Do Manatees Speed Date?

It’s often suggested the manatee was the basis for sailors’ tales of alluring mermaids. But from a human perspective, manatee mating habits are not alluring at all.

One female may be followed by as many as 30 males, according to Senior Biologist Sheri Barton.

“It is a type of mating strategy that some animals have, a scramble of competition,” she said. “And it’s one of the mysteries that nobody really knows about manatees. Which male is the successful sire?”

By taking DNA samples from manatees, it might be possible some day to determine paternity of manatee offspring. Mote researchers use a home-made tool to scrape the animal’s skin. The samples are then sent to Hood College in Maryland for analysis. The results are put into a database, along with photographs of the animals.

Barton says these “mating herds” can last for weeks, sometimes more than a month. Whenever one is spotted in the area, Mote tries to document the members. “We try to get skin scrapings for genetic analysis from all the participants.”

Trying to keep watch on a mating herd can be difficult because manatees are mobile. “They tend to move a lot. One day they are in Pansey Bayou [in Lido Key], and then down near Casey Key the next day,” she said. And the membership changes. “Some males will come and go.”

The effort is a small part of Mote’s attempt to gather DNA samples and match them with photographs of manatees on Florida's west coast. It’s part of a state-wide program. Mote and the Florida Fish and Wildlife Commission both take samples, although the FWC uses a “skin-plug” biopsy technique.

So far mote has sampled 267 manatees. Many bear unique scars from boat strikes, allowing researchers to quickly identify them. But not all manatees are scarred, and the DNA sample is one way to get a unique identification. Time and location are also put into the file.

The genetic database does more than determine manatee paternity. It will provide scientists with a method to determine the viability of the manatee population by looking at its genetic diversity.

“Greater diversity allows for better overall survival of a population,” said Barton. “It allows them to react to a change in the environment.”

And the DNA allows biochemists to determine the animals’ exposure to toxins in the environment by looking for “bio-markers.” Some toxins can subtly change DNA, and these changes can be noted.