Watch out!  There are Manatees About!

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Stephanie L. Swanson, Miami University

The Effects of Ecotourism, Recreational Boating, and Fishing on the Conservation of the Florida Manatee

Currently, the Florida manatee, a subspecies of West Indian manatee, is listed as endangered; however, it has been proposed that their status be downlisted to threatened.  With the growth of the human population, the popularity of recreational boating and ecotourism, and the possibility of lowered guidelines; it is more important than ever that we are mindful of our actions when around these animals.  This gentle giant predominantly resides in the warm coastal waters in the southeastern United States, as they are very sensitive to the cold, in a variation of habitats; such as rivers, creeks, sounds, bays, estuaries, marinas, and coastal waters.  These are the same waters that are popular with travelers and vacationers.

Florida manatees are large in size; weighing up to 1,590 kg. (3,505 lb.) and measuring up to 4 m. (13 ft.) in length.  They can range in color from gray to a grayish brown, and their skin is thick, coarse, and wrinkled.  Because of this, it is not uncommon to see algae or other marine organisms growing on their skin.  Travelers can often see them using their two front flippers to steer themselves as they swim or crawl through the water.  Their powerful paddle like tail allows them to glide along at 3-5 mph, but can propel them at up to 20 mph in short bursts.  As the only herbivorous marine mammal, the manatee consumes around 7% of its body weight in vegetation every day.  Their diet consists of mostly sea grasses, but is also supplemented with other freshwater vegetation.

There are three laws currently protecting the Florida manatee; the Marine Mammal Protection Act of 1972, the Endangered Species Act of 1973, and the Florida Manatee Sanctuary Act of 1978.  Under these laws, it is illegal to harm, harass, pursue, hunt, shoot, kill, capture, wound, or collect any manatee.  Even with these policies protecting the Florida manatee, understanding what these laws mean in terms of “take” and “harassment” can potentially be problematic.  The definitions of “take” and “harassment” differ slightly between the different acts causing confusion.  With the rise of recreational boating and ecotourism, it is imperative to clearly understand the rules these laws set in place.  Additionally, without a consistent black and white definition, each person may have a different view on what is and is not considered an act of harassment.

The number of watercrafts used in the waters of Florida are increasing each year.  According to the Florida Fish & Wildlife Conservation Commission, there were 982,907 watercrafts registered in Florida and an added 300,000 to 400,000 watercrafts used by Florida visitors in 2004.  That means there is the potential for up to 1,287,907 watercrafts sharing the coastal waters of Florida at any given time.  Studies show that the presence of fast watercrafts significantly changes the behavior and physiological responses of the manatee.  These responses ranged from reduced, disrupted, and/or avoidance of feeding activities, an increase in vocalization, a reduction in surfacing, and an increase in energy expenditure due to a rise in swimming speed.  Additionally, watercraft activity can sometimes lead to manatee displacement from warm-waters, leading to cold water exposure.  Furthermore, the large quantity of watercrafts increases the chance of propeller damage to sea grass beds and the manatees themselves, causing blunt and/or sharp force trauma to the manatees.

The manatee photo-identification database project is starting to catalog the identification of manatees with photos, such as researchers do with whales.  However, what may shock many is that they are using the unique scar patterns manatees obtain from watercraft collisions as identifiers.  It has been found by researchers with the United States Geological Survey, that all manatees in Florida have, or will have, scars on their backs from collisions with watercrafts.  Additionally, it was found that 97% of animals in the database show scars from multiple watercraft collisions.  This is not surprising as the leading cause of known manatee mortality is due to watercraft collision, averaging at 36%.  The chance of these collisions are increased when individuals are not aware of their surroundings and the signs that signify a manatee is presently in the area, or they do not obey speed limits set in place by manatee protection laws.

Recreational boating not only affects the manatee, but the ecosystem as well.  A watercraft that is uncleaned, or improperly cleaned, can introduce potentially harmful nonnative species into the manatee’s ecosystem.  Introduced species, such as barnacles, epiphytes, and other biota, can attach to and grow on manatees because of their slow moving nature.  This can cause damage to the skin from anchoring, increased water drag, increased weight, decreased flexibility, injury, and crowding by grazers trying to feed on the attached organisms; all of which can make it hard for the manatee to surface to breathe.  Furthermore, the ecosystem can also be damaged as nonnative organisms outcompete native species, which reduces the biodiversity of the entire ecosystem.  On the other hand, toxic chemicals used to clean and treat watercraft hulls, such as herbicides, can also cause harm to the manatee and its ecosystem.  Chemicals, such as copper and zinc, can have negative effects on the growth and reproduction of many freshwater aquatic plants, as well as the growth, reproductive function, and health of the manatee.

Critical warm-water wintering habitats for the Florida manatee have quickly become a tourism attraction to visitors that hope to have an up close encounter with these large but gentle marine mammals.  Each year, these warm-water wintering habitats located in the springs of Crystal River, Kings Bay, and Homosassa are inundated with visitors that pay to have a swim-with-manatees experience.  In a hope to reduce any negative effects ecotourism might cause to the wintering manatees, the Crystal River National Wildlife Refuge was created in 1983.  Within the refuge, seven seasonal manatee sanctuaries (where humans are not permitted) are maintained and monitored, speed limits are lowered, and manatee interaction guidelines are in place.  It is also required that all visitors hoping to swim-with-manatees and/or rent a watercraft, watch an informational video called Manatee Manners, showing the dos and don’ts of interacting with manatees before entering the water.

There are over 90,000 visitors a year to swim-with-manatees in Kings Bay.  Although there are guidelines in place to protect the manatees, there is no way of knowing if tour operators, watercraft rental shops, and private boaters are reading them and viewing the Manatee Manners video.  Additionally, every tour operator and individual visitor may interpret the guidelines differently.  For example, an operator and their group might have a disagreement on what it means to “chase” a manatee.  Some individuals may classify swimming behind a mother and calf as “following”; when the guidelines would classify this as “chasing”.  Furthermore, with the increase of watercraft and visitors in the area, the manatees are seeking refuge in sanctuaries and exhaust the food sources within those boundaries.

Entanglement in discarded fishing gear and ropes is another danger the manatee faces.  Manatees can become entangled in fishing gear in one of three different ways; by accidental encounters with undetected objects, indiscriminate/opportunistic encounters where the object is undistinguishable from the natural habitat, and deliberate situations where an inquisitive manatee investigates an object.  The most prevalent cause of manatee entanglement is through accidental encounters when foraging and interacting with their habitat.  The manatee uses its front flippers to propel through sea grass beds while using their upper lips to graze.  As the manatee crawls through the vegetation, it can become entangled in the fishing gear that was discarded by fisherman.  These entanglements cause injuries that can lead to infection, or inability to surface or swim.  Injuries caused by entanglement can prevent manatees from feeding, breeding, and potentially cause the death of the animal.

 

Take Action

As a traveler, there are several actions that one can take to insure the safety of the manatees and still enjoy the warm waters of Florida and encounters with these curious, kindhearted, and playful giants.  As a fisherman, don’t discarded monofilament line, hooks, or any other gear into the water; keep track of your tack the best you can.  As an eco-tourist that wishes to swim with manatees, research tour operators before traveling to make sure you are choosing a reputable organization.  A good way to do this is by looking over their website and reading customer reviews.  Always avoid tour organizations that promise interactions with or the ability to feed wild manatees.  Read guidelines before you head to your tour; your tour operator should go over these guidelines with you, but it never hurts to study ahead!  As a recreational boater, get to know the waters that you will be visiting, obey all speed restrictions, and make sure you have cleaned the haul of your boat properly.  If you hit a manatee while boating or notice an injured manatee while getting to know these gentle giants, alert the FWC Wildlife Alert by calling 1-888-404-3922.  There is no reason why we can’t peacefully coexist with these lovable giants.


Stephanie Swanson is a graduate student studying Conservation Biology with Project Dragonfly at Miami University in Oxford, Ohio and in conjunction with Brookfield Zoo.  The focus of her studies is marine mammal awareness and conservation.

 

 


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