- Endangered Species: Manatees; How many manatees are living? Depends on
who you talk to, Boaters 3000 plus manatees and the Conservationist 2000 some where in the middle is the correct answer. I would side for the
conservationist, I boat, scuba, snorkel and love manatees so I see first
hand the impact we have on nature.
- Size: Length, up to 13 feet.
Average sizes 8 to 10 feet
Weight: Up to 3500 pounds. Average
size 800 to 1000 pounds
2. West African
3. West Indian
Trichechus manatus (
Antillean and Florida)
4. Steller's Sea Cow is extinct since 1768
Habitat: The West Indian manatee can be
found in coastal waters and connecting rivers from Virginia around the
Gulf of Mexico. They inhabit shallow coastal waters, bays, estuaries
lagoons and rivers. Manatees are able to move freely from saltwater to
freshwater. They often congregate at sources of warm water such as
natural springs in Florida and power plant discharges. Manatees
have nomadic tendencies, pausing in areas that supply their needs and
then moving on.
Manatees are herbivores, mainly grass eaters.
Manatees can not survive in water temperatures below
68 degrees for long periods of time.
Active manatees needs to surface for air every 4 to 6
minutes and while resting manatees may stay down as long as 20 minutes.
Manatees spend between 6 to 8 hours feeding which
equals to about 10% of their body weight.
Manatees in the wild live to be around 30 years
and manatees in captivity live to be around 50 to 60 years of age.
Female manatees mature around 5 years of age and males
6 to 7 years of age.
Gestation is 13 months. Birth size and weight
approximately 39 inches 40 to 50 pounds.
Manatees mostly give birth to single calf, but it has
been known to give twins.
Mothers will nurse their young up to 2 1/2 years.
What Kills Manatees?
In the past manatees died for a few reason.
They where hunted and extremely cold winters. Well times have changed.
Manatees are no longer hunted, but mortality is on the rise for many
reasons, again from human related sources and natural causes.
Almost 40% of the manatee mortality is caused by
Watercraft Mortality is the largest known
cause, here is a break down on boating collisions.
- 60% is killed by impact injuries from
physical force of a boat traveling at a high rate of speed. ( Blunt
- 30 % is killed by rotating propellers and
fixed skews. (Sharp Force Trauma)
- 10% Combination of both Blunt Trauma and
Sharp Forced Trauma
Loss of Habit and Pollution
- This is probably the most serious
threats to the manatees and people. When people build around the water.
this causes another problem which is pollution. People love to have green
grass, but to make the grass green and free of bugs you have to have fertilizers and
pesticides. When it rains, the excess fertilizers and
pesticides washes into our water system which leads to other problems.
manatees eat the vegetation from a contaminated area, they could get
sick and die.
Swimmer, boaters, fisherman all
have there impact on the manatees. I have seen people wanting to feed and ride the manatees,
which is not good for the manatees and is against the law.
Yes, I offer snorkeling tours with the manatees, but in a totally different
way. Instead of placing 8 to 40 people on one or two
manatees we decided to limit our tour size. We have more education
and more control of our guest. It will have a
big impact on that person and the way they look at life after there
Our tour is designed for no or very minimal impact on the manatee. I
personally feel that some of the
tours operators only have one thing in mind and that is how much
money can they make. We call them cattle boats in the dive business.
Noise pollution from boats can disrupts communication.
Boat traffic can interrupt the mating session as well.
Red Tide can occur
naturally or by the help of humans (pollution) with a rapid growth in a
one cell organisms which grows in water with high levels of nitrogen and
phosphorus. Again, with the lost of habit, this is becoming more
prevalent today, with the run off of lawns, farms and golf courses. The
red tide consumes the Nitrogen and Phosphorus and produces a bloom which
looks like a blanket or carpet over the water, which in turns cuts off
the sunlight to the plants and absorbing the O2 as it grows. When the
fish and plants start to die, they decay absorbing even more O2, killing
the marine life by suffocation.
A couple of reason why the
manatees die from red tide, they eat sea grass which contains small
marine animals known as sea squirts or grass shrimp which contains the
toxins. Or they die from inhalation of brevetoxins. Red tide which can
effect humans as well, that live along the affected coast.
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