PREVIEW

New results published in Frontiers in Marine Science have shown for the first time that juvenile great white sharks prefer to swim within one kilometre from a shoreline, in warm and shallow waters.
Marine researchers studied a great white population by Padaro Beach near Santa Barbara in central California.
Study author Dr Christopher Lowe said in a statement, “This study is the first step in helping us understand how young white sharks make decisions about what habitats they choose, how long they remain in these areas, and the water temperatures they select on an hourly basis - which is really quite remarkable.”
They found that in the absence of maternal care after birth, great white ‘pups’ and juveniles gather in ‘nurseries’ unaccompanied by adults.
According to National Geographic, great white pups swim immediately away from their mothers after birth; they are seen as prey to adults.
“This is one of the largest and most detailed studies of its kind. Because around Padaro Beach, large numbers of juveniles share near-shore habitats, we could learn how environmental conditions influence their movements,” Lowe added. “You rarely see great white sharks exhibiting this kind of nursery behaviour in other locations.”
Researchers began their study in 2020, by using darts to tag 22 great white pups with sensor-transmitters.
At the time, the sharks were between one and six years old.
Great whites take 26-33 years to reach sexual maturity, and can live for up to 70 years.
The transmitters measured local water pressure and temperature, and updated the researchers on the sharks’ locations in real time.
After analysing the results, the researchers found that the great white pups dived to their greatest depths around dawn and dusk – while foraging on skates, rays, schooling fish, and other small bony fish.
They moved closest to the surface – under four metres deep – in the afternoons.
Researchers speculated the great white pups were trying to increase their body temperature.
“We showed that juveniles directly altered their vertical position in the water column to stay between 16 and 22 °C, and if possible between 20 and 22 °C,” study author Emily Spurgeon said. “This may be their optimum to maximise growth efficiency within the nursery.”
She continued, “Our results show that water temperature is a key factor that draws juveniles to the studied area. However, there are many locations across the California coast that share similar environmental conditions, so temperature isn’t the whole story.
“Future experiments will look at individual relationships, for example to see if some individuals move among nurseries in tandem.”
As adult sharks were rarely spotted in the ‘nursery’, the researchers concluded that great white pups spent much more time in shallower waters than adults.
They also hypothesised that the great white pups gathered to avoid predators.
Great white sharks are largely solitary, though some gather in feeding areas and others have been spotted swimming in pairs for extended periods.
“They’re not swimming places by accident, they’re actively choosing where they want to be based on temperature,” Spurgeon concluded. “They’re very picky, just like people.”