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Sharks and Climate Change: A Podcast You Can Sink Your Teeth Into
Sustainability

Sharks and Climate Change: A Podcast You Can Sink Your Teeth Into

By Sphera June 8, 2021

Ocearch scientist Bob Hueter joins the podcast to discuss how changing temperatures are affecting these creatures that have swum in the oceans for 400 million years.

 

James Tehrani:

Welcome to the SpheraNOW podcast, a program focused on safety, sustainability, and productivity issues. I’m James Tehrani, Sparks editor-in-chief. Today on the program I will be speaking with Bob Hueter. He is the chief scientist at Ocearch, an oceanic data research organization. We’ll be discussing sharks and how climate change is affecting these cartilaginous creatures. We’ll also discuss how he and others work with sharks safely. Thank you so much for joining me today, Bob. I really appreciate your time.

Bob Hueter:

It’s my pleasure, James. It’s good to be with you.

James Tehrani:

Great. So, before we get into this, can you tell us a little bit about yourself and how you got interested in shark research?

Bob Hueter:

Well, I am a marine biologist. I’ve had a career spanning more than 40 years at this point. And I started as a young student. I actually grew up in the state of Maryland, but I’ve been living in Florida since 1970. Why? Because if you want to be a marine biologist, Florida is a great place to be. Went to school-

James Tehrani:

That or Hawaii, right?

Bob Hueter:

That or Hawaii, or one of a dozen places that I’ve worked around the world. And the one thing about marine science is it does take you to beautiful places, some places that are heavily impacted by people. I know we’re working hard on those kinds of things, but nevertheless, beautiful places if you love the ocean. And I went to school at the University of Miami and the University of Florida, got my Ph.D. and have been studying sharks since the mid-’70s, when I was—as a young student in college—interested in the ocean, developed this fascination for how animals have adapted to their environment and so those two interests between marine science and animal adaptations kind of crossed on sharks. I just retired last December.

James Tehrani:

Congratulations.

Bob Hueter:

Thank you. In the middle of the pandemic so, no, there was no fanfare.

James Tehrani:

I wouldn’t imagine. So, it’s actually a good segue though because we’re talking about climate change and sharks. Normally on this program we talk about climate change and humans, so it’s an interesting twist, hopefully, for our audience here. So, I was looking online and I found that there are probably 440 known shark species or so, and you can correct me if I’m wrong on that. And I know it’s hard to generalize, but are there certain types of sharks that are more vulnerable to climate change than others?

Bob Hueter:

There are somewhere in the order of 400 to 500 species of sharks. We’re actually discovering new ones every once in a while, mostly in the deep sea. The sharks that live in the upper parts of the ocean and coastally are fairly well known. But they’ve been around for about 400 million years. So, they adapted to life on earth a long time ago and have changed relatively little in that long period of evolution. So, when it comes to climate change, sharks have to have certain habitats, just like any life.

Bob Hueter:

They have certain important, critical habitats for their life cycles, things like nursery areas, feeding grounds, mating grounds and temperature as well as the chemistry of the area. The ocean chemistry [is] important, what we call abiotic factors in determining shark success to do things like reproduce and feed. As our waters warm and push farther north in terms of the thermoclines that we experience every year in the ocean, the sharks are able to adapt somewhat to this. And in fact, we see the movement of some species farther north than they’ve been reported previously. What we don’t know is some of the details of how this might affect their reproductive success.

James Tehrani:

From the warmer temperature?

Bob Hueter:

Well, as a rule, when you’re talking about a change in temperature that’s going up, you’re going to be affecting the animals that are living close to the edge first. So, for example, let’s get away from sharks for a second and look at corals. Corals live in these tropical environments and they’re known to live at the edge, temperaturewise. So, as climate has warmed and the sea temperatures go up, the corals get affected very significantly. And that’s going to be true of a lot of the tropical shark species. In fact, some work has been done on some of these smaller sharks that live in reef environments that actually lay eggs and have a different lifestyle from the more advanced sharks. And you can see that they experienced significant problems in dealing with warmer temperatures in terms of productive success and growth and some other things. So, they’re going to be the ones that will be affected, but quite frankly, all of them are going to be affected because temperature is a very important part of a shark’s life, especially the migratory species that may be using temperature as a cue to move.

James Tehrani:

Right. And so, one thing I learned recently is invasive species like jellyfish are producing in droves because of the warmer temperatures. Does that affect the shark population at all?

Bob Hueter:

Well, I haven’t seen a particular environment where, say, jellyfish are driving out the sharks or are affecting sharks’ fitness for success, but the jellyfish story is more of a symptom or a sign of a degrading habitat or a changing habitat. The bigger worry or the bigger challenge, I would say, to the sharks is, as temperatures change, these are animals that come back to very specific geographic parts of their range if they’re migratory. Most of them migrate to some extent. Some of them are highly migratory, thousands of miles of ocean in a year, and then come back to a very specific place, very similar to what salmon do and sea turtles do. It’s a behavior that is called philopatry, and we see it in sharks.

Bob Hueter:

So, as that local area changes through climate change, temperature changes, even acidification, those kinds of things, when they come back to that area it may no longer be the area that they were adapted for. And of course, this will take some time to experience this. It doesn’t happen overnight, but things are changing pretty radically. And what would be the bigger problem for the sharks as predators will be, how’s it going to affect their prey and is there going to be enough food there when they return?

James Tehrani:

Yeah, I was in Alaska about five, six years ago, and our tour guide had told us that they were seeing great whites in their parts, which they hadn’t in the past. So, I’m curious how it does affect the animal population when sharks start preying on these different animals. Is that a consequence of climate change as well?

Bob Hueter:

Well, it could be. And in fact, with the organization I work with now, Ocearch, as their chief scientist, we’re conducting this long-term study of the white shark in the Northwest Atlantic from the U.S. coast up into Canada. And we discovered, beginning in 2018, the prevalence of white sharks up in places like Nova Scotia and in Atlantic Canada, and published a paper this past year to show that these animals are not rare in those waters anymore, that they’re pretty common in the summertime. And whether or not this has always been the case and we just missed it, kind of doubtful because white sharks, they’re pretty noticeable when they’re in the coastal zone.

James Tehrani:

It’s not like Jaws though, right?

Bob Hueter:

It’s not like Jaws. And there are some surprises that people have gotten from our work, like down in Florida in the winter time, how close they are to the beaches. But that’s because people aren’t swimming in the water in the middle of the winter down here. So, those sharks have always been there. So, a contingent of sharks probably has always been in Canada. We know the population is increasing because we’re starting to rebuild the population through conservation measures. But whether it’s actually shifting north more in the Canadian waters remains to be seen. If it is, yeah, climate change definitely plays a factor there.

James Tehrani:

So, a lot of people obviously are afraid of sharks. So, why is it important for the shark population to stabilize and to keep growing? Why would people care about that happening?

Bob Hueter:

I mean, sharks are a critical part of ocean ecology. They’re usually called top predators or apex predators, most of the species, and just like on land, where we have systems that require everything to be in balance with the apex predator and then the secondary carnivore that the predator might eat, plus the herbivores, the animals that eat plants, all the way down to the primary producers, the plants themselves, things need to be in balance. And if you just cut out a whole floor of that building, the building can collapse. And with sharks there at the top, removing them completely from the system destabilizes the balance of life in the ocean. It can destabilize. There’s some things that can fill in, but not a lot. So, they play a very important role in terms of ocean health, in terms of ecosystem balance. And where you find sharks in an area, that’s usually a healthy, very fishy spot, and there’s lots of life. Their benefit then, in that way to us, in terms of the natural ecological health and abundance of the oceans far outweighs any danger or risk that they pose for us.

James Tehrani:

Just piggybacking off that, I was watching an interview that Chris Fischer, the Ocearch founder, did a few years ago. And he said, ‘A healthy ocean is full of sharks. We should all be afraid of an ocean with no sharks in it. That means there’ll be no fish for our kids to eat.’ Can you explain that to me? That sounds a little bit counterintuitive to me.

Bob Hueter:

Well, it’s good to go to an example that many people are aware of on land and that’s the balance between, out West, the wolf population, deer, and what the deer eat, mostly plants. In that period in our history where wolves were shot because they were considered a nuisance or a threat, the deer population started to suffer because first there was overpopulation and then they overgrazed on their food, and so they wiped out whole habitats. Then they started to die off because of that, and disease spreads through the deer population because there’s no predator that’s culling the less fit animals, the sick and the wounded animals.

Bob Hueter:

The same thing happens in the ocean. So, you might get temporarily a little bit of a spike in those things that the sharks eat. But in fact, the effect of removal of the sharks cascades down even beyond the next level down into the habitat itself. And there’s actually good science, not theoretical, but actual empirical science that has shown that, for example, when you remove sharks from a coral reef system, that the effect works its way down to the reef itself and the reef can die because of that effect. So, these are very complicated relationships. It’s very important that we don’t mess with it too much because if we make a mistake, it takes decades, sometimes a hundred years or more, to rebuild something like a shark population.

James Tehrani:

So, you touched on this earlier. So, sharks have been around for hundreds of millions of years, and humans have been around a lot less, obviously. So, are you more concerned about the human population or the shark population in terms of climate change?

Bob Hueter:

Now, you’re setting me up to be really criticized because if I said I was more concerned about sharks, I think even my own family would give me a hard time. I mean, obviously I’m deeply concerned about how we as humans respond to this, but we have the ability, if we use science, we have the ability to respond the right way and we can adapt. We can adapt faster than sharks can adapt, that’s for sure. Whether it’s easier for one group or another, we’ll see. But when we look at things like, for example, fisheries and conservation management, it’s much easier to manage the fishermen and get the fishers themselves to adapt than it is to try to make the animals reproduce faster or something like that.

James Tehrani:

So, is overfishing a bigger problem, then, than climate change in terms of sharks?

Bob Hueter:

Right now, in 2021, overfishing is still by far the biggest problem for sharks. Yes. Environmental change, climate change, things like contamination of the environment, these things are starting to get bigger and bigger in terms of their significance. But I would say, roughly speaking, 90% of the problems that sharks face right now is still due to overfishing and removing too many of them. When we stopped doing that, we actually have achieved success in rebuilding the populations as we’re experiencing now with the great white shark on the U.S. East Coast. We stopped bycatch fishing. We stopped removing white sharks at a rate that was depleting their numbers, and they’re now showing recovery. So, it’s kind of a good story. Finally, in conservation, we got some good stories, that our actions actually can pay off. It’s not all doom and gloom. If we roll up our sleeves and do the right thing, we can rebuild the environment.

James Tehrani:

That’s fantastic. So, let’s talk a little bit about great white research. So, can you tell us a little bit about how you tag these animals and how you ensure the safety of the animal and the humans who are dealing with these large animals?

Bob Hueter:

Well, we’re involved in a long-term study of the white shark, or otherwise known as the great white shark, in the North Atlantic. We’re interested in figuring out their entire lives. That’s what we call the puzzle of their lives from birth to death. And we’re talking about an animal that lives 70, 80 years or more, so we’re sampling at various stages of these animals’ lives, everything from the newborns all the way up to the older adults. And our methods are unique. We have a research ship with Ocearch that has a very special hydraulic platform where we can actually take animals that our fishing crew has caught and lead these animals onto this platform that’s submersed in the water, lift the animals up, give the animals ventilation and take care of them. We have aquatic veterinarians who oversee the condition of all the animals.

Bob Hueter:

And then we give ourselves about 15 or 20 minutes, our science team, to run around the animal like a pit crew in a NASCAR race and take samples, take blood, take measurements, and then attach, before the animal’s released, attach up to three different kinds of tracking devices so we can continue to see where these animals live out their lives over periods of up to 10 years.

James Tehrani:

And some of these animals have their own Twitter accounts now, right?

Bob Hueter:

Yeah, yeah. Yeah. I mean, sharks have learned how to use Twitter, so that’s pretty cool. Yeah, because I can’t use Twitter. I have a Twitter account, but I don’t use it. But yeah, some of our sharks like Mary Lee and some of the more popular sharks, yes, have their own Twitter account. And the public can see where our sharks are in real time, right along with the scientists at the same time on our website, the ocearch.org website, or the shark tracker app that’s free for your smartphone.

James Tehrani:

What’s it like touching a shark for the first time, especially a great white? It’s got to be an amazing feeling.

Bob Hueter:

Well, that’s a great question for me because, having worked with sharks for about 45 years, I’ve touched a lot and I’ve tagged a lot and hundreds of species, sizes from little tiny animals no bigger than your hand all the way up to, oh, 35-foot whale sharks that I swim with and tag in the water. I had never touched a live white shark. I’d only seen dead ones in various places, but I’d never touched a live white shark until we got a shark named Lydia on Ocearch. And I was beginning to do my work with Ocearch, and we were working off the coast of Jacksonville, Florida, on a very cold March day and caught this magnificent big female. And I took a moment during the scientific process to make sure that I touched her and ran my hand down her.

Bob Hueter:

And sharks as a rule are kind of rough. The skin is very rough like sandpaper, especially if you rub from tail to head. But she was incredibly smooth. I mean, not like a mammal, like a dolphin smooth, but much smoother than most of the sharks I’ve worked with. I just took a breath. I mean, I was really emotionally actually struck by it and talked about it later when people asked me. So, white sharks are incredibly well adapted as these big ocean predators and long migrators that swim tens of thousands of miles and live for 80 to 100 years.

James Tehrani:

What data have you collected that surprised you the most since you’ve started doing these tagging programs?

Bob Hueter:

We’re running 21, 22 different projects, and they all have had surprising data. The most interesting part of the tracking, though, has been what we see with the females as they get to be a size where we think they’re reproducing. White sharks are actually fairly continental shelf-oriented animals. They’re not typically found way out at sea. Most of their lives are spent going back and forth up and down the continental shelf. In the case of the Atlantic, from Canada all the way into the eastern Gulf of Mexico, but pretty much staying on the shelf. Sometimes a bit farther out, but within, say, 50 to 100 miles of shore. But when you tag these big females, they, on a multiyear cycle, occasionally make these big runs way offshore out into the deep ocean, out into the open ocean.

Bob Hueter:

We have a shark that we’re tracking right now named Nukumi that we tagged last year in Nova Scotia, and she went all the way out past the Mid-Atlantic Ridge, which is the dividing line between the Western and Eastern Atlantic. And now she’s up somewhere up in the Grand Banks area. She’s looped back. So, these big offshore loops have been the most fascinating part of the puzzle. And the hypothesis we’re working on is that these are the pregnant females. That they mate along the coast, and we think it might be somewhere in the mid-Atlantic area around the Carolinas in the late winter, early spring, and then once the females have mated, they say, ‘I’m done with you guys. I want to get out of here.’ And they head offshore and have these long, many months of looping offshore and feeding on different kinds of food until they finally come back, either a year or 18 months later, to give birth to their young in the Northeast.

James Tehrani:

That’s very cool. What shark mystery do you most want to solve in your lifetime?

Bob Hueter:

Well, the one that we’re really focused on that we’ve been homing in on in our work on Ocearch over the last six years of this study is where these animals are mating. Mating in white sharks, there’s some anecdotal reports in the literature, but it’s never been chronicled in any kind of detail. It’s certainly not known for the Atlantic population. We need to know where that’s happening, because that’s obviously a critical part of their lives. We know it’s definitely happening or else the population would have died out a long time ago. And we’re seeing young being born. We know where the young are born. We figured that out and we’ve confirmed that, but we don’t know where mating’s occurring and how it occurs. So, that’s the holy grail of a lot of shark studies, but especially with the white shark in the Atlantic.

James Tehrani:

You’ve been on ‘Shark Week’ in the past, I believe, correct? Any plans to do anything else with that?

Bob Hueter:

I did ‘Shark Week’ when it started, believe it or not, all the way back. I think the first program might’ve been in 1989 or 1990, and I still have VHS tapes of that program. I digitized it recently and looked at it because some people were interested to look at how ‘Shark Week’ has changed over the decades. And I couldn’t believe how much good information was in there and how scientific it was. Since then, I’ve done a few. I did a really great one in 2015 in Cuba when I was doing work and still am doing work in Cuba with colleagues down there on sharks of the reefs of Cuba. But, otherwise, I don’t like a whole lot of what I see on ‘Shark Week.’

Bob Hueter:

I think they’ve kind of lost their way in terms of focusing on the science, and it’s overdramatized and it’s not a fair portrayal, really, of how science is done. So, we don’t do ‘Shark Week’ with Ocearch. We don’t make television shows. What we do is we share our experiences and our content in real time or near real time with our followers. And we do these short video clips that people can see online that explain the science that we’re doing and the results that we’re getting. We don’t jazz it up with a lot of drama and reality show type stuff, but we will show—

James Tehrani:

Not a fan of the robotic Megalodon, are you?

Bob Hueter:

No, no, no, no, no. Not a fan period to be honest with you. And I have colleagues that, they get a little bit obsessed with doing ‘Shark Week,’ and I think they’ve lost their way in some ways. That’s not what science is about. Science is about hard work, sometimes very tedious work. At the end of the day, working up your results and publishing it in peer-reviewed journals and then sharing that information with policymakers and of course with the public.

James Tehrani:

Great. Before I let you go, any final thoughts on sharks and climate change that you’d like to share?

Bob Hueter:

Well, you asked that great question about how significant climate change is with respect to some of the other threats. I will say that what we know about sharks and climate change is now transitioning from what was the theoretical to now what we call empirical. In other words, based on real evidence. And some great studies have been done on the East Coast of the United States to show the creeping of some of these warmer-water animals, species of sharks like the blacktip shark and the bull shark, farther north up the East Coast than they were in the past. So, here I am sitting in Florida, and last year we experienced a hurricane when we were in Nova Scotia to try and do our work. I watch a lot of hurricanes go north now. And Nova Scotia may be the new Florida one day, the way things are going.

James Tehrani:

That’s scary.

Bob Hueter:

Yeah. I don’t want that for Nova Scotia because I love it the way it is, but we need to adapt. We need to do what we can, obviously, to mitigate the effects and we need to take into consideration the role of climate change when we create these conservation plans, including fishery management plans for, not just sharks, but all life in the sea.

James Tehrani:

Bob, it was a pleasure talking to you today. I really appreciate your time. Thank you so much for being here.

Bob Hueter:

Pleasure talking with you too, and thank you for having us.

 

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