I’m Alex McInturf and I’m a shark biologist—AMA!

Can pushing the tip of a shark's nose really stop it from attacking something? I saw this in a video where two scuba divers are filming, and one of the sharks circle the filming scuba diver. The other scuba diver sees it, and lightly pushes the shark right as it was about to bite.

I'm going to say this is a yes and a no, only because of the term "attack" (if a shark is really inclined to "attack" something as prey, my guess is that a gentle push isn't going to do very much). But humans are rarely on the menu, and sharks don't have hands, so they have to rely on a lot of other senses (and the occasional exploratory bite) to really get an idea of what something is. The reason the nose may be an effective place to nudge if you're a diver is because in addition to the basic senses you might expect, sharks also use electroreception. That is, they can detect the electric fields given off by living things, and they do so by using special electroreceptors on their snouts known as ampullae of Lorenzini. They're thought to be pretty sensitive at the nose because of those electroreceptors, which is probably why you saw the diver targeting that part of the body.

1. Shark’s are incredibly unique as you look through the different types. Some are fast, and some are slow. Some are aggressive carnivores, and some are docile plankton eaters. Which shark has your personal favorite unique attribute, talent or skill? And which shark is your favorite overall?

2. Since you mentioned basking sharks, what have you noticed most about their population numbers or general health that you'd like the public to know?

3. Since you look at social interactions of sharks, I’ve read that some sharks enjoy “playing”, such as grabbing a ball and dashing away or rolling near the ocean surface. Have you ever encountered any playful sharks?

4. Generally people see sharks as Terminator-styled, blood seeking beasts. Is there anything you'd like to say against that?

So many great questions! I'll answer in order:

1. It's hard to pick favorites, but I will say that one of my favorite groups of sharks are those in the family Lamnidae - these are your whites and makos, porbeagles and salmon sharks. The reason I'm fascinated by these sharks is because they're regionally endothermic. This means that unlike most shark (and fish) species, they can regulate their own internal body temperature in certain places of the body, and this allows them to move quickly and through more regions of the ocean. My favorite shark at the moment has to be the basking shark - the more I learn about them (people used to think they were sea monsters because they're just SO big), the more I want to know!
2. Speaking of basking sharks, I will say that very little remains known about them. Their global population is thought to be less than 10,000 individuals, but with that being said, a lot of our current data relies on our ability to observe multiple individuals, often at the surface, and that can be hard to do consistently. One thing I'd like the public to know is that as scientists, a lot of our records come from public sightings schemes, so if you're interested in doing some citizen science, make sure you report your sightings and gather as much information from them as possible! I've noticed since doing my fieldwork that few people (except fishermen) even here in Ireland, seem to know that they're even present in these waters!
3. I've never personally encountered any "playful" sharks - I will say that I hesitate to interact with sharks in a way that would put me (or them) in a potentially unfortunate situation, so I haven't brought a ball with me on my free dives, but I do think that their social lives are much more complex than we expect. Their brain-to-body ratio is higher than most people realize, and many species have been known to gather in groups for reasons other than foraging or mating. We also still are gathering basic life history information on a lot of species, so looking deeper into complex social behaviors should be a next step in our understanding of these animals, and it's something I'd really like to be involved in!
4. As someone who's from a landlocked state, I will say that I still encounter people whenever I return home who think that sharks are these terrifying, mindless eating machines. I will also say I've been in the water without a cage with many of the alleged "man-eaters", including tigers, hammerheads, and bull sharks, and I've gone cage-diving with white sharks. Of course, I was careful in doing so, and I highly recommend that anyone who wants to swim with sharks should make sure that they are with people who know what they're doing, but I'm still here and have no close calls to date. I think that sharks are scary for a reason - we are programmed to fear top predators - but that doesn't mean that we should respect them less than we would any terrestrial predator.

Speaking of social interaction with sharks, do they have distinct "personalities"?

That's a great question! Animal personality is a niche in the field of animal behavior (particularly at UC Davis!), and the short answer is yes, personality has been examined in sharks. However, before we begin anthropomorphizing too much, personalities in animals are defined in a pretty specific way: as differences between individuals that are consistent across different contexts. So, for example, a "bold" shark will likely be bold in mating behavior as well as habitat selection (and for the record, "shysharks" are NOT necessarily shy!). Personality assays in sharks are pretty hard to conduct unless you're working with a smaller species or juveniles, but there has been a lot of recent interest in shark personality and how it influences different aspects of shark life.

How important are the sharks to enviroment? I dont think I have ever found any info about sharks role in ocean systems and what's their role in enviroment.

This is a question that I get a lot in terms of shark conservation - I call it the "so what?" question. A lot of people think that if sharks go extinct, it's actually a good thing, or at the very least will have a neutral effect. The reality is that sharks often play a critical role in the ecosystem as apex predators, or animals at the very top of the food chain. They serve to regulate populations of other organisms lower on the food chain. In a very simple system, for example, a shark may consume another lesser predator (such as a sea lion) that feeds on other fish. If the sharks aren't around anymore, the populations of that lesser predator may grow to the point where there are no longer enough fish to feed them. The fish populations collapse, and then the lesser predator, without food, can no longer survive. That's a very simple schematic, but food webs are quite complex, and we are still learning the different ways that sharks indirectly affect the populations of other organisms beyond just those with which they interact. As we do with the basking sharks, we can also use these animals as indicators of environmental change. If they aren't coming to places where they have been historically sighted, there's probably a reason, and we should look further into that ecosystem to see if it's still healthy.

Is there any way to realistically stop over-fishing?

This is a tricky question. Realistically and honestly, that's going to require concerted effort and awareness on behalf of everyone ranging from major international policymakers and leaders to each individual consumer. I will say the first step on a scientific level is to keep gathering data. We can only make so many inferences about the sustainability of a fishing method without knowing more about the populations we are fishing. On a more public level, however, I think we as the consumers are more powerful than we realize. Our choices (for example, if we eat fish and if so, which fish we eat) on a daily basis actually make a difference, because our demands are what drive the success of different fisheries. I've actually been in restaurants where shark meat was advertised on the menu, and when pressed about what species and how it was caught, the waiter informed me that it wasn't actually shark. Regardless, because of such deliberate misinformation I still choose not to go to that restaurant and encourage my family to do the same. That example is really to say that we can be more aware about what we choose to support, by asking questions and being informed. What drives me crazy, though, is this mindset of "I'm just one person, so my decisions don't matter." If everyone continues to think that way, then my answer is more simple: stopping overfishing is going to be very challenging.

Could you explain your educational background between finishing your undergraduate BA in Biology and being a PhD candidate?

As someone who recently finished their undergraduate BS degree in Biology and wants to pursue wildlife biology/ecology, I’d love to know your path!

First, congrats on finishing your degree! Seems like you're just in the right place to begin a career chasing wildlife. I've always known I wanted to specialize in shark biology or ecology (since I was literally 12). Instead of going for a research-based institution, however, I went to a liberal arts college because I wanted to make sure I had a diverse, interdisciplinary education before specializing in animal behavior in graduate school. I was never afraid I would lose my passion for sharks, but I wanted to be practical in terms of my future career. Jobs can be hard to find, especially if you're really specialized, and I knew I could focus on wildlife during my PhD. After I graduated, I spent a gap year working in the field at various field stations in South Africa (Oceans Research) and the Bahamas (Bimini Shark Lab) to get practical, hands-on experience. This also allowed me to see what would be feasible in terms of data collection for my own research, and opened my eyes to gaps in the field that I thought I could fill with my future work. During that year, I also read up on the scientific literature about different shark species, and came up with questions I thought I could apply to these species in graduate school. I also recommend reaching out to faculty and letting them know you're interested in their work if you want to go to graduate school! If not, I also met a bunch of recent undergraduates who decided to work full time at the field stations for a few years, or got jobs at different environmental agencies. It's really up to you and what you see yourself doing, but I would recommend NOT going to graduate school until/unless it's something you know you really want to do! It's a lot of time and effort to go through if your heart isn't in it.

Can you track sharks (if yes, how)?

Yes - that's what I do! You can't use typical radio tracking devices that you might use on terrestrial animals like birds because radio waves don't travel underwater. So, there are a few ways we do it. Sound travels farther and faster underwater than it does in air, and we take advantage of this to do acoustic tracking. We attach transmitters that give off a certain sound signal underwater to different animals, and then we can detect these signals either from a hydrophone lowered from a boat, or from a stationary "receiver" moored underwater. Other than acoustic transmitters, there are also different types of tags that can store data while the animal is moving and then pop off the animal after a certain amount of time. In many cases these tags transmit summary data or location data to satellites overhead every time they reach the surface, but in almost all cases the tag has to be recovered to download the full data set.

I'm interested in the feeding habits of basking sharks. I know they are filter-feeders, but any idea how they obtain their food? How big of a diet would they need to grow to that size?

Also, do they have any natural predators in the sea?

Yes! That's actually one of the topics we know most about for basking sharks, and there's still a lot to be learned. Basking sharks feed by targeting thick patches of copepods (large zooplankton) in the water and opening their mouths as they swim through it. Unlike whale and megamouth sharks (the other two filter-feeders), basking sharks do not gulp as they go. The zooplankton get filtered through specialized "gill rakers" (or mechanisms used to capture plankton) on the inside of the mouth and gills, and large plankton are caught. Then the shark swallows. It's still unknown the exact senses they use to locate patches of zooplankton within the water column - it may be visual, chemical, mechanical, electric, or a combination of all of the above. But the reason that the largest animals in the world are all filter-feeders, sharks included, is actually in part because they feed on plankton! It's a constantly renewable resource, so they don't have to spend a ton of energy hunting elusive prey like seals or other fish. They can "graze" all the time. As far as predators, there have been reports of the occasional kill by an orca, sperm whale, or even a bigger carnivorous shark, but those are few. In a weird way, the basking shark is an apex predator, even though it only feeds on plankton.

Could you tell about an extremely exhilarating moment that stands out in your mind from your field work?

Yes! There was one moment when I was working in Bimini, Bahamas at the Bimini Shark Lab. I was in the water with bait in my hands, as we were trying to see if the great hammerheads that reside in these waters in the winter months had returned. I had never seen a hammerhead before, and so I was casually scraping the scales off of my baitfish (note: we never feed the sharks, as we don't want them to associate humans with a free meal). All of a sudden a hammerhead shark swam out of the blue (literally) and right towards me. I hadn't been expecting one to arrive so quickly, and I immediately threw my hands and bait out of the water and let it approach. As soon as it came close, I put my fins up and nudged it underneath me, and then it disappeared. To this day, though, hammerheads are my favorite to swim with. They just don't look like real animals!

How do you NOT order Surf N Turf every time you go out to eat?

I'm answering this because I think it's funny - I actually don't eat any seafood because we often know little about how it's been caught (or whether it actually is what the menu says it is), but that's definitely not the first time I've heard that.

Why are basking sharks interesting to study? What about their behavior makes them different from other sharks?

There are a few reasons basking sharks are cool to study. Perhaps the most obvious is because we know so little about them that every discovery you make feels like a gold mine. For example, basking sharks were thought to "hibernate" offshore in the winter months up until the late 20th century (we now know that they can migrate across the entire Atlantic Ocean, or down to Africa and back in that time). We also don't know exactly what they're doing when they aren't at the surface, which, as it turns out, is a lot of the time! Most of our data are gathered from surface sightings or transmitters/biologgers that can gather summary information, but very little fine-scale behavioral data. So, we might know their general movement patterns between certain areas, but we can still really only speculate about what they're doing as they go. And for me, the really interesting part is their social behavior. Basking sharks have been spotted in massive shoals for centuries. Fishermen used to report so many in one place that "you could walk across them". And while this made them especially attractive to harpoon fishermen in the 19th and 20th centuries, basking sharks still gather (albeit in significantly fewer numbers) for reasons we don't completely understand. And when they do, they often exhibit certain behaviors (like nose-to-tail following, parallel swimming, and breaching) that are thought to be part of courtship, but the mating and nursery grounds for this species have yet to be identified. Finally, while basking sharks are a flagship species in this part of the world, they're also only one part of a super cool ecosystem all around Ireland and the UK - there are over 70 species of sharks, skates and rays in Irish waters alone!

What's a common misconception about shark behavior?

I would also say that another common misconception is that sharks are "mindless", or at least dumb. Again, brain-to-body ratio would say otherwise, and a lot of species are thought to form complex social groups and do behaviors (such as breaching, or throwing themselves out of the water) for reasons beyond just feeding or mating.

is it true that if sharks stop moving they die?

In many cases that's true, which is why shark finning is such a problem - you take off a shark's fins and it can't move anymore, and because sharks are negatively buoyant (aka do not float), the shark will sink and actually drown. Species that have to move to breathe are known as ram ventilators. However, there are some species that can stop moving because they can buccal pump, or stay still and "pump" water through their mouths over their gills to breathe.

Are there any animals (and it maybe humans) who threaten sharks? We are so used to sharks being "at the top of the food chain", was wondering if sharks ever worry about other animals?

There are! A lot of the sharks that we hear about are the big ones, the apex predators at the top of the food chain. But there are over 500 species of sharks, and honestly, a majority of them are less than 1-2 meters in length (that's 3-6 feet). In some cases, that doesn't mean they aren't still at the top of the food chain, but in some areas sharks are mesopredators (or animals in the middle of the food chain) that do have to be aware of other, larger animals. Those larger animals are often other sharks or whales. I am also studying the flapper skate, a cousin to the ray, and this species has teeth and feeds on smaller sharks and rays - a super cool example of an unexpected apex predator.