Why Do Sharks Attack Surfers? 7 Reasons Explained by Science
So, why do sharks attack surfers? In most cases it’s a mistake. From below, a surfer paddling on a board looks a lot like a seal or sea lion, and sharks can’t see fine detail or color well. Many bites are a single “test bite” from a shark checking what you are, not a planned hunt.
Shark bites on surfers are still rare when you consider how many people surf every day. But surfers do make up a large share of the people bitten, and there are clear reasons why. Here are the seven main ones, followed by practical ways to lower your risk.
Why Do Sharks Attack Surfers? 7 Reasons Explained
1. Mistaken Identity: Surfers Look Like Seals From Below
This is the most widely accepted explanation. Picture the view from underneath: a dark shape on the surface, with arms and legs moving at the sides. That’s very close to the outline of a seal, one of a white shark’s main foods.
A 2021 study led by Dr Laura Ryan at Macquarie University tested this using a computer model of how young white sharks see. The researchers found that, to a shark looking up, surfers, swimmers and seals on the surface look essentially the same. Neither shape nor movement gave the shark a clear way to tell them apart.
2. The “Test Bite”: Sharks Investigate With Their Mouths
Sharks don’t have hands. When they want to find out what something is, they often bite it. Researchers sometimes call this an exploratory or investigative bite.
This helps explain why many people survive shark bites. The shark bites once, finds that a person or a foam-and-fiberglass board isn’t the fatty prey it expected, and swims away. That’s little comfort if you’re the one bitten, but it shows that most bites aren’t sustained attacks.
3. Surfers Spend Time Where Sharks Hunt
Surf breaks are often close to the places sharks like to feed: near river mouths, channels, steep drop-offs and areas with lots of fish or seals. Surfers also spend long periods at the surface, lying still or paddling, which is exactly where sharks look for prey.
A scuba diver, by contrast, is below the surface and looks nothing like a seal resting on top of the water.
4. Dawn and Dusk Are Peak Feeding Times
Many surfers love early mornings and evening sessions. Unfortunately, low light is also when many sharks are most active. Poor light makes it even harder for a shark to tell a surfer from a seal.
5. Paddling and Splashing Can Look Like Prey
Irregular paddling, kicking and splashing send vibrations through the water. Sharks pick these up from a distance with their lateral line, a sense organ that runs along their body. Erratic movement at the surface can resemble an injured or struggling animal, which tends to draw a shark’s interest.
6. Sharks Can Sense the Electrical Fields of Living Bodies
Sharks have a remarkable sense called electroreception. Small jelly-filled pores on their snout, called the ampullae of Lorenzini, detect the tiny electrical fields that every living animal produces through its muscles and nerves.
Up close, this sense helps a shark home in on something alive, whether that’s a fish, a seal or a person. It’s a sense humans simply don’t have, and it’s one of many examples of animal senses we can only imagine.
7. Some Sharks Defend Their Space
Not every bite is about food. Some species, especially bull sharks, can be aggressive in shallow, murky coastal water, and they’re comfortable in exactly the kind of warm, near-shore spots that surfers use. A shark that feels crowded or threatened may bite defensively.
Signs of an agitated shark can include a hunched back, lowered pectoral fins and tight, jerky swimming, but most people in the water never get a clear look. If you see a shark acting strangely, calmly leave the water.
How Risky Is Surfing, Really?
The International Shark Attack File at the Florida Museum of Natural History tracks shark bites worldwide. Its yearly reports regularly show that surfers and other board-sport users are the group most often involved in unprovoked bites, largely because they spend so much time in the right place at the right time.
Even so, the number of bites each year is small compared with the millions of people who surf and swim. Drowning, rip currents and injuries from boards or rocks are far bigger dangers for most surfers.
The number of reported bites has risen over the long term, but researchers mostly link this to more people using the ocean, not to sharks becoming more aggressive.
Do Surfboard Colors Attract Sharks?
Divers have long joked about “yum-yum yellow,” the idea that bright, high-contrast colors attract sharks. The evidence for this is limited, and the Macquarie research suggests young white sharks see poorly in color anyway. Contrast and silhouette probably matter more than the color itself.
Some companies sell boards and wetsuits with disruptive patterns, and some surfers use electronic deterrents that create an electrical field around the board. Independent tests of some electronic devices have found they can reduce, but not remove, the chance of a bite. No color, pattern or gadget is a guarantee.
How Surfers Can Lower Their Risk
- Avoid dawn, dusk and night sessions in areas known for sharks.
- Stay away from river mouths and murky water, especially after heavy rain.
- Don’t surf near seal colonies, fishing boats or schools of bait fish.
- Surf with others rather than alone.
- Follow local warnings, beach closures and shark-spotting flags.
- Leave the water calmly if a shark is reported nearby. Smooth, steady movement draws less attention than frantic splashing.
- Remove shiny jewelry, which can flash like fish scales in the water.
Many of these become habits, much like surfing itself becomes a skill your body remembers even after time away.
Frequently Asked Questions
Do sharks deliberately hunt surfers?
No. Sharks don’t target humans as food. Most bites on surfers are believed to be mistaken identity or curiosity. People are bony and low in fat compared with seals, which is why sharks often swim away after one bite.
Which sharks bite surfers most often?
White sharks, bull sharks and tiger sharks are involved in most serious bites on people. Which one is most common depends on the region and water temperature.
What time of day are shark attacks most common?
Many sharks feed most actively around dawn and dusk, when light is low. More bites are reported during the day overall, simply because far more people are in the water then.
Should I worry about sharks every time I surf?
For most surf spots, the risk is very low. Check local conditions and warnings, avoid the high-risk situations listed above, and focus on the more common ocean dangers like currents and rocks.
The Bottom Line
So, why do sharks attack surfers? Mostly because, from underneath, a surfer looks like a seal, and sharks find out what things are by biting them. Add in surf spots near feeding areas, low light and splashing, and the overlap makes sense. The risk is small, and simple choices about when and where you surf make it smaller. If you enjoy strange animal behavior, read about how honeybees give directions by dancing.
