The CARMMHA team of 60 biologists, veterinarians, and field personnel began its second dolphin health assessment of the year in the waters just north of Grand Isle, LA.

carmmha team Barataria Bay

In this series of updates, we describe some of the many activities that must come together for a successful dolphin health assessment. We will also provide a daily update on our progress. To start, we are providing you with an overview of the process to select which dolphins we will work with.

Eric Zolman (NMMF) is the Barataria Bay capture-release lead. For the next two weeks, he will oversee all of our on-water activities, including working hard to keep our team and the animals we interact with safe, and helping us answer our research questions to the best of our ability. Once we’re away from the dock, Eric leads the team to search for dolphins. Today, we stayed close to our home base, the Louisiana Department of Wildlife and Fisheries (LDWF) Grand Isle Fisheries Research Lab, but later in the trip, we will roam further north into the bay and along the barrier islands to the east and west.

NMMF’s Eric Zolman, Barataria Bay Health Assessments Capture lead

Typically we see the animals’ dorsal fins when they come up to breathe, or we might see their flukes while they’re splashing around chasing fish or shrimp. Occasionally, we’ll even see a dolphin completely inverted, straight up and down with its tail out of the water (we think they’re digging around in the mud trying to catch flounder and crab).

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Many animals have unique dorsal fins due to small cuts, nicks, and notches– or they might still bear a tag from previous captures.

The team saw plenty of dolphins on the first day, but we need to be selective about the individuals we temporarily catch for health assessment.

Our team is ready to handle up to four dolphins in one catch, but on this day we were aiming to catch 1-2 animals at a time, to get back into the routine of collecting samples and releasing individual dolphins safely and efficiently. Once we see dolphins in a small enough group, Eric works with other field biologists using cameras and dorsal fin identification catalogs to determine whether we have previously collected any data on the individual. Members of our group have been working with dolphins in Barataria Bay since 2010, following the Deepwater Horizon oil spill, and we have photographed and subsequently identified and cataloged thousands of dolphins over the past 8 years. The veterinary team may be particularly interested in dolphins with a known health or reproductive history.

In addition, prior to any of our field projects with protected species, we work closely with NOAA to minimize the impact of our study design on the dolphins we work with. For example, if there is a calf in a group, Eric and the team will take a close look to assess its size, because we want to avoid dolphins less than 2 years old. Similarly, we want to avoid setting on too many dolphins in deeper (> 5’) water, as this adds complexities to the process. If these (along with many other criteria) are met, Eric will make the final decision to have our catcher attempt to encircle and capture the target dolphins.

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Dolphins captured and released

We conducted health assessments on five dolphins: a juvenile male, a juvenile female, a pregnant mom and her male calf (three years old), and an adult male. The last male was a fairly large animal (258 cm in length). While we don’t have an estimated age for him yet, he is likely over 10 years old; our photo-id team first identified him in 2010, just after the DwH spill. This year we discovered that he has an infected mass on his ventral (under) side. The veterinarians took samples of his blood and swabbed the lesion so that we can learn more about what types of bacteria and/or fungal pathogens are present.

Dr. Cynthia Smith examines a dolphin that is being photographed for later identification.

Our veterinarians performed full assessments, including new cardiac techniques, on all five dolphins today, and all were successfully released. We also collected blood, plasma, and serum for our new immunology and dietary/nutrition assessment techniques. We attached satellite tags to four of the dolphins, and over the course of the next few months, we will be able to track their movements around Barataria Bay.

You might be wondering, “How do you safely get a free-ranging, free-swimming dolphin into the hands of a veterinarian?” Stay tuned, in the next installment we will tell you about what happens after the animals have been selected.

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How do you take care of the dolphin’s nose?

The dolphin’s nose is actually on top of its head. It’s called a blowhole, and it’s where they breathe in air. We make sure that the animal isn’t sick by looking at whether there’s mucus around the blowhole and occasionally taking samples from the area around the blowhole. We also watch the blowhole carefully throughout a health assessment to monitor how often the dolphin is breathing. This tells us if the animal is calm or stressed and helps us determine the best way to care for the animal during the assessment.

CARMMHA scientists routinely collect blowhole samples on wild dolphins prior to their release.