Following an alarming increase of shark bites in Sydney鈥檚 waters, public policy expert and shark researcher Associate Professor Chris Pepin-Neff explains why shark incidents occur more frequently during certain weather events, shares some useful tips for avoiding a shark encounter and busts some common myths around shark-human interactions.
Why rain changes the risk
After heavy rainfall, stormwater runoff carries sewage, organic waste and nutrients into the harbour and coastal waters. This attracts bait fish closer to shore, and sharks tend to follow.聽
Pepin-Neff has warned that entering the water after rain is 鈥渁 terrible idea,鈥 particularly in Sydney Harbour, where stormwater and river systems funnel directly into popular swimming areas.聽
Reduced visibility also plays a role:聽murky water increases the chance of accidental encounters, as sharks rely on contrast and movement rather than clear sight.
Tips for avoiding a shark attack
Assess environmental conditions
Murky conditions, runoff and changes in marine behaviour mean that swimming after significant rainfall carries a higher risk, particularly in the harbour and near river mouths.
鈥淚f there鈥檚 heavy rain and the sewage has overflowed, or the baitfish are acting up 鈥 if you see dolphins, it鈥檚 more likely there鈥檚 a shark,鈥 Pepin-Neff said.
After heavy rainfall, Pepin-Neff recommends giving the water time to clear before heading back in.
鈥淲ait 72 hours after a storm to swim in the harbour and be mindful of swimming or surfing at ocean beaches for 24 hours after a large downpour."
While waves and tides can disperse runoff faster in the open ocean, near-shore areas can remain affected.
Swim between the flags
Swimming between the red and yellow flags doesn鈥檛 just mean lifeguards are nearby, it can also reduce the likelihood of a shark encounter.
鈥淪wimming between the flags is shark bite prevention,鈥澛爏aid Pepin-Neff. Sharks are highly sensitive to sound and vibration in the water, and large groups of swimmers create a level of disturbance that sharks tend to avoid.
鈥淭he sharks don鈥檛 know what the disturbance is. They don鈥檛 know what we are,鈥 Chris explains. "500 of us, or 300 of us, or 100 of us swimming and splashing between the flags, makes a noise and a reverberation that is not opportunistic for them.鈥
Maintain eye contact
If you encounter a shark in the water, how you respond matters.聽鈥淚f you see a shark, you always keep eye contact. Face the shark and swim backwards to the shore鈥 said Pepin-Neff.
Swimming slowly backwards helps you maintain awareness while creating distance and reduces the chance of a surprise approach.聽
Around 40 beaches along the coast of New South Wales (NSW) were closed after four shark attacks occurred in 48 hours.
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LinkBusting myths around shark-human interactions
Dolphins won鈥檛 protect you
People often assume that dolphins scare sharks away, and that seeing dolphins near the shore means it鈥檚 safe to get in the water. That assumption can increase risk.
鈥淭he myth about dolphins - that sharks and dolphins don鈥檛 get along, which is why it鈥檚 safe to go in the water when you see a dolphin - is totally false,鈥澛爏aid Pepin-Neff.聽
鈥淪harks and dolphins eat the same thing, so the presence of dolphins means it鈥檚 more likely that you鈥檙e going to see a shark."
In other words, dolphins are not a deterrent - they鈥檙e a sign that food is nearby.
Sharks cannot smell blood from a distance
鈥淭here鈥檚 also a myth that sharks can smell blood from like a mile away. That鈥檚 not real,鈥澛爏aid Pepin-Neff. While sharks do have an excellent sense of smell, the idea that they can detect blood from a significant distance away isn鈥檛 accurate.
Sharks rely on a combination of cues - including movement, vibration, contrast and environmental conditions - not just scent alone. Water clarity, temperature and proximity all matter far more than the popular myth suggests.
From fear to informed decision-making
As climate change intensifies rainfall events these warnings are likely to become more common.
For now, the advice is simple:聽if it鈥檚 rained heavily, wait it out. Clearer water and calmer conditions can significantly reduce risk.
Ultimately, the goal isn鈥檛 to instil fear, but to foster awareness. Being informed about when and where it鈥檚 safest to swim, and understanding the conditions that change that risk, can make all the difference.
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Associate Professor Chris Pepin-Neff shares advice on Instagram
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