Saturday, April 7, 2012

Manatees Overcome Their Trying Pasts

Manatees are known to be gentle giants, who simply swim around and mind their own business.  However, these animals have not always had a good reputation.  In the past they were regarded as pests, or just went completely unnoticed.  These were the main reasons why the mortality rate was so high in the past.  Today the mortality rates are high due to other human interactions such as boating accidents and natural effects from temperatures and red tides.


The very first thoughts of manatees were that they were hideous and that they had "a face only a mother could love."  In the late 1800s, Bangs, a biologist from Museum of Comparative
Biology at Harvard University, believed that over-harvesting of manatees, along with the increase of settlement and development in Florida, were reasons for the decrease of manatees in the area.  In 1893, manatees were declared a rare species, which was followed by the passing of a state law which would protect them.  Commercial fishers harvested manatees for meat remained the most serious problem to face in the recovery of the animals' stability (Goedeke 2004). 


Myths, believed to be true, caused an even more negative perception of manatees.  For example a previous myth was that they consumed large amounts of fish.  Another myth was that these animals would purposefully jump out of water to bite or attack a human.   These myths lead to intentional injury of manatees by humans in the form of harassment, along with vandalism (Goedeke 2004).  Many complaints came from boaters, in which they said manatees were nuisances because they would get in the way of the boat, and further cause boat propellers to break off on their backs.  Even more complains continued, especially ones from  anglers, because the manatees would rub against the traps which caused them to be buried into the muddy sediment (Goedeke 2004).



Even after the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973 established and strengthened federal protection of manatees, the Center for Action on Endangered Species still continued to report injuries and issues.  Finally, work on manatee behavior by Hartman, caused the nation and Congress to feel for the marine mammals later in the 1970s.  Hartman testified before the House of Representatives that the Florida manatees needed protection from negative human impacts, such as pollution and boating problems.  After this, State Senator Wilson claimed that ignorance of manatees was the problem for the mortality rates from human impacts.  He also sponsored the Florida Manatee Sanctuary Act of 1978.  A policy was created with the intention of riding accidental killing of manatees by unsuspecting boaters and ignorant youth (Goedeke 2004). 


Many educational opportunities opened up including the Save the Manatee Club (STMC) which started in the 1980s with the help of Jimmy Buffet and later with more help from Governor Bob Graham (Goedeke 2004).  A random survey was taken around the same time which used a statement (true or false) "The manatee is an insect."  Only 26 percent of the individuals who participated in the survey answered correctly, with false.  After which, the STMC sponsored many scientific research opportunities which lead to more knowledge being gained, concerning the manatees.  The United States Fish and Wildlife Service and the Florida Power and Light Corporation also increased awareness of manatees by creating activities and educational events (Goedeke 2004). 


Now that manatees were deemed harmless and endangered, they were less referred to and thought of as ugly and hideous.  Terms now used for the gentle giants include: placid, intelligent, social, friendly, etc, words that would be used to refer to a puppy (Goedeke 2004).  Ninety-four percent of Florida residents surveyed said that manatee restriction laws were either in someway important (Goedeke 2004).   


Currently, the mortality rate of manatees is due to human impacts such as boating accidents and other natural impacts such as temperature and red tides.  In the Gulf of Mexico, blooms from dinoflagellates occur, and produce polycyclic ether toxins known as red tide toxins, or brevetoxins which accounted for 150 manatee deaths in 1996.  Also, if the temperature stays under 21°C for a prolonged amount of time, it may lead to suppressed immune systems in the manatees.  The Florida Fish and Wildlife Conservation Commission has claimed that 11.3 percent of 961 manatees deaths were due to cold temperatures and 17.2 percent due to red tides in 2000 (Walsh, Luer, & Noyes 2004).   


Since manatees already have a low metabolic rate, lessening their ability to control body temperatures, they are even more so susceptible to the cold.  Prolonged cold (2-3 days, below 21°C) may lead to "cold-stress syndrome" which will suppress the immune system of a manatee and make them even more vulnerable to pathogens and diseases.  Infectious bronchopneumonia, generalized infectious dermatitis, and enterocolitis are common consequences from the cold-stress syndrome.  Other infections include fungal infections of the skin and lungs (Walsh, Luer, & Noyes 2004). 


As for human threats, watercraft collisions and coastal development lead to negative impacts for the manatees.  Manatee and human use of waterways coincide which increases collisions and mortality.  In Lee County, Florida, three overall regulations have been created to reduce the mortality: 1) slow speeds all year, 2) slow speeds April 1 - November 15; and 25 mph the rest of the year, and 3) 25 mph within marked channels.  This county has more human-related manatee mortality occurrence than any other county in Florida: 15 per year over the last 10 years.  Rapid dispersal of manatees also contributes to mortality rates (Semeyn, Cush, Scolardi, Hebert, McBride, Grealish, Reynolds. 2011). 

 

 Overall, manatees are much more accepted today than they ever have been.  They started out heading for the worst, but with many supporters they were able to begin to stabilize their population.  However, manatees still encounter multiple mortality causes.  These reasons for death include both human and natural impacts.  Conservation organizations for manatees are still working toward ways to keep these gentle giants safe.  

2 comments:

  1. While I was younger we took a yearly trip to Florida. One year when we went my mothers friends took us to a part of the ocean/estuary where the manatees would usually be seen swimming. We went in the water with them and they were so gentle and loving. It was amazing! They swam right up to us enjoying us petting them and they would not leave. I cannot believe how friendly and cute they were. I am not sure how people find them ugly. But also, while we were swimming with them we could see the cuts on their skin from boat propellers and it was very sad to see this done on such a gentle creature due to human ignorance. Great post.

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  2. Thanks! I also have no idea how anyone could look at one of these creatures and think of them as ugly... they're so cute. And that's awesome... I have always wanted to pet one. ):

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