Florida’s winter season begins in November, and when the water temperatures change, manatees instinctively travel closer, hugging the coastlines of Florida’s warmer waters. In Hernando County, some manatees migrate to areas along the Weeki Wachee River. The inlets like Mud River and Jenkins Creek the water temperature is steady at 72–74 °F, a perfect place for a manatee’s winter retreat.
Interesting facts about the Florida manatee
- They do not have eyelids
- They can hold their breath up to 20 minutes
- They can reach up to 15 miles per hour
- Manatees can move their lips independently
- Manatees have finger-like bones in their flippers
- They also have fingernails
- They are water acrobats! They can swim upside down, roll, do somersaults!
Over three months, Brittany Hall-Scharf Marine Agent II from the UF/IFAS Extension Hernando County and I observed a few locations in Hernando County to get a better idea of how many manatees were congregating along our coast.
We primarily focused on Linda Pedersen Park off of Shoal Line Blvd in Spring Hill. The park embodies Jenkins Creek, an inlet of the Weeki Wachee River. The park is a popular tourist spot in Hernando County for fishing and kayaking. We also took the time to observe other channels, including Rock Creek, Weeki Wachee River, and Mud River.
It’s not so easy counting manatees from the riverbank, kayak or even from Jenkins Creek fishing pier. Another observation method was to reach the top of the 40-foot tall observation tower at Linda Pedersen Park.
Counting and Abundance
Within those three months, Brittany Hall-Scharf and Stacy Strickland, county Extension director, Extension agent III, Ph.D. with UF/IFAS Extension Osceola County, conducted drone counts to compare with our manatee observations from land.
Drone flights conducted in December of 2019 through March 2020 during cold snaps had an average of 45 manatees counted in areas of Linda Pedersen, Jenkins Creek, Weeki Wachee River, and Mud River.
“The Florida Fish and Wildlife Conservation Commission conducts similar surveys using airplanes. Planes are limited to flying no lower than 500 feet and can be costly (fuel, pilot’s time, plane rental, employees’ time) to conduct. With a drone, we are able to fly 150-200 feet above the creeks and rivers to grab an accurate count of the manatees within 20 minutes. Specific filters on our drone even allow us to capture images of identifying marks that biologists can then use to monitor the population,” Hall-Scharf said.
To get a better understanding of the abundance of manatees during winter migrations along the coast, we reached out to Dr. Holly Edwards, an assistant research scientist for the Florida Fish and Wildlife Conservation Commission (FWC).
The Florida Fish and Wildlife Conservation Commission conducts Synoptic Surveys from one to three times per year, however this year, due to the higher than average temperatures, weather conditions did not meet their criteria to organize an aerial flight survey.
Aerial flight criteria for a Synoptic Survey:
- · Water temperatures less than 69 degrees for three of five days before the survey
- · Air temperatures below 49 degrees on three of five days before the survey
- · Light winds and sunny conditions on the day of the survey
“We have several different types of surveys, some give us information about distribution, some give us information about abundance, and others will give us information about the use of natural springs or power plants,” Edwards said. “So we’ve got a variety of different surveys that we fly throughout the year. Our abundance survey is really the survey that tells us how many animals we have. In 2015-2016, the “Abundance Survey” documented over 8,000 manatees along the west and east coasts of Florida.”
Edwards added, “We have distribution surveys that we usually fly twice a month for two years if we want to look at where animals are in every month of the year for purposes of determining speed zones, or sanctuaries or protected areas. All of that comes from the information that we collect from the distribution surveys.”
Weeki Wachee River and along the coastline is not a significant priority for monitoring Florida manatees; however, there are talks of upcoming surveys that will put Hernando County on that list.
“You’re the “springs coast”, and there are a lot of springs there that we don’t know much about,” Edwards said. “So part of what our aerial surveys would do is to look at those areas. This spring, we will be covering the Withlacoochee River, and we’re covering springs along the “springs coast” to see how many manatees are using them.”
Dr. Holly Edwards, with twenty years of experience in her field, knows that education and public awareness efforts are extremely valuable for the conservation of the Florida manatee.
“In terms of helping the public, we oftentimes get requests for information from private citizens who maybe want a speed zone in their neighborhood or someone who wants a manatee sign showing boaters to be careful,” Edwards said. “Aerial surveys have been a very, very important part of manatee conservation across the board from helping to inform grass root efforts of neighborhood associations all the way up to the federal government.”
Research is crucial to a better understanding of where and why manatees travel to different locations. As new technology develops over the years, this gives researchers and biologists a better opportunity to track a manatee’s movement as well as gather other important information, such as feeding locations.
Biologist James Reid from the U.S. Geological Survey, Wetland and Aquatic Research Center in Gainesville, FL, has been involved in manatee radio tracking research for over three decades.
“We have been doing research on manatees as a part of a federal recovery effort dating back to the 1970s. My part has been movement and habitat use of manatees’ different study areas, and all that work began in the early 1980s,” Reid said. “Some of our early research was in Crystal River and Blue Springs, and since then, we have also performed habitat studies and movement analysis along the Atlantic coast, the Everglades and in Puerto Rico. We also just completed a cooperative study in the northern Gulf of Mexico looking at manatee use from northwest Florida westward along the Gulf of Mexico.”
A tethered radio tag is attached to a belt around the base of the manatee’s tail. The satellite-monitored GPS radio tag is an efficient way to monitor their movements. For the manatee’s safety, the belt is installed with a weak link located on both the tether and belt, in case the manatee’s radio tag becomes entangled.
“Radio tagging is just one research tool that we can use to understand the biology of manatees. What we have done for our Gulf of Mexico study is to capture manatees and conduct health assessments, which involve advanced medical and analytical techniques as well as the opportunity to radio tag and follow the movement of the individual. That way, we can understand the range for some of these individuals but, more importantly, which habitats they’re utilizing along the coast,” Reid said. “This is one way that we can document the destination and resources that these animals are using in other locations.”
Concerns for the well-being of Manatees
On March 30, 2017, the U.S. Department of the Interior announced the downlisting of the West Indian manatee from endangered to threatened. The downlisting means that the Florida Manatee (West Indian) is no longer under threat of extinction; however, it will continue to be protected under the Marine Mammal Protection Act.
“It is a good thing that the manatee population has recovered to the extent that the management agencies have downlisted them from endangered. We are fortunate that manatees are doing as well as they are, but certainly, we have not fully understood some of the limiting factors and challenges for manatees in Florida,” said James Reid.
The Florida Fish and Wildlife Conservation Commission releases Manatee Mortality Statistics each year and updates monthly. In 2019, 606 deaths were documented and 136 of those deaths were due to watercraft collisions.
A recent report from January 1st, 2020, through February 21, 2020, 125 manatee deaths have been documented. Fourteen of which were watercraft collisions and 13 were undetermined due to the body being too decomposed. The public report can be found here: https://myfwc.com/research/manatee/rescue-mortality-response/statistics/mortality/
Three main concerns surround the Florida manatee. Those concerns are the following: red tide, cold stress, and human interaction.
“Cold stress is a major source of mortality for manatees; they’ve got to find warmer waters when it gets below about 68 degrees,” Dr. Holly Ewards explained.
Manatees suffering from cold stress go through a physiological change when they are unable to adapt to lower water temperatures. Their metabolism slows down, decreases their appetite and they eventually succumb to a weakened immune system leading to their death if not rescued in time.
Florida manatees are large herbivorous marine mammals that primarily feed on seagrasses and eel grasses.
Additionally, small crustaceans and barnacles, called epiphytes, grow on the blades of these grasses and filter out tiny particles from the water for food. Red tide cells produce a toxin called brevetoxin (which is a neurotoxin) that damages nerve cells and tissues of many organisms. When epiphytes remove brevetoxins from the water during a red tide event, the toxin is harbored in the gut of the epiphyte. This toxin is then passed on to manatee if grass with epiphyte is consumed.
Because manatees are air-breathing mammals, they must surface to breathe through their nostrils at least every 20 minutes. If manatees pass through a red tide bloom on their journey inland, they can become exposed to airborne toxins released by red tide cells.
Toxin transfer through the consumption of vegetation or air passages can cause paralysis or infections that eventually can lead to death (Fewelling 2008). Manatees poisoned by red tide can have seizures and lose control of their motor function. Without timely intervention, the manatee can die by drowning.
Rehabilitation and Recovery at Zoo Tampa
When a stranded manatee is transported to Zoo Tampa Marine Critical Care Center, the manatee is carefully examined and the utmost importance goes towards their individual care and recovery.
Tiffany Burns, with a background in marine animals and Psychology, is in her third year as the associate curator with Zoo Tampa.
“We have a variety of manatees here right now; we have orphan calves, red tide, cold stress, and boat injuries,” Burns said. “Anytime the manatee comes in, we first get all the information we can from the people that rescued. Where the animal was found, what the animal is doing, it’s breathing, it’s behavior, all of that is going to give us more information on where that animal is healthwise.”
Those that are involved in the rescue process are equipped with newer technology that these biologists can conduct tests on the scene. They are able to send those results to that care center facility more efficiently and quickly. Since there are only a few manatee hospitals in the state of Florida, Jacksonville Zoo, Miami, Zoo Tampa, and Seaworld, time is critical for the care and recovery of any injured manatee.
Trained veterinarian staff collects as much information about the rescued manatee being transferred to the care center, such as blood work, measurements, weight, and a full-body condition check.
“For cold stress a lot of the time you can see the actual stress on the animal, discoloration. For red tide they basically almost go comatose, so they are kind of out of it, they are not really responsive,” Burns said. “Each has different kinds of signs and symptoms and depending on where they are found. It gives us more information.”
“Every animal is different, just like us. They (manatees) have different weights, metabolisms, and health things going on, so every single manatee that comes in, while we might treat it similarly for its conditions, we take it case by case,” Burns added.
Eco-tourism and Human interaction
Weeki Wachee Springs is the headwaters (a spring that is the primary source of a stream) of the Weeki Wachee River and is a beautiful place for many tourists to visit. There is important information the public should be aware of with Florida manatees, especially during this time of year when more manatees are migrating to warmer water.
Kayaking and canoeing are often the popular choices to explore the pristine waters of the Weeki Wachee River, and by chance to encounter manatees.
The one rule that is often misunderstood is that of human interaction. People are not allowed to touch, pet, feed, or water manatees in their natural habitat. If by chance, a manatee is swimming around the area, view how amazing and wonderful these mammals are from a safe distance and let them be. (https://myfwc.com/education/wildlife/manatee/viewing-guidelines/)
Throughout the state of Florida, manatees have become a development for ecotourism. Some tourism businesses offer ‘Swim with the Manatees’ scuba diving or snorkeling adventures. There are also manatee viewing tours by kayaking or pontoon. These tourist adventures can be an enjoyable and exciting experience for many people; however, manatee awareness and education is extremely important regardless if you are on a guided tour or not.
So what’s the big deal about petting a manatee? It’s illegal. Manatees are curious and gentle creatures; however, drawing them closer into a human interaction can cause more harm than good.
Human food is not in their diet and does not necessarily have the nutrients they need.
Giving them water from hoses off your dock or boat creates an unnatural dependence on you as a source of freshwater and will prevent them from seeking natural sources of fresh water.
Harassment is any distraction caused by people that takes the manatee (or any other wild creature) away from its natural behavior.
Splashing, causing a disturbance or approaching the manatee may startle them and may cause them to swim out of warmer waters or even collide with a motorboat.
The manatee is protected under federal law by the Marine Mammal Protection Act of 1972, which makes it illegal to harass, hunt, capture, or kill any marine mammal. The manatee is also protected by the Florida Manatee Sanctuary Act of 1978, which states: “It is unlawful for any person, at any time, intentionally or negligently, to annoy, molest, harass, or disturb any manatee.”
For more information: Protecting Native Wildlife – Florida Manatees
How you can help
Become a stranded response volunteer- UF IFAS in Hernando County Marine Animal Volunteer Responders course is currently full for the May enrollment. However, there are other courses available.
Be on the lookout and report sick, injured dead or tagged manatees: Report a distressed or dead manatee and report violations by calling 888-404-FWCC (888-404-3922). Cellular phone users can also call *FWC or #FWC, or send a text to [email protected]
Donate. There are many ways to donate by purchasing a manatee license plate or a manatee decal. https://myfwc.com/research/manatee/trust-fund/