UNF Marine Mammal Research Team

After documenting a mom and calf group in Mayport, the winds picked up and created choppy conditions in the river. So we made a detour and decided to run our annual survey of the Intracoastal Waterway (ICW) yesterday. As our students saw firsthand, there are far fewer dolphins in the ICW than the SJR. However, we know from prior collaborative projects that our dolphins occasionally use the ICW as a passageway to reach other estuaries to the south. We didn't recognize any of the dolphins sighted in the ICW yesterday, which is interesting since many had really distinct fins. A few even had some interesting marks and scars (pics below). We'd love to know if our collaborators to the south recognize them! We'll be back on the river early next week.

We started yesterday's dolphin survey downtown, but the most interesting sightings were near the end of the day in Mayport. Several large groups were following the incoming tide upriver. In one of those groups juvenile dolphins were surfacing with seaweed (sargassum) on their dorsal fins; we didn't see any adults doing this, so we think it might have been intentional. We also found a group with four newborns (YOYs) and a few larger calves and juveniles. The new moms were Bubbles, Sydney, Kylan, and one we haven't identified yet. Notably, Bubbles and her newborn were in the same group as Bubbles' mom and her current calf; so three generations of this family were traveling together.

For the second week in a row we've found Athena and her kids in a tight knit group. The newborn (YOY) was consistently surfacing in between Athena and her prior (recently weaned) calf. This suggests that the older sibling is female. Although sons usually separate from mom and her social network when they wean, the opposite is true for daughters. They tend to continue associating with mom after weaning and integrate into her social network. By spending time with mom and their younger siblings, daughters can observe and practice parenting skills that will help them when they eventually have calves of their own. Athena is a supermom and a wonderful role model for her daughters.

Tuesday was the first day on the river for Team B of our Dolphin Behavioral Ecology field course. We started our survey in downtown Jax and there was a lot of dolphin activity in the area including another newborn calf! Sadly, one of these sightings included an entangled dolphin. It has very thick rope, possibly from a crab trap float line, wrapped around the base of its tail and cutting through its flukes. NE Florida has the highest dolphin entanglement rate in the state. We're working to provide a detailed sighting history for this dolphin so our partners at NOAA and FWC can attempt an intervention.

If you're out boating and happen to see this dolphin, please call FWC's Wildlife Alert Hotline at 888-404-3922 or from your cell phone. Please do not attempt to disentangle it yourself; we are very fortunate to have a highly trained marine mammal response team in our area.

Yesterday was the first day on the river for Team A of our Dolphin Behavioral Ecology summer field course. They must be good luck because we had our first newborn sighting before we even left the dock. By the end of the day we added 5 more newborns to our list of summer 2026 calves. Congrats to the moms - Elsa, Hera, Athena (our super mom), Pandora, and Lilikoi. We also saw a lot of socializing behavior, mostly among calves and juvies, and a mating herd of 6-8 manatees! Not bad for a first day of class!

Wishing a happy early Mother's Day to all of the moms in our lives, both humans and dolphins. We got drenched by a storm during last week's survey, but all of the newborn sightings made it worth it! We're happy to report that Stuart's calf survived its first week and now has several new playmates. We found Stuart, Pele, Aurora, Guava and their newborns in a group with a few other dolphins near Ft. Caroline. Aurora's newborn was the tiniest and stuck close to mom in echelon position (parallel to her dorsal fin). Stuart's calf is probably the oldest (~2 weeks) and seemed to be showing off to the other newborns with its spyhop-like surfacing (see below). If you're out boating this summer, please keep a constant lookout for dolphins and give them a lot of space. These little ones don't have the diving skills to avoid boats yet.

Congratulations to the most recent graduate of our UNF Dolphin Research Team! Megan Pew earned her Master’s of Science degree today!! Her thesis is titled “Female reproductive parameters in a bottlenose dolphin community with high male alliance complexity.” She found a few surprises - female inter-birth intervals (spacing between sibling births) were shorter than expected and calf survival (to year two) was higher than expected. Our SJR 🐬 are great moms despite all of the challenges they face in the river. Megan processed and analyzed a tremendous amount of data (over 200 documented births) but she plans to process one more breeding season of data over the summer before submitting her work for publication. We are so proud of Megan and grateful to have her on our research team!

We're a few days behind on posting due to the SEAMAMMS conference, but the first newborn (YOY) of the 2026 season belongs to Stuart! Right on schedule, we saw them near the intersection of the SJR and the Intracoastal Waterway (ICW) last Thursday (Apr. 23). Stuart is Chelsea's first documented calf and was born in the SJR in 2011. This poor mom has had a rough few years; she was hit by a boat in early 2025 while she was pregnant with her last calf. 😢 The propeller scars are still clearly visible along her left side body/belly. She was sighted with her first calf (a tiny newborn) on Sep. 18, 2025, but unfortunately that calf didn't survive its first week of life. Stuart was emaciated at the time and may not have been able to produce enough milk. Although Stuart is still visibly thin, we are hoping this little one will make it. 🐬❤️

*Stuart may seem like an unusual name for a female dolphin, but she was named back in 2023. She had not yet had a calf, despite being old enough, and was spending a lot of time with adult males at the time. We now realize that the males were likely showing a lot of interest in her as a potential mating partner.

Our UNF Dolphin Research Team is at UNC Wilmington this weekend for the Southeast and Mid-Atlantic Marine Mammal Symposium (SEAMAMMS). We had 7 presentations from our lab today! So proud of our students and all of their hard work; they’re representing UNF well!

Exciting update! Our former graduate student Andrea Swinehart just published one of her thesis chapters in the journal Scientific Reports! This is the first report of bottlenose dolphins eating violet gobies. Congrats to Andrea and our collaborators at FWC's Florida Fish and Wildlife Research Institute!

Novel prey item identified for estuarine bottlenose dolphins (Tursiops erebennus) in the Southeastern United States - Scientific Reports The community of Tamanend’s bottlenose dolphins (Tursiops erebennus) inhabiting the St. Johns River (SJR) in Jacksonville, Florida, is affected by a suite of challenges including dredging, vessel traffic, fishing gear entanglements, pollution, and natural disturbances. Despite regular observations...