Katie conducting an ultrasound on a blacknose shark Credit: Field School
Katie Miller is a master’s candidate in the Marine Conservation Program at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science. Her research focuses on shark reproduction. She is also an intern with Field School and the logistics coordinator for the University of Miami’s Shark Research and Conservation Program, where she coordinates shark tagging trips with local schools and organizations on SRC’s research vessels.
Katie also has a master’s degree in early childhood special education. Prior to attending the University of Miami, Katie spent a decade working in public schools in Minneapolis and New York City. She maintains her passion for education and devotes a significant amount of her time to SRC’s education and outreach efforts.
Follow her research on Instagram: Katie Miller AND Shark Research Center
Make sure to check out our page about SHARK REPRODUCTION to learn more about shark gestation and reproduction.
What is your favorite shark and why?
This is such a tough question, and my answer probably changes from week to week. Each shark species has its own unique characteristics that make it exciting to observe and work with. Currently, I’m a big fan of tiger sharks because of the challenge they present during an ultrasound. I’ve recently had the opportunity to ultrasound a few pregnant tiger sharks, and I’ve noticed that their ultrasounds look wildly different from most other species – while the pups from many other species are lined up neatly and easy to identify in their mother’s womb using ultrasound, tiger shark pups are all over place. The first time I conducted an ultrasound on a tiger shark, I had no idea what I was looking at!
What is one shark you would love to see/dive with/ or study?
I would love to use ultrasound to study reproduction of great hammerheads in Biscayne Bay. They are such an amazing species but, unfortunately, they are critically endangered. While we already know that they use Biscayne Bay and its surrounding areas as a nursery site, opportunities to observe and ultrasound them are very rare. I think an ultrasound study focused on great hammerheads in and around Biscayne Bay would be extremely exciting.
Can you tell us a little about your current research?
I am working on my master’s degree under Dr. Catherine Macdonald. My project is focused on studying shark reproduction in Biscayne Bay and its surrounding areas using ultrasonography and hormonal assays.
Whenever we catch a mature female shark, I use a handheld ultrasound device to determine whether they are pregnant and to observe the embryos – the same way that doctors use ultrasounds on people. With hormonal assays, we take plasma from sharks’ blood samples and review it in the lab to determine the levels of certain reproductive hormones (like testosterone and progesterone). Together, ultrasonography and hormonal assays give us a lot of information about where sharks in the Biscayne Bay area are in their reproductive cycle.
Tiger Shark Pup in Womb: Credit Katie Miller
My focus species are sandbar and blacknose sharks, but I conduct an ultrasound on any mature female that we catch. This is because those ultrasounds can also contribute to other students’ projects. For example, we have another student who is researching maternal offloading in blacktip sharks – that is when a mother transfers heavy metals, like mercury, to her pups while they are in the womb. We can also use ultrasound in connection with that project to confirm whether a blacktip we’ve caught is pregnant, and then compare the level of heavy metals in their muscle tissue to non-pregnant samples.
Ultrasound of a pregnant bonnethead shark
Credit Katie Miller/Univ. of Miami SRC
What is the most interesting aspect of performing ultrasounds on sharks?
I enjoy how every ultrasound is different, whether it’s a new species, a size of shark I haven’t encountered before, or simply because every shark is unique. I’m constantly learning how to adjust the ultrasound settings and technique to get the clearest image possible of the shark we are ultrasounding, and I’ve learned to enjoy the challenge that every ultrasound presents. I also love performing ultrasounds when we have students on board – it is always exciting to see their reactions when they learn a shark is pregnant, and I do my best to show the ultrasound to the students and answer their questions.
What is the most challenging aspect of performing ultrasounds on sharks?
I had no experience with ultrasonography before joining Field School – I was taught by an amazing intern who was a trained ultrasound tech, and I’m still learning. Every ultrasound I conduct is an opportunity for growth, and some species are easier to ultrasound than others. For example, bull sharks and nurse sharks are extremely difficult to read because their skin is so thick. And even when a species is relatively “easy” to ultrasound, at the end of the day I am still trying to decipher fuzzy black blobs from fuzzy white blobs!
Ultrasound of a pregnant blacktip shark
Credit Katie Miller/Univ. of Miami SRC
The other challenging thing about conducting ultrasounds on sharks is that the technology doesn’t always cooperate. There have been moments where we’ve had a shark on board that we suspect is pregnant, I go to get the ultrasound, and the software needs to be reset or has some other glitch. When that happens, we often have to skip the ultrasound altogether, given the limited amount of time we have to conduct a work-up on a shark.
Why is having the ability to ultrasound sharks important for conservation?
Ultrasound helps us identify when and where sharks are pregnant, and understanding shark reproduction is extremely important to conservation. That includes identifying areas where sharks engage in mating activity, where they spend time while they are pregnant, where they give birth, and where their nursery grounds are. Identifying areas that are important at different stages of shark species’ reproductive cycle impacts how we protect those areas and species.
Beyond its practical applications, I’ve seen how this type of study creates a lot of interest and excitement by students and other groups that join us on shark tagging trips – that interest and excitement gives me hope that our work is also contributing to developing the next generation of shark conservation scientists.
Katie conducting an ultrasound on a tiger shark Credit: Field School
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