Wednesday, 27 May 2015 08:50

Great White Shark Pups

Very little is known about the location of mating and pupping of Great White Sharks. A Great White Shark birth (and mating) has yet to be photographed/filmed/or otherwise documented anywhere in the world!  They are ovoviviparous, give birth to 2-14 live pups, and may only produce 4-6 litters in a lifetime. The size of newborn pups can be up to 1.5m, and they are highly mobile from birth, further complicating our understanding of where they are born.

Due to the warmer waters brought on by this year’s El Niño, baby shark season has officially begun off the Southern California Coast. White sharks throughout the world move inshore during certain seasons. It is very rare to see adult Great Whites along the Californian coastline. However, the presence of large adult females and then the immediate presence of young pups (<1.5m) strongly suggests that these waters are also a white shark pupping ground from spring – early summer

In Southern California, white shark pups favour many of the same coastal fish species that humans do, like halibut.  So it should come as no surprise that white shark pups are often caught accidentally by coastal fishermen as bycatch.     

Dr Chris Lowe and his students took advantage of this great opportunity to work with local fishermen in the area in order to study baby white sharks.  From their catch/tag/release study, the Lowe Lab found that these white shark pups follow fairly predictable behaviours inshore, staying shallower than the “isotherm” at 60m depth.  Isotherms are boundaries in the water column between warm surface waters and cold deep waters. White shark pups don’t stray deeper than the 60m mark, whether they are in relatively shallow waters or in the deeper waters of the continental slope.  This shows that their choice in habitat relates to water temperature. 

Dr. Lowe and his team release a juvenile white shark back to its inshore waters.

Fewer large predators and an abundance of food, like stingrays and flatfish, draw sharks to the shallower waters

The great white shark is most commonly associated with the coasts of Australia, California and South Africa, but there have been occasions when this increasingly rare animal has been spotted in the Mediterranean. Some experts believe that the Mediterranean is a nursery where great white sharks give birth. The Sicilian channel, near the Italian island of Lampedusa, is the only location in the Atlantic region where both pregnant females and newly born great whites have been sighted. The warm waters of this particular area of the Mediterranean are high in nutrients and attract large pelagic fish, dolphins and turtles which form the staple diet of great whites. This area is a shallow shelf area which keeps the young in warm water throughout the year and reduces competition from blue and mako sharks.

Interesting facts obtained from Dr Lowe and his team:

While it’s rare for white sharks to become stranded on the shore, baby salmon sharks, a close cousin to the white shark, will often strand themselves because of a bacteria that infects their brain and causes them to die, according to Dr Lowe.

85% of all the great white sharks that are by-caught in their study area were <1.75m in length 

These sharks were often found alive when the soak time of the fishing nets was less than 20hr

When released, 92.9% of the pups survived - those are some tough babies!

More in this category: Sharks Spotted in 2014 »
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