Study Shows Juvenile White Sharks Prefer Warm, Shallow Waters Near to Shore
Earlier this year, a newborn white shark was filmed for possibly the first time ever. However, that moment of discovery only highlighted how little we actually know about juvenile great whites. Recently, though, scientists have managed to add just a bit more to our knowledge of the reclusive beasts. They’ve proven, for the first time, that juvenile great white sharks select warm and shallow waters to congregate within one kilometer from the shore, as Phys reports.
The findings were published in Frontiers in Marine Science by researchers from Cal State Long Beach and the University of Minnesota. The scientists studied a population of great whites off Padaro beach near Santa Barbara, in an area known as a “nursery,” where juveniles will gather en masse.
“This is one of the largest and most detailed studies of its kind,” said senior author Dr. Christopher Lowe, a professor at California State University and director of the school’s famous Shark Lab. “Because around Padaro Beach, large numbers of juveniles share near-shore habitats, we could learn how environmental conditions influence their movements.”
In 2020 and 2021, Lowe and his team used darts equipped with transmitters to tag 22 juvenile white sharks, aged between one and six years old. These transmitters measured local water pressure, temperature, and the position of each shark. The tracking was paused during the winter, when juveniles tend to leave for deeper waters. In addition, further data was collected using an autonomous underwater vehicle.
With the help of AI, the results were then used to train a 3D model of the sharks’ temperature and depth preferences. They found that the juveniles dove to the greatest depths around dawn and dusk – most likely to feed. They would then move closer to the surface in the afternoon, possibly to heat their bodies in the sun.
“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,” said Emily Spurgeon, a former master’s student and current research technician in Lowe’s team, “This may be their optimum to maximize growth efficiency within the nursery.”
However, while the researchers were able to prove the juvenile great white sharks did in fact spend their time in much shallower water than adults, it’s still unclear exactly why they do.
“Our results show that water temperature is a key factor that draws juveniles to the studied area,” added Spurgeon. “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.”
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