Three ninja-skilled sharks have been discovered in the icy waters of Alaska, off populated beaches of New York, and lurking in ghostly shipwrecks off the coast of North Carolina. Dr. Craig O'Connell and Madeline Marens share what they’ve learned about these sharks' unique and deadly qualities.
Three ninja-skilled sharks have been discovered in the icy waters of Alaska, off populated beaches of New York, and lurking in ghostly shipwrecks off the coast of North Carolina. Dr. Craig O'Connell and Madeline Marens share what they’ve learned about these sharks' unique and deadly qualities.
Stream exclusive Shark Week content on discovery+. Daily Bite podcast listeners get a 7-day free trial—go to https://www.discoveryplus.com/dailybite to get started.*
*discovery+ is currently only available for US subscribers.
Find episode transcript here: https://shark-weeks-daily-bite.simplecast.com/episodes/these-ninja-sharks-have-deadly-skills
LUKE TIPPLE: Good day everyone, I'm Luke Tipple. Welcome to the Daily Bite. Today we're diving into the Shark Week show, Ninja Sharks 2: Mutant Rising with the stars, our guests, marine biologist Dr. Craig O'Connell and Madeline Marens. We're going to be exploring the nearshore waters of New York and the ghostly shipwrecks off the coast of North Carolina.
SPEAKER 1: Millions of years of mutation and evolution have created the perfect predators.
SPEAKER 2: It's like they develop the ultimate superpower.
CRAIG O'CONNELL: For years, scientists have been tracking them, and with recent breakthroughs, are closer than ever to discovering their secrets. Shark trackers are plunging into the shadows.
SPEAKER 3 (ON RADIO): Hold on, hold on. There's a shark chasing the shark divers.
SPEAKER 1: And risking their lives.
SPEAKER 4: We got to get out of here. I don't think this is going to work.
SPEAKER 1: To unmask these ninjas of the shark world.
LUKE TIPPLE: Craig, Madeline, welcome to the Daily Bite.
CRAIG O'CONNELL: Thank you so much for having us.
MADELINE MARENS: Hey. Thanks for having us.
LUKE TIPPLE: Yeah, very welcome. Excited to have both of you here, excited to see the show Ninja Sharks. Craig, perhaps you could just tell us a little bit about who you are, what you do, and what your research is.
CRAIG O'CONNELL: Well, I am Dr. Craig O'Connell. I am an executive director from O'Seas Conservation Foundation. And my research primarily focuses on shark behavior, and I specifically am starting with target thresher sharks because they're such an impressive animal. It's like my new passion. They're incredibly hard to find, and so I'm trying to do as much as I possibly can to learn as much as I possibly can about them.
LUKE TIPPLE: And Madeleine, you definitely win the background award for all these interviews so far. You're a pretty cool spot. Who are you, what do you do, and what's your research?
MADELINE MARENS: Hey, guys. My name is Madeleine Marens. I work at the North Carolina Aquarium at Fort Fishers. So behind me, you see one of our cool tanks behind the scenes at Shark Cove right now. So we've got some fishy friends behind me.
I'm a researcher here at the North Carolina Aquarium. I'm studying sand tiger sharks off the coast of North Carolina. We see them here in groups of over 100 sharks through certain times of the year. And we're really interested in what these sharks are doing here off of our coast, particularly at shipwrecks that we see here.
LUKE TIPPLE: Yeah. That footage is absolutely incredible. We're going to get to that in a minute. But since time is limited, I want to dive right into Ninja Sharks because we've got some pretty amazing footage coming up. So Craig, first of all, we've got a clip of you putting it all on the line.
SPEAKER 5: It's getting a little spooky. The lights get pretty low. I just saw the silhouette of a shark out there. It's like it flew.
SPEAKER 6: Another one back there.
SPEAKER 7: I have personally seen blue sharks hunting in packs, circling and herding prey before they swoop in for the kill. So I get a little bit on edge when I see a bunch of blue sharks all around us at once.
SPEAKER 4: We got to get out of here. I don't think this is going to work.
LUKE TIPPLE: So Craig, you're in low light, you're looking for threshers, and suddenly you get mobbed by blue sharks. What was going through your mind at that point in time?
CRAIG O'CONNELL: Well, the thing is we are trying to find this new non-invasive way to put tags on thresher sharks. That get really stressed out so we didn't want to catch them. So we came up with this brilliant idea to go out there and churn the waters and hopefully try and free dive down and put a camera and a tag in these sharks. And the light was getting low, things weren't working out, and before we knew it, we were completely surrounded by these blue sharks. And it was getting really uncomfortable out there.
I was losing light, you could barely see them. You wouldn't see them until the last second. They were coming from every direction. And sometimes, they were bumping your legs. So they'd surprise you. They'd come out of nowhere. So I was at the point where we had to call the dive. I saw that this technique wasn't going to work. But I mean, it was exhilarating. It was amazing. Blue sharks are absolutely beautiful animals.
LUKE TIPPLE: Exactly where were you?
CRAIG O'CONNELL: So we are at this special reef about 7 miles from Montauk. And the thing that makes it so special is it's a very small reef, and during two weeks every single year, it's absolutely mobbed by thresher sharks. You can go there and you could see thresher sharks jumping out of the water, swimming around, and then all of a sudden at the end of that two weeks, they completely disappear. So yeah, just off the coast of New York, we have blue sharks, we have thresher sharks, great whites. It's really special location.
LUKE TIPPLE: So you're talking about the threshers because I've actually always been fascinated by thresher sharks. It's one of the few sharks that I've yet to see in the wild. You've got them in your backyard and you've only got them from a couple of weeks. Why are they there and why do you want to work with them?
CRAIG O'CONNELL: So that was the whole point of our expedition. I'm fishing in my own backyard. I have these massive sharks in my own backyard, and these thresher sharks are showing up in massive numbers for these two weeks and then they disappear. So the goal was to figure out why. So we used a bunch of different technologies, and eventually at the very end, we figured it out.
The temperature is just right, and there's these massive bait balls, the size of football fields, coming over that reef. And when they come over that reef, it's like an underwater buffet for these thresher sharks. They're feasting on it. But then at the end of that two weeks, the temperature starts to change, the bait seems to disperse a little bit, and So do the thresher sharks.
LUKE TIPPLE: So you did manage to eventually get an acoustic tag on. How many acoustic tags are currently, or tags in general, are on thresher sharks right now that you're responsible for?
CRAIG O'CONNELL: So right now, we only have one acoustic and one satellite tag because that was really the beginning of the research. Now we're going to continue it this summer. The unfortunate thing with the satellite tag, we're still trying to figure it out. But that particular thresher shark that we caught wound up going all the way to Block Island and made its way on land. So we don't necessarily know if that animal was actually captured by a fisherman and killed I mean, it is a highly prized fish. People like to eat thresher sharks, and it's a very big possibility that it was captured and killed. So totally disappointing.
LUKE TIPPLE: I know what that feels like. We did a study out in Marshall Islands where I put out 18 tags on reef sharks trying to prove inter-island movements for these animals. And every single one of them except two of them within a month of us being there shows-- they actually showed some inter-island movement and it was fairly like normal swimming speed and everything like that. And then they pretty much went straight line all the way to Indonesia.
I'm like, OK. Fishing fleets just came in and wiped them out. It's heartbreaking when you put all that work into tagging, and you just see them go away. But obviously that data might be corrupted, but what is your best guess? Like where are they coming from, where are they going? Are they just following the warm water as it moves down?
CRAIG O'CONNELL: So it's difficult to say because we have a lot more work to do and it's a very understudied species of shark. I mean, you're thinking about great whites, there's so many tags out on great whites, everyone loves great whites. But I feel like we kind of miss out on these awesome other shark species, the threshers, the sand tiger sharks.
And so I think we need to do a lot more work. But if I had to guess, I think the sharks are following this particular water temperature. They make their way up to Massachusetts and then they make their way back down South. There's a lot of them down in North Carolina during particular times of the year, especially the winter time. So they're seasonal residents in Montauk and then they move on.
LUKE TIPPLE: Well, since you mentioned sand tiger, they're like one of my favorite sharks actually, I'd love to talk about Madeleine's spot on the show because Madeleine has some of the most incredible footage I've seen of sand tigers on Rex.
MADELINE MARENS: Yeah, thanks. So North Carolina coast is world-renowned for its diving. We're known as the graveyard of the Atlantic. We have shipwrecks that wrecked over 200 years ago during the Civil War up to World War 2, so some of these shipwrecks have been there for over 200 years. And over time, encrusting organisms have settled like barnacles and sponges and have become like their own ecosystem oasis where these really productive habitats are happening where you have small fish settling and then you have your larger predators coming in like your sharks.
So people come from all over the world to dive off the North Carolina coast and can see these large aggregations of sand tiger sharks swimming and hovering over these shipwrecks. But it's really been fascinating to researchers over time who are thinking, what are these sharks doing here on these wrecks? They're highly migratory. We can see sand tiger sharks through past studies go all the way up to New Jersey, there's nursery habitats north of Cape Cod.
They're highly migratory though and they will come back down to southern waters in the fall and winter. And some of them are seasonal residents. So they may be staying in North Carolina for long periods of time but we don't know why. So the focus of my study is what are these sand tiger sharks doing off of our coast. I'm particularly looking at mature females as we think this might be an important reproductive habitat for these sharks.
LUKE TIPPLE: Well, that's fascinating. I actually didn't know that they weren't resident in that area. So you're saying that some of them will hang out on wrecks or at least in the area year-round. Obviously, you said you're still trying to figure that out, but is there any preliminary idea? Like is it sex, is it size, age?
MADELINE MARENS: Yeah exactly, that's a great question. So we do. As they are highly migratory, they will make spring and summer migrations up to places like Delaware Bay. And then in the fall and winter, they'll return South to southern waters from North Carolina to Florida. And divers anecdotally see sand tiger sharks from spring to fall. And we do see mixed sex. Interestingly, we do see some females with scarring in the spring and summer months.
So there might be mating occurring here. But there hasn't been the coverage from acoustic telemetry studies in North Carolina. We know that it's a pit stop, but we don't know who these seasonal resident sharks are.
LUKE TIPPLE: Interesting. So you have the enviable job of actually getting to go and dive with these guys. Put me in the water with you because I was watching this footage-- and the show is amazing. When you're in the water, it's so clear, it's pretty, and I'm a huge wreck geek, so I love seeing that. And then you see a couple of sand tigers then you look up, and there's a couple of shots that blew my mind where there's probably 60 to 100 individuals just kind of hovering there. Put me in the water with you, guys. What's that experience like?
MADELINE MARENS: Absolutely. So most of our days are not like that. A lot of times we're diving, we're putting down receiver equipment that detect these tagged individuals, we're working in visibility of less than 1 foot and really strong currents and really cold water. But during the summer and fall months you get really clear water right off the coast of Cape Lookout. And you're on these shipwrecks, some of them from World War 2, so these big u-boats, which were German submarines that were sunk right off the coast.
And you go down, and there's just a group of or an aggregation of 50 to 100 sharks just hovering almost motionless and then these bait fish swimming around. It's really just like another world and it's just so awesome to be in their element and share that space with them.
LUKE TIPPLE: So how often are you on one of those, dark, cold, low visibility dives and you're just swimming along and bumping into sand tigers? Is that happening very often?
MADELINE MARENS: That did actually happen one time. I was going down with my dive safety officer and we could see each other. It was kind of murky, we had about 10 feet of visibility and we're going down the line about to hit the wreck. And I see that there was a juvenile sand tiger shark swimming up underneath him, almost nosing up checking him out. And I was like, check it out. Shark, shark. And he actually bumped into him and the shark swam away and we were OK.
LUKE TIPPLE: That's a good result. I was watching the show and it threw me back to some work that I did with swordfish. So we're on deep shipwreck. It was for a Shark Week show. But we were tipped off that the swordfish might be semi-resident or they might be using it as a sort of mating area or at least a refuge. and I did see some footage of about half a dozen individuals, so I thought we might have a pretty good chance to go on and find swordfish on this wreck. But the visibility was terrible, the current was terrible.
And there was like one dive where I'm zooming around on a scooter doing 4 knots underwater. And the visibility was shocking. It's like 230 feet and I was able to see maybe 6 feet in front of me. And I did have this thought in my mind I'm zooming around way too fast way too deep, and I can't see anything. I'm trying to find a 15-foot animal with a sword for a nose whose instinct is to go like this when it's in defense. I'm thinking, this is a really, really dumb idea. I guess we found it. The mechanism for buoyancy in the sand tigers is really, really interesting. Can you explain that for me?
MADELINE MARENS: Absolutely. So sand tiger sharks are unique in that they can actually go up to the surface and they'll gulp air and keep that air in their stomach that acts like a flotation device. So we'll see them go up, gulp air, and come down. And then they can control how much air they want in their stomach and they'll release air bubbles. It kind of looks like a shark burp. So if you're lucky enough and you see a sand tiger shark releasing some air, that's them controlling their buoyancy.
They lack a swim bladder like a bony fish do, they do have really large livers, which are really rich in oil, which helps them also float. But this also extra flotation device lets them hover almost motionless. And they can use the current to kind of position themselves where they're hovering over the wrecks. And we don't really know why they're doing this. They could be seeking prey. They are known to aggregate, and this may be a social behavior.
So these wrecks are really productive habitats, so they may be a great prey resource. But we think that there may be a behavioral component. This may be a great area where they're getting together and mating. Also these mature females may be partially segregating themselves from the population. With the rest of the populations going up to Delaware Bay in the summer, we are still seeing mature females and we have identified pregnant females that are staying on these wrecks through the summer, fall, and winter. So this may be an important reproductive and birthing habitat for sand tiger sharks.
LUKE TIPPLE: With your best guess, do you actually think they're giving birth and popping on the wreck or is it just a safe place for them to be until they move somewhere else?
MADELINE MARENS: That's a great question and something that we're trying to figure out. What we were talking about with really low visibility, it's really hard for us to go down and directly observe this happening. With the advent of technologies like acoustic telemetry, we can tag these individuals, but they have to be in range of these receivers that tag that equipment. Then you have satellite tags, which are great, but sometimes you are dealing with tag loss or malfunction of the equipment.
So we are starting out looking at these shipwrecks, and we are-- with onboard ultrasounds, we're actually able to identify pregnant females and kind of gauge how far along she is. So sand tiger sharks have a really long gestation period of like nine to 12 months. But we can kind of say, OK, she's about four to five months in and then look at her detection data and say, OK, she stayed in North Carolina or she moved a little bit inshore or offshore. So those are some of the next questions I think we're going to look at.
LUKE TIPPLE: That's amazing. So talking about footage from this show, Craig, you guys put together a rig that captured some of the most incredible behavioral footage from a thresher that I think has ever been filmed. Let's check that out.
SPEAKER 1: Craig employs a towable camera rig to draw them in.
CRAIG O'CONNELL: It's got a camera here. We're going to attach bait to each one of these arms. And if these sharks are really here to feed, we should get a strike on this.
SPEAKER 8: Mackerels rigged and ready.
CRAIG O'CONNELL: I dropped our baby in. I got the port engine going. You have a read on the video?
SPEAKER 8: Yeah, we can see it.
Oh, my God.
CRAIG O'CONNELL: Let it go, let it go. Get over here, get over here.
SPEAKER 8: Oh my God.
CRAIG O'CONNELL: I swear to God, we got what we wanted.
SPEAKER 9: Holy-- holy-- What?
SPEAKER 8: Oh, my God.
SPEAKER 1: It's a thresher just yards away from their boat on the hunt for prey.
CRAIG O'CONNELL: Get in, get in.
SPEAKER 1: The shark eyes up its prey, locks on target, then moves in for the kill.
CRAIG O'CONNELL: Light with the tail.
SPEAKER 1: The motion is so fast, it's over in one frame of video, 1/30th of a second. But Craig spots the blade-like tail slicing across the bottom of the screen. A ninja on the hunt for food.
CRAIG O'CONNELL: Oh, wow.
SPEAKER 9: Oh my God.
CRAIG O'CONNELL: Crushed it. Slapped it with its tail.
SPEAKER 8: Look at that. What's that.
CRAIG O'CONNELL: Super graceful. The tail moved like a ribbon, and then whammo. Sheer power.
LUKE TIPPLE: So Craig, not only did you get a fin cam on a thresher shark during this show, you also got footage of a thresher shark actually predating on your trawl cam. What made you think that would work to start with?
CRAIG O'CONNELL: To be honest, we didn't necessarily know what was going to work when we were out there. We just thought a bunch of different technologies to try and figure out what in the world these thresher sharks were doing. So we did the fin cam, we got some groundbreaking footage. No one's ever done that before. We were thrilled that we even recovered the fin cam because it's like finding a needle in a haystack, this tiny little camera system floating in the middle of the ocean.
So we got that back, we were super excited. And then I had this trawling camera and I was like, this is worth in places like South Africa where I've towed a tuna, and a great white shark would come out from absolutely nowhere and swallow up that whole tuna. And to me, it was an indication that sharks are feeding on this, it's an indication that they're motivated to feed in this general area.
And so I decided, guys, why don't we tow this TroPro behind the boat, put a bunch of fish around and make it look like a school of fish. And if the threshers are there and motivated to feed, we should get a strike. And the crazy thing about it is that within just about five minutes of putting it down, we had the live feed running and all this, a thresher shark showed up. And it was a massive thresher shark. It was like 12 to 15 feet.
And you could see it was following it. It was checking it out, it was very curious. It was using its vision to try and determine what it was. And then at the last second, it accelerated towards the TroPro, the trawling camera, it took a dive down, and we were like, oh, we lost it, but then you saw the tail take a swipe at the bait. And to me, it was the most incredible thing. We saw these massive schools of bait. Now we got that visual evidence of a predation and we figured out why these sharks are at that reef. So to me, it was groundbreaking. I could not believe it.
LUKE TIPPLE: Yeah. It certainly looked like a pretty powerful moment for you because you're dealing with animals that aren't there that often, they're pretty mysterious, and you guys managed to actually capture that on film. It's super rare and I was stoked for you when you got it. When you brought the mackerel back up, first of all, I wanted to ask you, how fast were you trawling at?
CRAIG O'CONNELL: We weren't trawling it very fast. We were moving right around 5 knots. If we went too fast with that trawling camera system, it would start spinning and it would make everything look unnatural. And so basically, we just towed it 5 knots. We felt that speed, the fish were swimming perfectly, everything was just right. And it paid off.
LUKE TIPPLE: Yeah. I was curious about that because the way that they attack. They're swimming, swimming, swimming, they almost have to come to kind of a stop before they whip their body around and use their tail as that whip. So I'm wondering like is there-- there has to be some type of limiting speed that they can't go after some type of prey because they'd simply out-swim them by the time they've made that turn, right?
CRAIG O'CONNELL: No, I 100% agree. I think there's an optimal speed, and that's something we learn in fishing in general. When you're trawling for certain types of fish, either throw really fast for things like wahoo or you trawl a little bit slower. I think the same thing applies for the thresher sharks. The only thing is I've tried multiple other times to trawl through that area at that same exact speed and we haven't had any luck. So I'm really grateful it happened when the camera was there.
LUKE TIPPLE: Yeah. Which is why you were super stoked when it happened. So when you brought the mackerel up, you could almost see the indentation from where the tail hit it. It was pretty much pulverized, its ribs were all kind of blown apart. Was that very indicative of the attack, was that super lucky, is that what they always do?
CRAIG O'CONNELL: I've seen a lot of thresher predations in places like the Philippines, and you could see that they go through their tails moving 30 to 40 miles an hour. That shark stops, whips its tail, it's like that massive weapon. And it stuns its prey and its prey will slowly sink down to the sea floor, and that's when the thresher shark comes in and feeds. So when we actually looked at the evidence of the whipping of the tail, it made perfect sense. I mean, it completely turned that mackerel into a pancake, and it shows the power behind the thresher shark's tail. You don't want to get hit by it.
LUKE TIPPLE: When I first started tagging whale sharks, I was trying to get used to their movements and everything like that. And one time, I just got in the wrong place at the wrong time after tagging and it kind of took off, but I got smacked by the tail. And the tail was like 10 feet high, and I got hit by the caudal peduncle. Just went smack straight in my ribs and knocked my mask off and almost knocked my rig out. It kind of threw me for a loop there.
And before that, I was thinking, that's probably one of the worst tails to get hit by. And then I saw this thresher, I thought, yeah, I don't want to get hit by that either. I know it's super unlikely, but if a person was to get smacked by that, what kind of damage do you think it would do?
CRAIG O'CONNELL: Well, it happened down our shoot, that's the thing. We were pulling in a thresher and it was our first one of the whole expedition. It took a couple of days to get them, we were super excited. And my assistant Caroline was getting ready to get the tail so we can get the rope around the tail, secure the shark, and do all that stuff. I was pulling the shark, and as she reached over the tail, the thresher decided to swim really fast and the tail hit her square in the forehead.
And it made the sound that was just incredible. It was like the perfect slap. And I looked over at her, and like her eyes-- she was stunned. She was completely shocked. It was like severe trauma. And I had to grab her so she didn't fall in the water because she almost got knocked out by the tail of a thresher shark. But I've heard of many other people getting hit by the tails of threshers when they are fishing and it broke their ribs. So it's not anything you want to mess with.
And I went diving with them down in the Philippines and I got a little close. Now, these are pelagic threshers in the Philippines. The ones we work with in New York are common threshers. But I got a little bit close to this pelagic thresher, and at the last second, it whipped its tail and you could feel the water just move away and push against your body. So they're very, very powerful animals, they're underrated, and they're just absolutely incredible predators.
LUKE TIPPLE: You mentioned before that you wanted to be very careful about not stressing them too much I guess and you didn't want to have to catch them on hook and line. How fragile are they and how much do they tolerate getting roped up and tagged and stuff like that?
CRAIG O'CONNELL: With a lot of shark species, is a common thresher shark is a ram ventilator, so it needs to keep swimming in order to breathe. And what we've noticed is that if you handle these sharks for too long-- let's say if you have them on the fishing line for too long and they're fighting for a couple of hours, that animal might look really healthy when you decide to release it because it's going to swim up.
But what people don't recognize is sometimes those animals swim up and then they'll get exhausted and sink right down to the bottom. And so you might think you're doing a good thing by releasing it, but inevitably, that shark is going to die.
So what we like to do when we do our research with basically any shark in general is we limit our handling time to two to three minutes. Because we feel like after that time you start to see the stomach of the animal get a little bit red, which is an indication that it's getting stressed out. So we get our samples, we put tags in it, we release it. The animals have thus far been very healthy. We haven't had any mortality. But yeah, you have to be very careful when you're working with sharks. They're sensitive animals.
LUKE TIPPLE: Now kind of opening this up to a little bit both of you here but you both have the unique experience of living in highly productive waters. You've got lots and lots of shark species, you've got lots of tourists, lots of fishing activity. Madeleine, perhaps to start with you, what are the challenges out there in working with sharks and especially with tagging and stuff like that where you are dealing with places that have people fishing, perhaps taking animals or perhaps being scared by sharks? What are the challenges you face out there?
MADELINE MARENS: Well, like any field work, you really have to be reliant on really good conditions. Sometimes we have to go pretty far out offshore to get to these shipwrecks. Because we're called the graveyard of the Atlantic, that's by no mistake. That's because we're right off of-- the continental shelf is right there and the Cape Lookout and Cape Fear jut out right into those slopes. So we have really treacherous waters sometimes, so you have to make sure we have a really split clam day and we're working over the side of the boat.
So interestingly, we started out with long lining to tag these animals, but sand tiger sharks are quite lazy. So we actually had to-- with some trial and error, we actually went to using some really heavy duty rod and reel gear to get these animals up. And unless you like bonk these sand tiger sharks on the head with food, they're actually not going to come off of the wreck. You get food. So we had to really tailor and make sure that we were going to wreck with a lot of animals on there at the day.
We actually really rely on communication with our fishermen and our wreck divers. We're huge in ecotourism and we actually have started a citizen science program where people can go down and take pictures of tiger sharks. And they have spot patterns on their side that are unique to that animal like a fingerprint. So we can actually answer some questions about seasonal residency and individuals that are coming back to the same site year after year or season after season.
And also, fishermen also understand the importance of sharks. As top predators, they help keep fish populations in balance and promote a healthy ecosystem. And they realize that sharks are important and we need to protect these critical habitats that are important for their feeding and growing and reproducing. And yeah, as a coastal shark, sand tiger sharks face a lot of problems and need these protections from habitat loss and pollution and degradation and overfishing.
Sand tiger sharks have one of the lowest reproductive outputs of any shark species. It takes a really long time for these sharks to mature and they're only giving birth to one or two pups every other year. So a sand tiger shark female just states and gives birth after nine to 12 months, and then she takes a resting year because of how energetically expensive that was. So she's not giving birth to a lot of pups. So even minimal fishing pressure can be really detrimental to these amazing creatures.
LUKE TIPPLE: Yeah. And the wrecks that they tend to hang out on a super productive areas and divers love them because they're easy to find lots and lots of different species. I'm curious about the numbers of sand tiger sharks there though. Are they outcompeting or the other big predators?
MADELINE MARENS: I don't think so. I think there is a bit of a hierarchy. I think that they are the top predator on those wrecks, but our acoustic receivers are picking up a lot of other shark species too. We've caught really large tiger sharks and adult sandbars and dusky sharks. The North Carolina coast sees upwards of 60 shark species.
What I think is that these larger predators-- and white sharks too are found off our coasts on some months. I think they're hanging off the wrecks. I think they're actually more shy than these sand tigers are to divers. So divers aren't seeing these tigers and white sharks, but they're there. They're just hanging out in the distance.
LUKE TIPPLE: So we've talked a little bit about sharks and their movements up and down your coastlines. Craig, with so many shark species there, is a fairly regular that you're seeing migrations go through? It's kind of like clockwork with some of these animals, right?
CRAIG O'CONNELL: Yeah. I think Montauk especially in New York is like a shark superhighway. And during different times of year, we're seeing different species moving through. Initially, it starts out with the adult white sharks that are making their way from Florida, and then they come past Montauk and they go up to the Cape to go feed on all those seals. And then as the waters warm, we see a lot of those species that Madeleine is seeing down in North Carolina, the duskies, the sandbars, we even get really large tiger sharks.
And then there's a spot just off shore of Montauk where we see species like whale sharks. And whoever thought you'd see this massive tropical species off of New York? So it's a really special location. It's very productive, there's an abundance of prey. And I'm grateful it's my own backyard because I can go out there and do research on so many different species.
LUKE TIPPLE: At some level, it must be a little frustrating though because you're thinking, OK, I want to put out more tags on thrashers but I've only got two weeks for it to happen and the weather sucks. How much pressure does that put on you as a doctor trying to do your research?
CRAIG O'CONNELL: There's so much pressure, and you're exactly right and Madeline was saying the same thing. We're going out relatively far in Montauk and you've got to rely on having relatively good weather to go out and do this work. Because if it's a little bit rough, it's going to be extremely difficult and potentially dangerous to be working with a 15-foot shark right next to your boat. So it's frustrating but we keep at it. We pick the right days and you have to be very productive on those days and those days to be very, very long.
You might get lucky in the morning and catch a blue shark and you can get a tag in it and you're tired from it, but you have to use that whole rest of the day because research costs a lot of money. And so we have to go out there and make the best of each day, tag as many sharks as possible and learn as much as possible. And I think the other thing that's really beautiful about where I work is the locals are starting to take part in our research.
And instead of them going out and catching and killing a mako shark or a thresher shark, they're going out and helping me with my research. So if they do catch a shark, they tell me, I go over to their boat and I tag the shark and they release it. So it's kind of promoting conservation, and citizen science is something that's really important. You get as many people involved in your research, as many people as possible aware about sharks, there's going to be more people out there that want to protect them. And I think that's a win-win for everybody.
LUKE TIPPLE: What made that turn? I mean, you said you're starting to see that happen. But you live in a fairly infamous area for shark fishermen, so what made that turn and made the public want to join in your cause?
CRAIG O'CONNELL: Initially I went to Montauk and I was very shy and I put my head down and went out on my boat, did my research, came back in and I didn't really tell too many people what I was doing and what I was trying to achieve. But it wasn't until I actually started speaking up and telling the local commercial fishermen about what I was doing where they got interested and they're like, we want to help you with that. We know some of these really productive spots where we can help you with your research.
And it was just basically word of mouth and teaching people about the importance of sharks and how at the end of the day, if we have these large predators in our ecosystem, they have the ability to top-down regulate the entire reef. And at the end of the day, everyone benefits from that. And by teaching them that, they wanted to take part in the research and help me out, and I am extremely grateful.
LUKE TIPPLE: That's awesome. Another great tool for education for people to learn about sharks I've found is aquariums. And it's one of these conversations I've had many, many times, and honestly, I've been both for and against on both sides. When I was freshly out of college and I was out in the field and tagging stuff and I heard about whale sharks going to an aquarium, I blew up and I was actually pretty mad about it.
I remember talking to people and saying this is not a good idea and I'd give presentations where I was working in Honduras. And I'd worked with the government and we're saying we're trying to save these things in the wild, but why are we putting them in an aquarium? I couldn't wrap my head around it. And then the benefit of agent experience I guess, I started learning a lot more about aquariums. So Madeline, perhaps you can tell people who have the same type of questions or concerns the benefit of aquariums in shark education, and perhaps if there's any cons against it as well. I'd love to hear it.
MADELINE MARENS: Yeah. So my favorite thing about working at aquariums and being part of AZA, so that's the Aquarium Zoo Association, it's this world-renowned organization that is helping conservation initiatives and taking part in field research so we can take better care of animals that in our care and then bring that to the public. The aquariums have such an important public platform to teach and inspire future conservationists.
So I grew up coming to aquariums. I'm from upstate New York so I didn't grow up around the ocean, but I always knew I wanted to be a marine biologist. And it's from these hands-on experiences and educational programs I saw at these aquariums growing up and being able to go and point my finger at this tank with these huge animals that I've never seen before and learning about them.
So the North Carolina Aquarium is looking at sand tiger sharks in the field, but we're taking ultrasound images and we're doing other field like taking blood samples and looking at genetic spin samples and bringing that back into the lab and then learning about shark reproduction in the field that can help us with our shark populations in the aquarium care so that we can actually-- so we're not taking from the wild, but we're actually breeding and we're having-- what's the word? We're having our own successful breeding program in aquariums.
LUKE TIPPLE: Is that actually happening now, you're getting births in your aquarium?
MADELINE MARENS: There are some places in the world that have had successful birth of sand tiger sharks. Sand tiger sharks are interesting in that this funny thing called intrauterine cannibalism happens. So sharks are born, live but they are hatched in the mother's womb and then they'll actually start eating their brothers and sisters in the womb. So that's something that we have to think about.
But the best thing to do is to think about every aspect of an animal's welfare and be able to simulate it in the aquarium environment, so that we're simulating as much as we can their natural environment. So a happy shark or a happy fish is going to breed on its own, and we can just let them continue their natural life cycle like they would in the wild.
LUKE TIPPLE: Yeah, intrauterine capitalism has always been one of my favorite things to teach about because it's gnarly and it's gory, but it really exemplifies sharks for me. They're fighting to be the biggest and strongest basically from inception. I've always thought that was so cool. What is the average sort of litter size for a sand tiger?
MADELINE MARENS: So female sand tiger sharks actually have two uterine chambers. So she can ultimately give birth to two pups, but it's only one per uterine chamber. So yeah, it's like the biggest and baddest shark in that womb is going to be the one that makes it. It's like survival of the fittest in the womb. The ultimate sibling rivalry.
LUKE TIPPLE: So kind of moving offshore again, you guys are living in areas that are subject to pretty gnarly weather and you get very warm and very cold currents going through. Craig, I think you can speak to this really well. But over the years and your research out there, are you seeing differences in migratory patterns, times of year, et cetera, with global warming and changes to the water?
CRAIG O'CONNELL: Yeah, it's funny you ask that because this summer was the strangest summer that's probably ever that showed up in Montauk that was almost 70 to 80 degrees in the peak of the summer. And I think what was so fascinating about that is we wound up catching blacktips and spinner sharks offshore of Montauk. I mean, that was the first time I've ever heard of that happening. So that's a species that you typically see down in Florida and they make their way up to New Jersey in the summer, but never quite Montauk.
And if you think about it too, we're starting to learn that the ranges of some of these other shark species, like the bull shark, it's starting to extend because of warm water, the climate is changing. And so we're seeing this happening right now and it's real. It's really changing the movements of these sharks.
LUKE TIPPLE: Are you seeing the opposite happen in the winter where it's way colder, or is it just generally over the entire year? Is it just warming up?
CRAIG O'CONNELL: It seems to be warming up in the summer. In the winter, we typically don't work out there in Montauk because a lot of the shark species make their way down South. It's very quiet. But I think it's been pretty consistent in the winter, maybe slightly colder. But yeah, the summer, it's been drastically different. I've been working there since 2014 and I've seen a change.
LUKE TIPPLE: Yes. Perhaps a better way to phrase that question would be, is the shark season longer? Is there a longer warm period going on right now?
CRAIG O'CONNELL: Yeah. So essentially because the water temperatures are changing, the shark season is a little bit longer. The white sharks are showing up a little earlier in May, and they're passing through Montauk again a little bit later in October. So initially, that was a much smaller shark season, shorter shark season, and now it's changed. But with the thresher sharks, it's still only those two weeks, and for some reason it's just-- they show up to the day on that reef and then they disappear to the day from that reef. It's just incredible.
Again, we've determined that it was prey-based, but I just find it really strange that you could count on them being there on one particular day in August and leaving on one particular day on August and you won't see them there anymore.
LUKE TIPPLE: Wow. So if it is prey-based, is that prey also a targeted fish? Are we going after them, are we targeting them for food or bait or whatever else?
CRAIG O'CONNELL: That's actually a major issue right now and was another reason why I wanted to work extensively with these threshers. What they're primarily feeding on that particular reef is a fish called Atlantic menhaden or bunker, and that's a species that's been extensively fished. We started to let the populations recover. And so they started showing up and we got these massive schools again off of New York and the thresher sharks would show up and feed on them.
But all of a sudden, they were looking to lighten the commercial fishing regulations so that people could go out and use these massive nets and take the entire school, menhaden, out of the ecosystem. I find that to be or I call it the fuel of the Atlantic Ocean because there's so many different species feeding on this Atlantic menhaden or bunker. You have whales, you have white sharks, you have blue sharks, you have so many different animals.
And so now they started to ban the commercial fishing of these bunker once again, which I think that's a win for the Atlantic Ocean, for the entire eastern seaboard of the United States because if you have the prey, you're going to have the predators.
LUKE TIPPLE: Obviously, you have a big passion for the thresher sharks. What's your dream experience with a thresher that you haven't had? I mean, you've been to off the coast where you are, you've been to Philippines, all over the world looking for these things. What's the ideal experience that you've yet to have?
CRAIG O'CONNELL: So I absolutely love the thresher. It's such a unique animal and it has a weapon for a tail. How cool is that? And I've only seen footage of thresher sharks hunting. I've been to the Philippines and I go to the sites where they see the sharks hunting, and every time I go, they're never there. And so my ultimate goal is to be in the middle of a bait ball, seeing a thresher shark hunt right in front of my very eyes. I think there wouldn't be anything cooler than that.
And so I'm going to have to keep going to the Philippines. Or maybe I'll get lucky and see it in New York, but the water is murky in New York and Philippines is beautiful. So I'm going to keep going until I get it.
LUKE TIPPLE: I hope you get it. Madeleine, same question. You work with sand tigers. What's the ideal experience for you? You probably already had it.
MADELINE MARENS: Yeah, I've had a lot of amazing experience with sand tiger sharks off of our wrecks, but just maybe witnessing a live birth off the coast of North Carolina. That's where it's happening. That would just be the coolest thing ever to see. When these sharks are born, they're born 3 feet in length, top predators, eating machines, ready to go. They're just born the perfect predator, so it'll just be so cool to see a baby shark.
LUKE TIPPLE: Have you ever seen juveniles on the wrecks or do you think they're moving somewhere else away from all the adults?
MADELINE MARENS: Yeah, we actually have-- during the summer, we do see mixed sex aggregations and we'll see some juveniles and some adults. It is thought that they're young of year. So the babies are actually migrating extensively up to nursery habitats off of Cape Cod and also the New York Bay. It's a recent nursery that they found. So they actually might be seeking refuge away from the adult population.
What's interesting too with climate change, I'm interested in how recent that extent has moved upwards and if that's going to continue to move upwards or not. Sand tiger sharks have a pretty extensive range. They're warm temperate shark species. They hug coastlines and they're attracted to physical features. But I'm interested in how that might change over time due to climate change.
LUKE TIPPLE: Yeah. Curious, have you ever seen gut contents of an adult sand tiger and found juveniles?
MADELINE MARENS: I have not. They are known to be opportunistic and we'll eat smaller shark species. The sharks that we catch, we do try and use fresh bait. But they're pretty generalist and sometimes we've actually caught them with like two-year-old freezer dried flounder. So they're not that picky.
LUKE TIPPLE: It seems that if you've got the ability to kind of hang out on a beautiful wreck pretty much all the time and just snap up whatever goes past your mouth, you'd probably get pretty lazy.
MADELINE MARENS: Yeah, exactly. And that's why they have this really cool jaw feature where their upper jaw is suspended. So they can be hovering on the wreck with their flotation device that they have. And a schooling fish could be coming by, and their jaws are able to jut out and they might be able to grab a quick snack.
LUKE TIPPLE: So is there any actual inhalation, sort of vacuum effect, to that jaw jutting?
MADELINE MARENS: Yeah. They definitely got their prey pretty quickly. They're just the perfect ambush predator.
LUKE TIPPLE: That's so rad. Well, hey guys, I want to thank you for your time today. Is there anything else you wanted to add while you're here with the Daily Bite?
MADELINE MARENS: Sharks are cool.
CRAIG O'CONNELL: Yeah, I agree with that.
LUKE TIPPLE: Sharks are definitely cool. Well Craig, Madeline, thank you so much for your time today. Everyone at home, that was your Daily Bite. Happy Shark Week.