The Manatees’ Winter Vacation

The Florida manatee (Trichechus manatus latirostris) is a large, slow moving marine mammal that inhabits the coastal bays, estuaries and rivers within the southeastern United States.  It is an endangered, tropical species, with closely related species endemic to regions near the equator.  Manatees found in the United States are in their northernmost habitat range.  During the winter months in Florida when water temperatures drop, manatees are subject to the effects of hypothermia, frostbite and pneumonia in a condition termed “cold stress syndrome”.  Their tolerance threshold for exhibiting signs of cold stress is around 20?C (68?F).  Therefore, in order to avoid long-term exposure to cold water during the cooler months, manatees travel to natural and artificial sources of warm water.  Among these natural sources of warm water are the artesian springs found throughout Florida.  Crystal River, located in Citrus County, Florida, is one of the most popular sites manatees exploit during the winter months, and the number of animals using this warm water refuge continues to increase each year.  Artificial sources of warmth at power plant discharge canals are facing closure due to aging plants shutting down as they become out of date.  Because of this, natural sources like the springs at Crystal River will become even more significant for sustaining the manatee populations during the winter months.   When temperatures cool, manatees can be seen congregating in these warm water sources that are crucial to their survival.

Manatees are friendly, charismatic, and playful animals, characteristics attractive to tourists seeking a close-up wildlife encounter.  Crystal River is undoubtedly the most popular destination for divers to view manatees in the wild.  Within Crystal River is Three Sisters Springs, an area characterized by clear, blue water that is filtered and heated within the earth.  Water here is discharged through an aquifer at 22 – 24?C (72 – 74?F) year round.  These warm temperatures allow the manatees to use this spring as a resting place in a refuge away from the cold.  However, they are not alone.

Each year, there is a 20-30% increase in the number of visitors to Crystal River.  In 2012, the United States Fish and Wildlife Service (USFWS) estimated that over 250,000 people utilized the waterway.  Of these, 117,000 were transported by local dive shops and charter services to see and interact with manatees in the water.  An additional 20,000 people rented boats or used their own source of transportation.  Though these interactions are beneficial for educating the public, they do not always result in a positive effect for the manatees.  Divers and snorkelers who wish to get an up-close, in-water view of these large creatures are causing harm to this endangered species.  With so many people in such a small area, the manatees are often disturbed.  For example, swimmers have been observed cornering the manatees as they try to pet and grab at the resting animals.  This interference may alter the manatees’ natural behavior patterns and causes the animals to leave the warm waters of the spring run in order to find a peaceful resting place elsewhere.

Furthermore, swimmers and snorkelers that may not be experienced or comfortable in the water, exhibit poor skills and can unknowingly stand upon, kick or startle the animals that are not typically exposed to such excessive noise and splashing.  The most problematic circumstance occurs when swimmers separate calves from their mothers.  Young manatees are dependent on their mothers for their first two years of life and require the warmth of these springs to thermoregulate.  These interactions with humans can place unnecessary stress on young manatees, and separation from their mothers could be deadly.  All of these circumstances are considered harassment and are against Florida state and federal laws.

Manatees provide an important economic resource for Citrus County.  Visitors to the area spend money supporting the economy and local businesses.  Therefore, a reasonable solution may not be to prohibit human interaction with these animals completely, but perhaps to limit the number of divers with access to the animals at any given time.  Furthermore, on days of extreme cold when a majority of the animals are using the springs, the USFWS can institute a moratorium on any activities within Crystal River for a given amount of time.  There are also a number of steps that swimmers and kayakers can take to reduce harassment and disturbance to the manatees.  The Save the Manatee Club, a nonprofit 501(c)(3) organization that endeavors to protect the endangered manatee and their aquatic habitats, recommends the following guidelines:

• Do not enter designated manatee sanctuaries for any reason.  Manatee sanctuaries are areas away from people that animals can go to rest undisturbed.  The animals know where the sanctuaries are, and sanctuaries are a place they can “get away”.
• Look, but do not touch.  Observe manatees from the surface of the water and at a distance.  Passive interaction allows you to observe manatees’ natural behaviors, and being relaxed puts the animals at ease as well.
• Avoid unnecessary noise and splashing while in the water.  Rapid movement and loud noises can startle and scare manatees causing them to leave the area.
• Use snorkel gear when attempting to watch manatees.  The sound of scuba gear may cause causes excessive noise, and disrupt resting manatees.  The use of fins is not even necessary, as most areas within the spring are very shallow.  Further, wearing a wetsuit will only make you more buoyant.
• Never disturb a manatee at rest, or separate mothers from calves.  Interrupting a resting manatee may alter natural behavior of the animal, or cause it to exit the area.  Dependent calves need their mothers in order to survive, and separating them places stress on the young animal.
• Don’t feed manatees or give them water.  This changes the manatees’ natural ability to find food and freshwater on their own.  Giving them food or water causes them to become dependent on people for food, and is against the law.
• Call 1-888-404-FWCC (3922) or *FWC or #FWC on your cellular phone or send a text message to Tip@MyFWC.com. You can also use VHF Channel 16 on your marine radio if you see an injured, dead, tagged or orphaned manatee, or if you see a manatee being harassed.

Divers who float along the surface at a safe distance from the animals may be the ones who experience the most rewarding encounter after all.  Manatees are curious by nature; thereby, being passive in the water may help to gain their interest and may rouse animals to approach and interact on their own terms.

Following these important guidelines can help to limit harassment, and manatees will be able to utilize these natural springs that are imperative for their survival when cold weather approaches.  Educating dive communities and the public is necessary to ensure that interactions are rewarding for both humans and manatees.  With these guidelines in place, everyone will be able to enjoy these remarkable marine mammals for many years to come.

——————————————-
Post by Aarin-Conrad Allen
Aarin-Conrad Allen is biologist and the South Florida Museum and a NAUI instructor