Florida manatees and the threats to their survival

¶ … Florida Manatee Conservation Efforts

Saving the Gentle Giants of Florida

Gliding through the water on paddle-shaped fins, the manatee, otherwise known as the "sea cow," looks like a larger, more passive version of a seal. Adults can weigh around 1,000 pounds and are typically 9 to 10 feet long, but have the potential to grow as large as 13 feet and weigh more than 3,000 pounds (Reynolds and Odell). Compared to the males, female manatees tend to grow bigger in weight and length (Odell).

Manatees are herbivorous creatures, subsisting on seagrass and other types of aquatic vegetation. The sea mammal has few natural predators and can live for several decades, with adult females giving birth approximately once every three years. The West Indian manatee (Trichechus manatus) has two subspecies, the Florida manatee (Trichedhus manatus latirostris) and the Antillean manatee (Trichechus manatus). The subject of this paper, the Florida manatee, can be found in freshwater, saltwater, and brackish (combined fresh and salt water) habitats in Florida and southeastern Georgia. Completely dependent on warm water, manatees must migrate to south Florida and natural warm water springs during the winter or when the water temperature dips below 68 degrees Fahrenheit. Another popular manatee location during the winter is around industrial plants and power plant discharges, which provide man-made sources of warm water (U.S. Fish and Wildlife Service North Florida Ecological Services Office Website

Manatee population is a bit of a mystery. Throughout history, there has never been an exact number recorded of the species. Aerial surveys are performed every year, however, due to fluctuating weather conditions, manatee behavior, and water clarity, scientists are reluctant to use these surveys as an accurate representation of manatee population. Currently, scientists monitor adult survival rates, reproduction, and population growth rates to assess population (U.S. Fish and Wildlife Service North Florida Ecological Services Office Website).

Despite the fact that manatees have few natural predators, there are other natural and human-related hazards that threaten the species. Natural threats include poisoning from red tide, hurricanes, and exposure to cold temperatures. Human-related threats include collisions with watercraft, loss of warm water habitats, water pollution or direct destruction of seagrass or other aquatic foods, and being trapped or crushed by flood gates and canal structures.

The greatest human-related threat to manatees is death or injury due to collisions with watercraft. At least 78 manatees were killed by watercraft in 2000. Another key threat is the loss of reliable warm water habitats that help the manatees survive the cold winter months. Increased water supply demands are impacting natural springs and there may be a need to replace aging power plants. Also, as the power industry faces deregulation, the man-made sources of warm water may also be affected. (U.S. Fish and Wildlife Service North Florida Ecological Services Office Website).

Water pollution and direct destruction of the seagrass and aquatic vegetation that manatees consume is also a major concern. Industrial chemicals, herbicides, and pesticides are found in manatee habitat, thus contaminating the water and vegetation and encouraging build up of these chemicals in manatee tissue. However, some studies have indicated that pesticide residues in manatee tissues are below levels of pathologic significance and that manatees are relatively uncontaminated by mercury, lead, or organochlorines (O'Shea, et al.).

Additional threats to the manatee are flood gates and canal structures. These mechanisms can kill manatees by crushing them or trapping them underwater until they drown. In Dade County, Florida, this problem is particularly severe, as automatic flood-control structures kill more manatees than boat traffic (Frohlich 2000).

Conservation Efforts

Although the manatee's circumstances may seem grim, there are many positive conservation and recovery efforts, legal protection, and public education endeavors being applied to help this endangered animal. Federal, state, and local government and industry protection is available, as well as encouragement and support from private organizations and citizens. For example, the State of Florida has implemented a large number of manatee speed zones in Florida rivers, bays, and various waterways. State-approved manatee protection plans are currently underway in Duval, Dade, Citrus, and Collier counties. Also, to help protect the manatees in Crystal River, Florida, seven federal manatee sanctuaries have been established (U.S. Fish and Wildlife Service North Florida Ecological Services Office Website).

Additionally, private marine facilities, such as large aquaria and zoos, along with a broad network of manatee volunteers and specialists, help rescue a number of sick and injured manatees every year. Once rehabilitated, these animals are reintroduced to the wild.

Efforts to reduce water pollution are also in place to help restore and maintain aquatic vegetation. Plus, to help prevent the number of manatee deaths related to flood-control structures, navigation locks are now being equipped with pressure-sensitive protection devices that can sense a manatee's presence. But despite the fact that this technology shows immense potential, there is still more testing and fine-tuning needed to ensure that these structures are completely safe for manatees (Frohlich).

An important source of manatee protection comes from The Endangered Species Act of 1973 (ESA). Enacted by the Senate and House of Representatives of the United States of America in Congress, this act was created to provide for the conservation of endangered and threatened species of fish, wildlife, and plants, and for other purposes (Endangered Species Act of 1973). In addition, the manatees are also protected under the Federal Marine Mammal Protection Act of 1972 (Marine Mammal Protection Act of 1972).

These laws make it illegal to "take" manatees, which basically means the act of harming, harassing, injuring, or killing these animals. According to section 7 of the ESA, which focuses on interagency cooperation, federal agencies have the authority to evaluate development impacts on manatees and their habitat, thus making sure that development efforts do not endanger the species or its continued existence. These agencies also have the authority to enforce and establish state and federal manatee protection areas, which are designated to prevent take, and include manatee sanctuaries and refuges.

The Florida Manatee Sanctuary Act offers another form of protection for manatees. And in 1989, a state policy further identified 13 key counties which needed to create manatee protection plans (U.S. Fish and Wildlife Service North Florida Ecological Services Office Website).

What's Next?

Per the North Florida Ecological Services Office, there are key, logical next steps that need to be taken in order to ensure the survival of the magnificent Florida manatee. As stated earlier, four Florida counties have state-approved manatee protection plans, and the remaining nine key counties and several others have implemented speed zones for manatees. However, there are still no protective measures in place for manatees in some counties where watercraft-related injury and mortality continue to occur. There is also a strong belief that appropriate manatee conservation programs should be in place in all Florida and southeast Georgia counties where manatees occur regularly.

Further efforts to secure warm water wintering sites need to be initiated as well as ongoing maintenance of critical spring flows in the Upper St. John's River and other reliable sites in northwest, southeast, and southwest Florida. And finally, it is essential that conservation efforts focus on ensuring that there is enough seagrass and other aquatic vegetation available to support a recovered population.

Overall, it appears that the greatest threat to the manatee is the human. Whether through pollution or water-craft, our actions have caused the most damage to this peaceful species. In some ways, this is encouraging because we actually have the power to become aware, change our habits, and turn this situation around. "Perhaps the most important gesture not just for the manatee but for us all -- would be to recognize that our culture has put us out of balance with nature. This is what the amazing Kogi people call "Koyaanisqatsi." A human culture more in tune with its natural surroundings would instinctively and reflexively choose manatees over speed boats." (Mickey Z.)

Citations

Endangered Species Act of 1973. o16 U.S.C. 1531

Frohlich, Kipp. Personal communication. Florida Fish and Wildlife Conservation

Commission, Bureau of Protected Species Management (2000). Web. 30 Mar. 2010.

Marine Mammal Protection Act of 1972. SEC. 17. o16 U.S.C. 1543

Odell, D.K. "The West Indian manatee Trichechus manatus Linnaeus." Wild Mammals of North America. J.A. Chapman and G.A. Feldhamer (eds.). 828-837. Johns Hopkins University Press, Baltimore. Web. 30 Mar. 2010.

O'Shea, T.J., J.F. Moore and H.I. Kochman. "Contaminant Concentrations in Manatees in Florida." Journal of Wildlife Management. (1984.) 48(3):741-748. Web. 30 Mar. 2010.

Reynolds, John E., III, and Daniel K. Odell. Manatees and Dugongs. Facts on File, Inc.

New York, NY. (1991.) Web. 30 Mar. 2010.

U.S. Fish and Wildlife Service North Florida Ecological Services Office Website. 26 Feb. 2006.

Web. 30 Mar. 2010.

U.S. Fish and Wildlife Service, Southeast Region. West Indian Manatee 5-Year Review:

Summary and Evaluation. (2007). 1-86. Web. 30 Mar. 2010.

Z., Mickey. "Save the Manatees or Let Them Go Extinct? It's Our Choice." planet green, A

Discovery Company Website. 29 Jul. 2009. Web. 31 Mar. 2010.