do they carry that sperm packet and how long is it until their body breaks down the shell."
Written By: Paul Rincon
continue to source article at bbc.com