WPTV5 reports that area beaches in Palm Beach, Florida have been closed to swimming due to large numbers of spinner sharks (Carcharhinus brevipinna) and blacktip sharks (Carcharhinus limbatus) migrating through the area as they head north. Breaching spinner sharks could be seen from the shore, while helicopter footage from WPTV5 gives some perspective on the number and density of sharks in the area.
Spinner and blacktip sharks are not known to hunt large prey, and humans are not a natural food source of the species (or any other shark species, typically). However, the large number of sharks close to the shore does present a significant increase in the risk of shark bites to beach goers, and swimmers in the area are urged to observe the warnings and beach closures for safety reasons.
Blacktip sharks have been identified as being involved in 20% of Florida’s “unprovoked shark attacks” from 1920-2012, while spinner sharks were associated with %16, according to the International Shark Attack File.