Alarm quickly spread after two children were bitten in July while swimming off Fire Island, New York, because great white sharks (Carcharodon carcharias) frequent the region. We can vouch from DNA analysis that another, relatively harmless, shark species was responsible for biting one of the individuals, and, in our view, probably the other as well.
We extracted DNA from a decontaminated fragment of shark tooth recovered from one of the bite wounds. Comparison with mitochondrial DNA sequences of some 900 species of cartilaginous fish enabled us to identify the DNA source as a sand tiger shark (Carcharias taurus; unpublished results). This shark is generally not considered to be dangerous to humans (J. I. Castro The Sharks of North America Oxford Univ. Press, 2011), despite its size (up to 3 metres long and weighing more than 200 kilograms).
The incidents occurred some 7 kilometres apart and within minutes of each other. This is not as surprising as it might seem — sand tiger sharks prey on schooling fishes, tracking them as they move inshore. This makes it more likely that the sharks will mistake nearby swimmers for prey and bite them. However, such random events are extremely rare.
Nature 561, 33 (2018)