In this podcast episode, Katie interviews Chloe Mikles, a PhD student studying bluefin tuna. They discuss Chloe's research on bluefin tuna and blue marlin movement ecology and population structures. Chloe explains the process of tagging fish and the importance of tracking their migration patterns. Katie and Chloe also talk about the bluefin tuna fishery in North Carolina and the international management of bluefin tuna populations around the world. Chloe shares her background and interest in studying bluefin tuna and discusses her PhD work on population differentiation. They also touch on the handling and care of tagged fish and the differences between handling bluefin tuna and billfish. In this conversation, Katie and Chloe discuss the tagging and tracking of marlin and tuna throughout the Atlantic Ocean. They explore the use of satellite tags and archival tags to collect data on the fish's behavior, including their location, depth, and temperature, and why it is important. They also discuss the challenges of tag recovery and the importance of collaboration with fishermen. The conversation highlights the physiological adaptations of bluefin tuna and their exceptional ability to cross the ocean. The rebound of the bluefin tuna population is also discussed, along with the importance of fisheries management and the economic impact of the fishery. Chloe offers advice for young scientists, emphasizing the importance of following one's passion and staying open to opportunities.

Takeaways

Chloe Mikles is a PhD student studying bluefin tuna and blue marlin movement ecology and population structures.

Tagging fish is an important part of Chloe's research to track their migration patterns and understand population differentiation.

The bluefin tuna fishery in North Carolina is regulated by size limits and quotas, and the fish are harvested for commercial purposes.

International collaboration is crucial for the management of bluefin tuna populations, as they are highly migratory and cross the jurisdictions of many nations.

Proper handling and care of tagged fish, such as minimizing air exposure and swimming the fish before release, help reduce mortality rates. Satellite tags and archival tags are used to track the behavior of marlin and tuna, providing data on their location, depth, and temperature.

Tag recovery missions can be challenging, as the tags are small and can be difficult to locate in the vast ocean.

Bluefin tuna are endothermic fish, able to regulate their body temperature and withstand a wide range of temperatures.

Foraging hotspots and oceanographic conditions play a role in the feeding patterns and migration of bluefin tuna.

Collaboration with fishermen is crucial for successful research and fisheries management, as they have valuable knowledge and observations of the fishery.

The rebound of the bluefin tuna population demonstrates the effectiveness of strict management regulations and the importance of sustainable fishing practices, despite the many challenges that can be derived from these efforts.

Find Chloe on instagram at @coastal_chloe

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TRANSCRIPT

Katie (00:22 .905)

Hey, what's up you guys? Welcome to the Katie C Sawyer podcast. I'm sitting here with Chloe Mikles, a remarkable young woman that I have been fan-girling over on the internet for years now. Chloe, thank you so much for being here with me.

Chloe (00:37 .698)

Thank you so much for having me. Yeah, I feel like likewise, I've been fangirling over you for years too. So it's always fun to sit down and talk with you.

Katie (00:45 .849)

That's so sweet. I really appreciate it. All right, you guys, Chloe is a PhD candidate at Stanford University, working with Dr. Barbara Block, a legend, studying bluefin tuna and blue marlin, movement ecology and population structures. Chloe, can you tell our listeners just like a brief synopsis of what that means?

Chloe (01:07 .882)

Yes, so yeah, we oftentimes get caught up with like tossing in a lot of scientific jargon with our work. So Basically, I am in graduate school and for my dissertation work. I am learning from my advisor Barb Block and I am doing everything from going out into the field to tagging the fish which is the most fun part and probably what we'll talk the most about and then reading a bunch of papers to the scientific literature and

I do some lab work as well, and then it all ends up, the culmination of the PhD is basically writing a bunch of scientific papers that summarize our findings.

Katie (01:47 .477)

So what kind of questions are you asking about these populations?

Chloe (01:53 .258)

So you can start off like very, you can go from very simple to very complex, basically, these questions. The most basic question is, we're putting tags on animals to see where they go. And you can make that more and more and more complex. So for example, from Marlin in North Carolina, blue marlin have been tagged all over the world, but not that many have been tagged off the coast of North Carolina. So by focusing efforts regionally in different locations,

we can get a better idea of where the fish that pass through there go. And basically like if their migration patterns are different, if there are different populations of fish that are traveling elsewhere and just trying to learn more and more about these fish because it's so hard to study the ocean. I mean, it's not like, you know, a deer or a mountain lion or something where you can actually like watch where they go and track them or, you know, put a radio color on them and see where they go. The ocean is really hard to study. Everything's underwater.

Everything's innately then more cryptic. Um, the technology is much more difficult to actually get something that can track animals underwater. So the more tags that we put out and the more data that we collect, it's like, we're constantly learning more about these fish every single time.

Katie (03:07 .065)

really love that you just like compared the ocean towards land mammals and land predators out there and animals that we've been studying and trying to manage for a long time. We still have so far to go to properly manage our wildlife on land and the ocean is that much more difficult to do. So we'll get into that a little bit a little later because I want to really touch on what you're doing and what kind of questions and answers we're getting from that. But for the sake of

Chloe (03:18 .536)

Mm-hmm.

Chloe (03:22 .764)

Right.

Chloe (03:26 .322)

Exactly.

Chloe (03:32 .415)

Yeah.

Katie (03:36 .979)

I'm a blue marlin girl. Let's focus our energy on the bluefin tuna because it's just there's such fascinating animals and I have so many questions for you. So first off let's start with where you started. Where did you grow up?

Chloe (03:38 .982)

I know. Cool. Yeah. Mm-hmm.

Chloe (03:55 .074)

So I grew up in North Carolina and that is, yeah, that's a big reason why I've chose to study these fish for my PhD. So my family had a place on the coast of the Southern Outer Banks. And I just grew up there always being so fascinated by the ocean. And then kind of like in my most formative years when I was an undergrad and like right out of college, I made, you know, I made some of my best friends in my life and was fishing constantly. And...

that reason, like, I love animals. I have always been passionate about studying them. It probably could have been anything, but the fact that, like, in those years I became so obsessed with offshore fishing, that's, yeah, that really did it. I know. Yeah. So...

Katie (04:38 .381)

I got chicken skin. I feel that. I feel that on so many levels. So you did your undergrad at Cornell, right? You had a, didn't you have a full ride scholarship swimming?

Chloe (04:51 .17)

So I did swim there for four years. The Ivy League actually doesn't provide like athletic scholarships, which is interesting. Yeah, but yes. So I swam at Cornell for four years. I majored in animal science. My original plan was to be a vet because I loved animals. And then I was doing a couple of internships with North Carolina State University and their Marine Station on the coast, actually working with both like fisheries biologists and Marine veterinarians.

Katie (04:53 .111)

No big deal.

Chloe (05:21 .038)

And I was like, this is so cool. Like I didn't realize that there was a career where you can actually study the ocean. Like I was getting paid as an intern. I mean, not much, but I was getting paid as an intern to go offshore and tag Mahi. I was like, this is so much fun. This is so cool. Um, and then as far as bluefin tuna, um, I just saw firsthand how important that fishery was to the local community. And it was like this amazing seasonal thing where every winter,

Katie (05:35 .441)

Yeah.

Chloe (05:50 .994)

It's like everyone would be commercial fishing for them. Like you would get your hardcore commercial fishermen who fish all year round fishing for bluefin tuna. But then you would get people who just do different jobs, um, take off weeks to partake in the commercial bluefin fishery for a couple of weeks. And yeah, it's a really different, I think it's a very unique commercial fishery. It's very different from most places in the country and the world. Um, it's a very short season, but

Katie (06:07 .493)

That's fascinating.

Chloe (06:19 .934)

I saw how much money it brought in to the local community, how excited people were, like, you know, there'd be little kids coming to see the bluefin brought in. And it was just like this, and it coincides with, you know, T