Female sharks always return to their birthplace to have babies

December 9, 2013 10:03 PM

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Female sharks always return to their birthplace to have babies

This is especially true when these magnificent creatures want to give birth after having wandered far and wide across the planet’s oceans for several years at time.

A 20-year study, conducted in the Bahamas, shows that despite their impressive travels, female lemon sharks always return to the same location where they were born to give birth.

The idea of females returning to their place of birth has been shown in a number of marine species, including salmon and sea turtles.

The international team, who reported their findings in the journal Molecular Ecology, said this is the first time this behaviour has been seen sharks.

‘We used each shark’s individual DNA fingerprint to construct a large family tree,’ explained Dr Kevin Feldheim at The Field Museum and the lead author of the study.

‘We found that new born sharks captured in the mid-1990s left the safety of the islands when they were between five and eight years old.

Lemon sharks are so-called because their yellow-brown pitted skin can have the appearance of lemon.

This helps them to blend in against sandy seafloors where they can lay motionless.

‘Yet, despite leaving and visiting many other islands in their travels, these sharks “remember” where they were born after a decade of roving, and are able to find the island again when they are pregnant and ready to give birth’.

The researchers don't know the reason behind the drive to return, but they believe it could be widespread in other shark species.

Many researchers had long-believed that female sharks have this ability, but up until now had never been proven because it is very difficult to keep track of sharks from birth to maturity.

‘The lagoon in Bimini is almost like a lake,’ said project founder Dr Samuel Gruber, president and director of the Bimini Biological Field Station Foundation.

Sharks live a long time and take many years to mature, which is one reason why they are extremely vulnerable to overfishing.

The researchers said that evidence that sharks use the same nursery areas across generations underscores the importance of preserving local nursery habitats.

‘When we tagged the first baby sharks in Bimini, Bill Clinton was President of the United States,’ said Dr Demian Chapman, a co-author of the study.

The Bahamas recently enacted a law to fully protect all sharks in its waters, which will, among other benefits, sustain an annual $80 million shark tourism industry.

‘National efforts to reign in the shark fishing industry by many countries are likely to benefit homing shark species, like lemon sharks,’ said Dr Chapman.

Source: dailymail.co.uk

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