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Baby Great White Sharks Form ‘Nursery’ Near California Beach To Stay Warm And Possibly To Avoid Predators

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California State University
A video showing a newborn great white shark was revealed for the first time earlier this year, highlighting the mystery of the species’ birthing habits, and now scientists have shown for the first time that juvenile great whites gather in nurseries close to shore to stay warm.
Baby great white sharks, known as pups, do not receive any maternal care, instead gathering with other pups and juveniles in nurseries without any adults, according to marine scientists. The sharks can live between 40 and 70 years, according to researchers.
Researchers from California State University studied one such nursery off Padaro Beach on the state’s central coast near Santa Barbara, and found the young sharks prefer being closer to shore, where it’s warmer and there are fewer predators.
The study, published this week in Frontiers in Marine Science, was funded by the state of California Shark Beach Safety Program, in an effort to understand their behavior in order to both conserve the species and protect humans from shark encounters at beaches.
“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,” said senior author Christopher Lowe, a professor at California State University. “You rarely see great white sharks exhibiting this kind of nursery behavior in other locations.”
In 2021 and 2022, Lowe and his team tagged 22 juvenile sharks — including males and females between one and six years old — with sensor-transmitters that measure water pressure and temperature and track location. Researchers gathered additional temperature information using an autonomous underwater vehicle. Tracking was paused during winter months when the juveniles temporarily moved farther offshore.
Using artificial intelligence, the researchers trained a 3D model of the juvenile sharks’ depth and temperature preferences.
They found that the juveniles preferred the shallower waters within about one kilometer, or a little more than half a mile, from shore. But because water temperatures were highly variable, the baby sharks were constantly on the move to find their optimal water temperature.
“We showed that juveniles directly altered their vertical position in the water column to stay between 16 and 22 °C [60.8 to 71.6 degrees Fahrenheit], and if possible between 20 and 22 °C [68 and 71.6 degree Fahrenheit], said first author Emily Spurgeon, a former masters student and current research technician on Lowes team. This may be their optimum to maximize growth efficiency within the nursery.”
The juveniles dived to the greatest depths around dawn and dusk, likely hunting for skates, rays and schooling fish, and returned to the surface, between zero and 13 feet deep, during the afternoons, possibly to increase their body temperature.
In addition to temperatures impacting the sharks’ vertical position, variable water temperatures also affected their horizontal distribution. They tended to spread out a greater depths when seafloor temperatures were higher, and grouped closer together near the surface when deeper water was cooler.
But water temperature preferences alone don’t fully explain why the sharks formed a nursery off Padaro Beach, and not at other locations. Researchers say they may be there to avoid predators.
“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 isnt the whole story, Spurgeon said. Future experiments will look at individual relationships, for example to see if some individuals move among nurseries in tandem.
TMX contributed to this article.