Should bull sharks be culled? The truth behind shark bites and how people can actually stay safe

0:00 Should bull sharks be eradicated? That is the big question that people are asking after four serious bull shark bite incidences happened in 48 hours in Australia near Sydney. This is a question that everybody's having and people have some pretty extreme views on what we should be doing with bull sharks in the future. How do you feel about a shark cu Well, I don't know. Look, I, I always feel like when something tragic happens, obviously we, we need to be seen to be doing something. Mm. But whether this is the answer, I'm not sure there are about 20,000 bull sharks in the Harbour at any one time. That's what my friend told me anyway, Um, So I feel like it would just be kind of something to do. Yeah. To show that we're trying, I mean, it's saying that though, if this happened to my family or someone in my family.

0:42 I probably wanna drain the ocean. Yeah. You know, get rid of everything. I think that's a really good point. I would too. Um, but I mean, we've been talking all morning and I've been covering this story for 20 years and, and it happens every time. Mm. But I would say this, um, as I said on Monday, all the way along the coast, my friends have been telling me there's more sharks. The bull sharks, as far as I'm concerned, are the bin chickens of the ocean. Yeah. There's no one out there. There's so many of them. There's no one out there who's empathetic to a bull shark. So I've got no problem. Eradicating them, absolutely none. But I'm, I'm gonna have Peter on my shoulder and saying whatever, but I just don't, they're good for nothing. Today in this episode of the How to Protect the ocean Podcast, we are gonna be talking about why these events happen, what the data has shown that's happened in the past, and how we can reduce shark human risk in the future.

1:26 That's on this episode of the How to Protect the Ocean Podcast. Let's start the show. Hey everybody. Welcome back to another exciting episode of the How to Protect the ocean Podcast. I am your host, Andrew Lewin, Marine biologist and science communicator here to tell you what's happening with the ocean, how you can speak up for the ocean, and what you can do to live for for better ocean by taking action. And on today's episode, we're gonna be talking about the four bull shark incidences, shark bites that happen in less than 48 hours in Australia, near Sydney. One happened in Sydney Harbour and others happened nearby beaches. Manley Beaches, one of them. And we're gonna talk a little bit about like why this stuff is happening. Every time when there's some kind of shark incident, there's a lot of out of pocket kind of takes on it.

2:07 Just like we showed in this intro, there was a daytime talk show in Australia where the person was like, Hey, look like these are just garbage can type bull sharks. These sharks are not really iconic. They're not really what people love. I'm just fine if we eradicate all of them. Like he just wanted to go eradicate all and thinking that's going to decrease any kind of shark human interactions instead of just adapting and living with these interactions and finding out what we can do more about it rather than just taking these out of pocket takes, in my opinion. But before we get into the science and, sort of the ideas that people have and what we should be doing. I wanted to just be respectful of the people who were bitten. A person lost his life. It looks like a little boy, a 12-year-old boy may lose his life.

2:50 He's in critical condition. Last reports that I saw, it didn't look like he was gonna make it through. This is the utmost tragedy. Anytime somebody loses a life or anytime someone's bitten and is in critical condition, doesn't matter, child or adult, it hits hard. And it's something that we have to respect. I'm not going to talk about what they were thinking of or try to assume what they were thinking of when they were going into the water. I'm not going to discuss if this is something that was appropriate or not. What I'm going to do is focus on the science. I'm going to focus on what we know of bull sharks in this area at this time of year, what we know about some of the environmental conditions in this area. And things that we can do to reduce the risk of things like this happening in the future again.

3:33 This is not something we want to see. Whether you're a shark advocate or you care more about the humans or both obviously 'cause we both care. If you're watching this show or listening to this show, you care about whether people are hurt by sharks, and also you care about how people look at sharks after some of these incidents happen. So that's what we're gonna be focusing on today. We're not gonna be focusing on the assumption of what people were thinking. We're not gonna be taking away anything from what happened to them. You just never know when these things happen. But we are gonna focus in on the science. So let's start with something that we should be looking at. And let's not get lost in the panic of something like this happening. Although it's very rare that this happens obviously has happened and we have to acknowledge it.

4:15 But the thing is, bull sharks have been present around Sydney Harbour and nearby New South Wales coasts. That's not new thing. They've been doing this for a long time. Sciences have been tracking sharks in Sydney Harbour and documenting patterns of occurrence in seasonality for years. One study that I found in PLOS One mapped out how different shark species use different parts of Sydney Harbour and at different times of the year. Specifically noting that this kind of information has implications for managing human shark interactions, including education programs and modifying human behavior during high risk periods. Even more directly, a long-term acoustic telemetry study followed dozens of bull sharks in Sydney Harbour over multiple years and described their residency and movement pattern in a large temperate estuary where human activity is high.

4:59 So we know that these bull sharks are there. We know that they've been there for multiple years. This is something that isn't new. There are some conflicting reports that people are saying, oh, we're seeing more bull sharks around. Fishers have said that. I've seen a lot of comments being like, Hey. The bull shark population has increased unprecedentedly. And this is something that can't be confirmed or denied at this point. All I know is that people know that there are bull sharks in the area at this time of year. We know that their population has a range, but scientists haven't noticed any massive increase, so we can't speak to any of that increase. In other words, there's no physical evidence or there's no population evidence that I found before I joined this show that had that.

5:41 And it's not just the Harbour that they're found. A multi-year tagging and monitoring study also found in New South Wales beaches that tracked hundreds of bull sharks and examined when and where larger bull sharks are more actively to be present, finding seasonal patterns that matter for beach risk management. So in other words, when it's really hot outside like 20 to 26 degrees Celsius, maybe even higher, these bull sharks are there. And so they will come close to shore during these times because they like the warmer periods. Anything below 21 or 20 degrees Celsius, they're not there. In Sydney Harbour, other shark species are found in areas where it's cooler than 20 degrees. So, there is definitely a pattern here, a spatial pattern and seasonality pattern that we see. So when we talk about why is this happening now, part of the answer is because bull sharks predictably use these waters and particularly in warmer months.

6:30 So in the summer months. I know right now, like I'm recording this on a Sunday evening. There's a massive snowstorm, like we're getting 30, maybe even more centimeters out here in Ontario, so it's winter here, but in Australia it's summer, it's hot. And so you're gonna find bull sharks predictably in the warmer months and scientists have been documented for a long time. Now, why these incidents are likely happen? Let's talk about conditions, because conditions actually matter here. We have warmer months. We know that these sharks are in there, the bull sharks are in there, and the warmer ones, especially in Sydney Harbour. But bull sharks are strongly associated, not only with warm water and coastal systems including estuaries and areas of highly influenced by freshwater flow. So they have this ability to go up into freshwater rivers, estuaries, and go into the freshwater area and in areas where you can't see them.

7:16 It's not very clear. When you look at a river system, they're not always perfectly clear. A lot of the times you get a lot of sediment. You might get some pollution in there but it's pretty turbid in those areas 'cause usually it's shallow, there's a lot of sediment that's around it. And if it's in a area where there's a lot of sediment that's going in, or it's faster, you might start to see it be essentially brown or darker or, just you can't see through it. And so you'll see a lot of that turbidity in there and those sharks can come in and you don't even realize they're there. And that's been a lot of the times where the bull sharks are notorious for having shark human incidences when they come into these areas where you can't see them. They're just there. They can't see very well. They end up taking a bite or an exploratory bite, whether they find it intriguing or not.

7:58 And they go for it because they're looking for food and they're in hunting mode. And so when you have all that in those estuaries, in those river systems, you get more shark human interactions if there are people in those river systems. We've seen that not only in Australia. We've seen in Africa, we've seen it everywhere where bull sharks are. You have to be careful in those areas. So they use any area that it could be turbid, it could be more fresh water. They could be up in the estuaries. Long-term tracking has worked, links their presence and then their movement to predictable seasonal patterns and habitat use within a Harbour system where there's a lot of entries of different estuaries. And so that's been a thing that they've had to look at. Now you add summer rainfall in this area.

8:39 There's some season for Australia, as far as I'm told, some pretty heavy rain. So in summer storms you often get increased runoff into coastal waters and Harbour systems that runoff can turn the water murky and reduce visibility. Bull sharks are adapted to low visibility environments, like I said, so they'll be in murky waters. Risk can increase because the visibility cues that humans rely on drop fast and bull sharks do not rely on their vision the way people assume sharks do. They use multiple senses, including electroreception and vibration cues. So they have the ampullae of lorenzi across their snout. And so they detect like electromagnetic fields or even electromagnetic movements in muscles. So that's how they tell if there's something there which could be part of the why that they thrive in turbine systems 'cause they don't use sight.

9:24 So essentially in murky waters, the odds of a mistaken bite can increase. That's not a moral statement, it's just a risk assessment. Right? It's a risk statement. Clusters can happen. So a small number of high profile incidences close together can be driven by a temporary overlap. So you got warm waters, seasonal presence, high beach use with people 'cause it's summer and short-term environmental shifts, you know, summer rains and things like that. Long-term science base is what helps us talk about this overlap with clarity instead of fear. Scientists have known that these incidences can be at higher risk during this time. And so the question is, is how come people don't know about it? I looked through and I saw a lot of scientific journals talking about this, but let's be honest, we know from a scientific journal standpoint, from a scientist myself, we know that these scientific journals can be exclusive.

10:11 They don't get to everybody. They don't get to lifeguards, they don't get to beach managers, they don't get to police, they don't get to firefighters and paramedics to educate them on the risk unless there are programs in place for that to happen. We look at this and we're like, why isn't this happening every year? In this case is obviously it's a larger case in a shorter time. But the risk isn't just sharks. It's sharks plus the conditions plus people. Everything has to happen at the same time. So some years have different rainfall patterns. So you know, sometimes it's not as hard or it's not happening all at once. You have different water clarity, different ocean graphic conditions. You have different surf conditions and different levels of exposure from swivels and surfers. So this is why year to year, the bite numbers fluctuate.

10:53 So sometimes you'll see like an increase like this year because the conditions just kind of matched everything. So not only was it the summer months, not only was there high rainfall, and not only were there people coming in more towards beaches or trying to jump off a rock or things like that. It was just a lot of things happen together that risk increases. So the level of exposure to swimmers and surfers will increase. And there is another layer that is becoming more important is warming oceans. A recent paper reports that migrating bull sharks have increased residency at summering rounds off Sydney over a long time series with a trend of longer seasonal presence, so they're staying there longer, which has implications for how New South Wales communities may need to adapt to risk for messaging and monitoring over time.

11:35 We wanna make sure that people aren't going in the water when there times where these bull sharks are close to shore. When they're in the warmer waters, when they're in turbid waters and they can't see you just as much as you can't see them, that becomes a dangerous time. And so people need to be educated better. Not to say that they're not educated now, but obviously there are some people who haven't gotten the message as much as they could have and went in the water instead of staying outta the water during these times. So it doesn't mean that more bites are inevitable but it does mean that the window of overlap between people and bull sharks could expand. And that is a management and education challenge, not a reason for a panic response like eradicating these animals. When you get incidences like this, people want something immediate.

12:17 And even in the clip that I showed you at the beginning of this episode, someone was saying, Hey, look, if this happened to me, like, you know, if my child or my relative or a friend got bitten by a shark and their life was altered, whether it was fatally or otherwise, they even admitted they like, they would want to see the oceans drain. Like could go to extremes, right? You know, I want, I get all rid of all the bull sharks in a minute, but this is not like a call feels immediate. But there are three problems that almost never get said out loud in these public debates. So the problem one. Bull sharks move. Removing some animals in one place does not erase the risk in that place. So other animals may come in because there's less competition. Problem two.

12:57 Lethal control often kills non-target species and can create ecological harm without proving long-term reduction in bite risk. So by eradicating all them, obviously it's not gonna change anything. Other animals get may get cut. Other species, they're just probably gonna look for species that are big enough. We've seen these called programs happen in Australia in the past. It's very interesting to see this. Problem three. It shifts focus away from what actually reduces risk. So information, surveillance, warnings and behavior change. Those are the biggest things. So those three problems need to be solved. And that leads us into the most important part of this episode, which is basically what actually helps people stay safe.

13:38 So in New South Wales, there are documented programs where scientists, government agencies, and surf life saving personnel are actively involved in surveillance, public warnings, and risk reduction. New South Wales Shark Smart Program describes a multi-layered shark management approach that includes surveillance technology such as drone patrols, operate through surf Life Saving and New South Wales as part of the New South Wales Shark Management program. These drones are not just for show. If you go on Shark Smart's own website, they describe that the drones allow lifesavers to spot sharks respond quickly, including actions to clear the water when needed. So if they see bull sharks close by. You can fly a drone over quickly.

14:19 You can do a patrol. You can see if there's sharks in the water, and then you can say, Hey, you know what, let's come out. These sharks look big, or these sharks look like they can do some damage. Let's make sure our beachgoers are safe and our swimmers are safe. Let's take them outta the water. So recent reporting also documents New South Wales expanding these efforts after this cluster of incidences, including additional investment tied to surveillance, bull shark tagging and shark safety education and expanding drone coverage to more beaches through peak season. So there's gonna be more investment into that safety, which is what we want to see. We don't wanna see people go out and culling these animals. We wanna make sure that we can properly fit ourselves with the technology that they can go out and they can see what can be done and make sure that people are safe.

15:00 So when someone asks, are scientists actually working with lifeguards? The answer in New South Wales is actually, yes, and through an ongoing program that includes surf lifesaving patrols, surveillance technology, shark listening stations for tagged animals and public education components. This is what prevention looks like. What you really need to hear is actionable clarity. So if you're swimming in waters where bull sharks are known to occur, or where estuaries and river mouths influence water conditions, avoid swimming after heavy rains especially, when the water is murky. Be cautious in your river mouths and Harbour entrances after runoff events. Pay attention to beach warnings, drone alerts, and lifeguard instructions.

15:44 Just to add on to that, if you're in a new area, if you're a tourist or you're somewhere in a new beach, make sure you know the color symbols of the flags of what's danger and what's safe to go into. A lot of these flags systems could be quite sophisticated. They'll have purple flags. They'll have green flags, they'll have red flags. They'll have yellow flags. They'll have blue flags. They'll have flags with lines in them. Learn what they are. There should be signage posting to see like if there's a dangerous animal in the area or if it's like a rip current. There's all these different signs and flags to make sure that you are safe. Ensure that you look at those flags before you even step onto the beach or before you even go into the water because that could save your life. ' cause you just never know what's happening to the beach. A beach could look perfectly fine.

16:25 Maybe have a few ways, but you have no idea if there's a rip current. You have no idea if there's an animal out there, if you're not paying attention to the signage. You could also even go up to lifeguard stations and ask them, Hey, like, is there anything dangerous in the water or is there anything I should know about this? And they'll have a frank conversation with you. They might be a little bit more conservative and be like, there're always animals that might be able to hurt you in there, so you are taking a risk. But we haven't seen any so far, like that's been outward, like a concern. So that's something that you can go through, especially in Australia. If you're on a remote beach or you pass by certain areas, I would just be very cautious. There are a lot of animals in there in the river systems and so forth that could harm you. And so make sure that you know where you're going. We've done episodes on this podcast before.

17:06 We've talked about how talking to locals before you go out into a river or a lake, especially in Australia, could really help you in saving your life. 'cause there's a lot of crocs in these areas and you gotta be careful, not necessarily in Sydney, but definitely in the northern edges. But also talk to any locals before you go out there. And of course the last point. If beaches are temporarily closed, treated at that as prevention. Not an inconvenience. Don't just say, oh, I came all the way out here to go to the beach. I'm gonna the beach no matter what. If they close the beach, there's a reason why they close the beach. So just be cautious and maybe like, you know what, today's just not the day that I'm going into the ocean. So these are the kind of behavior changes that a science and form lifeguard system is designed to support. And in New South Wales is actively expanding surveillance and education efforts around exactly this problem.

17:48 So should there be an eradication of bull sharks after, you know, four incidences in 48 hours? Eradication is not the strategy. It's an emotional reaction. The strategy is what New South Wales and other regions increasingly focus on. Surveillance, tagging and detection, education and real-time risk communication paired with clear public guidelines during these high risk conditions. And if we wanna honor the people who have been affected by these tragedies, we do it by reducing the chance that another family can get that phone call using evidence and prevention, not fear. I would love to hear your comments and what you think about these incidences and what I've talked about here in terms of the prevention and further investment into prevention and surveillance and science and research.

18:33 Love to hear your thoughts. Let me know in the comments below. If you're listening to this on audio, you're listening to this through your favorite podcast app, whether it be Apple Podcast, Spotify, Amazon Music, whatever that might be, let me know what you think by going to speak up for blue.com. Speak up for blue.com/feedback. Speak up for blue.com/feedback. I'd love to hear what you have to say. You can either leave a voicemail or you can write it out. And of course, if you're watching this on YouTube, you can do the same thing. I always love to hear from you. This is the start of a conversation, not the end. We wanna continue these conversations around safety, around prevention. Love to hear your experiences. Love to hear what's going on in a beach near you, wherever you live. So I wanna thank you so much for joining me on today's episode of the How to Protect the Ocean Podcast.

19:13 I'm your host, Andrew Lewin from the True Nord Strong and Free. Have a great day. We'll talk to you next time and Happy Conservation.