Sharks are mistaking humans for food, study shows

By Australian Geographic 27 October 2021
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A groundbreaking study has given convincing evidence of the mistaken identity theory, which despite being widely cited, until now had not been scientifically proven.

The mistaken identity theory as an explanation for dangerous or fatal shark encounters has been around for some time. It suggests that, rather than intentionally biting humans, white sharks are mistaking us for prey such as seals. 

A groundbreaking paper published today in the journal Royal Society Interface has finally given scientific proof to the theory by studying white shark vision. The research has the potential to change perceptions around sharks and offer new ways to prevent fatal shark bites.

The team of scientists captured footage of a seal and humans paddling on a surfboard and swimming. The videos were then altered to reflect the visual perspective of the white shark.

“White sharks have much lower visual acuity than us, meaning they cannot see fine details, and likely lack colour vision,” says neurobiologist Dr Laura Ryan, who led the study. Previously, the similarities between seals and humans has only been assessed from a human perspective. 

A surfer from a shark perspective.

A seal from a shark’s perspective.

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The research also explains why most shark bites involve younger white sharks. “Compared to adults their acuity, ability to see detail, would be lower because as an animal grows and their eye becomes bigger their acuity improves,” Laura says.

However, the scientists were quick to add that the mistaken identity theory doesn’t explain all shark encounters. “We confirm the plausibility of the mistaken identity theory from a visual perspective, but sharks can also detect prey using other sensory systems.

“While it seems unlikely that every bite on a human by white sharks is a result of mistaken identity, in circumstances where surface objects, like surfers, are targeted from below, it is very possible.”

Laura hopes the research changes the public’s perception of white sharks and improves how we respond to these incidents. “White sharks are often portrayed as ‘mindless killers’ and ‘fond of human flesh’, however, this does not seem to be the case, we just look like their food. 

“The uncertainty around why bites occur generates substantial public concern and typically leads to measures to reduce shark abundance, which often also harms other marine life. 

“Understanding why shark bites occur can help prevent them. In fact, the findings of this study have inspired the design of non-invasive vision-based shark mitigation devices, which are currently being tested.”

Read the full research paper here.