While huge congregations of these sharks are not out of the ordinary, they’re usually found much further south in Miami-Dade and the Ft. Lauderdale area. Biologist Dr. Stephen Kajiura, from Florida Atlantic University, helped document the en masse migration and is working on a tracking project to uncover the source of this behaviour change.
http://www.iflscience.com/plants-and-animals/tens-thousands-sharks-seen-swimming-florida-coast