Examining the social networks of sharks

Date: October 4, 2016

Source: University of Delaware

Thanks to movies like "Jaws," we tend to think of sharks as loners who prefer to do their own thing. But if the ocean were a mixer, they'd actually be networking their fins off, not standing in the corner staring at their iPhones.

New research conducted at the University of Delaware found that sharks prefer to travel in groups of various sizes and spend a surprising amount of time together. Some individuals even spent up to 95 consecutive hours together over the course of the year.

Researchers gathered this data by using a novel tagging procedure to collect tens of thousands of interactions between 300 or so tagged sand tiger sharks along the Eastern Seaboard. They also documented interactions between sand tigers and seven other fish species.

The findings, published in the Nature journal Scientific Reports, could help researchers in future efforts to improve the life cycle of sand tiger sharks.

Documenting shark encounters in the open ocean

The project began in summer 2012, when UD researchers tagged 20 sand tiger sharks with implanted acoustic transceivers to study their interactions and movements. When the scientists recovered the tags from two male sand tiger sharks in 2013, the downloaded data told an unexpected story.

"Based on previous work, we knew that during the summer the sand tiger population formed groups in the Delaware Bay, with male and female adults and juveniles all together in the same places, sometimes very close together," said Danielle Haulsee, the paper's lead author and a doctoral student in the College of Earth, Ocean, and Environment's School of Marine Science and Policy.

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