[00:00:00] Speaker A: What fish has been swimming the oceans for over 400 million years, has multiple rows of teeth hunts using electroreception, and whose presence is vital for healthy oceans? You guessed it, sharks, the apex predators of the big blue.
Welcome to Rewildology, the nature podcast that explores the human side guide of conservation, travel and rewounding the planet. I am your host, Brooke Mitchell, conservation biologist and adventure traveler.
Today I'm sharing with you another compilation minisode. In this 30 minutes, information packed episode, you'll hear from two badass women's shark biologists who have been starred on the show. Frida Laura, PhD, shark researcher, Tahore guide and cofounder of Orcas in Mexico and Camellia Arnes, Hammerhead and thresher, shark researcher in the Galapagos Islands.
Both discuss the insightful studies they conducted to understand shark behavior and movement patterns in their study region and share lots of facts about sharks, some of which may surprise you. Grab your virtual snorkel gear and embark on an educational journey into the blue depths to understand the lives of Galapago sharks, silky sharks, hammerhead sharks, and more.
But really quickly, before I let you dive into today's minisode, be sure to give the show some love, however you want. Some suggestion by leaving a rating review on your favorite podcast app, engaging with the show on social media, and signing up for the newsletter at the website.
Also, if you're interested in volunteering with rewatology, head on over to rewatology.com and check out volunteer opportunities under the about tab. The deadline to apply is February 19, which is right around the corner.
All right, everyone, please enjoy this toothy, salty, and enlightening episode with Frida and Cammy today on rewatology.
First up today is Frida Laura, PhD from episode 116. In this clip, Frida shares her research with the Galapagos sharks and silky sharks in a mexican protected marine reserve.
[00:02:29] Speaker B: Well, for my phd, actually, it was interesting because I went to Mexico city with my sister.
[00:02:37] Speaker C: It was her graduation.
[00:02:39] Speaker B: She's a doctor. So I saw this talk that my supervisor was giving in a dive shop in Mexico City, like super random, but I saw that he was talking about bull sharks in the Caribbean and everything. And I was like, I want to go. And I went with my sister, and I normally don't talk to presenters because I'm kind of shy. But that day I was like, my sister was like, no, you have to go and introduce yourself. So I went with Mao and I say, ah, hi, nice to meet you, mao.
[00:03:09] Speaker C: I just came back from Seychelles and.
[00:03:12] Speaker B: I learned this technique that is very useful, and we haven't used it in Mexico, and maybe you are interested and.
[00:03:20] Speaker C: We can talk about it.
[00:03:21] Speaker B: And he said, like, yes, I really like that idea. I have a project that is starting.
[00:03:26] Speaker C: In Revilla, Jijero, in Sokoro island. So, yeah, he sent me an email.
[00:03:30] Speaker B: And that's how everything started. So I started talking to Mao.
[00:03:35] Speaker C: We started discussing the ideas.
[00:03:38] Speaker B: And basically what we were trying it was to find distribution patterns. So basically how sharks are using a national park or an archipelago. So you have four islands in this.
[00:03:49] Speaker C: Park, and in each place you have different environments.
[00:03:52] Speaker B: You have very flat, sandy bottoms that are perfect. Now, we know for tiger sharks. So we found tiny little baby tiger sharks that are almost impossible to see.
[00:04:04] Speaker C: Diving because they are super, super shy. And we found, like, steep walls full of silky sharks now.
[00:04:11] Speaker B: So we start seeing how all these species, because in Mexico, rabbi call it the mexican galapagos, because it's super diverse. We find around 20 species of sharks in each of the dive sites. So seeing how they share the environment and how they use it and where you find the juveniles, where you find.
[00:04:33] Speaker C: The adults, just by using the cameras. So it was a very powerful technique.
[00:04:38] Speaker B: And I spent basically four years going.
[00:04:41] Speaker C: Every month to deploy the cameras.
[00:04:43] Speaker B: And in different places, you cannot select specific areas. You can have some samples in each.
[00:04:50] Speaker C: Island, but it has to be random.
[00:04:52] Speaker B: So basically, you put them everywhere and you start seeing patterns. Some areas are more diverse.
I see them like airports now. So you have some international airports that are super busy with more species, and then you have areas that are not.
[00:05:08] Speaker C: Diverse and they are more quiet and not a lot of fish and sharks.
[00:05:14] Speaker B: So, yeah, it was really interesting.
But at the same time, I was feeling like there was not enough for a project that was four years long. I felt like we had to include.
[00:05:25] Speaker C: Something else to tell the story.
[00:05:28] Speaker B: So that's why I asked Mao and.
[00:05:30] Speaker C: My supervisor to use other kind of technique.
[00:05:34] Speaker B: And I combined the information that we.
[00:05:37] Speaker C: Had from the cameras with telemetry.
[00:05:39] Speaker B: So we're using all the data from.
[00:05:42] Speaker C: Sharks that were targeted in Revilla Jedo.
[00:05:45] Speaker B: And seeing how they were traveling from.
[00:05:47] Speaker C: Revillia to the other marine reserves in the central tropical Pacific.
[00:05:52] Speaker B: So we have data from Cocos, Clipperton.
[00:05:55] Speaker C: Galapagos, Malpelo, all these places.
[00:05:58] Speaker B: And it was really cool because the researchers in the other countries allow me to use the information to start seeing these connectivity patterns. So we have connectivity that can be.
[00:06:10] Speaker C: Related to the genes, so it's genetic.
[00:06:13] Speaker B: Connectivity, but we also have physical connectivity, so real movements of animals traveling between.
[00:06:19] Speaker C: Each place and each marine reserve.
[00:06:22] Speaker B: So, yeah, in the PhD, basically I.
[00:06:25] Speaker C: Used tons and tons of detections of silkies and Galapau sharks and seeing how they were moving between each of the areas on each of the islands.
[00:06:36] Speaker D: Wow.
[00:06:37] Speaker E: Okay, I have two questions.
[00:06:40] Speaker B: One.
[00:06:41] Speaker E: The first one, I want to go back to your airport analogy, which I thought was so big heathrow or lax, or these big J B. These massive international airports that everyone has to fly through whether or not they want to.
[00:06:56] Speaker B: You got to go through that massive.
[00:06:57] Speaker E: Airport to get to that part of the world, or a little local one that has, like, three gates, and you're super bored, totaling your thumbs. So what's the difference? When you were starting to look at the data? Why were there shark? Or why were there underwater international airports? And why were there just like, little ones where there really wasn't much action going on? Was there anything obvious that was the difference between the activity, or was it temporal? Was it different times of year? Or why was the wildlife using these different spots differently from what you found?
[00:07:33] Speaker B: So, to determine that, I use network analysis that basically are the same as what we use sometimes for Internet or.
[00:07:42] Speaker C: Like, servers, where you put dots and.
[00:07:44] Speaker B: Each dot is one of the dive.
[00:07:46] Speaker C: Sites or one of the receivers. So I had literally networks of different.
[00:07:51] Speaker B: Movements between the sharks and how they.
[00:07:53] Speaker C: Were traveling between each of the places.
[00:07:56] Speaker B: And then you can find bigger circles or bigger airports, and then the smallest.
[00:08:00] Speaker C: Ones are the ones that they don't travel that much.
[00:08:04] Speaker B: And we have two options. One is that naturally, some areas are more diverse and they have steep walls.
[00:08:12] Speaker C: Or a lot of current.
[00:08:14] Speaker B: So, for example, Darwin Arch in Galapagos is that kind of a specific place.
[00:08:19] Speaker C: That has cleaning stations. It has a lot of preys. It's a perfect place for adults to.
[00:08:25] Speaker B: Hang out and reproduce. So you have DC mounts or places.
[00:08:29] Speaker C: That are with a lot of productivity.
[00:08:32] Speaker B: And obviously, sharks can get advantage of being around that area. And you can have other places that.
[00:08:38] Speaker C: Are more stable, like sandy bottoms that.
[00:08:42] Speaker B: Probably have less current and probably less.
[00:08:45] Speaker C: Preys for the shark.
[00:08:46] Speaker B: So they don't spend a lot of.
[00:08:48] Speaker C: Time in those places.
[00:08:49] Speaker B: And the other thing is also the.
[00:08:51] Speaker C: Impact, the human impact. So you can have areas that have.
[00:08:55] Speaker B: Been strongly impacted by, for example, trolling.
[00:08:58] Speaker C: Or industrial fishing, where you have less.
[00:09:02] Speaker B: Preys or is already impacted by different.
[00:09:07] Speaker C: Destruction, the habitat destruction.
[00:09:10] Speaker B: So these places could be less important through the time. So, for example, here in the Gulf of California, we have a very famous.
[00:09:19] Speaker C: Sea mount that is called elvajo. Elvajo.
[00:09:22] Speaker B: Back in the 70s used to be.
[00:09:24] Speaker C: Even better than galapagos, like tons and tons of sharks.
[00:09:29] Speaker B: In a normal dive you could see schools of 200 hammerheads, and nowadays it's.
[00:09:35] Speaker C: Almost empty, like you don't see any shark.
[00:09:39] Speaker B: And what we found it is that in the mexican government allowed industrial fishing to come and catch everything. Even like japanese or people from other countries were allowed to come and catch.
[00:09:52] Speaker C: Sharks there, because we thought we had.
[00:09:54] Speaker B: A very diverse and rich environment that never will empty. So we allowed them to catch with.
[00:10:02] Speaker C: Huge nets, a lot of sharks.
[00:10:04] Speaker B: And now obviously the species had some.
[00:10:06] Speaker C: Consequences of that and is slowly recovering. We are seeing more and more sharks, but it's not the same as used to be.
[00:10:14] Speaker B: So now we know that we have.
[00:10:16] Speaker C: To protect this area.
[00:10:17] Speaker B: Andrevia hijedo, where I did the PhD, is a perfect example of large, fully and highly protected areas where no fishing is allowed.
[00:10:27] Speaker C: And what it happens is that the environment has a chance to recover and.
[00:10:31] Speaker B: Then help the other environments or the.
[00:10:33] Speaker C: Areas outside to also recover.
[00:10:37] Speaker B: So actually the industrial fishing is like.
[00:10:38] Speaker C: Getting more jellofintuna, and the sharks inside.
[00:10:41] Speaker B: That area are getting bigger and healthier, so they can travel to other places and recover other airports.
[00:10:49] Speaker D: I love that description.
[00:10:53] Speaker F: It's so good.
[00:10:54] Speaker B: Yeah.
[00:10:54] Speaker E: Where's all the action happening? Like, sharks want to be there. I don't blame them.
Next, continuing on to that, it's all part of all of your research.
What movement patterns did you find?
[00:11:09] Speaker F: Well, okay, I have a question and a question.
[00:11:11] Speaker E: So you mentioned that you focus on silky sharks and galapagos sharks, which why those two species? I mean, I know when it comes to research, you got to focus on something, otherwise you're just like, you'll be there for the rest of your life trying to figure out all the sharks, everything. And we have to graduate with a PhD at some time. So why those two sharks? And maybe some cool facts about them, if you wouldn't mind sharing. And then what did you find? How were they moving around? How were they using your research area in their airports?
[00:11:42] Speaker D: Accordingly?
[00:11:44] Speaker C: Yes.
[00:11:44] Speaker B: So for the PhD, we selected two species that were present in all the.
[00:11:49] Speaker C: National parks in the area, in the region.
[00:11:52] Speaker B: So galapagos and silky sharks are present.
[00:11:55] Speaker C: In the Gulf of California, obviously in.
[00:11:57] Speaker B: Revia, but they are also present in Clipperton.
[00:12:00] Speaker C: And in the galapagos we have other species, for example, doski sharks.
[00:12:04] Speaker B: They are not very common in the.
[00:12:06] Speaker C: Southern part of the eastern tropical Pacific.
[00:12:10] Speaker B: And silver tips, they don't tend to.
[00:12:12] Speaker C: Go to the shore areas, to the coastal areas.
[00:12:14] Speaker B: So we needed to find two species that were present in all the national parks because potentially they had the chance.
[00:12:21] Speaker C: To travel between the different places.
[00:12:24] Speaker B: So these two species are. Silky sharks are one of the most.
[00:12:28] Speaker C: Caught species in the world.
[00:12:31] Speaker B: They catch tons and tons of silky sharks because it's a pelagic species.
[00:12:36] Speaker C: So they tend to be very related to jellofin tuna.
[00:12:40] Speaker B: And obviously they are target for the industrial fishing boats. So, for example, there is a study from fow that shows that for every ton of tuna they catch around 100 silky sharks.
And some of the crew in these tuna fishing boats cut the fins and they sell these fins for the asian market. So it's not the target for the.
[00:13:04] Speaker C: Boat, but they still are doing a huge impact for the species.
[00:13:08] Speaker B: And, yeah, it was interesting to have a very pelagic species that we knew. It was traveling a lot. If you see the anatomy, they are travelers. Their fins are very long and very elongated. So that means that they are made.
[00:13:21] Speaker C: And designed for traveling.
[00:13:23] Speaker B: And then you have galapau sharks that are more like isolated. They normally tend to be more in these oceanic islands and they travel, but.
[00:13:33] Speaker C: They are more resident most of the time.
[00:13:35] Speaker B: So we wanted to compare two species.
[00:13:37] Speaker C: That had different patterns.
[00:13:39] Speaker B: And what was very surprising was that we were able to see how sharks were traveling, obviously between the Gulf of California to revia, but also from Revia.
[00:13:50] Speaker C: To Clipperton and then galapagos, so they.
[00:13:54] Speaker B: Can do migrations of 3000. Other interesting thing is why they do it.
[00:14:01] Speaker C: Yeah, so we think it's a lot about connectivity. So if you have different genes and different populations, then your population is stronger.
[00:14:12] Speaker B: So probably the females are moving and the males are moving between different countries and different reserves, just to have that.
[00:14:20] Speaker C: Diversity of genes between different places.
[00:14:24] Speaker E: So cool.
[00:14:26] Speaker B: And that makes total sense why you.
[00:14:28] Speaker E: Chose those different species.
That was really helpful. Thanks for exploring that.
[00:14:33] Speaker F: And you also just mentioned something, just.
[00:14:36] Speaker E: These different lifestyles and that these sharks just naturally adopt. Like, this is just how they evolve. The silky sharks sounds like they're more an open ocean versus the galapagos sharks, which may be more resident and mere things. And we had this long conversation the last time you and I sat down, and I would love if you could talk about it a little further. So we tated a lot about the open sea, the open ocean versus coastal regions, and how these have very different consequences for both conservation and lifestyle and just all the stuff when it comes to sharks. Could you possibly explain this a little further? Why? Because we think of the big blue and everything that's in it is just dealing with the same shit, but that's not actually the case at all. So what is the difference for sharks that are in the open ocean versus coastal regions? And is one of these groups having more issues than the other, or are.
[00:15:30] Speaker D: They both just not doing well?
[00:15:33] Speaker C: Well, yes, as you say, what we have found is that most of the.
[00:15:39] Speaker B: Species are already not doing very well. Like, 70% of the sharks around the world are under kind of a risk of extinction. And this is because the huge impact that we have, especially from the industrial.
[00:15:53] Speaker C: Fishing, that is affecting many of the.
[00:15:56] Speaker B: Key areas where the sharks are reproducing or feeding or doing something part of their life cycle. We have seen, for example, that hammerheads, they use a lot of the mangroves.
[00:16:08] Speaker C: Or the shallow areas to grow, and.
[00:16:11] Speaker B: Then when they get big enough, they start swimming and going through, like, more oceanic islands or sea mounts, where they.
[00:16:18] Speaker C: Can find bigger preys and also find a mate. But what we found is that sometimes.
[00:16:25] Speaker B: Especially in Mexico, it's easier to protect big areas in the oceanic environment because it was just used by industrial fishing.
[00:16:32] Speaker C: But there were not other stakeholders, and.
[00:16:36] Speaker B: It was easy to work with the government and try to deal with the industrial fishing and find an agreement with them to protect a huge area. But when we talk about coastal communities and protecting areas where you have thousand.
[00:16:51] Speaker C: Fishermen relying on that resource, it's a different story.
[00:16:55] Speaker B: So what we found in the last years is that we also need to protect the coastal areas because a lot of the species are coming here in the Gulf of California to give birth and have the babies. And the babies rely a lot into.
[00:17:11] Speaker C: Mangroves and the shallows.
[00:17:13] Speaker B: So now that's how the second part.
[00:17:16] Speaker C: Of my work is now, is to.
[00:17:19] Speaker B: Focus on working with the coastal communities.
[00:17:21] Speaker C: And trying to find ways where they.
[00:17:24] Speaker B: Understand the importance of the area. And we find ways to have new.
[00:17:29] Speaker C: Opportunities for them so they can help us to conserve the sharks.
[00:17:35] Speaker A: Our next sharky expert is Camellia Arnez from episode 110. In this clip, she shares her research with hammerhead sharks in the Galapagos Islands. And in case you missed that episode, this girl free dives with sharks. She is such a badass. As you're going to soon hear.
[00:17:52] Speaker F: After I finished the seaman project, I.
[00:17:55] Speaker G: Applied for a grant to study hammerheads. There are a lot of hammerheads in the Galapagos island. That's actually the northern part of the Galapagos. Darwin and Wolf islands are known as the sharkiest place on earth, like one.
[00:18:06] Speaker F: Of the sharkiest places on earth.
[00:18:09] Speaker G: And there was a study in 2016.
[00:18:12] Speaker F: That determined that this islands, these tiny.
[00:18:16] Speaker G: Islands in the northern part, host one of the largest biomass of shark species in the world.
[00:18:21] Speaker F: So if you go dive in there, you would see big whale sharks, like.
[00:18:27] Speaker G: Potentially pregnant big mama whale sharks, schools.
[00:18:31] Speaker F: Of hammerheads, schools of silky sharks. So I applied for this grant to.
[00:18:38] Speaker G: Study the feeding ecology of the hammerhead sharks, because this wasn't done before in the Galapagos.
[00:18:45] Speaker F: It was a big knowledge gap in.
[00:18:47] Speaker D: That area, especially not exactly what they.
[00:18:52] Speaker F: Were feeding off, but how they were.
[00:18:54] Speaker G: Using the reserve, like how they were foraging, what strategies were they using, what areas were they exploding, and also what their niche was. So, yeah, I got this grant. I received this grant in 2019.
[00:19:07] Speaker F: I was super excited. And as part of this, we had to go to the northern part of.
[00:19:14] Speaker G: The reserve and free dive among hammerhead sharks because they're super believable, they're super shy. If you go with the scuba gear.
[00:19:22] Speaker F: They would go away because they don't like the bubbles. So you had to be like a.
[00:19:26] Speaker G: Ninja underwater with using a hawaiian sling.
[00:19:31] Speaker F: That had a modified tip and it had a biopsy dart. So you were free diamond with this hawaiian sling, and then you would draw the sling and puncture the base of the dorsal fin.
[00:19:45] Speaker G: But it was a tiny.
[00:19:46] Speaker F: It was like a mosquito bite for them, didn't hurt.
[00:19:49] Speaker G: We obtained, like, tiny samples of their.
[00:19:51] Speaker D: Muscle and then we took it to the lab.
[00:19:55] Speaker F: So a lot of feeding studies look at the species stomach content, but because we're in a marine reserve and in a very protected area, and also because.
[00:20:06] Speaker G: I don't condone invasive studies, I don't.
[00:20:10] Speaker F: Like killing animals for the sake of science.
[00:20:13] Speaker G: There are other ways now, especially with.
[00:20:14] Speaker F: Technology, so there's no need to do that, really.
[00:20:18] Speaker G: We looked at the stable isotopes of the samples, which are this element of these very stable elements that you can study. So everything's made out of isotopes, as we are all made out of atoms.
[00:20:32] Speaker F: And the isotopes are just another versions of the atoms.
[00:20:35] Speaker G: They have different neutrons, so you have lighter isotopes and heavier isotopes. So we look at carbon and nitrogen.
[00:20:41] Speaker F: Isotopes that would tell us different things about the animals.
[00:20:45] Speaker G: So, like, if we look at carbon.
[00:20:47] Speaker F: Isotopes, we would know if they were.
[00:20:49] Speaker G: Feeding in the coastal area or how.
[00:20:51] Speaker F: Deep were they feeding, or if they.
[00:20:54] Speaker G: Were using more oceanic areas.
[00:20:55] Speaker F: And then if we look at the.
[00:20:57] Speaker G: Nitrogen isotopes, that will tell us how high or like their position on the.
[00:21:01] Speaker F: Tropic web, and if they're feeding down the foot web or up the foot web.
[00:21:07] Speaker G: So that gave us a lot of information. And there was another layer to the study. So we did this for four years. It was a four year study.
[00:21:14] Speaker F: And during that four year period, an.
[00:21:17] Speaker G: El Nina happened, and also at La.
[00:21:19] Speaker F: Nina, so we could see how their strategies and their feeding behavior shifts with.
[00:21:26] Speaker G: Climatic events and the climatic variability.
[00:21:28] Speaker F: So that was an awesome thing to learn and understand.
[00:21:33] Speaker G: So I had a lot of fun doing this study.
[00:21:36] Speaker E: Okay, we're going to dive in. I got to stop saying that. Okay. I really want to understand this further. How exactly does a heavier or lighter nitrogen or heavier or lighter carbon tell you these things?
[00:21:55] Speaker D: How does that work?
[00:21:57] Speaker G: Yeah, so it's based on the principle.
[00:21:59] Speaker F: That you are what you eat. We are what we eat.
[00:22:02] Speaker G: So we incorporate all the chemicals and all the information of the food we.
[00:22:06] Speaker F: Ingest and we store it in our tissues.
And you have these light and heavy.
[00:22:15] Speaker G: Isotopes, and so the ratio of them.
[00:22:17] Speaker F: Will tell you a lot of information.
[00:22:20] Speaker G: So, for example, lighter isotopes in the water, lighter oxygen isotopes, they evaporate with temperatures.
[00:22:28] Speaker F: So then you'll know that if you take a sample, you might find more heavy isotopes.
[00:22:35] Speaker G: So, like this proportion or this ratio tells you a lot of information.
[00:22:40] Speaker F: So if you have higher carbon readings, that will tell you that the organism.
[00:22:48] Speaker G: Are feeding or the species is feeding closer to coastal habitats. Because coastal habitats are super enriched in carbon. They're highly, highly enriched in carbon.
[00:22:56] Speaker F: And as you move to offshore environments, carbon signatures decreases.
[00:23:02] Speaker D: So that's how you read it.
[00:23:05] Speaker F: That's how we interpret the results. So we look at this ratio, and.
[00:23:08] Speaker G: Then with nitrogen as well, the predators.
[00:23:11] Speaker F: Would take in the nitrogen of their preys.
[00:23:14] Speaker G: So the higher you are in the.
[00:23:16] Speaker D: Food chain, the higher your levels of nitrogen will be.
[00:23:21] Speaker G: So for example, an orca or a.
[00:23:23] Speaker F: White shark, which are super top predators, they're going to have crazy high nitrogen levels in their tissues. So that's how it works. I got you.
[00:23:32] Speaker A: Okay.
[00:23:33] Speaker E: No, that's really helpful. So if they're feeding, tell me if I've interpreted this correctly. So if they would have high levels of carbon, then they were feeding more towards the coast. So does that mean they were eating more just like kind of like lower bottom fish? Like fish instead of versus maybe like a tuna that's higher up the ecosystem? I don't know if they eat tuna. That was just a guess, but meaning because I specialize with predators on land. So I guess I'm just trying to make an analogy in the water.
Let's say that we have our top dog hammerheads, and they were eating like meso predators, maybe that would be like a tuna or something, versus maybe like the herbivores, which are like the bottom fish. I know that this isn't a correct analogy, but I'm trying to understand in the way my biologist brain works, is that kind of similar or not?
[00:24:25] Speaker D: Yeah.
[00:24:26] Speaker G: So as sharks, as other animals, as lions, they also have like a favorite prey item.
[00:24:32] Speaker D: So for example, if a lion, they.
[00:24:36] Speaker F: Have gazelles all the time around them.
[00:24:39] Speaker G: And they have other animals, they're going to choose the gazelle and they're always going to go for their preferred prey items. So sharks are like that as well.
[00:24:46] Speaker F: And hammerheads love squid.
[00:24:50] Speaker G: Squid is also not like down the footweb. It's like a meso predator as well, squid. And they take vertical migrations at night. So the sharks love squid.
[00:25:01] Speaker F: And also they're highly rich in oil and nutrients, so that's their preferred prey. They love it.
[00:25:09] Speaker G: Although they can eat other things. They can eat anything, right?
[00:25:12] Speaker F: Like sharks are apex predator and they.
[00:25:14] Speaker G: Are like the white cells of the sea. They maintain the health of the ocean.
[00:25:19] Speaker F: That they love squid. So when the conditions are good and.
[00:25:24] Speaker G: Temperatures are stable and it's actually kind.
[00:25:26] Speaker F: Of like a little bit colder than.
[00:25:29] Speaker G: Usual and nutrient rich waters, there are a lot of squid available, and hammerheads will stay in one place. So their niche is very narrow and it's very specialized.
[00:25:39] Speaker F: They would just feed on squid and they're happy to eat squid.
[00:25:44] Speaker G: But then when conditions change and the.
[00:25:47] Speaker F: Water gets warmer and the squid is.
[00:25:50] Speaker G: Not readily available, they might go deeper, they might not undertake this migration. And sharks cannot find their preferred prey.
[00:25:57] Speaker F: They would venture into, they will take.
[00:26:00] Speaker G: These big migrations and go and feed.
[00:26:02] Speaker F: Somewhere else, and they could eat maybe.
[00:26:04] Speaker G: Herbivores, maybe like other organisms than the food web. So that's how they behave. So their niche become. They become more generalist and opportunistic, and.
[00:26:15] Speaker F: They actually might be feeding on anything.
[00:26:17] Speaker G: They could find, but not like highly nutrient craze.
[00:26:21] Speaker D: It's just like anything that they encounter.
[00:26:23] Speaker F: So this shift might actually also alter their nutrient intake and their overall health. Oh, that makes total sense.
[00:26:33] Speaker E: Thank you so much for helping my brain also understand this and hopefully for anyone listening, too. So then super cool then, that you had a la Nina and an El Nino during this study.
[00:26:44] Speaker F: So what did you find?
Yeah, so we found that they're super.
[00:26:51] Speaker G: Resilient as soon as their conditions in their environment change.
[00:26:56] Speaker F: So they have a preferred temperature and a preferred prey, like I mentioned, and.
[00:27:03] Speaker G: They'Re happy if the conditions are stable, but as soon as they change.
[00:27:06] Speaker F: So when Eldino happened, they just went away.
[00:27:10] Speaker G: They just went off the coastal environments.
[00:27:12] Speaker F: They went outside the Galapagos marine reserve boundaries. They were feeding in pelagic ecosystems, depleted.
[00:27:20] Speaker G: In just their diet shifts from being specialized to being generalist opportunistic feeders.
[00:27:28] Speaker F: When conditions are harsh, they just have.
[00:27:29] Speaker G: To adapt, but they're very resilient and very flexible.
[00:27:32] Speaker F: So as soon as conditions change, they go away. But during La Nina years, so in.
[00:27:39] Speaker G: 2018 was a la Nina year, and their niche became very specialized again, they were even sweet, they were super happy.
[00:27:47] Speaker F: They just stayed in coastal environments. So mostly around the northern part of the Galapagos, they just stay there around.
[00:27:55] Speaker G: These tiny islands are when the wolf islands. So, yeah, there's no need to move or go anywhere else if you have.
[00:28:02] Speaker F: Everything you need and everything you like right where you are.
[00:28:05] Speaker D: So that's what happened.
[00:28:07] Speaker G: And we could demonstrate that after this four year study and after looking at their icicles.
[00:28:11] Speaker F: So, yeah, that was our results.
[00:28:13] Speaker B: And it was super exciting.
[00:28:14] Speaker G: It was the first of its kind, kind of study for the Galapagos marine.
[00:28:19] Speaker F: Reserve that was very helpful as well.
[00:28:22] Speaker G: Especially these studies are very helpful for the Galapagos National park directory. They plan the zoning scheme and they are the ones that have to divide the area, the Galapagos Marine Reserve, and actually designate areas like fishing areas or tourism areas or like, no, take areas. So they use these sort of studies.
[00:28:44] Speaker F: To be able to designate.
[00:28:47] Speaker G: So after this study, they could say, oh, we know that this species is using this coastal environment for this part of the reserve. Maybe we can protect that even further.
[00:28:57] Speaker F: And take other measurements. So this type of studies help to conserve these populations as well.
[00:29:04] Speaker E: So maybe could you give us just a spew, some really cool facts about hammerheads?
[00:29:08] Speaker F: Sure. So hammerheads, they have this hammerhead like shaped head, and they're actually the most, I would say, like evolved sharks of all. Their detection system is super advanced, and they actually use their hammerhead head, their.
[00:29:30] Speaker G: Hammer, their hammerhead, to pin down some of their prey. So there was actually a photo taken.
[00:29:36] Speaker F: Recently of a great hammerhead shark pinning down an eagle ray, or like a.
[00:29:42] Speaker G: Ray just on the ground and just like with his head, like an actual hammer. So they use their head as a.
[00:29:48] Speaker D: Tool to eat, which is crazy.
[00:29:53] Speaker F: And they can navigate, they're super sensitive to electromagnetic fields and electromagnetic signals, and.
[00:30:02] Speaker G: Actually they use sea mounts. So this is how sea mounts and sharks are related. So hammerheads use sea mounts as underwater highways to guide their big migrations.
[00:30:13] Speaker F: And it's crazy because scientists have put.
[00:30:16] Speaker G: Tags on them to see how they move and where they go. And actually, you can see the tracks from their tax.
[00:30:23] Speaker F: They do like 90 degrees turns.
[00:30:27] Speaker G: They swim straight if they're following the sea mount chain, and if it changes, they actually will completely turn and follow the sea mount chain.
[00:30:35] Speaker F: So sea mounts are like their highway.
[00:30:38] Speaker E: Whoa. That's so cool. So all of your things are just like naturally coming together.
[00:30:44] Speaker D: That's amazing.
[00:30:46] Speaker G: It's a connecting line. But they're over fish because they take these long migrations, they go outside reserve.
[00:30:54] Speaker F: And they get caught at a spy.
[00:30:57] Speaker G: Catch, but also they're targeted for their.
[00:30:59] Speaker F: Fins, which is so sad.
[00:31:02] Speaker G: Like 100 million sharks die every year for their fins. And hammerheads are not excluded.
[00:31:11] Speaker F: Yeah.
[00:31:12] Speaker G: And also because they take these long migrations.
[00:31:14] Speaker F: So there are some studies that demonstrate that they go from, for example, they.
[00:31:20] Speaker G: Go from Galapagos to Cocos in Costa Rica and to Malpelo island in Colombia.
[00:31:25] Speaker F: There's this triangle that they use. They move around and they also go to the mainland in South America to give birth.
[00:31:34] Speaker G: So you can find baby hammerhead sharks in mainland Ecuador as well, and in Colombia.
[00:31:39] Speaker F: So that makes them more vulnerable as.
[00:31:42] Speaker G: Well, because if they feed in one place, they reproduce in another place, and they have to move between these places.
[00:31:49] Speaker F: They just get caught all the.
Yeah, so that's.
[00:31:55] Speaker E: I definitely. I've definitely heard a lot about that triangle migration. So when I interviewed Frank Garrida, he was costa rican and worked on whales and talked about the exact same triangle. So it seems that maybe several large sea like marine species must use the.
[00:32:15] Speaker F: Same migration route, right?
[00:32:18] Speaker G: Yeah, for sure.
It's a very specific highway and actually a lot of megaphona.
[00:32:24] Speaker F: So turtles, whales and sharks, they use the same route to move around.
[00:32:30] Speaker D: So, yeah, it's the same. It's like their own highway.
[00:32:34] Speaker G: Their own underwater highway.
[00:32:36] Speaker E: Yeah, because remember in that episode, like 50 episodes ago, that's freaking crazy because actually went to Costa Rica and actually got to meet Frank and everything, which was really, really cool because that. Oh, my God, maybe you know what it's called? I totally forgot. But that whole area was just protected. Like, it just happened. That whole triangle highway had just gone under protection for international waters from the Ecuador down to Costa Rica. That whole area had just been put under some sort of really high strict protection, which was really incredible.
[00:33:12] Speaker F: This year, the beginning of this year.
[00:33:14] Speaker G: So end of last year, beginning of.
[00:33:15] Speaker F: This year, an extra 66.
[00:33:19] Speaker G: So 60,000 added to the existing Galapagos Marine Reserve.
[00:33:24] Speaker D: And that actually connected the Cocos island.
[00:33:27] Speaker F: Reserve with the Galapagos Marine Reserve.
[00:33:30] Speaker D: So they're now kind of connected, but.
[00:33:33] Speaker F: Governments are still working and putting in place all the protection and the monitoring, the patrolling system and all the strategies.
[00:33:43] Speaker G: Are yet to be determined. They're still working on that. But yeah, it was recently declared, like the expansion of the reserve, it's called.
[00:33:51] Speaker D: Right, right.
[00:33:52] Speaker B: That's good news.
[00:33:53] Speaker D: Yeah, incredible news.
[00:33:55] Speaker E: I mean, especially for your sharkies here.
[00:34:01] Speaker A: If you'd like to hear more about thresher sharks with Cami or the power of shark conservation tourism with Frida, dive into the archives and check out episodes 110 and 116.
[00:34:13] Speaker H: Thank you for joining me on this wild adventure today. I hope you've been inspired by the incredible stories, insights and knowledge shared in this episode. To learn more about what you heard, be sure to check out the show
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[00:35:22] Speaker E: Love.
[00:35:23] Speaker H: Remember, rewilding isn't just a concept, it's a call to action. Whether it's supporting a local conservation project, reducing your own impact, or simply sharing the knowledge you've gained today, you have the power to make a difference.
A big thank you to the guests that come onto the show and share their knowledge with all of us and to all of you rewildology listeners for making the show everything it is today.
This is Brooke signing off. Remember, together we will rewild the planet.
