A Day With the Dolphins:
A Biopsy Sampling Trip

    Our day starts at 9 am on the docks of the Duke Marine Lab. This is a very kind start time- I’ve been on trips that began before sunrise. On this day, the sky is a brilliant blue and the light wind hardly ruffles the surface of the water. It’s a perfect day for a biopsy sampling trip.

    We load the gear onto the boat: two cameras, an iPad, a cooler, and a crossbow. From the outside eye, we might look like hunters, but the crossbow isn’t for anything violent. Instead, our mission is to collect tiny blubber and skin samples from bottlenose dolphins. Our trip leaders had shown us the modified darts that are loaded into the crossbow; they look like tiny little tubes, only about an inch deep. They’re designed to be as harmless as possible. 

    We push off from the dock right on time. Zach Swaim, our fearless captain, is the one driving the boat while the rest of us are tasked with keeping our eyes peeled for any dorsal fins in the distance. Including me, there are four undergrads, all of whom have been doing work with the samples collected on trips similar to this one. We also have Greg Merrill and Dr. Ashley Blawas, two then-graduate students who have experience with biopsy sampling.

    We’ve decided to focus our attention on the estuary dolphins that live in the waters surrounding the marine lab. This means we don’t travel for very long before we see the telltale triangles and hear the whoosh of powerful breaths rising out of the water in front of us. We fumble our way into readiness; us undergrads aren’t very fast, as we’re still learning the ropes. 

    Two students man the cameras, taking photos of the dorsal fins in order to identify each individual dolphin in the group. Another keeps a constant eye on the position of the dolphins and reports back to Zach. I take the iPad and start filling out a data sheet: time, location, number of dolphins, etc. Greg Merrill has the most important job: he loads a bolt into the crossbow and heads to the front of the boat. It takes an incredible amount of communication between Zach and Greg in order to get Greg a clear shot, as the dolphins are small, fast, and almost impossible to see until they surface. According to Zach, bottlenose dolphins are much more annoying to sample than humpbacks or other giants of the sea.

    A dolphin surfaces directly in front of us. In the space of a breath, Greg lets his bolt fly. Both students click photos as fast as they can, making sure that they’ll be able to identify this particular animal so we don’t sample them again. But the shot misses. With another blink, the dolphin is gone under the water. 

Nobody is upset- this is simply part of the sampling process. We’ll try again. One student tracks the bolt in the water, pulling it back onboard, while I record the attempt in our data sheet. Greg rolls his shoulders and pulls another bolt out of a box. The bolts are sterilized to prevent infection, so he can’t reuse the bolt he just shot after it’s gone into the water.

    We make sure to always choose dolphins with distinctive dorsal fins, so our next try can be on a different animal. It’s important to note that our most important goal isn’t getting a sample. Instead, it’s minimizing harm or harassment to these animals. Shooting biopsy darts is not something to be taken lightly. In fact, it’s illegal unless you have a permit from the National Oceanic and Atmospheric Administration. Greg had trained for years in order to be able to legally take up the crossbow. Even approaching the animals like we are is something that should only be done with legal permission. Otherwise, it’s a violation of the Marine Mammal Protection Act. When I’m a member of the public, not part of a permitted research team, I make sure to always give marine mammals plenty of space.

    Zach swings the boat around and Greg readies another bolt. He counts the breaths of his target animal; sometimes there’s a specific pattern of surfacing that you can catch. I see him take a deep, calming breath. Then there’s the twang of the crossbow firing, a small splash, and a shout from Ashley. We have a hit!

The excitement on the boat is palpable. I’ve been part of day-long sampling trips where we had no luck at all, so any sample is a cause for celebration. One student tracks the dolphin that’s been hit (to ensure there are no ill effects), I record the success on the data sheet, and another student grabs the bolt like before. This time, the end of the bolt with the sample is quickly cleaned and placed into the small cooler. Once we return to the lab, the small amount of skin and blubber will be subsampled for each of the different projects. There’s talk of taking some of this sample for a cell line, while other parts of it will likely be used for our population genetics work. We make sure that even these very small amounts of tissue will be used effectively.

    While discussing these sampling trips with my friends and family, several of them have been initially uncomfortable with the idea of shooting dolphins with crossbows. I understand their hesitancy. However, policy makers and scientists have worked together to ensure that taking biopsies is as humane as possible for all marine mammals involved. We would not be doing this if there was any significant risk to the dolphin. Instead, we have very strict rules about who, when, where, and why these samples can be taken. At the end of the day, we are doing our best to preserve and protect these populations while also conducting our vital research.