Juvenile great white sharks use certain areas of the sea as ‘training grounds’ where they can fine-tune their hunting skills and prepare for adulthood without facing competition from larger creatures, research suggests.
The study, published in the journal Environmental Biology of Fishes, is based on more than 3,000 shark sightings off the coast of Mossel Bay in South Africa.
The researchers said the bay offers a sheltered environment for the juvenile sharks and is home to different types of prey, in the form of fish and rays as well as seals and small whales.
The scientists said their work could help prevent the species from becoming extinct. They have been classed as ‘vulnerable’ by the International Union for Conservation of Nature (IUCN). Very little is known about great white shark populations, although many experts believe that their numbers are falling.
“Our findings could help protect specific habitats that these sharks utilise at different stages of their life,” said Dr Nicholas Ray, a researcher in Nottingham Trent University’s School of Animal, Rural and Environmental Sciences. “It might also bring about further legislation to support a vulnerable species at risk of extinction.”
The researchers studied the great white shark population at Mossel Bay to see how they used different habitats during various stages of their lives.
Read more about great white sharks:
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As the world’s largest known predatory fish, these sharks can weigh up to 1,100kg and swallow their prey by ripping them into pieces, using about 300 teeth.
The team found more than four in five (81 per cent) great white sharks spotted at Mossel Bay were juveniles, measuring between 1.75m and 3m in length. The researchers did not see any adults, which can grow up to 6.4m long, but spotted what they called ‘sub-adults’, measuring between 3.1m and 3.6m.
The creatures were more abundant when water visibility was more than three metres, which according to the experts, make for ideal hunting conditions.
They believe that juvenile great white sharks are using Mossel Bay as a place to learn how to hunt while avoiding competing with larger sharks.
Just 6.9 per cent of great whites sighted were identified by the team as male, the researchers said, suggesting that females may also favour protected bays when they want to avoid mating harassment from males.
“Very little is known about great white populations and how these sharks use different habitats during their life stages,” said Ray.
“We know that these sharks have capacity for social learning, and the greater numbers of juveniles sighted throughout our study suggests that younger great whites have adopted this bay as a crucial nursery and potential training ground where they can learn to hunt in relative safety.
“It appears the sheltered conditions and abundance of food are ideal and serve to increase their growth and development and help them to avoid predation, competition and harassment from larger sharks. It would appear they’re using these waters to prepare for adulthood.”
Reader Q&A: How powerful is a great white shark’s jaw?
Asked by: Peter Cole, Reading
Computer models suggest that the maximum bite force for a large shark would be 18,000 Newtons (18,000kgm/s²), but this hasn’t been measured on a living shark. Sharks have very sharp teeth and rely on slicing and head-shaking to rip off chunks of flesh, so they don’t need to bite down with their full force.
Even 18,000N isn’t that high when you take into account the shark’s size. The bite force quotient (BFQ), which compares bite force to body mass, is about 164 for a great white, compared with 181 for a Tasmanian devil and 440 for the Nile crocodile.
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