Nearly 1,400 basking sharks were spotted in aerial photos in a puzzling gathering off the East Coast of the U.S.
The unusual plankton-eating basking sharks are the second largest fish in the world — surpassed only by the whale shark — and have been generally believed to be solitary swimmers. The huge fish can reach 32 feet in length and weigh as much as five tons.
An analysis of satellite and aerial photos found hundreds of them collected in a kind of shark conference in the waters off southern New England in 2013, according to a new study. Scientist suspect the gathering wasn’t related to mating. The animals were all classified as either adults or juveniles, according to the research published this month in the Journal of Fish Biology.
Researchers speculate the sharks may have been in a feeding frenzy on a plankton bloom in the area before setting off on their annual autumn migration south. A survey the National Oceanic and Atmospheric Administration conducted shortly after the 2013 gathering found high concentrations of zooplankton, adding support for that theory.
Until the study, basking sharks were known to gather occasionally, but only a few hundred at a time at the most and generally in the Pacific, according to experts.
The population estimates for the area are “in the hundreds,” marine conservation biologist Boris Worm told the Canadian Broadcasting Corporation. “So 1,400 would be not just a large group, but a large chunk of the population.”
Scientists found the unusual gathering by studying more than three decades of aerial photos that were collected in studies seeking North Atlantic right whales. Ten significant aggregations of basking sharks were identified off the coast of Nova Scotia and New England between 1980 and 2013, ranging from 36 to at least 1,398, the largest ever reported.
Whatever the reason for the mysterious gathering, scientists see it a positive sign for the species.
- This article originally appeared on HuffPost.