Florida manatees (Trichechus manatus latirostris) return to Florida’s warm water between October and November, and remain there through the winter months until March or April. Florida might be a cozy home for the winter, but it can also be pretty dangerous for these gentle manatees.
Sailors for the Sea is a nonprofit ocean conservation organization that educates and engages the boating community in the protection of our oceans. Every month, they publish an article on a marine conservation issue and this month’s was written by Professor Roger Reep of the College of Veterinary Medicine, University of Florida. He discusses personal experiences and gives advice on how humans can co-exist with manatees in their natural habitat.
A manatee’s lifespan is about 60 years. It spends most of that time eating, sleeping, and meandering through slow rivers, canals and coastal waterways. In the winter you can find high concentrations of manatees, “packed like sardines” in any warm water, Professor Reep explained to MST over the phone. Unfortunately for the manatee, humans also like to spend time in warm water and we don’t always share well.
Habitat destruction, entanglement in fishing gear, and pollution all threaten manatees, in addition to natural dangers like cold stress.
Manatees need warm water, but they have another competing need: food. Packed in such high concentrations and confined to warm water, manatees very quickly consume all the seagrass in the surrounding areas. As the weeks go by, “it becomes more and more stressful to stay and keep warm without food,” Professor Reep said. They have a choice: don’t eat, or risk venturing into cooler waters to find food. If exposed to the cold for too long, manatees’ immune systems weaken and they can suffer from frostbite and starvation.
But the biggest threat of all is not from food or cold, but from boats. In the essay, Professor Reep emphasizes the correlation between human population growth, increases in boat registrations throughout Florida, and the increase in manatee deaths from boat strikes. In 2008-2012, an average of 88 manatees per year died from boat strikes alone.
According to the Florida Fish and Wildlife Conservation Commission (FWC), 25-30% of annual manatee deaths are attributed to watercraft. Deaths are more often a result of blunt-force impacts than propeller cuts. Efforts are underway to protect manatees from boat strikes by implementing and enforcing reduced speed zones. By reducing boat speeds, both the manatee and the boater have more time to react and avoid a collision.
“Reduced speed zones have been implemented at designated locations in 18 Florida counties,” writes Professor Reep. “They include portions of over 20 major rivers, but constitute only a very small fraction of the total amount of navigable waterways used by manatees in Florida.”
Why aren’t there speed zones everywhere? Professor Reep explained to MST that it’s a political and social issue. Most people don’t want to have to deal with speed restrictions when they’re trying to enjoy a weekend out on their boat — only about 60% of boaters comply with the slow speed zones. And, “there are not nearly enough marine patrol officers to cover the area in question.”
So what can we do to help manatees?
“The single most important thing is to obey the speed zones,” says Professor Reep. Twenty-five percent of manatees “are dying because boats hit them. Forensic evidence from necropsies tells us this…so we need to somehow lessen the number of boats hitting manatees. Go slow when you’re supposed to go slow.”
Spread the word. Maybe if more people know, boater compliance will be up to 80% by Manatee Awareness Month next year.
To learn more:
- Read the Ocean Watch Essay
- Read the news release from Sailors for the Sea
- Read more about 2013 manatee deaths
Copyright © 2013 by Marine Science Today, a publication of Marine Science Today LLC.