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Should bull sharks be culled? The truth behind shark bites and how people can actually stay safe · How To Protect The Ocean

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Should bull sharks be eradicated?
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That is the big question that people are asking after four serious bull
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shark bite incidences happened in 48 hours in Australia near Sydney.
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This is a question that everybody's having and people have some pretty
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extreme views on what we should be doing with bull sharks in the future.
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How do you feel about a shark cu Well, I don't know.
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Look, I, I always feel like when something tragic happens, obviously we, we need
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to be seen to be doing something.
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Mm. But whether this is the answer, I'm not sure there are about 20,000 bull
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sharks in the Harbour at any one time.
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That's what my friend told me anyway, Um, So I feel like it would
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just be kind of something to do.
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Yeah.
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To show that we're trying, I mean, it's saying that though, if this happened
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to my family or someone in my family.
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I probably wanna drain the ocean.
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Yeah.
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You know, get rid of everything.
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I think that's a really good point.
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I would too.
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Um, but I mean, we've been talking all morning and I've been
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covering this story for 20 years and, and it happens every time.
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Mm. But I would say this, um, as I said on Monday, all the way along
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the coast, my friends have been telling me there's more sharks.
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The bull sharks, as far as I'm concerned, are the bin chickens of the ocean.
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Yeah.
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There's no one out there.
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There's so many of them.
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There's no one out there who's empathetic to a bull shark.
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So I've got no problem.
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Eradicating them, absolutely none.
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But I'm, I'm gonna have Peter on my shoulder and saying whatever, but I
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just don't, they're good for nothing.
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Today in this episode of the How to Protect the ocean Podcast, we are
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gonna be talking about why these events happen, what the data has
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shown that's happened in the past, and how we can reduce shark human risk
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in the future.
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That's on this episode of the How to Protect the Ocean Podcast.
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Let's start the show.
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Hey everybody.
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Welcome back to another exciting episode of the How to Protect the ocean Podcast.
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I am your host, Andrew Lewin, Marine biologist and science communicator here
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to tell you what's happening with the ocean, how you can speak up for the
1:40
ocean, and what you can do to live for
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for better ocean by taking action.
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And on today's episode, we're gonna be talking about the four bull
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shark incidences, shark bites that happen in less than 48
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hours in Australia, near Sydney.
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One happened in Sydney Harbour and others happened nearby beaches.
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Manley Beaches, one of them.
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And we're gonna talk a little bit about like why this stuff is happening.
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Every time when there's some kind of shark incident, there's a lot of
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out of pocket kind of takes on it.
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Just like we showed in this intro, there was a daytime talk show in Australia where
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the person was like, Hey, look like these are just garbage can type bull sharks.
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These sharks are not really iconic.
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They're not really what people love.
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I'm just fine if we eradicate all of them.
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Like he just wanted to go eradicate all and thinking that's going to decrease any
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kind of shark human interactions instead of just adapting and living with these
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interactions and finding out what we can do more about it rather than just taking
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these out of pocket takes, in my opinion.
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But before we get into the science and, sort of the ideas that people
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have and what we should be doing.
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I wanted to just be respectful of the people who were bitten.
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A person lost his life.
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It looks like a little boy, a 12-year-old boy may lose his life.
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He's in critical condition.
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Last reports that I saw, it didn't look like he was gonna make it through.
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This is the utmost tragedy.
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Anytime somebody loses a life or anytime someone's bitten and is in
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critical condition, doesn't matter, child or adult, it hits hard.
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And it's something that we have to respect.
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I'm not going to talk about what they were thinking of or try to
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assume what they were thinking of when they were going into the water.
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I'm not going to discuss if this is something that was appropriate or not.
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What I'm going to do is focus on the science.
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I'm going to focus on what we know of bull sharks in this area at this time
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of year, what we know about some of the environmental conditions in this area.
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And things that we can do to reduce the risk of things like
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this happening in the future again.
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This is not something we want to see.
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Whether you're a shark advocate or you care more about the humans or
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both obviously 'cause we both care.
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If you're watching this show or listening to this show, you care about whether
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people are hurt by sharks, and also you care about how people look at sharks
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after some of these incidents happen.
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So that's what we're gonna be focusing on today.
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We're not gonna be focusing on the assumption of what people were thinking.
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We're not gonna be taking away anything from what happened to them.
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You just never know when these things happen.
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But we are gonna focus in on the science.
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So let's start with something that we should be looking at.
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And let's not get lost in the panic of something like this happening.
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Although it's very rare that this happens obviously has happened
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and we have to acknowledge it.
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But the thing is, bull sharks have been present around Sydney Harbour
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and nearby New South Wales coasts.
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That's not new thing.
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They've been doing this for a long time.
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Sciences have been tracking sharks in Sydney Harbour and documenting patterns
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of occurrence in seasonality for years.
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One study that I found in PLOS One mapped out how different shark species
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use different parts of Sydney Harbour and at different times of the year.
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Specifically noting that this kind of information has implications for managing
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human shark interactions, including education programs and modifying human
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behavior during high risk periods.
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Even more directly, a long-term acoustic telemetry study followed
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dozens of bull sharks in Sydney Harbour over multiple years and
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described their residency and movement pattern in a large temperate estuary
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where human activity is high.
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So we know that these bull sharks are there.
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We know that they've been there for multiple years.
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This is something that isn't new.
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There are some conflicting reports that people are saying, oh, we're
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seeing more bull sharks around.
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Fishers have said that.
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I've seen a lot of comments being like, Hey.
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The bull shark population has increased unprecedentedly.
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And this is something that can't be confirmed or denied at this point.
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All I know is that people know that there are bull sharks in
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the area at this time of year.
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We know that their population has a range, but
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scientists haven't noticed any massive increase, so we can't
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speak to any of that increase.
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In other words, there's no physical evidence or there's no population
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evidence that I found before I joined this show that had that.
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And it's not just the Harbour that they're found.
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A multi-year tagging and monitoring
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study also found in New South Wales beaches that tracked hundreds of bull
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sharks and examined when and where larger bull sharks are more actively to
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be present, finding seasonal patterns that matter for beach risk management.
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So in other words, when it's really hot outside like 20 to
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26 degrees Celsius, maybe even higher, these bull sharks are there.
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And so they will come close to shore during these times because
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they like the warmer periods.
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Anything below 21 or 20 degrees Celsius, they're not there.
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In Sydney Harbour, other shark species are found in areas where
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it's cooler than 20 degrees.
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So, there is definitely a pattern here, a spatial pattern and
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seasonality pattern that we see.
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So when we talk about why is this happening now, part of the answer is
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because bull sharks predictably use these waters and particularly in warmer months.
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So in the summer months.
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I know right now, like I'm recording this on a Sunday evening.
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There's a massive snowstorm, like we're getting 30, maybe even more centimeters
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out here in Ontario, so it's winter here, but in Australia it's summer, it's hot.
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And so you're gonna find bull sharks predictably in the warmer months
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and scientists have been documented for a long time.
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Now, why these incidents are likely happen?
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Let's talk about conditions, because conditions actually matter here.
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We have warmer months.
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We know that these sharks are in there, the bull sharks are in there, and the
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warmer ones, especially in Sydney Harbour.
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But bull sharks are strongly associated, not only with warm water and coastal
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systems including estuaries and areas of highly influenced by freshwater flow.
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So they have this ability to go up into freshwater rivers, estuaries,
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and go into the freshwater area and in areas where you can't see them.
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It's not very clear.
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When you look at a river system, they're not always perfectly clear.
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A lot of the times you get a lot of sediment.
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You might get some pollution in there but it's pretty turbid in those areas
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'cause usually it's shallow, there's a lot of sediment that's around it.
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And if it's in a area where there's a lot of sediment that's going in,
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or it's faster, you might start to see it be essentially brown or darker
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or, just you can't see through it.
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And so you'll see a lot of that turbidity in there and those sharks can come in
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and you don't even realize they're there.
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And that's been a lot of the times where the bull sharks are notorious for having
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shark human incidences when they come into these areas where you can't see them.
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They're just there.
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They can't see very well.
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They end up taking a bite or an exploratory bite, whether
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they find it intriguing or not.
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And they go for it because they're looking for food and they're in hunting mode.
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And so when you have all that in those estuaries, in those river systems, you
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get more shark human interactions if there are people in those river systems.
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We've seen that not only in Australia.
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We've seen in Africa, we've seen it everywhere where bull sharks are.
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You have to be careful in those areas.
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So they use any area that it could be turbid, it could be more fresh water.
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They could be up in the estuaries.
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Long-term tracking has worked, links their presence and then their movement to
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predictable seasonal patterns and habitat use within a Harbour system where there's
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a lot of entries of different estuaries.
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And so that's been a thing that they've had to look at.
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Now you add summer rainfall in this area.
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There's some season for Australia, as far as I'm told, some pretty heavy rain.
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So in summer storms you often get increased runoff into coastal waters
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and Harbour systems that runoff can turn the water murky and reduce visibility.
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Bull sharks are adapted to low visibility environments, like I
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said, so they'll be in murky waters.
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Risk can increase because the visibility cues that humans rely on drop fast
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and bull sharks do not rely on their vision the way people assume sharks do.
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They use multiple senses, including electroreception and vibration cues.
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So they have the ampullae of lorenzi across their snout.
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And so they detect like electromagnetic fields or even
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electromagnetic movements in muscles.
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So that's how they tell if there's something there which could be part
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of the why that they thrive in turbine systems 'cause they don't use sight.
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So essentially in murky waters, the odds of a mistaken bite can increase.
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That's not a moral statement, it's just a risk assessment.
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Right?
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It's a risk statement.
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Clusters can happen.
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So a small number of high profile incidences close together can be
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driven by a temporary overlap.
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So you got warm waters, seasonal presence, high beach use with people
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'cause it's summer and short-term environmental shifts, you know,
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summer rains and things like that.
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Long-term science base is what helps us talk about this overlap
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with clarity instead of fear.
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Scientists have known that these incidences can be at
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higher risk during this time.
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And so the question is, is how come people don't know about it?
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I looked through and I saw a lot of scientific journals talking about
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this, but let's be honest, we know from a scientific journal standpoint,
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from a scientist myself, we know that
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these scientific journals can be exclusive.
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They don't get to everybody.
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They don't get to lifeguards, they don't get to beach managers, they
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don't get to police, they don't get to firefighters and paramedics to educate
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them on the risk unless there are programs in place for that to happen.
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We look at this and we're like, why isn't this happening every year?
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In this case is obviously it's a larger case in a shorter time.
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But the risk isn't just sharks.
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It's sharks plus the conditions plus people.
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Everything has to happen at the same time.
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So some years have different rainfall patterns.
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So you know, sometimes it's not as hard or it's not happening all at once.
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You have different water clarity, different ocean graphic conditions.
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You have different surf conditions and different levels of exposure
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from swivels and surfers.
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So this is why year to year, the bite numbers fluctuate.
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So sometimes you'll see like an increase like this year because the conditions
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just kind of matched everything.
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So not only was it the summer months, not only was there high rainfall,
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and not only were there people coming in more towards beaches or trying to
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jump off a rock or things like that.
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It was just a lot of things happen together that risk increases.
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So the level of exposure to swimmers and surfers will increase.
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And there is another layer that is becoming more important is warming oceans.
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A recent paper reports that migrating bull sharks have increased residency
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at summering rounds off Sydney over a long time series with a trend of
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longer seasonal presence, so they're staying there longer, which has
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implications for how New South Wales communities may need to adapt to risk
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for messaging and monitoring over time.
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We wanna make sure that people aren't going in the water when there times where
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these bull sharks are close to shore.
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When they're in the warmer waters, when they're in turbid waters and they can't
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see you just as much as you can't see them, that becomes a dangerous time.
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And so people need to be educated
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better.
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Not to say that they're not educated now, but obviously there are some
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people who haven't gotten the message as much as they could have and went
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in the water instead of staying outta the water during these times.
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So it doesn't mean that more bites are inevitable but it does mean
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that the window of overlap between people and bull sharks could expand.
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And that is a management and education challenge, not a reason for a panic
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response like eradicating these animals.
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When you get incidences like this, people want something immediate.
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And even in the clip that I showed you at the beginning of this episode,
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someone was saying, Hey, look, if this happened to me, like, you know, if my
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child or my relative or a friend got bitten by a shark and their life was
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altered, whether it was fatally or otherwise, they even admitted they like,
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they would want to see the oceans drain.
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Like could go to extremes, right?
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You know, I want, I get all rid of all the bull sharks in a minute, but this
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is not like a call feels immediate.
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But there are three problems that almost never get said out
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loud in these public debates.
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So the problem one.
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Bull sharks move.
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Removing some animals in one place does not erase the risk in that place.
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So other animals may come in because there's less competition.
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Problem two.
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Lethal control often kills non-target species and can create
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ecological harm without proving long-term reduction in bite risk.
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So by eradicating all them, obviously it's not gonna change anything.
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Other animals get may get cut.
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Other species, they're just probably gonna look for species that are big enough.
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We've seen these called programs happen in Australia in the past.
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It's very interesting to see this.
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Problem three.
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It shifts focus away from what actually reduces risk.
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So information, surveillance, warnings and behavior change.
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Those are the biggest things.
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So those three problems need to be solved.
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And that leads us into the most important part of this episode, which is basically
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what actually helps people stay safe.
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So in New South Wales, there are documented programs where scientists,
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government agencies, and surf life saving personnel are actively
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involved in surveillance, public warnings, and risk reduction.
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New South Wales Shark Smart Program describes a multi-layered shark management
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approach that includes surveillance technology such as drone patrols,
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operate through surf Life Saving and New South Wales as part of the New
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South Wales Shark Management program.
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These drones are not just for show.
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If you go on Shark Smart's own website, they describe that the
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drones allow lifesavers to spot sharks respond quickly, including actions
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to clear the water when needed.
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So if they see bull sharks close by.
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You can fly a drone over quickly.
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You can do a patrol.
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You can see if there's sharks in the water, and then you can say,
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Hey, you know what, let's come out.
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These sharks look big, or these sharks look like they can do some damage.
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Let's make sure our beachgoers are safe and our swimmers are safe.
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Let's take them outta the water.
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So recent reporting also documents New South Wales expanding these efforts
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after this cluster of incidences, including additional investment
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tied to surveillance, bull shark tagging and shark safety education
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and expanding drone coverage to more beaches through peak season.
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So there's gonna be more investment into that safety, which is what we want to see.
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We don't wanna see people go out and culling these animals.
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We wanna make sure that we can properly fit ourselves with the
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technology that they can go out and they can see what can be done
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and make sure that people are safe.
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So when someone asks, are scientists actually working with lifeguards?
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The answer in New South Wales is actually, yes, and through an ongoing
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program that includes surf lifesaving patrols, surveillance technology,
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shark listening stations for tagged animals and public education components.
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This is what prevention looks like.
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What you really need to hear is actionable clarity.
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So if you're swimming in waters where bull sharks are known to occur, or where
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estuaries and river mouths influence water conditions, avoid swimming after heavy
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rains especially, when the water is murky.
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Be cautious in your river mouths and Harbour entrances after runoff events.
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Pay attention to beach warnings, drone alerts, and lifeguard instructions.
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Just to add on to that, if you're in a new area, if you're a tourist or you're
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somewhere in a new beach, make sure you know the color symbols of the flags of
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what's danger and what's safe to go into.
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A lot of these flags systems could be quite sophisticated.
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They'll have purple flags.
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They'll have green flags, they'll have red flags.
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They'll have yellow flags.
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They'll have blue flags.
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They'll have flags with lines in them.
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Learn what they are.
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There should be signage posting to see like if there's a dangerous animal in
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the area or if it's like a rip current.
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There's all these different signs and flags to make sure that you are safe.
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Ensure that you look at those flags before you even step onto the beach
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or before you even go into the water because that could save your life.
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' cause you just never know what's happening to the beach.
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A beach could look perfectly fine.
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Maybe have a few ways, but you have no idea if there's a rip current.
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You have no idea if there's an animal out there, if you're not
16:30
paying attention to the signage.
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You could also even go up to lifeguard stations and ask them, Hey, like, is there
16:35
anything dangerous in the water or is there anything I should know about this?
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And they'll have a frank conversation with you.
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They might be a little bit more conservative and be like, there're always
16:42
animals that might be able to hurt you in there, so you are taking a risk.
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But we haven't seen any so far, like that's been outward, like a concern.
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So that's something that you can go through, especially in Australia.
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If you're on a remote beach or you pass by certain areas, I
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would just be very cautious.
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There are a lot of animals in there in the river systems and
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so forth that could harm you.
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And so make sure that you know where you're going.
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We've done episodes on this podcast before.
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We've talked about how
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talking to locals before you go out into a river or a lake, especially in Australia,
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could really help you in saving your life.
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'cause there's a lot of crocs in these areas and you gotta be careful,
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not necessarily in Sydney, but definitely in the northern edges.
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But also talk to any locals before you go out there.
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And of course the last point.
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If beaches are temporarily closed, treated at that as prevention.
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Not an inconvenience.
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Don't just say, oh, I came all the way out here to go to the beach.
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I'm gonna the beach no matter what.
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If they close the beach, there's a reason why they close the beach.
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So just be cautious and maybe like, you know what, today's just not the
17:36
day that I'm going into the ocean.
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So these are the kind of behavior changes that a science and form
17:40
lifeguard system is designed to support.
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And in New South Wales is actively expanding surveillance and education
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efforts around exactly this problem.
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So should there be an eradication of bull sharks after, you know,
17:52
four incidences in 48 hours?
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Eradication is not the strategy.
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It's an emotional reaction.
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The strategy is what New South Wales and other regions increasingly focus on.
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Surveillance, tagging and detection, education and real-time risk communication
18:08
paired with clear public guidelines during these high risk conditions.
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And if we wanna honor the people who have been affected by these tragedies,
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we do it by reducing the chance that another family can get that phone call
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using evidence and prevention, not fear.
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I would love to hear your comments and what you think about these incidences
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and what I've talked about here in terms of the prevention and further investment
18:29
into prevention and surveillance and science and research.
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Love to hear your thoughts.
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Let me know in the comments below.
18:35
If you're listening to this on audio, you're listening to this through your
18:37
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18:41
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18:45
Speak up for blue.com/feedback.
18:49
Speak up for blue.com/feedback.
18:52
I'd love to hear what you have to say.
18:53
You can either leave a voicemail or you can write it out.
18:55
And of course, if you're watching this on YouTube, you can do the same thing.
18:58
I always love to hear from you.
18:59
This is the start of a conversation, not the end.
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We wanna continue these conversations around safety, around prevention.
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Love to hear your experiences.
19:06
Love to hear what's going on in a beach near you, wherever you live.
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So I wanna thank you so much for joining me on today's episode of the
19:11
How to Protect the Ocean Podcast.
19:13
I'm your host, Andrew Lewin from the True Nord Strong and Free.
19:15
Have a great day.
19:16
We'll talk to you next time and Happy Conservation.