Annual Dolphin Report for Marco Island

Another year comes to an end and the dolphin study team on board the Dolphin Explorer is more than happy with the information they have gathered in 2023. Throughout the calendar year, the team documented a total of 4,763 individual sightings of 128 different, identified bottlenose dolphins.

Our dolphins do not migrate but stay in this area all year long for two major reasons. The rivers, bays and estuaries provide more than enough food for the entire population and there are no major, large predators that roam their waters. Young dolphins, from birth to about three years old, have to be on the lookout for bull sharks and hammerhead sharks but, once they reach the age of three or four, they are too big and too fast for these sharks to bother them anymore. Because the coastal water systems are so shallow, there is no big food source for larger sharks to feed which means our bigger, faster dolphins have no worries with the smaller, coastal sharks.

Food supply is plentiful, due to the estuaries and proximity to the Gulf of Mexico. The 128 documented residential dolphins here range from newborns to older, 50-year-old dolphins and, collectively, this society will eat about one ton of fish each day!

Adult female dolphins outnumber adult males by a ratio of three to one. In 2023 we documented nine new babies born to this female population and three of those young were born to first-time mothers. With 18 years of data, these new births now help add to the number of grandmoms that we have here. There are now seven known grandmoms.

Over the past six years the team has witnessed 52 new calves added to the population with 42 surviving. The success rate of calves reaching their third birthday in our area is more than 80%. Worldwide the number of calves reaching birthday number three is about 60%. We have a good, healthy environment and no huge predators here.

The adult male population is experiencing some changes. In the last decade, six males have ruled the mating rights with area females. These males will form teams of two called “Male Pair Bonds.” One of these pairs might follow a female for the purpose of mating. Single males will have a rough time approaching that female with two big boys following her.

However, during the past year, the team has documented four males that have recently reached maturity in recent years. These four seem to be forming two new male pair bonds and may give the older males some competition when it comes to courting the ladies.

Calves that are one to four years old and still by their moms’ sides are doing well. These young will nurse from mom’s milk for about 18 to 24 months, then fish by mom’s side until they leave her at three to four years of age. Mothers that have had more than one offspring in their past are now veterans in raising young and these little ones do very well.

Once a calf does leave mom, it is not mature until it reaches an age of seven to 12 years old. From calf status until maturity, these members of the society are known as “sub” adults. This segment of the population is doing extremely well, with some forming groups of three to five sub adults that feed and play together quite often.

In general, the dolphins of north Marco are thriving. The mix of females to males is healthy and suggests that an average of nine calves born per year will remain steady. The calves are doing well next to experienced moms and will add nicely to the sub adult groups when they leave their mothers. The sub adults are very, very social and their numbers do not tend to decrease.

There have not been any major environmental issues to affect the normal activities of our dolphins. Algal blooms, such as Karenia Brevis (Red Tide) were more prominent north of Collier County and did not cause any major toxins in our area. There were few tropical depressions and hurricanes this past Summer and Fall with no ill effects on our dolphins.

The team on the Dolphin Explorer will continue to document their findings to share with the public. They do send out quarterly reports to colleges, universities and other dolphin study programs and institutions and will continue to educate the world about our nonmigratory residential bottlenose dolphin population.

Stay tuned for constant updates here at Coastal Breeze News as well as on our website dolphin-study.com.

Bob is the Lead Naturalist of the dolphin study team on board the Dolphin Explorer. He is the author of two books and is twice a national award-winning columnist for Coastal Breeze News. He is a regular speaker at area venues. Bob loves his wife very much!