Tom Rowland Podcast Episode 1023 is a conversation with Dr. John Carlson, a research fish biologist with NOAA Fisheries, about the Florida shark debate — how shark populations can be in global decline while feeling overpopulated on the water in Florida. We also cover shark depredation and the “bad bears” theory, the smalltooth sawfish spinning event and its recovery, why some sharks rebound in a few years while others take decades, the sandbar stock assessment and whether commercial harvest could reopen, deterrents and DNA bite-swabs, and whether eating shark is part of the answer.
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Shark depredation is when a shark takes a hooked or landed fish before the angler can get it to the boat. In the episode, Dr. Carlson and I discuss survey work suggesting it now affects a large share of Florida anglers, with the Florida Keys among the hardest-hit areas and species like bull and sandbar sharks most often responsible. For many guides it has become a daily reality, forcing them to abandon a spot the moment fish start getting eaten. NOAA is actively researching how widespread and systematic the behavior really is.
This is the central tension of the episode. Dr. Carlson contributed to the 2021 global study showing oceanic sharks and rays declined about 71% since 1970, but he stresses that figure is global. The United States has some of the best shark management in the world, so local populations, especially in Florida, can be healthy or growing even while many populations elsewhere remain severely depleted. Global decline and local abundance are not contradictory; they describe different scales. NOAA is now reassessing specific US species, such as sandbar sharks, to put a scientific measure on what anglers are seeing.
Microbiologists are still working on the exact cause, but Dr. Carlson explains that current evidence points to a type of algae found in the benthos, the bottom layer of the ocean. The event killed a number of large adult female sawfish. There have been no new reported spinning events since, which is encouraging. Since sawfish are endangered and cannot be sacrificed for research, the carcasses recovered during the event actually expanded what scientists know about sawfish biology, including the finding that these animals can live up to 40 years.
Not all sharks are created equal, a point Dr. Carlson returns to throughout the episode. Some species, like sharpnose sharks, reach sexual maturity in about two years, and black tips in four to five, so they respond to management relatively quickly. Others, like dusky sharks, may not mature until around 20 years old and reproduce slowly, so rebuilding a depleted population takes decades. Lemon sharks sit in between at roughly 11 years. This wide range in life history is the reason some US populations are now harvestable while others remain protected.
Sandbar sharks are currently prohibited from commercial harvest outside a small group of permitted fishermen. Driven by public perception that sandbars have exploded, and by their role in depredation on species like red snapper, NOAA has begun a new stock assessment and held a data workshop with both commercial and recreational participants. Dr. Carlson explains that if the assessment shows the population is healthier than the 2018 evaluation found, managers will work together to set a new, sustainable harvest regulation. NOAA is also moving toward species-specific quotas rather than lumping large coastal sharks together.
Dr. Carlson lays out a stepwise plan. The first step is determining whether there really are more sharks than 10 to 15 years ago through new stock assessments. The second is figuring out whether depredation is systematic or driven by a small group of individual sharks that have learned to associate boats with an easy meal. NOAA is planning a project with recreational and commercial anglers to monitor high-depredation areas, expand DNA swabbing of bite marks to identify the species involved, and test deterrents like rare-earth metals and electrosensory devices for both effectiveness and cost.
Yes. Dr. Carlson eats shark and grills shark steaks in the summer. The key is handling: bleed the fish out and get it on ice immediately, because sharks retain urea in their flesh and it will taint the meat if the fish is left in the sun. Shark fins are illegal for fishermen to possess in the US, which removed the main driver of the old fin fishery, though there is still a market for the meat that is less profitable than fins once were. Dr. Carlson sees building demand, the way the lionfish market was built through public education, as one sustainable piece of the depredation puzzle.
The shark conversation is the topic around the docks in the Florida Keys right now, and it has far more than two sides. I hear it every day: guides losing fish to sharks, divers dealing with it on every drop, tourist operators who make their living taking people to see sharks, and conservationists pointing at global decline. Living inside that echo chamber, it is easy to believe you already know the answer. I wanted to talk with someone whose actual job is measuring this, not to win the argument, but to understand the side of it I do not live. Dr. Carlson is that person.
This is the question I brought to Dr. Carlson, because it is the one every angler I know keeps asking. The 71% figure gets quoted constantly, and it sounds like a closed case, right up until you ask what that number actually measures and at what scale. Dr. Carlson walks through how a population can be crashing in one part of the world while holding steady in another, and why Florida sits where it does on that map. He lays the distinction out starting around 43:40.
Dr. Carlson's passion is the smalltooth sawfish, and I could have spent the whole hour there. These are 12-to-15-foot animals that can live up to 40 years, give birth deep in the Everglades, and have declined roughly 95% from their historic range. What caught me is how a single die-off can ripple through a population that recovers this slowly, and which recovery signals he is actually watching for. He gets into the sawfish story starting around 6:27.
Any flats angler already knows this mystery: one spot always holds fish, and the identical-looking spot across the channel never does. Dr. Carlson has the same problem with baby sawfish, and his team is trying to quantify what our eyes cannot see, from prop-root density to canopy overhang to the number of pneumatophores. There is also a chance the females simply return to where they were born, regardless of the habitat. He describes crawling into the mangroves to find the answer around 14:45.
Guides describe running 200 miles and finding sharks waiting at every stop, which points to something anglers already suspect. Dr. Carlson calls the leading theory the “bad bears,” a handful of individual sharks that learn boats mean an easy meal, the way certain bears learn garbage cans. The competing idea is that the behavior is systematic across the whole population. He explains where the research stands around 56:29.
The instinct among a lot of anglers is simple: if there are too many sharks, let commercial boats harvest them responsibly. Dr. Carlson does not dismiss that, and he explains how management already flexes with the science and what would have to be true in the next assessment for sandbar harvest to reopen. He also raises the parts nobody loves discussing, from markets and handling to the reality that a solo guide cannot wrestle a large shark aboard a boat full of tourists. He works through it starting around 49:43.
The day after this conversation, the thing that stuck with me was not a statistic. It was how carefully Dr. Carlson uses the word “global.” Most of the fights I hear on the dock come from collapsing a global number and a local reality into a single argument, when they do not belong in the same sentence.
I still do not think anyone in my world wants to wipe out sharks. What they want is to be able to fish, and to feel like someone is measuring what they are living through every day. Dr. Carlson made a convincing case that someone is.
He offered to come back in a year, once NOAA's depredation strategy takes shape. I intend to hold him to it.
Press play in the player above, or grab Episode 1023 on Apple Podcasts or Spotify.
Dr. John Carlson · NOAA Fisheries · Panama City Laboratory · American Elasmobranch Society · Everglades National Park · Ten Thousand Islands National Wildlife Refuge · smalltooth sawfish · oceanic whitetip shark · giant manta ray · Florida Fish and Wildlife Conservation Commission · Mote Marine Laboratory · IUCN Red List · ICCAT · University of Mississippi (Ole Miss) · Florida State University · Florida International University · Rep. Rob Wittman · SHARKED Act · 2021 Nature study on global shark and ray decline
Dr. John Carlson is a research fish biologist with NOAA Fisheries, based at the Panama City Laboratory, where he has spent roughly 25 years studying the conservation and management of sharks and other elasmobranchs. He earned his PhD at the University of Mississippi, focusing on the ecological physiology of sharks, and leads NOAA research on endangered species including the smalltooth sawfish, oceanic whitetip shark, and giant manta ray. He contributed to the 2021 global assessment (published in Nature) documenting a roughly 71% decline in oceanic sharks and rays since 1970, works on IUCN Red List assessments, and mentors graduate and undergraduate researchers across several universities.
Transcript
Tom Rowland Podcast — Episode 1023: Dr. John Carlson
In this episode: the Florida shark debate and how populations can decline globally while feeling overpopulated locally, the smalltooth sawfish spinning event and 40-year lifespan, the ‘bad bears’ theory of depredation, the sandbar stock assessment and whether commercial harvest could reopen, shark deterrents and DNA bite-swabs, and whether eating shark is part of the answer.
Dr. John Carlson: I'm Dr. John Carlson. I'm a research fish biologist with NOAA Fisheries, and I'm very happy to be on the Tom Rowland podcast.
Tom Rowland: That was perfect. Okay. So we just go for about an hour, if you got that time, and we'll just kinda roll through it. So one of the things that I definitely want to do is to understand who you are and how you got into this position. So we'll cover some other things before we get into that, but we'll just go now. All right. So Doctor Carlson, how are ya? You told me you were in a hotel room in New Orleans. Are you on business there?
Dr. John Carlson: Yes, in fact I'm attending the American Elasmobranch Society annual meeting and it's been the first time I've attended it in several years, so I'm very excited to reconnect with a lot of my shark colleagues and talk about various research projects we have, various issues. So it's been a really good meeting.
Tom Rowland: Okay. And what goes on at that meeting? What is the subject of that?
Dr. John Carlson: It's a variety of scientists, policymakers, conservationists. We present, if we're scientists, our latest research, some of our management and policy people are here to present our latest guidelines in terms of where we're moving forward with managing our shark populations, and then some of our conservationists are also presenting some papers as well. So it's a really good exchange of a variety of people.
Tom Rowland: Okay. Has that already been going for a couple of days?
Dr. John Carlson: Yeah, we just finished. Yesterday was the last day.
Tom Rowland: Okay. So we have fresh data to talk about, I guess. Okay, good. Well the reason I invited you on here was because the shark issue has two sides, or maybe multifaceted, it has a lot of sides. But that is definitely the topic of conversation around the docks. It's certainly in the Florida Keys and in a big part of Florida it is the topic of conversation. So I wanted to have you on here because this is what you do. Can you tell us what your role is at NOAA?
Dr. John Carlson: Yeah, I'm a research biologist within NOAA, and basically my research focuses on determining the conservation and management of shark populations, but not just sharks. We have a couple of species now that are listed on the US Endangered Species Act. Those include the smalltooth sawfish, the oceanic white-tip shark, and the giant manta ray. I'm very much involved in smalltooth sawfish research in Everglades National Park, in Ten Thousand Islands National Wildlife Refuge. We're doing research now to determine what methods we need to move forward with the recovery of the population. There's a misconception about the Endangered Species Act. The goal when we develop a recovery plan is to get the animals off the Endangered Species Act, show the recovery. So one of the things that I'm doing is looking at their habitat use, their population growth. We're looking at the number of smaller individuals that come into the population every year, see how that may vary over time. As you or some of your audience may note, we had that big sawfish spinning event that occurred. We want to try to determine what impact that had on the sawfish population. Is this something that's going to be very detrimental or is it just a blurb in their population growth?
Tom Rowland: So where are we with that? Are people still reporting spinning sawfish?
Dr. John Carlson: No, fortunately there has been no reports of any new sawfish spinning events. So that's good news. Right now, what we're monitoring is that many of the individuals that were killed as part of this spinning mortality event were the large adult females. And although a lot of these large adult females are found in the lower keys, they generally move up into the northern part of Everglades National Park to give birth. Part of my study is to monitor that. So if the spinning event did have a significant impact on the population, the trend in abundance, we might see a dip. And we could say, uh-oh, this had more of an impact than we thought. We're still looking at how this affected the recovery of smalltooth sawfish.
Tom Rowland: When you see one of those really big sawfish, how big can they be, tip to tip?
Dr. John Carlson: They can be ten, twelve feet long. Up to fifteen feet in some cases. They're very impressive animals.
Tom Rowland: Yes, and you're right. Some of the lower keys areas, that's where I've seen the very biggest ones. You go over a deep channel, you look down and there's something that looks like it's as big as your boat down there. So do we have any idea how old a fish like that is?
Dr. John Carlson: Yeah, a colleague of mine just redid the life history on the animals. Before, we were going on a very small number of individuals we could age. Just so your audience knows, the way that we age the animals is we look at sections of their vertebrae and like rings on a tree, we count those rings to determine their age, and generally these rings are formed once a year. Before we were working with a very small set of data because they are an endangered species. We can't sacrifice these animals. We have to take advantage of animals that have died from natural or unnatural causes and use those for our samples. The spinning mortality event allowed us to get a lot more animals because the Florida Fish and Wildlife Conservation Commission did an outstanding job with colleagues from Mote Marine Laboratory, NGOs, to recover these carcasses and gather as much biological data as we could. So this has allowed us to advance our knowledge of sawfish biology and now we know they may live up to forty years old.
Tom Rowland: Forty years old. Wow. And so, I know we'll get to the sharks here in just a minute. That's what we're here for. But I'm fascinated with the sawfish because it's such a large and weird fish. It's got the bill with looks like a chainsaw. And what I understand about your work is that you go way back into the Everglades where I've been back in some of those areas and you do see the very small sawfish and so that tells me it's a nursery back there. But what does a sawfish life look like? Why are the big ones down in the lower keys and probably other places and then why do they go back into the Everglades to give birth like that?
Dr. John Carlson: Well, the very young sawfish are very tied into the mangrove habitats. I've actually seen them swimming up in and around the mangrove prop roots. So as these animals get bigger, they move larger distances. The smaller ones, which we generally find up into those mangrove prop roots, way up into the ecosystems of the national park, but also we see them on the small islands and keys that are found throughout Florida Bay. Some of the keys, for viewers familiar with like Eagle Key or Lake Key, that have these little inlets that run into the back part of the island. We've gone way back up in there on paddle boards and found these little sawfish up in there. So they're using that area as a nursery. The mangroves provide a place to hide. The predators for sawfish are things like lemon sharks or bull sharks, so they can get up in those prop roots and hide. But also those prop roots hold a variety of bait fish, pinfish, small sardines. That's what the little guys eat. So as they get bigger, they begin to expand their territories out further and further. And when they get five, six feet long, then they start moving out into the larger Florida Bay system and start to make that migration that we're starting to see again, where historically we knew that sawfish were moving up and down the East Coast, but also up and down the Gulf. And we're starting to see some of the larger individuals make those migrations. So one of the research studies that we do is we implant acoustic tags, acoustic pingers, into the animals. And there is a big collaborative network among a variety of scientists that could be studying anything from red drum to sturgeon. We all have our own little arrays, and if one of the sawfish that I tagged is picked up in someone else's network, that's awesome. And on the flip side, the array that we have, we picked up things like tarpon, red drum for colleagues that work for the state or for a university. So it's a great collaborative project.
Tom Rowland: That was described to me by another scientist I had on and they're saying that data is automatically uploaded so there's like a database that all the scientists can look at.
Dr. John Carlson: Yeah, and you'll get an email that says, hey John, I'm from the state of Georgia, and I just picked up one of your sawfishes in an array off of Savannah. So yeah, it's a really great network that has been developed.
Tom Rowland: What do we know about the sawfish migration? How far do they travel based upon the arrays that you've picked up?
Dr. John Carlson: Historically we had records all the way up to North Carolina. And when we were developing the recovery plan, one of the signals that we thought may be indicating that they are starting to recover is when we start to see those historic migrations. And actually we're starting to see that. There was a colleague that was working on sturgeon in Georgia that picked up a sawfish that one of my colleagues at Florida State University tagged in the lower Florida Keys. So it went all the way back up there. That's one of the signals that we're starting to see.
Tom Rowland: I mean the sawfish is not, maybe it has this in it, but I've never seen one swim very fast. That seems like a, they're like a nurse shark, just slow moving. So it would take forever for them to get up there. What's the idea of why they migrate that far? Are they following food or is it just...
Dr. John Carlson: Yeah, I mean it's a seasonal pattern we see with a lot of fishes. They move up in the summertime and then move back down in the wintertime. It's a common characteristic we see amongst a lot of fishes. Like I like to fish for tarpon, and I live in the Florida panhandle. In the summertime we've got tarpon, but then in the wintertime they're back down into the Florida Keys. So it's just that classical seasonal migration. But for sawfish, because their population was so depleted and had declined so much, they weren't making that migration anymore because there weren't very many individuals to do that.
Tom Rowland: And so when we see them returning to that migration, that's a good sign for the overall population?
Dr. John Carlson: It's a positive sign that things are on the right trajectory. But then again, like I said, that spinning mortality event, we are still trying to evaluate what the ultimate consequences are of that event to the recovery of these animals.
Tom Rowland: The consequences are one thing, but do we have any idea what the cause was?
Dr. John Carlson: There's microbiologists that are currently working on that now. In fact this week we had a special symposium on that event and it's related to some sort of algae that's found in the bottom of the ocean, in the benthos.
Tom Rowland: One more question about the sawfish. I know that on a lot of fish they'll age them with the bones in their ears, right?
Dr. John Carlson: Yes. Fishes have otoliths. Elasmobranchs don't have otoliths. The ear bones.
Tom Rowland: And so the vertebrae operates basically the same way with the rings. And so in order to get a vertebrae you're going to have to kill that fish or find one.
Dr. John Carlson: Well, that's what I said, because they are an endangered species, we cannot sacrifice an animal for that. But looking from a positive perspective, although it was a negative event, we were able to really expand the number of individuals we could age to get a better sample size.
Tom Rowland: That's got to be one of the more frustrating, difficult things when you're dealing with a species that is so in danger that you cannot get this data.
Dr. John Carlson: Yeah, well we're looking at alternate non-invasive techniques for aging animals now and one of the things that shows a lot of promise is genetics. We may be able to age just by taking a simple fin clip from the animal, which doesn't harm the animal at all. We may be able to use genetics to determine the age. So we're in a project now that's beginning to work on that.
Tom Rowland: Alright. Well, that's interesting. And how much of your time do you think you're spending on the sawfish versus the shark?
Dr. John Carlson: It varies, probably ten to twenty percent on sawfish. I have a lot of hats that I wear. I go in the field for two weeks out of the year, four times a year, because we're monitoring the abundance of the little animals, but we're also looking at habitat utilization. The mangroves are very important to sawfish. One of the questions that's really interesting is that to our eyes, we'll look at a mangrove habitat and it looks the same. There's no difference between this habitat. But it could be related to female sawfish returning to the same areas to give birth. They're what we call philopatric. We can go into an area that's only a couple square miles and we'll go to one mud flat or one mangrove habitat and we always see and capture sawfish there. You look at the same habitat, and there's never any sawfish there. So what's the difference? Is it that we're not quantifying what the difference is in that mangrove habitat? Or is it the fact that the females always go to this particular area because historically this had the best quality to give birth? So it's a really interesting question. We go into these mangrove habitats and we collect information on the prop root density, on the overhang of the trees, on the number of pneumatophores. So we're trying to refine what that is, and one of my colleagues published a paper last year to predict the occurrence of sawfish in a certain area. The density of the prop root system, you would see more sawfish.
Tom Rowland: So the more dense, the more sawfish.
Dr. John Carlson: More dense, more sawfish. And again, it could be related to that prop root system giving them, as a little sawfish, a nice place to hide from a lemon shark, but it also provides an area where there's a lot of food. For anybody that's ever put a mask on and crawled up in the mangroves, it's always got little shrimp and little fishes up in there. So for the sawfish, it's a good place to get some food.
Tom Rowland: The challenge for a scientist that's trying to figure out what is it about this particular little spot that makes the baby sawfish want to be here or need to be here. That's the same thing that happens with anglers, right? You can go to a flat and there are always bonefish here, but the one across the channel, there are never bonefish there. And you try all the different tides, and you're like, why can they be right there and not right there? There's something about it.
Dr. John Carlson: There's something, I mean, it's all important from what we're seeing, but there's definitely better places to go. It's really interesting because what we have to do is we fish very small nets. They're only a hundred feet long. A lot of times we have undergraduate interns, and I'll say, go crawl up in the mangroves and put that net up in there, or else we're not going to be able to sample properly. And they'll hop off the boat and they sink up to their knees in mud and they crawl across the mud to get the net up into the mangroves. So it's really challenging.
Tom Rowland: That's when you say, so you wanted to be a marine biologist.
Dr. John Carlson: Exactly. As soon as you get up there, for those of us that know, you get covered with mosquitoes, you're up to your knees in mud. It's not everything you see on TV. But it's really rewarding.
Tom Rowland: Well, speaking of seeing on TV, that's one of the few places where you haven't seen these survival shows go because I don't know that they could make it. Like you go naked and afraid or something in the Everglades, everybody's tapping out almost immediately.
Dr. John Carlson: Yeah. Well people get excited when they apply for internships, they see, I'm not afraid of sharks, I can go in a shark cage. And I'm like, I don't need an intern for that. I need an intern that wants to crawl across a mud flat in ninety-five degree temperatures and get swarmed by mosquitoes and still come back smiling. Some of the interns I've had over the years, their zeal is unbelievable.
Tom Rowland: How many of those do you find? Really?
Dr. John Carlson: It's so high. It's great.
Tom Rowland: That's fantastic. And especially today where there are so many other distractions and career fields for people to go into, that you're still finding very excited, enthusiastic young people moving into this field.
Dr. John Carlson: One of the things about this meeting that I'm attending this week is we had so many great graduate student and undergraduate student presentations on stuff that they're doing. So it's very exciting that the next generation of scientists is coming through and they have all this zeal and excitement about what they work on.
Tom Rowland: That's cool. So what about your own personal story? How did you, what was it about your background or your activities that made you want to pursue this career?
Dr. John Carlson: Well, I grew up in Connecticut. My dad was a big fisherman. From the time I could walk he had me out on his boat. He was a big striped bass fisherman up in Long Island Sound. So I would do that with him since I was a kid. That got me the feel for the ocean. I've loved the ocean, I surf, I paddleboard. So I ended up going into biology when I went to college. That carried on into my master's degree. For my master's, I actually studied the diet of little flounder the size of your pinky. We were looking at how feeding differed between an area like New Haven Harbor, where there's a lot of shipping traffic and disturbance, as opposed to one that was more natural. Then in between my master's and my PhD, I did some fish physiology research, but then I started looking around for universities to do my PhD. I ended up at the University of Mississippi, Ole Miss. So I went from Connecticut to Mississippi, a bit of a change. Because I had this physiological interest, the professor that I worked with at Ole Miss, we did experiments on how sharks, everybody says that sharks need to swim all the time to breathe. If you take a fish and put it in water that's hypoxic, has very low dissolved oxygen, a fish can pump more water over their gills. A shark can't do that. A shark has to swim faster to get more water over its gills. So we were looking at that from a behavioral and energetic component to see how they respond. It was an ecological physiology project, how the physiology and the ecology are related to how the animal distributes itself, feeds, etcetera. And just by serendipity, the lab director at the NOAA Fisheries Panama City Lab was really interested at the time about bringing graduate students into the lab. He knew my major professor. Just before I got to Ole Miss, they were at a meeting together, and he said, I have a new student that's coming in that's going to do shark research. And the director at the NOAA lab said, really, would he be interested in doing it here? So I ended up commuting back and forth from Oxford, Mississippi to Panama City, Florida for my PhD. And when I was finishing up my PhD, NOAA Fisheries was just ramping up the shark programs in the southeast. There was an interest in getting more scientists devoted to sharks. So I was able to acquire a position at NOAA. That's the long and short of how it all ended up. A lot of it was being lucky at the same time. It's been great. I've had twenty-five years with NOAA and a really productive, exciting career. I originally thought I was going to go into academia and become a professor, but the latitude of my research has still allowed me to work on graduate students' committees. We have a very active intern program. And I still work a lot in academia with a lot of my colleagues. So it's been great.
Tom Rowland: Yeah, that's really cool. And then my notes here tell me that you wrote this paper in 2021 that is a landmark paper. Can you tell me about that? All this stuff kind of came from AI, so it could be correct and it could not be correct. If it's not correct, please tell me. But it says that you were a co-author on the 2021 Nature study showing oceanic sharks and rays declined seventy-one percent since 1970. Can you tell me about that, and why you started into that, and what the results were?
Dr. John Carlson: Yeah, this was part of the IUCN, the International Union for the Conservation of Nature. They have what's called a red list assessment. We evaluate from a global perspective what the status of sharks, rays, and chimeras are. The IUCN has specialist groups, everything from sharks to algae. Every five years we try to reevaluate the red list assessments based on IUCN criteria. Just so you're aware, the IUCN criteria is different than how we do assessments in the US. So in some cases the IUCN Red List assessment may say that a species of shark is endangered, but that endangered is global. The status may be different on a regional level. In any event, referring to that paper, we looked at it from a global perspective. We looked at all the available data that we had on abundance trends, everything from the stock assessments that are done by some of our regional fishery management organizations like ICCAT, the International Commission for the Conservation of Atlantic Tunas. We took stock assessments from there, from other RFMOs in the Indian Ocean, from other RFMOs in the Pacific Ocean. Where we didn't have a stock assessment available, we looked at what we could find for abundance trends. Long of the story is we took all that information together and combined it into a big meta-analysis to determine the status of the pelagic species from a global perspective.
Tom Rowland: Okay. And the result was seventy-one percent down since 1970. One of the things that has been a topic of conversation here with divers, I've had so many different people on here talking about the sharks and everybody has a different perspective. You have the divers that are spearfishing, and their catches are getting taken too, and it's pretty dangerous down there at times. Then you have the tourist operators that are diving with sharks. You have snorkel boats. Then you have above the water fishermen, inshore, offshore. And I've had international people on talking about the sharks. One of the things that was a theme for a while is that certain people just could not even consider that the global population could be going down but a local population could be going up. What is your opinion on that and where are we right now, because it certainly seems as though Florida has a lot of sharks?
Dr. John Carlson: Yeah, there is definitely some localized differences. You can go to areas in Florida where the populations of sharks, the US has some of the best shark management in the world. We have to pat ourselves on the back for that. Australia also has very good management, but in some of the developing countries they just don't have the resources to manage their fish populations that we have in the US. So in some areas of the world, the populations have been severely depleted. Before the US actually implemented shark management in the 90s, a lot of our shark populations were depleted in the 80s. So a lot of it depends on where you are in the world and the resources that the government or area has to successfully manage their shark populations.
Tom Rowland: So in the seventies and eighties, you'll hear a lot of the fishermen that have been around for a while say, man, it wasn't like this when I first started, we didn't see this many sharks. So with your experience and studies and knowledge of shark management, what has changed between the seventies, eighties and today? Could you give us an explanation of the management and commercial fishing?
Dr. John Carlson: From a US perspective, there was no management for sharks. Our first federal management plan was in 1993. Prior to that, we had two types of impacts on our shark populations. One was from the recreational industry after the movie, we call it the Jaws effect. After the movie Jaws was released, a lot of people wanted to go out and fish for sharks. They used to have the winner of the tournament be the person that could bring in the most sharks or the largest sharks. So you had a lot of fishing pressure from that perspective. And along the same time, many of our shark fisheries started to ramp up. The demand for shark fins increased because China had opened up its borders to global imports. So you had a product that was very marketable, very much in demand and very valuable. In the early years, because we had no management of our populations, that caused a large decline in many of our species. Recognizing that, we implemented our first shark fishery management plan in 1993. And unlike teleosts, like sardines, that have a very different life history where they can respond to management much quicker than sharks can, many of our shark species don't reach sexual maturity until twenty years. Our dusky shark probably doesn't reach sexual maturity until about twenty years. And they were ones that were heavily depleted in the 70s and 80s.
Tom Rowland: Twenty years? Really?
Dr. John Carlson: We're starting to see them come out of the basement, but it's been much slower than for other species like black-tip sharks, which reach sexual maturity about four to five years. So it's a big wide spectrum among our shark populations, and that's what I want to get to your audience, is that not all sharks are created equal. Some sharks, like sharpnose sharks, reach sexual maturity in two years.
Tom Rowland: What about the lemon and black tip? Because those are the two that are responsible for a lot of the attacks that people are having on their fish right now. What's their sexual maturity age?
Dr. John Carlson: Well ironically, I just published a paper revisiting lemon shark biology, because the only other information we had was back in the 80s. Things could have changed with their biology over the last twenty-five years. What we find for lemon sharks is they're actually much more productive than we had before. This could be a response to the change in management where they're now growing faster than they were beforehand. For lemon sharks, it's around eleven years that they reach sexual maturity, and then things like black tip, it's half that for black tips, about four.
Tom Rowland: And would you have any idea on how big an eleven year old lemon shark would be?
Dr. John Carlson: Probably, I'm thinking on the metric system, so probably around seven, eight feet long.
Tom Rowland: Okay. So those are the ones that you see. You see a lot of them, but you also see smaller ones for sure.
Dr. John Carlson: Yeah, definitely. Part of the stuff we do for our surveys for sawfish, like when we're in the Everglades or in Florida Bay, we're always catching little lemon sharks. Always catching little lemon sharks. And they're cool to watch because we'll go along the shoreline. You see the little lemons cruising in and out of the little banks. So they're neat.
Tom Rowland: Yeah, they're definitely around. So when you mentioned 1993, there was a change in the commercial fishing regulations, or recreational fishing also?
Dr. John Carlson: There were quotas. We put the initial quotas. We put a recreational bag limit.
Tom Rowland: So could we go back to just right before 1993 and then right after, what changed and then what the result was?
Dr. John Carlson: Well, it was just the implementation of regulations. But like I was saying, for sharks, you're not going to see a change like that. These management regulations kicked in. We did our first stock assessment for sharks, so we had a quantitative estimate of how many were out there. One of the problems we initially had was when sharks are recorded as landings, it was just recorded as sharks. We had no species-specific information. And blacktip sharks are a lot different in their life history than sandbar or dusky sharks, but it was all still lumped together. So we had to do a lot of detective work to try to differentiate what proportion of sharks being landed was what particular species. We've made big progress on that. A lot of the dealers now, we've had education where we're training not only scientists, but dealers, commercial fishermen, recreational fishermen, because not all sharks are created equal.
Tom Rowland: Right. It's easy to misidentify some sharks too.
Dr. John Carlson: Definitely. And it still goes on. I'll be perfectly honest. Sometimes it takes me a couple minutes and I'll see a shark and go, wait a minute, no, okay, it's that. Especially when in the water, it gets difficult. One of my first jobs when I worked for NOAA is I worked as an observer on commercial fishing boats. And you're out at night and sharks are coming in and you're trying to identify them, and it takes some training. But I must say some of our commercial and recreational anglers are really good because they can identify them.
Tom Rowland: Well, they handle them and they could probably tell you even when one's on the line what it is versus another one.
Dr. John Carlson: Yeah, definitely. They go to certain spots and they go, we're going to catch this kind of shark because we're here.
Tom Rowland: Over the years, I feel like, and this may or may not be true, but I feel like the science community has more embraced the recreational community's data. Commercial fishermen obviously have been a good source of data because they're bringing in dead species, landing them. A recreational angler is saying, we saw tons of sharks out there. What does that really mean? For one person it's five, for another person it's five hundred. But it does seem that the trusting of recreational data has been more accepted by the scientific community. Is that true or not?
Dr. John Carlson: Not necessarily. We evaluate each data source. We scrutinize every bit of data that we have to the best of our abilities. So we don't favor one particular source of data over the other. We look at each data set individually, evaluate its validity, and then apply the appropriate level of uncertainty to that data when we use it in our models. We don't take everything at face value, we look at what was the source, where'd it come from. So I would not necessarily say we favor one source of data over the other.
Tom Rowland: I wasn't saying favoring. I was just saying even acknowledging that it could be a legitimate source of data. It seems like more of the scientists that I've talked to have been more open to hearing what the recreational anglers have to say.
Dr. John Carlson: No, we take the value of both, whether they're recreational or commercial fishermen. In fact, we just started our assessment of sandbar sharks again, our stock assessment for sandbars, because there's a lot of public perception that sandbar sharks have exploded. The last time we did an assessment was back in 2018. Because of the comments that we've been receiving that there are too many sandbar sharks out there, this past year in May we had our data workshop where members of both the commercial and recreational communities were participants in the process. So we take everything from all our constituents, not one over the other.
Tom Rowland: Yeah, that's cool. So we have this situation in front of us and I'm trying as hard as I can to be non-judgmental on what I've seen with my own eyes and try to be as ethical as possible. Okay, well, I'm seeing one thing, other people are seeing bigger things, but when all the guides are saying basically the same thing, that they're getting attacked by sharks or their catches are being attacked every day, it starts to make you, well, you're living in an echo chamber. That's what you're hearing every single day. But there are other sides to the story. And I'm trying to understand the other side. I did come up with some different stats here, and like I say, I don't know if they're accurate or not, but these are kind of the two sides of it. So the depredation numbers, this would be the anglers' case for people that are like, there are too many sharks, they're attacking everything, we have to do something about it. So forty-three percent of surveyed Florida anglers experienced depredation from 2020 to 2023. Probability on a given trip ranged from ten to sixty percent. Eighty-six percent of identified depredation events were caused by sharks. Bull sharks were number one, thirty-three point eight percent of IDs, then sandbars. The worst spots were the Florida Keys, fifty-seven point four percent, Western Panhandle, forty-eight point five percent, Southeast Florida, forty-seven point one percent, and the worst season was in the spring. Fifty-four point five percent of affected anglers were targeting snapper-grouper species, also tarpon inshore, and the dolphin-wahoo-blackfin tuna complex. So when I hear that, those are different sharks that are attacking those different fish. Tarpon are certainly getting attacked by bull sharks now more than I've seen previously, but that's typically been a hammerhead.
Dr. John Carlson: Right, usually great hammerheads. In fact, I'll interrupt you, but what's interesting is an intern that came through my program, that's what she worked on for her PhD.
Tom Rowland: Really? That would be a good one to work on. I find those sharks very interesting. The sharks that are getting the dolphin, wahoo, blackfin, you might get an occasional hammerhead attack there, but that tends to be a different shark. And those are different areas also, offshore, inshore.
Dr. John Carlson: Yeah, the pelagic species are probably a different suite of sharks.
Tom Rowland: Let's get back to it. Thirty percent median share of hooked fish lost per a separate Gulf survey where seventy-eight point six percent of anglers reported depredation. In one study, fifty-one fish stocks, twenty-two shark species, scope of depredation from Maine to Texas, with bull and sandbar most implicated. And the method for that was forensic DNA swabs of the bite marks.
Dr. John Carlson: Bite marks, yeah. I know the scientists that did that study, they were here and we were chatting this week.
Tom Rowland: Okay. So that's the angler side. And then the conservation counter numbers, the science case maybe, or the divers' case in a lot of situations. There's a seventy-one percent decline in global oceanic sharks and rays since 1970. One of your papers is cited here. A third of shark species threatened with extinction. Eighty to a hundred million sharks are killed per year globally, mortality is still rising despite finning bans. 2070 and 2107, rebuilding target years for sandbar and dusky. So that's proof of how slowly these animals recover. The people that are saying do not kill all the sharks are saying, well, not all sharks are created equal, some take a lot longer than others to get back. They're saying that the bites are down in 2024, forty-seven unprovoked bites worldwide on people. Florida had the most at fourteen, but the trend fell in the same window that people claim there is an overpopulation. Then it says there's two hundred and twenty-one million dollars, thirty-eight hundred jobs that revolve around the shark encounter dive economy. So sharks are worth a lot of money. Well, they're worth a lot to anglers too. The people that are saying something should be done about it, I don't think they're saying we want to kill all the sharks. So when you hear those numbers and the two different sides of this issue, what are your remarks to that?
Dr. John Carlson: Well, the first thing regarding the numbers that you cited about the declines, the big word as we talked about is these are global declines. These are global studies. The study that I was on, that was a global perspective. And as I mentioned earlier, there are some bright spots among shark populations, in particular in the US. We're one of the most successful countries to manage our shark populations. That being said, we still have declining populations within US waters that haven't fully recovered yet. We're in the process now of going back and re-examining some of the species we have not assessed, like sandbars, which is one of the big ones that people say there are so many of them, they're depredating a lot on our reef fish populations, red snapper. I see the same thing. People tell me they can't get a snapper ten feet off the bottom without a sandbar shark. I'm a diver too, and I spearfish, and there are a few areas that even if I shoot and miss, the thunk, a sandbar will be in the area. But regarding the differences of opinion determining whether there are too many sharks out there or the sharks are severely depleted, we have to look at the details of the study. Was this a study done on the global scale, which largely were the IUCN shark red list assessments? If you look more specifically, like Australia's stock assessments, some are very healthy shark populations they have in Australia, again because they're good at managing their species. There are some blue sharks managed in the Atlantic Ocean that are sustainable right now. They're just at maximum sustainable yield. So again you have to approach it from the perspective of what area of the globe you're talking about. If you're talking globally, everything kind of bounces together.
Tom Rowland: Well, for the most part, I think that people listening to the show will say, I don't really care about the world population of sharks. My world that I'm living in right here is Florida. And every time I go out, I'm seeing more sharks than I've ever seen before. And it's frustrating to hear, no, they're on this big decline. So how can you have overpopulation and overfishing at the same time?
Dr. John Carlson: When a lot of people are citing these ninety-seven or seventy percent declines, again, it's the global. And this is why NOAA Fisheries now is moving more into analyzing or reanalyzing the status of species that haven't been assessed in quite a few years. And then for some species like bull shark that we've never had a full stock assessment done, that's the next species we have in line to examine what the status is. A lot of the information is public perception that we want to try to put a science measure on.
Tom Rowland: So when you do a stock assessment of a certain species, let's talk about the bull shark, what would that look like?
Dr. John Carlson: We're taking all the available information that we have. We look at its biology, because you can't assume that all sharks are created equal in terms of their biology, because that has a great impact on their productivity. Sharks can't respond as well to being harvested because their populations just don't grow that quickly.
Tom Rowland: Now, we didn't say what the sexual maturity of a bull shark was before. Do you know?
Dr. John Carlson: I'm trying to remember off the top of my head. I think it's around, similar to a lemon shark, around ten to twelve years old, if I remember correctly. I can easily look it up. I actually worked on a study for bull sharks, but this was over ten years ago in the Gulf, and I'm sorry I can't remember off the top of my head. In any event, we're going to be reevaluating that life history for this upcoming assessment for bull sharks because it may have changed over time for various reasons. When a species gets depleted, sometimes its biology changes and they become more productive than they were before. So we have to look at those factors as well. Then we try to gather all the available information we can on the abundance trends. We look at commercial data, recreational data, scientific surveys as a trend to monitor abundance. And then lastly we also look at the harvesting rates, how many sharks are removed recreationally, commercially. And if they're caught and released, what are those discard rates like? So all of those pieces go into the puzzle of our population assessment model.
Tom Rowland: Okay. And then I guess what I hear more than anything is, what are we going to do about it? If the shark population is healthy and there are more than we've seen in a long time, and taking into account that each shark is different in their sexual maturity, what would be a recommendation by NOAA to decline those numbers or to bring them back into what would be considered a healthy number? It seems like it's a little out of balance if you ask the fisherman.
Dr. John Carlson: Well, I'll use sandbar for example. After this assessment for sandbar sharks, sandbar sharks have been prohibited from commercial harvest, outside of a small group of fishermen that are still allowed to harvest sandbar sharks. If this next assessment for sandbar sharks shows the population is much healthier than what it was in 2018, then obviously our management group will work together to provide a new regulation for the sustainable harvest of sandbar sharks. So it'll be adjusted based on the next population assessment that we do. And we're moving a lot faster too. Going back to the early 90s, we used to have what was called a large coastal shark quota, which was everything from sandbar sharks to hammerhead sharks to bull sharks. It was a big grouping. But since 93, we're now moving towards species-specific quotas. So we can have a sandbar shark species-specific quota that commercial or recreational anglers can utilize.
Tom Rowland: Well, I think the commercial is probably more important because if you take a charter guy that's fishing in a twenty-five foot boat and you catch a shark early in the day, are you really going to have that, you don't have a hold that's big enough to put the thing in. Are you really going to have it sitting on the deck? Lefty Kreh always said that there is no such thing as a dead shark. They can bite you long after. So you can't have the thing sitting on the deck and have tourists walking around this shark that seems to be dead. So a lot of people are like, well, opening commercial fishing up is one thing. You can kill a shark today, but rarely do you see that happening because it's a very large animal. And if you're a guide by yourself, you don't have a mate, are you really going to single-hand that thing into your boat?
Dr. John Carlson: No, most of the large sharks you see that are caught recreationally are generally released. Unless it's for a tournament. We have directed shark tournaments.
Tom Rowland: Right, for a lot of reasons. You'll have people that like to do that and they're equipped to do that and they have a mate and a boat big enough. But I think that most people are saying it feels like it's time to open up commercial fishing for sharks responsibly.
Dr. John Carlson: Yeah, and that's exactly what I was saying, all our management policies are derived from the science. As I said, sandbars are currently prohibited outside of a small group of commercial fishermen that can still harvest them. If this next assessment comes back and says the populations are much healthier, obviously those management recommendations will be adjusted.
Tom Rowland: And then the market for that, is there a market for the sharks?
Dr. John Carlson: Well, right now it's illegal for the fishermen to possess the fins, and that was a primary driver for many of the shark fisheries. They were exported to Asia for shark fin soup. There is a market for the meat. It's not as profitable as the fins were, but there is a market for the meat. And actually someone had sent me a link on a Facebook page where there's a group in Alabama that are trying to market shark burgers, which I thought was interesting. Shark is good.
Tom Rowland: Well, it's the same kind of thing with lionfish. If you create a market for it in the restaurants, then people will get them.
Dr. John Carlson: People will do it. I've eaten shark before and it's good. If you do it properly. Whenever I've been out recreationally fishing and I catch a small black tip, if it's legal size, I always tell people if you want to eat shark, first thing you do is you want to bleed it out and then stick it on ice. Don't leave it sitting in the sun. Because sharks, due to their physiology, retain a lot of urea, and that will taint the flesh pretty bad. But if you properly bleed it out and put it on ice, it's pretty tasty. I do shark steaks in the summertime on my grill.
Tom Rowland: Somebody told me the other day, we saw a bonnethead shark while we were fishing and he goes, oh that's good, that's the best shark. And I've never heard of anyone eating bonnethead shark. But he loved it. He said they were fantastic. Our bonnethead sharks in the Florida Keys tend to be kind of smaller. And I know that in South and North Carolina, that's where the world records come from and they're much bigger. And I think they do eat them up there.
Dr. John Carlson: They're actually fun to catch recreationally. Bonnetheads are one of the animals I did my dissertation work on. A lot of times I would catch them recreationally for my experiments.
Tom Rowland: Sure. Well listen, jack crevalle and bonnethead sharks have saved more charter days than a lot of people would care to admit.
Dr. John Carlson: Yeah. So getting back to the market, I think it's more just educating the public like we did with lionfish, that it's actually pretty good to eat. I like to go spearfishing for lionfish and one of my favorite things to do is make lionfish ceviche. I'll post on Facebook or Instagram a picture of my lionfish and I'll get people that comment, that flesh is poisonous. And I'm like, no it's not. There's nothing wrong with the flesh, it's very tasty.
Tom Rowland: The spine is poisonous. Well, come to the Florida Keys. There is one restaurant in the Florida Keys that has lionfish eggs Benedict. Eggs Benedict with lionfish on top of it. It's fantastic. It's in Marathon. I'm trying to remember the name. We did a show and we went to this restaurant. I'll try to put it in the show notes if I think of it. I'm sorry to the restauranteer that is waiting patiently for me to say what it is, but I can't remember. What about some of the people that are against any sort of shark commercial fishing or harvest? One of the things they say is that there's actually too much pressure on the fish and the sharks are just hearing the boats and coming around. Just like what you said about the spearfishing, when you're in the water and you can see that with your eyes, that's one thing. But they're saying that they hear the boat, and it's because there's so much pressure on the fish that the sharks are coming right to the boat.
Dr. John Carlson: Yeah, it's actually one of the things that we're beginning our research on. There are many different theories about depredation. Is it a select group of sharks? We're calling it the bad bears. Is it the same bad bears that get into your garbage cans all the time? Or is it something more systematic, that all the sharks? So we're trying to test that theory right now. We're going to be getting a project where we're going to try to get the cooperation of the recreational anglers, commercial anglers, and the scientists, and we're going to monitor some of these areas that have high depredation to see, are the sharks there all the time? And if they're not there all the time, what's the cue that they're using? Is it the engine, the first time they hear the engine? Or is it that first wriggly red snapper that goes to the surface that they're attracted to? So what's that mechanism that's driving the depredation for these particular areas?
Tom Rowland: Right. Well, I think that a lot of fishing guides will say, look, if I go two hundred miles this way, you go two hundred miles this way, no matter where you stop, it's like that. And so those sharks aren't following you two hundred miles. They can't swim that fast and they're not going to swim that far. So when you relocate to another spot and the sharks are there, they didn't follow you there. You're in a different group of sharks. So what it tells me is that there are just a lot of sharks around. And obviously if they get tuned to, well that boat means an easy meal, then those sharks are responding to the boat. It's not like they're following you around all day moving at forty or fifty miles an hour. That's not possible. But what is possible is that there are just a lot of them there, no matter where you stop.
Dr. John Carlson: Yeah. And we also have a lot more recreational fishing effort on the water than we did twenty years ago. So there are a lot more fishing spots, the benefit of GPS, the benefit of the great stuff we have for bathymetry. So it could be an artifact too. If there are just a lot of recreational guys out there, or not even recreational, just fishing out there, that sharks are starting to tune in to, like you said, the sound of the engine, or the wriggly fish to the surface. That's one of the things we want to try to get a better handle on. And that's not just me, a lot of my colleagues that I've been talking to this week, we're all brainstorming about how we're going to evaluate those types of questions.
Tom Rowland: And did you come up with any solutions?
Dr. John Carlson: No, we're just starting this. Going back to the study you talked about with the DNA analysis, that was a really great way to start, but we want to expand that to try to get more samples.
Tom Rowland: Now that's from the bites?
Dr. John Carlson: The bite. When you bring up a fish that's been bitten, you can take a Q-tip swab, put it in a vial with some solution, and then we can genetically identify what species of shark that was. So we want to expand the universe by trying to get more volunteer anglers. All you guys need to do is carry a test tube with a Q-tip in it, keep it in a cool spot, and if you come up with a bitten grouper or snapper, swipe that, put it in a tube, and send it to the scientists.
Tom Rowland: That's cool. Is there already a program like that?
Dr. John Carlson: That's where they're starting to build. My colleagues that did this initial work are trying to expand that more.
Tom Rowland: Yeah. What do you know about, I had Congressman Rob Wittman on the podcast twice now talking about the SHARKED Act, and I think that he was one of the people that brought that to the floor. What do you know about the SHARKED Act?
Dr. John Carlson: It's primarily, I don't know a lot about it. It's primarily designed around increasing public awareness about the issue, but also increasing how we can move forward with analyzing this issue on depredation. So I don't know the details of it, I just know the overall ideas behind it.
Tom Rowland: Right. What he was saying is that the idea was to decrease depredation. And I don't know, when I hear that I kind of think, well, the easiest way to decrease depredation is to not allow anglers to go into certain areas. And so my hackles come up on that because that's the one thing that I feel like you want to protect as an angler, your right to go someplace. Because typically when it gets closed it does not get reopened, certainly in the time frame that you would like. So I just wondered if you knew anything about that.
Dr. John Carlson: Yeah, another part of the SHARKED Act and part of a lot of the research we're doing is not limiting the angler's experience, but looking at various deterrents that might work. Sharks, like some of the rare metals, some of the electrosensory stuff. A lot of these are being tested experimentally now. A colleague that I'm good friends with at Mote Marine Laboratory is doing some work on a new metal. There's some electrosensory stuff being done by colleagues at Florida International University. So there's a lot out there, and one of the things I've been working on with a lot of my colleagues is, let's do a big meta-analysis of all these various deterrents, because some may work for some species but may not work for others. And then of course we want to get into the cost. We may have this rare metal that works great for repelling sharks, but if it's seventy dollars for an ounce, you can't expect the average recreational angler to be spending seventy dollars on a sinker to add to their line.
Tom Rowland: Right. Well, the right one in the right situation would be happy to do it. If it's a tournament or something.
Dr. John Carlson: Yeah, it's going to depend on the various anglers, but you just want to find something that is cost effective. Like everything, you want to find that it's cost effective.
Tom Rowland: Right. So I really appreciate your knowledge and your being on the show, and I certainly did not get through anywhere near what I wanted. I think we should do this again.
Dr. John Carlson: We could do part two if you want later. It might be worth it because we're working now towards developing a strategic plan for dealing with depredation and for reevaluating our shark population. So six months, a year from now, if we want to follow up, I'd be more than happy to discuss how we've come from this chat to a chat a year from now.
Tom Rowland: Well, I'd really appreciate that. So I guess to wrap this up, the question that everybody has is what is to be done about it, if there is a big explosion in sharks, like it appears that there is, and they're taking all the fish. It's become much more difficult for fishing guides because you used to be able to just go to a spot, fish there until your people were tired of it, and then move on. But now you go there, you drop three or four times, you catch a couple of good fish, then one might get eaten. Okay, well it's time to go for the ethical angler. We're just going to feed these sharks. There's no reason to fish here. So now you have to go to another spot. So guides have to have a lot more spots than was required ten, fifteen years ago. And for the recreational angler that makes it even more difficult, because a lot of recreational anglers have two or three good spots, or maybe thirty, but if you have thirty good spots and the wind blows a certain direction, twenty of those are unfishable. And so now you have ten. It puts pressure on these certain spots. So I guess the question that most people have is, what is to be done about it? What you're telling me is that NOAA is already on the way to doing these different studies, but maybe you could put it in your own words about what is to be done about this controversy.
Dr. John Carlson: Well, there may not necessarily be a silver bullet to take care of all these issues, but we hope to find reasonable recommendations that we can make to recreational anglers, commercial anglers, based on the science that we're doing now. It's going to be a stepwise process. One, are there more sharks out there than there were ten, fifteen years ago? We're doing that now. Two, is it systematic or is it just an isolated group of sharks that have figured it out? Step three, if there are more sharks out there, we will obviously adjust our management based on those recommendations. And then creating more markets for shark meat like we talked about, making it a little more, I want to go get a shark burger rather than a hamburger. As I said, people have talked about global shark populations, and yes, in some areas of the globe, they are in really bad shape. But the US has one of the most successful shark management programs, I would argue globally. And we want to encourage that sustainability. No one wants to see sharks like sawfish being in danger of extinction, but if they are sustainable, we should try to promote those markets. Some people may just say we don't want to catch sharks at all. And that's your personal opinion. Some people are vegetarians.
Tom Rowland: Right. Well, there is the fact that they do fight back. They bite. And it's not always good for your boat, it's not always good for your passengers. But what I know about things is that commercial fishermen are extremely good at what they do. And if there is a market...
Dr. John Carlson: Yeah, and some recreational guys are really good at what they do too. I fish with a couple professional guys and it's like, right there, John, throw your line right there, and boom, hook up.
Tom Rowland: Yeah, they're really good at catching fish and then typically releasing them. But the commercial guys are set up with boats that are big enough that they can harvest. And if there is a market and it is open, they will do an outstanding job of getting whatever they are allowed to get. That seems like the answer to me, if we find a sustainable way to do it. That's the real issue at hand, what is the answer to too many sharks and how do you do that in an ethical, responsible way that you're being a steward of the ocean rather than just doing what is best for your own interest, which is I want to catch more fish. If people are interested in reading more about the things that are currently going on, the studies that NOAA has, are those public? Can you go someplace?
Dr. John Carlson: Yeah, there's a webpage now. If someone wants to Google NOAA shark depredation. We actually did a report to Congress a few years back where this initial issue came up. And it wasn't just on shark depredation, it was also on marine mammal depredation, because in some areas bottlenose dolphins are worse than sharks. And then if you go to Hawaii, you have things like false killer whales and pilot whales that depredate. When my dad was alive, I used to go back home every year to go fishing with him. We were fishing in a striped bass spot and a seal would pop his head up and he's like, see, that's why we're not catching any striped bass anymore. And I'm like, wait, dad, stop. So it varies depending on where you are too. But as you said, I think we all want to be ethical and responsible stewards of the ocean.
Tom Rowland: Yeah, hopefully. We have some resources, we've got some homework to look at, and I would love to have you back again. I learned a lot. You have some information that no one else that's been on the podcast has, and that is that you are, from what I can tell, responsible for the different species and which ones are in trouble and which ones are not. And I wonder if just as a closing thought you could tell us which species, they don't have to be sharks necessarily, of your knowledge, which ones are the most in danger all the way to the ones that are recovering and maybe might be off the list soon.
Dr. John Carlson: Well, the smalltooth sawfish that I work on is probably one of the most, and it's not a shark, it's basically a big skate, a big ray. Not just the populations left here in the US. One of the interesting things about sawfish is there are only little remnant populations, because sawfishes, the smalltooth that we work on, used to be found throughout the Atlantic Ocean. Now they're pretty much extirpated from Africa, and there are only little isolated pockets. One here in Southwest Florida, probably due to the creation of Everglades National Park and the National Wildlife Refuge, which provided what we call the lifeboat for sawfishes. Some areas in the Bahamas you still see sawfishes, but really it's little pockets, tiny little pockets of the population. We estimated that they've probably declined by ninety-five percent from their historic ranges. It's also one of the pelagic species that I work on, the oceanic white-tip shark. That's also listed on our Endangered Species Act as threatened with extinction. In some areas, for example in the western central Pacific, they did a full population assessment and found the population had declined by ninety-five to ninety-nine percent. So those are the ones that pop into my head immediately. But a lot of the less charismatic species, people think white sharks, tiger sharks, but a lot of the batoids, like the wedgefishes, we don't have a lot of the populations of those, but they're found a lot in the Indo-Pacific and in tropical Atlantic waters, and their populations are in very bad shape in a lot of those areas as well. That's another thing that gets back to when people refer to globally sharks having declined, it's also taking into account a lot of the declines that we have with our rays and skates, which people don't tend to think about. So those are the kind of animals that I think about that are not doing so well, not only from a US perspective, although we're starting to see some positive signs, but from a global perspective. Some of our shark species are harvestable, they're sustainable, because of management regulations, but also due to their life history, their biology. They're a lot more productive than some of our other species that don't reach sexual maturity until nineteen, twenty years old. Obviously they cannot respond to commercial or recreational fishing harvests as well as some of the other species do.
Tom Rowland: Right. Is there any good news? Do we have any species that are doing really well?
Dr. John Carlson: I'm thinking of blacktip populations. Our assessments suggest that they are healthy, one of the species that pops into the top of my head. Bonnetheads also. Some of those species from our assessments do appear to be doing well, and it's not just in the US, some of the other areas of the world they're also healthy.
Tom Rowland: What about the greater hammerhead? Any of the hammerhead species?
Dr. John Carlson: We're just finishing up the population analysis on hammerhead sharks. We started that assessment and we're just finishing up the final results on where the hammerheads are, but some of the populations are doing quite well. One of the things we had talked about is I love watching hammerheads in the shallow water swimming in and out. Because I'm a surfer, a lot of times I'll be going down and you see a big hammerhead cruising and people get nervous and excited about it, and of course they do, but I'm like, no. They're in there because one of the big prey that hammerheads have are stingrays, and that's where they are in those shallow waters looking for stingrays to feed upon. So I really like hammerhead sharks. Except if you're tarpon fishing in the keys.
Tom Rowland: I do too. I think they're fantastic. Even watching those things hunt one that's on a line, but if you're ever lucky enough to see one cut one out of a school and get it, that has nothing to do with a human whatsoever. It's just a natural thing. You just happen to be poling down and you see this hammerhead come in, it cuts a fish out of a school and chases it down and eats it. It's one of the most incredible things. It's a similar experience to watching a lion take down a gazelle in Africa. It's really amazing how good they are at what they do.
Dr. John Carlson: Yeah, an animal so big. I saw a hammerhead once make like a, it was chasing pufferfish. And for a big animal like that to do a three-sixty that quickly is like, whoa.
Tom Rowland: It's incredible. How they can move. It's absolutely incredible. All right. Well, thank you so much for your time today. I really appreciate it. And we have some resources out there. They'll definitely be in the show notes and we'll do this again. I really appreciate you coming on.
Dr. John Carlson: You're welcome. My pleasure. Thank you very much. Have a good day.
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