Newborn dolphins are expected in the Potomac River any day now – Here's what we're learning about them
/Ask an Expert: Verena Conkin, Potomac-Chesapeake Dolphin Project
IMAGE COURTESY OF Verena Conkin, THE POTOMAC-CHESAPEAKE DOLPHIN PROJECT. TAKEN UNDER NMFS Permit No. 23782
Verena Conkin
Biologist and PhD Candidate at Georgetown University studying dolphin behavior and ecology with the Potomac-Chesapeake Dolphin Project.
Each year since the Potomac-Chesapeake Project (PCDP) began, our team has been amazed by the number of tiny newborn dolphins spotted swimming alongside their mothers. These calves are instantly recognizable as newborns: not only are they quite small, with an almost toddler-like swimming style, but they have unique fetal lines along their bodies. While in utero, calves are curled up tightly, and these folds are distinctly visible during the early months of life – and we see them throughout our summer field season.
Analysis of 2015-2019 data from the PCDP supports the idea that mothers are giving birth and traveling with their babies to the Potomac and mid-Chesapeake to spend their first months of life. There are many reasons dolphins use the area: abundant fish, few predators, and great warm weather.
IMAGE COURTESY OF Verena Conkin, THE POTOMAC-CHESAPEAKE DOLPHIN PROJECT. TAKEN UNDER NMFS Permit No. 23782
Unfortunately, we know from studying other dolphin populations that many do not survive past their first birthday. We’re trying to identify factors that contribute to calf mortality, and using photo-ID to try to determine how many newborns survive and return to the area with their mothers in the following years.
Potomac Conservancy works to ensure that dolphins and other aquatic animals have a healthier habitat! These creatures come to the Potomac River every year to raise their newborn calves, and we want to keep the water clean so they can return year after year. The Potomac and the animals that call it home are only as healthy as the surrounding land which is why protecting upstream forests, removing litter, and advocating for clean water laws is critical work.
Challenges of being a baby dolphin and testing their resilience:
From the get-go, dolphin calves need to be able to breathe, swim, nurse, and follow (and identify) mom. Unlike humans, breathing is a conscious task for dolphins, not automatic. When a newborn surfaces, sometimes they don’t breathe right away, as if they need to remember why they came up to the surface in the first place.
They also breathe much more frequently, coming to the surface many more times than older individuals. When they’re quite young, they can’t dive very well, so their mothers can’t accelerate or dive to forage as they risk separation from young calves. They’re a ‘follower’ species, so a calf has a strong instinct to follow its mother, who can call to the calf with a special whistle, helping them to stay close.
The threats dolphins face throughout their lives (predation, disease, pollution, boat collisions, etc.) can be even worse for newborns since they are still learning many basic skills for survival, like breathing, swimming, and diving.
To keep their calves close, mothers tend to travel more when the calf is young. It seems counterintuitive at first given that very young calves can’t swim well and wouldn’t be able to keep up, but mothers position their calf carefully alongside them, allowing them to draft on the water flowing past. By staying on the move, mothers can keep their newborns close to the surface as they gain more control over their surfacing, breathing, and maneuverability.
Since they forgo consistent foraging in the early weeks of their calf’s life, nursing represents a massive energetic cost between the loss of fat reserves going to milk production, and the lack of food intake to make up for the costs of nursing. As the calf grows, mothers will gradually increase their foraging time, particularly as the calf improves in their ability to swim, dive, and keep up.
Diving into our 2024 Field Season
The dolphins found in the Potomac River and mid-Chesapeake Bay were recently designated as a new species, Tursiops erebennus, Tamanend’s Bottlenose Dolphin. Until recently, we used long-term data gathered on Tursiops truncatus, common Bottlenose Dolphins, as a reference for body size, growth rates, and survivorship estimates. Knowing now that we have a new species, these parameters are thrown into question.
We’re especially interested in the growth and development of newborns, who we think might be maturing faster than other Tursiops species. Understanding their first year of life is especially important, as this can inform us about age-specific and overall threats to dolphins. This field season, I’ll be following moms with newborn calves like last year to further study their behavior and gather information on the calf’s body size as it grows.
IMAGE COURTESY OF Verena Conkin, THE POTOMAC-CHESAPEAKE DOLPHIN PROJECT. TAKEN UNDER NMFS Permit No. 23782
What can you do to help?
Dolphins in the Potomac River need your help to keep it a clean and safe place for them and their calves. While dolphins of all ages are susceptible to human impacts, this risk is much greater for newborns.
IMAGE COURTESY OF Verena Conkin, THE POTOMAC-CHESAPEAKE DOLPHIN PROJECT. TAKEN UNDER NMFS Permit No. 23782
As tempting as it is to get up close, these newborn calves are not good swimmers and cannot get out of the way of a boat, which can lead to accidental boat strikes and injury. Pollution and run-off also make dolphins more susceptible to disease, which is a major threat to this population.
Being good stewards of the environment is an easy and critical way to decrease these disturbances.
Advocating for improved, climate-friendly infrastructure to reduce waste are two ways you can make a difference.
For those of you who recreate in the Potomac, maintaining a safe distance from dolphins is key to reducing sound pollution and avoiding accidental injury. Dolphins use sound to communicate and hunt but boat engines can drone out their ability to do either. Under the Marine Mammal Protection Act, people must remain 50 yards or half a football field away from dolphins.
Join Potomac Conservancy for a river cleanup! Polluted runoff is a big concern for baby dolphins’ health and their habitat.
It is important to identify disease early on. If you see a dead dolphin while out on the Potomac, please report it to the Virginia stranding hotline at (757) 385- 7575 or the Maryland stranding hotline at 800-628-9944. They will determine the cause of death.
Lastly, this work is costly given the equipment, boat fuel, personnel, and living costs associated with data collection. Donations are immensely helpful in covering these costs. If you would like to donate to this research project, please visit our donation page.
Data & Photo-ID Submission Acknowledgements: Any Engelhaupt with HDR Inc. supporting the U.S. Navy’s Marine Species Monitoring Program, Annie Gorgone previously at the NOAA Beaufort Laboratory, Jessica Taylor of the Outer Banks Center for Dolphin Research, and Kim Urian with Duke University Marine Lab.
