An angler fishing the flats of the Mud Key sandbars was treated to a rare find Monday afternoon when he spotted a blue shark cruising the shallows.
The species generally inhabit cooler, deeper water, said Neil Hammerschlag, shark expert and research assistant professor at the University of Miami's Rosenstiel Marine School of Marine Atmospheric Science.
They are more commonly found in the waters off more northern sections of the East Coast of the United States.
Geiger Key resident Lee Zangrillo was fishing the flats when he spotted the 9-foot blue shark, he said. He started casting his rod at the shark, thinking it was "the bull shark of a lifetime," he said.
As the shark bolted for some nearby mangroves, Zangrillo realized it was not a bull shark, but the deep-waterspecies of blue shark. The shark was "thrashing about," clearly panicking and out of its typical natural surroundings, Zangrillo said.
Zangrillo tail-wrapped the shark with a rope in an attempt to pull it from the mangroves and rescue it, he said. However, the shark ingested mud and sand into its gills and may have died from suffocation, Zangrillo speculated.
"The water was real warm. It must have been stressed out," Zangrillo said.
While Zangrillo was unable to save the apex predator, he did call the encounter an "experience of a lifetime." He brought the shark to the dock and showed Florida Fish Wildlife Conservation Commission officers, who confirmed it was a blue shark, Zangrillo said.
Blue sharks inhabit deep waters in the world's temperate and tropical oceans. Preferring cooler waters, blue sharks have been known to migrate long distances, such as from New England to South America, according to various online research reports.
"(It is) super rare," Hammerschlag said of Zangrillo's encounter. "I believe several years ago a mako (shark) was also found in such a situation. The prevailing thought was that it followed a school of tarpon inshore."
The odd looking blue shark has long pectoral fins and a narrow shovel-like head. Squid are the preferred prey for blue sharks, but their diet also includes other invertebrates such as cuttlefish and octopus, lobster, shrimp and crab.
Blue sharks often school in packs, which has led to their nickname "wolves of the sea."
Zangrillo's encounter comes a week after a group of fishermen had a great white shark follow their chum slick in roughly 200 feet of water off Key West. Great white shark encounters are also rare in the Keys, Hammerschlag said.
Hammerschlag speculated that the great white shark may have came in with the Gulf Stream, which was close to the Lower Keys at the time. The Gulf Stream was within 2 miles of the Sand Key Lighthouse, according to the National Weather Service officials.