Researchers found juvenile great white sharks near San Diego fled to warmer waters during Tropical Storm Hilary but are now returning.
SAN DIEGO — New research reveals how young great white sharks respond to significant storms off the coast of Southern California. During Tropical Storm Hilary in August 2023, juvenile great whites near San Diego abandoned their coastal nursery in search of warmer waters, but they are now beginning to return.
As Hilary struck, scientists noted that the storm resulted in a drastic sea surface temperature drop of more than 10 degrees Fahrenheit within a single day. This sudden cooling likely prompted the young sharks to migrate to warmer areas. Researchers from UC San Diego’s Scripps Institution of Oceanography and Cal State Long Beach tracked 22 juvenile great white sharks using acoustic tags. Before the storm, they detected up to 19 sharks an hour off Torrey Pines and Del Mar. However, those detections halved once the storm hit.
This story continues below.
“During the storm, the sharks moved to calmer, more sheltered waters,” the researchers said. “They returned just days after the storm passed and ocean waters warmed back up.” With the current El Niño phenomenon leading to warmer coastal waters, scientists anticipate that more sharks could remain closer to the shoreline for an extended period.
The researchers emphasized that this study provides the first direct evidence showing how juvenile great white sharks respond to extreme weather events. They expect the warmer waters may lead to a longer stay for sharks at their nursery hotspots.
Interestingly, the study also analyzed shark bite incidents and found no increase, despite a growing shark population and more people entering the water. “We haven’t seen bite risks increase,” a researcher stated, “that just really speaks to the fact that these sharks are a natural part of a healthy ecosystem and they’re really not going after humans.”
As strong storms become more frequent, understanding how sharks react to extreme weather is increasingly important, particularly since people and sharks continue to share coastal waters.