The Florida Manatee - Trichechus manatus latirostris
By:
Jonathan Purcell
(Picture by Biologicaldiversity.org)
Listing Date, Type
of Listing, Description, and Ecology of Organism:
The
Florida manatee (Trichechus manatus latirostris) is a marine mammal that was listed as
“endangered” as of October 30, 2001 (U.S. Fish and Wildlife Service). The Florida manatee lives in brackish
and freshwater habitats. It has no
hind limbs, but possesses paddle-like forelimbs and a horizontally flattened
tail. Manatees must come to the
surface for air every 3-5 minutes (Manatee Observation and Education Center). Manatees are herbivores, with a diet
consisting of sea grasses and freshwater vegetation. According to Defenders of Wildlife, manatees can live for
50-60 years in the wild. They can weigh
anywhere between 1,500 and 1,800 pounds and have an average length of 10-12
feet. The manatee is a k-selected
species with no specific mating season (Defenders of Wildlife).
(National Geographic – Picture by Paul Nicklen)
Also
known as the “sea cow”, manatees are graceful swimmers and range from
travelling at 5-15 miles an hour.
National Geographic states that the typical range for the Florida
manatee is the entire coastline of Florida, which is divided up into four
regions: Northwest, Southwest, Atlantic, and the Upper St. Johns. The Florida manatee is seldom preyed
upon.
(Picture by Oxford University Press – Journal
of Mammalogy)
Geographic and
Population Changes:
The
U.S. Fish and Wildlife Service have sampled the Florida manatee population
since 1991. The most recent
population survey, which was completed in February of 2015, states that there
are at least 6,063 manatees in Florida, specifically in the four regions listed
above. According to Save the
Manatee Club, the population of the Florida manatee (juvenile and adult) has
steadily risen since the surveying began despite the threats to its continued
existence.
Cause of listing
and main threats to its continued existence:
The
Manatee Observation and Education Center states that the three most common
threats to manatees are:
1.
Injury or death from boat strikes (commercial and recreational)
2.
Poor water quality due to commercial and agricultural runoff (which includes
coldwater runoff)
3.
Alteration of coastal lands, wetlands, rivers, and streams for housing,
agriculture, and various commercial operations
For
mortality statistics of the Florida manatee, visit: http://myfwc.com/research/manatee/rescue-mortality-response/mortality-statistics/
(Picture by John Daily Digital Pictures)
Description of
Recovery Plan:
The U.S. Fish and Wildlife Service’s Florida
Manatee Recovery Plan outlines criteria for the proper recovery of the species,
which is broken up into two main categories:
1.
Reducing or removing the main threats to its continued existence (listed above)
by protecting the manatee’s habitats and ranges. This would entail the implementation of federal, state, and
local regulations that would protect and monitor warm-water refuge sites,
foraging habitats, and other significant manatee habitats.
2.
Through the implementation of the above regulations and protection, the
population in each of the four Floridian regions, there must be statistical
confidence that the average adult survival rate is above 90%. In addition to
this, there must be statistical confidence that there is a first or second year
calf with at least 40% of adult females.
Lastly, there must be statistical confidence that the average annual population
growth is equal or greater than zero.
If
all goes as planned, the estimated date of full recovery is between fourteen
and twenty years after the Florida manatee is down listed from endangered to threatened. The estimated cost of full recovery is
$10,000,000.
(Picture
by Save the Manatee Club)
For further
information on the Florida manatee, please visit:
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