Dead Sea - Where sharks gather to hunt

Scientists discovered great white sharks often gather to hunt together in the clear waters of Guadalupe island off western Mexico.

Great white sharks hunt with friends in the waters near Guadalupe Island.

Dozens of sharks congregate in the island's coastal areas in search of food in the fall and winter, but they are hardly solitary. According to new research published March 23 in the journal Biology Letters, a group of tagged great white sharks formed close-knit swarms in 2017 and 2018. They like to hang around foraging with close friends or in same-sex couples. Sometimes they swim together for more than an hour.

One pair of sharks in particular surprised scientists by spending more than 70 minutes swimming together, longer than many other sharks, according to study leader Yannis Papastamatiou, an ocean scientist at the International University Florida. This type of long-term interaction is more likely to be "social attachment", not random interaction. He thinks this is an example of you hunting in sharks.

In the new study, scientists put tracking tags on six great white sharks including three males and three females near the island of Guadalupe between October 2017 and December 2018. The device tracks each shark's speed, depth and swimming direction, and alerts the team whenever a tagged shark approaches another. Each tag also contains a small video camera, which falls off the shark's dorsal fin after about five days.

More than 30 great white sharks from the island have been tagged on previous research expeditions, providing scientists with ample opportunity to see how the tag works. They recorded hundreds of social interactions between great white sharks.

In general, male sharks like to congregate with other males, and so do female sharks. But the social behavior of each shark varies greatly. One shark interacted with dozens of others for 30 hours before struggling causing the tracking tag to fall off. Another shark wore the tag for five days but only bonded with two of the same species. Many of the great white shark interactions occur near seal breeding grounds, indicating that the sharks spend a lot of time together when prey is near. Due to the relatively small sample size in the study, the scientists concluded that more observations were needed to draw firm conclusions about the social network of great white sharks in Guadalupe.