Sara Casareto busts the shark stereotype myth in “Jaws vs Boats”

Sara Casareto films multiple sharks to observe how they react to the electronic pulse. (National Geographic/Mike Heithaus)
Sara Casareto explains where the team will be conducting the electroreceptivity experiment. (National Geographic/Joseph Lupo)

We got to sit down with Sara Casareto, a Ph.D. candidate at Florida International University, who studies sharks, specifically their biology and behavior, and is featured in the SharkFest segment “Jaws vs Boats”

All across YouTube, viral videos abound of great whites and other sharks attacking boats with a ferocity and anger that has never been seen before. The question is, why? Is this simply a case of more people having cameras to video the behavior, or is something else happening? Dr. Mike Heithaus and Sara Casareto set out to investigate what’s causing this clash between sharks and boats.

Originally from Maryland, Sara grew up scuba diving and spending family trips in the water. Sara graduated from the University of Tampa with a degree in Biology and Marine Science and a minor in Chemistry. She has presented her research at various conferences, as well as interning at the MOTE Marine Laboratory. 

Check out our interview with Sara!

First off, can you introduce yourself and your official title?

Sara: Yes. So I’m Sara Casareto. I am a PhD student at Florida International University and I am looking at, for my dissertation, the different factors that affect habitat use decisions of juvenile sharks in estuarine habitat.

How did you get into sharks?

Sara: I first got into sharks because I was very lucky to have a family that was very adventurous growing up. So, I actually started scuba diving at the age of 11 and I think I saw my first shark probably within my first four dives in the ocean. It was a Nurse Shark, which I think is most people’s first shark, unless they go somewhere else, specifically, to see other shark species. And then I think by the next year, I went diving somewhere with Caribbean Reef Sharks and it very quickly became this fascination and love for these animals that I saw who clearly were just minding their own business on these dives, not interested in 11-year-old me at all. And I wanted to just know more about their biology, their importance in the ocean and what they were doing and why they were doing it, kind of what was fueling their behavior and their actions.

I don’t think I’ve ever seen a shark in person outside of an aquarium. So that, to me, is impressive.

Sara: Well, I am going to strongly suggest that you try to get out there because they’re cool. You go diving and you see them and you’re like, ‘ah, it makes sense that they’re in the ocean. Like they’re perfectly designed to be where they are.’

Multiple lemon sharks swim next to a boat. (National Geographic/Mike Ladissa)
You have a segment in SharkFest called “Jaws vs Boats.” What can we expect from it?

Sara: You’re going to learn a lot about shark biology in a very fun and unique way. Dr. Heithaus and I go out there and we try to figure out and try to explain to the audience and to everyone, all the different biological mechanisms that the sharks use to understand their surroundings and figure out if there’s food around, that sort of stuff and how that can play into activities that humans are participating in when they’re out on the ocean. One of the things that’s a big takeaway, as you kind of start to notice a lot of these videos that go viral of sharks being near boats and potentially showing bolder behavior is that, like nine times out of 10, there’s a fishing rod in the background or there’s bait overboard or the person was actively fishing and the shark is now on the line. And you start to notice and keep an eye out for those things. Dr. Heithaus and I talk about all the different physiological and biological mechanisms that sharks use or potentially can be stimulated by, and then you start to plug those pieces together. My friend described it as, it was kind of for someone who’s not a scientist watching the show, they found it to be like a “Mythbusters” for sharks. Because with “Mythbusters” it’s like, ‘okay, why is this happening and what’s the science behind it?’

I like that, it makes it a little clearer from the nonscience side of things. 

Sara: So, one of the things that I’m Dr. Heithaus and I do is explain that we’re going to see sharks but this is why we’re gonna see sharks. We’re revving the boat engine and so they’re hearing it and they’ve gotten accustomed to knowing that boats in this area means that there might be a free meal hanging around. They’re kind of like a dog. You know, your dog learns that when you get up from your desk after working all day, they might get a treat because they’ve been laying down next to being really good or your dog learns that if they go to the door after they’ve been let out, they get a treat and they sit there and they stare at you. And they’re like, ‘where is it’ and if you don’t give it to them, they’re very confused because they’re like, ‘I get this treat at 5pm every other day. You opened the door. I’m confused. What’s happening?’

How did you two get to work together for this segment?

Sara: I’m actually in his lab, so I’m one of his graduate students in his lab at Florida International University. One of the great things that you’ll see throughout a lot of the SharkFest segments is that we’re not just random actors who’ve been just kind of thrown together to do a show. We are scientists and we work together. So me being out on a boat with Dr. Heithaus is really, other than the fact that there’s a film crew when we’re talking about certain things and having to talk between breaks, it’s really no different than if I were just going out in the field with my principal investigator, my PI, which is Mike, and going out and doing my own research or helping him with other projects. And you see that in a lot of the other segments with other scientists. We’re out there with people we go out with and we enjoy spending time with and we work with on a day to day basis.

Sara Casareto photographs a shark underwater. (National Geographic/Mike Heithaus)
What was that like? Having to do your research but also having to kind of engage with the camera. Did that disrupt your normal process?

Sara: Yeah, so quick, small clarification. I wasn’t working on my dissertation at all, but we were using scientific methods and talking through things for that sort of stuff and working together. My dissertation doesn’t involve that. It’s just I was just helping the science and helping with other stuff there. I work with baby sharks on the other coast. But to actually answer your question it’s a little different, however, a lot of the students at Florida International University, we actually have kind of experience with this sort of thing. A lot of the shark biologists and students who focus on shark research, we actually help with this nonprofit research organization called ANGARI, out of West Palm and we actually go out and we are collecting research data for a lot of the students’ research projects, while educating kids and teachers. And if you can get a middle schooler to listen to you while you’re handling a shark, you can get a full grown man of the camera to listen to you while you’re handling a shark. 

But it is important that and one of the great things about, at least the film crew I worked with, is that they’re very understanding of like when you’re out there and you are working with these animals, the safety of the scientists and everyone on board comes first, then the safety of the animal and the well being of the animal, and then everything else comes secondary. So if you need a shot, but the shark is getting really agitated and we just need to release it so that way it stays calm and everyone’s happy, we’re going to release it so the shark stays calm and everyone’s happy. 

When working with the sharks, were there any particular sharks that you tracked throughout the process, or was it just at random?

Sara: So we were for part of it. We definitely were trying to engage with Bull Sharks for a section of the segment simply because Bull Sharks have such a bad reputation of being aggressive. And I know the film crew definitely wanted to get Dr. Heithaus and I out there talking about and just being in the water with these animals. And they are so fun to dive with. They mind their business. 

You see us interacting with really two different species of sharks, a Lemon Shark and a Bull Shark. Lemon Sharks have no concept of personal space, at least the ones there don’t. They’re just like, ‘I’m gonna go this way. And if I whack you, sorry,’ and then they just keep going. They’re like bulldozers. And it’s not aggressive, it’s just very much like, ‘I’m minding my business and I’m gonna swim in this direction.’ While Bull Sharks, most of the ones we are talking about, they were keeping a little bit of distance. You saw some individual variation, like some are maybe a little more curious and got a little bit closer, but they were, I would like to say they were very polite. They didn’t just bump or ram into you. But I know there was definitely that goal to kind of be able to depict the sharks in a different light than what media and social media has really portrayed them as. And one of the things that’s super important to note is, Bull Sharks have this really unique tolerance for freshwater compared to other shark species. So that means you’re gonna find Bull Sharks in estuaries, in rivers, and waters that maybe stereotypically people wouldn’t think of, ‘oh, there’s a shark.’ And when you have that sort of situation, you have an animal that can go in both marine and freshwater the chance of encountering it is just higher. So, like the chance of a human potentially bumping into a Bull Shark compared to a Caribbean Reef Shark might be higher simply because, ‘oh, I never go to the beach so I’ll never see one.’ Okay, well, do you go fish in the Everglades because you might bump into a Bull Shark there.

Gotcha. So, are Bull Sharks dangerous for humans? Like when you hear of shark attacks, is it a Bull Shark usually?

Sara: I think it’s really hard to just classify any specific species as dangerous or not dangerous simply because one, shark attacks are so rare when you actually look at the statistics with how many people are constantly in the water, engaging in water behaviors. And then you may even add in the fact that like, ‘Okay, what was going on? Was there fishing involved? Was there bait involved? Did someone put themselves in a potentially-’ and obviously, there’s always fluke, random encounters. It’s hard to put ourselves in the mind of an animal because we don’t know what they’re thinking. We really don’t actually know what they are thinking. We can study their behavior, study what sort of things are driving them and kind of get an understanding of it, but we don’t necessarily know what is in their mind, like, oh, is the shark feeling sad right now or feeling angry? We don’t know that. I think that there are certain animals that you potentially have more of a chance of encountering because of potentially the habitat you’re in, or just the abundance or what you’re doing and what’s going on. And I think that’s where you hear about, ‘oh, this Bull Shark rammed this boat!’ Well, Bull Sharks are found in marine and freshwater so the odds of bumping into them in a lot of different habitats just increases statistically.

Divers get close to the sharks to examine them. (National Geographic/Mike Heithaus)
The reason I ask is, is your segment’s main purpose to educate the audience about Bull Sharks and Lemon Sharks in regards to the situation or is it more to educate people on this while also telling them not to do certain things? If that makes sense.

Sara: I think it’s more focused on, ‘hey, when you are potentially going on the ocean, there’s always the potential of interacting with a predator, much like if you go into the African Savanna, you might bump into a lion.’ You’re just taking that risk if you go into their habitat and we’re just kind of going back to like the “MythBusters” thing. While we are interacting and seeing these animals, we’re also showing like, how they’re responding to changes in stimuli, and how, ‘oh, you’re seeing them do this sort of behavior,’ these are the different stimuli that could be resulting in that behavior you’re seeing. I don’t ever want to dissuade someone from going out and enjoying the ocean or enjoying the animals. But, if you’re going out on a boat and you have bags of bait overboard, and you’re fishing for tuna, there’s a chance of encountering a different animal just like there is when you go in any sort of habitat. We kind of say it towards the end of the segment that a lot of shark populations worldwide are dwindling in their numbers. It’s kind of well understood with the scientific community that shark populations are not doing too great for a variety of reasons. If you get to see a shark when you’re out there, it’s cool. Take pictures, take videos and enjoy it. And just be happy that you’re getting to see an animal that a lot of people don’t get to see and a lot of people are working really hard to try to protect.

What is contributing to the dwindling populations?

Sara: There’s a lot of different reasons. They’re very similar to what we’re seeing worldwide with many animals. Habitat degradation is one of them, just the damaging of reefs, the damaging of nursery areas, fishing pressure is another one of them. As human populations have increased worldwide, so has the demand for food. And fishing and food from the ocean is a very common source of protein for a lot of individuals worldwide and across cultures. And it’s really hard to control what’s going to bite at the end of a hook, whether or not it’s target or not. So, you could be targeting sharks because they are a fish and there is a fishery for sharks to actually eat. But then there’s also the pressures from unintentional targeting, if you’re going out and you’re just putting lines of bait out to target other fish, a shark could potentially bite it and be what’s called bycatch, which is when you catch something that isn’t the targeted species. And that’s not just with fish, we see it happen with turtles, we see it happen with dolphins. And a lot of technological advances have been kind of geared to like, ‘okay, how can we mitigate bycatch while still getting the fish that we want to get?’

This is all really fascinating.

Sara: I mean, one of the things I think that I’m a huge proponent of is that everyone kind of needs to remember that like we’re not separate from the food web or the ecosystem. We play a very direct and heavy role. We all learn about the food web in elementary school, and the food chain. Like grass is eaten by the grasshopper, the grasshopper is eaten by the mouse, the mouse is eaten by a snake and the snake is eaten by Hawk, right? We all learn about that. But, we also forget that we are also part of this food chain and we’re part of this food web and we have a very strong impact because we have this technology and we have the ability to get a lot of animals in one sitting with our technology and just remove it in one go to fill up our grocery shelves. Obviously, we need food, we need to eat and part of it is getting research to understand how to do these sorts of things in a sustainable manner to keep the balance of the ecosystem. I’m a huge believer that we need to really push for us in the way we think to work with the food web and not against the food web.

Sara Casareto prepares to extract a blood sample. (National Geographic/Mike Heithaus)
I’m realizing just how much I don’t know  about sharks, so thank you for that explanation.

Sara: Yeah, of course. I hope I made that clear. I know it can be like, oh, wow, there’s a lot of words coming out of me right now.

No, it’s all good. It’s all good. You mentioned earlier that you would never discourage someone from going out and seeing sharks. So, if someone is afraid of sharks because of movies, TV news and things like that, what advice would you give them to kind of lessen that fear?

Sara: First off, I do want to say that fear is a very normal emotion and sometimes you can’t control it. Like, I have a friend who’s terrified of frogs. I know, frogs? A frog is not going to come around and eat you, you know? Like, it’s a frog. It’s not gonna squish you under its big foot or something. And there’s sometimes no logic behind emotions. That being said, if someone is scared, maybe they saw Jaws as a kid and it kind of made them really, really scared of sharks, but they want to lessen that fear, for those who can go to aquariums. It’s a controlled setting, you get to see the animal, you get to learn about the animal. Watch documentaries and shows like SharkFest with National Geographic because they do a really good job of presenting things in an entertaining manner but maintaining the factual integrity of the information that’s being put on screen. And almost everyone I know, like so many of my friends, are not in marine biology and they’re all like, ‘I can’t believe you do this.’ And after like three years of  hanging out with me constantly and just me showing them videos, they’re like, ‘you know, I want to go snorkeling with you. I want to see this. You’ve talked about it so happily and like you’re still here so it can’t be that bad.’

Photo courtesy of National Geographic
You can catch Sara on “Jaws vs. Boats” during SharkFest and you can follow along on social media @bluewavz.