Coming up, Jonathan goes to Florida to join the manatee assessment team for a day doing
checkups on manatees!
Welcome to Jonathan Bird’s Blue World!
The West Indian manatee is a marine mammal that lives in the shallow coastal ocean around
Florida and the Caribbean sea.
As a mammal, it has to surface to breathe just like dolphins and whales.
But unlike dolphins and whales, the manatee eats only plants, making it the only completely
herbivorous marine mammal.
Because they are slow and completely harmless, manatees were hunted extensively in the past,
and the population has been diminished by pollution, encroachment on their habitat and
even accidents with boats.
Most of the time, manatees are solitary animals, keeping to themselves.
It’s rare to encounter more than one.
But in Florida, at the northern end of their range, the water can get pretty chilly in
the middle of winter, and the manatees swim up rivers to reach warm water springs, where
they wait out the cold weather.
At Three Sisters Spring in Crystal River Florida, hundreds of manatees gather for protection.
And since they have been protected by law for more than 40 years, their numbers are
finally growing.
Waiting out the cold weather isn’t very exciting.
With very little to eat here, and with naturally anti-social personalities, the manatees mostly
just rest in the shallow water.
Algae grows on their backs, providing a buffet for schools of fish.
These winter aggregations of manatees provide the perfect opportunity for biologists to
study the population.
Back in the first season of Blue World, I met Dr. Bob Bonde, one of the world’s top
manatee experts, as he was performing in-water manatee assessments to gauge the health of
the animals in Crystal River as part of the US Geological Survey Sirenia Project.
Now, more than ten years later, manatees have made a huge comeback in Florida, and the USGS
is still doing health assessments once a year, but the process has grown to a bigger operation.
With the cooperation of dozens of state agencies and volunteers from institutions all over
the state, Dr. Bonde is now running quite an operation.
It’s really important that we get a glimpse of what they are doing and how they’re resolving
their issues in the environment.
And we do that through these health assessments.
The good news is, they look pretty good up to this point.
What we expect is…this population has grown.
When we started with about 100 manatees 20, 40 years ago, now we’re up to over 1,000
in this county.
Is there enough carrying capacity out there?
Is there enough food?
Is there enough warm water sanctuary for them to persist and survive and carry on?
These days, it takes a lot of help to conduct the assessments.
Dr. Bonde gives an introduction to more than 100 volunteers who are about to have a very
long day.
The process begins by setting a net on a busy section of Crystal River, where dozens of
manatees swim by every hour.
Soon a manatee swims into the net, and the volunteers have to gently pull him to shore.
Of course the manatee is scared, having no way of knowing that no harm will come to him.
There is no question that people get wet during this process!
Next, the
volunteers lift the manatee using a sling, and carry it to a waiting boat.
It’s a special manatee rescue boat designed specifically with a removable transom and
open stern to allow getting manatees in and out.
They ferry the animal just a few hundred yards to a place where there is a little more space
to work.
Then they carry the manatee into a nice warm tent.
A
team of veterinarians descend to check the manatee’s health.
They take its temperature.
They use ultrasound to measure the thickness of the fat layer.
A healthy manatee has a good thick layer of fat to keep it warm, but animals that are
not getting enough to eat will have a thinner layer, and this is a good indication of the
health of not only the individual manatee but also the entire manatee population.
They also measure the manatee.
And they listen to its lungs.
I watch with interest and try to stay out of the way.
They do their best to keep the animal comfortable.
Dr. Bonde helps keep the whole operation running smoothly.
Meanwhile the manatee is moved to a giant scale.
He is calm, but maybe a little apprehensive.
Using a winch, they lift the manatee to get his weight.
Although a typical manatee weighs around 1,000 pounds, a really big one is too heavy for
this scale, which has a 2,000 pound limit!
Then, having been out of the water for only half an hour, he is carried back to the boat.
They take him out into the middle of the river and let him go, none the worse for wear, though
perhaps with a good alien abduction story for his buddies.
Over the course of the weekend, they capture, evaluate and release 18 manatees!
The next day, I stop in at the USGS office to catch up with Dr. Bonde’s wife Cathy
Beck, who is in charge of the manatee photo ID system that has been used to track individual
manatees for more than 40 years.
When we started this Photo ID database, and started the research on manatees in the late
‘70s, the estimated population was less than 1,000.
And they had just been listed both under the marine mammal protection act and the endangered
species act.
Since then, the population has just grown tremendously.
Survival rate has gone up.
Sadly, most manatees have scars from old injuries, often from encounters with boats.
But these unique scars can be used like fingerprints to identify individual manatees.
Usually, by the time they are sub adults, usually by the time they are adults for sure,
they have some kind of feature that we can use for identification.
And every one of these is a different…
…is a different code, right.
So…
I don’t see it on your picture but…
Yeah, I didn’t update the sketch.
But this long, skinny one there, what’s that?
That’s the…sorry this is the SLB, so this is the scar on the left, mid-body.
B is “mid body.”
One large gray line.
When we’re in the field and take pictures, we come back and we don’t know who it is,
so I’m entering codes to search, to see if I can match it to a known animal, and that’s
how we bring it all together.
Like if I put that in as a scar, left side, mid-body, one large white, or gray line, it
was a gray line, right?
One large gray line.
And let’s do all areas, okay.
So I have 141 possibilities which is a whole lot better than 4369!
Right?
So it helps a lot to have codes for all of our animals in the database, and then we code
the animal.
This is a crazy amount of work!
It is a lot of work!
The benefit of a Photo ID system is that animals can be tracked over large periods of time.
They have learned a lot of about manatees with this system.
For example, three manatees in the database have been known to swim all the way to Cape
Cod in Massachusetts, a 3,000 mile round trip!
One female has given birth to 13 calves over the 40 years she has been in the database.
They have learned how fast manatees grow, how far they swim, and all kinds of useful
information, which has been used to help protect the species over the years.
The annual manatee assessment is an important part of the protection plan because a small
random sampling of animals ought to reveal a lot about the general health of the population.
And what they are finding out is that manatees are definitely on the road to recovery.
In 40 years, the population of manatees in Florida has risen from 1,000 to 6,000.
That is certainly not a full recovery, but it shows that the protections are working
and the manatee is making a slow comeback.
Which is how manatees do most everything…in the Blue World.