Do sharks attack humans for a reason?

If they smell blood. Just stare them in the eye and they will go away.

Hunger maybe?

Sharks aren't unthinking killing machines as popular culture may suggest, however some species of shark are noted for aggressiveness. probably the one most feared but least encountered, depending upon region is the great white. Overall, probably the most aggressive towards any animal is the Bull Shark. Additionally Bull sharks have been found in estuaries, brackish waters of bays and bayous, and it is presumed that a Bull Shark was responsible for attacks in river in New Jersey.

Sharks though aren't as much visual as they are sensory animals, in that they use bio-electric fields of other animals and feel often to determine potential prey. It has been shown that the shadow outline representing seals, a food animal of whites, can develop engagement. However sharks will oft brush against a subject to get a sense of if it is a viable food as well. The skin of a shark also has the ability to taste so to speak. That is also why a Chum trail is so effective in sport fishing for sharks. Blood and other things suggest food is available and blood says a weakened food source is easy pickings for shark.


So maybe you shouldn't be in waters when menstruating or have an open sore that is oozing. That could help start the next piscine feeding situation.