Subject: Re: HOLA!

Nancy Sadusky (
Wed, 14 Oct 1998 22:28:49 +0000

Dear Dara,

Thanks for your question:

My question  is why are so many of the manatees endangered or hurt?  
What causes this to happen?  

Also how can people around the world  prevent thing like this from 

Here's the answer:

     One of the problems manatees face is that their reproductive rate
is slow.  Scientists believe female manatees don't become sexually
mature until around five years of age.  Males are mature at
approximately nine years.  Manatee females usually bear one calf every
two to five years, and twins are rare.  Because the reproductive rate
is so low, the species as a whole adapts very slowly to changing
situations or unnatural stress.
     Any species  of animal living in the wild will suffer losses from
natural causes and can usually overcome those losses, but the manatee
population must also deal with additional mortalities caused by
human-related factors.  Research from the Florida Marine Research
Institute (FMRI) has shown that human-related activities accounted for
44 percent of all manatee mortalities from 1976 though 1997, where
cause of death could be determined.  FMRI statistics also show that
most human-related manatee mortalities occur from collisions with
     Manatees are slow moving animals.  Because they have no natural
enemies, they never developed speed as a defense mechanism.  Manatees
can swim up to 20 miles per hour in short bursts, but usually only
swim about three to five miles per hour.  Because manatees are
mammals, they need to surface to breathe air.  They also prefer
shallow waters where they feed on submerged seagrasses.  All of these
factors combine to make them vulnerable to boat hits. Most
manatees in the wild bear scars from at least one watercraft
collision.  In fact, manatee scars are so commonplace, researchers use
them as a method of individual indentification.      
     Another cause of human-related manatee mortality includes the
accidental ingestion of discarded fishing line, hooks, plastic
six-pack holders and other debris left floating in waterways. 
Entanglement in crab trap lines and monofilament line also cause
manatee injury or death.  Manatees can be crushed in closing flood
gates and canal locks that are used to protect against salt water
intrusion and flooding, or drowned when the tremendous suction created
by water rushing through opening gates pins animals under the water.  
     Harassment, too, is a problem for these gentle animals. 
Harassment can include pursuing or chasing manatees; poking, 
grabbing, or riding them.  These actions are potentially 
life-threatening because they can force manatees to leave preferred
habitat such as warm water refuges, or can lead to the separation of a
mother and calf.  Feeding manatees or giving them water from a hose
can also be considered harassment because it disrupts their normal
behavior and conditions them to take food or water from people. 
     Ultimately, however, loss of habitat is the most serious threat
facing manatees.  The growth in Florida's human population with its
added pollution, litter, and boat traffic, has degraded and eliminated
manatee habitat.  Many fresh water and marine grassbeds -- food
sources for manatees -- have been lost because of herbicide use,
surface runoff, propeller dredging, and dredge and fill projects.  In
fact, there are very few places left where manatees are free from
danger, stress and harassment posed by human activity. 
     To ensure the survival of the manatee population, mortality
levels must be reduced and their habitat protected.  Because
human-related manatee deaths are preventable, this is the most logical
way to reduce mortalities. 

Nancy Sadusky

     Communications Director
      Save the Manatee Club
       500 N. Maitland Ave.
       Maitland, FL  32751
         (407) 539-0990