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Exotic alien species Projecte Estany [Lake Project]
Chapter 7 Exotic turtles
The problem with exotic species,
and invasive exotic species in particular,
is that they are native to other territories
but, as a result of human intervention,
they now occupy our natural space.
And, considering
that they may be predators, or may carry diseases
or may carry diseases
or may have an impact on the ecosystem as a whole,
they have the potential
to end up causing
important changes
in the food chains
of different ecosystems,
they can end up displacing
those species which are native to our territory.
It is very difficult
not to find any invasive species in a particular place,
because people have turtles at home.
When an American turtle grows big, it is no longer funny,
so people don't want it anymore,
and there are some conscientious people who take it
to the right place
but there are some people who simply leave it and say goodbye.
Whether it is Banyoles residents or other people
because these things don't always
happen by themselves.
And it is the same for all of these,
these exotic species that were introduced to the lake
a long time ago.
We now know that turtles can be bought anywhere,
turtles have spread everywhere, they call them Florida turtles,
in fact, they are called
red-eared sliders
because there are other turtles that come from Florida
and, what's more, these are not found only in Florida,
they are found in many different places which are considered to be their native territory.
This species has spread everywhere
and it causes problems
for our Mediterranean turtles
and for our European pond turtles.
And why has it spread?
Well, because it was a pet animal,
a mascot, a toy let's say for lack of a better word.
One of the problems at the Banyoles Lake is
the decline in amphibian populations
which is because
of the non-native fish
but we also think that these turtles
are amphibian predators.
So this is yet
another problem for the native wildlife:
the presence of these species, of these turtles.
We have mentioned amphibians
but it is also the case
when recovering native fish populations,
such as the Mediterranean barbel for example,
where this turtle can also
be a predator of Mediterranean barbel fry.
I mean, this is something
that interacts with the native wildlife
in a very negative way.
We buy this tiny turtle and bring it home
for the children,
and after about three, four, five years,
it continues growing and growing and that is when the problems start.
The aquarium is no longer big enough,
we need to buy a bigger aquarium,
the turtle needs lots of space,
it becomes aggressive and bites,
then the turtle's water really stinks
and we have to change the water on a daily basis.
And, after a few years, the tiny little turtle
becomes a nuisance
at home
and the easiest solution for people is
to take the turtle
and, thinking about their turtle's welfare,
they release it into a river,
into a lake, into a pond
and then, yes it is true, this turtle
will be very happy in its new environment
but when so many of them are released,
they become
competitors
with our native turtles.
It becomes an important competitor
as much in terms of habitat
and food resources,
in terms of feeding, predation.
There are cases in which these Florida turtles
prey on the young of native turtles.
It is not possible to ban a particular species because, if we do that,
they stop exporting this species
but they will export another one
and then another one,
and then, instead of resolving the problem,
we have made it worse.
Because instead of having
one species in competition with our native species,
we have two, five, ten
and the problem grows.
As part of the project, one of our tasks is
to eliminate the exotic turtle species
by setting traps.
We are setting different types of baited traps,
with sardines, or some traps
in the form of
floating PVC tubes
which act like sunning platforms
where the turtles can climb up and sun themselves
and then
they fall in and they can't get back out.
With these trap systems, what we are doing is
catching
all of these exotic turtles,
removing them from the environment
and, using the specimens we have caught,
we are gradually collecting a series
of data, the length, the weight,
to allow us to better understand their population.
Like, for example,
we know
that most or many of the specimens
have been pets released from homes
but there is also a significant number of these turtles
that have been born in the Banyoles Lake itself
and we will be able to tell this from their size and the shape of the shell
and all of this information
allows us
to obtain a lot more data
as well as
find the different species.
There are others
which are much more dangerous and much more aggressive
such as the common snapping turtle, the pond slider, the Asian leaf turtle,
I am talking about species
which are not so available
in stores but which end up in people's homes all the same
and so there is a risk that they could end up
in these environments.
Obviously, the problem with these species
is that they are capable of eliminating each other
in these environments.
Due to the fact that
pond sliders, box turtles, and cooters
are generally very aggressive species,
very carnivorous,
which may even prey on
the young
of our European pond turtle.
We act as a reception centre for,
let's say, non-native turtles, exotic turtles.
Many turtles come from private homes,
some have been confiscated at airports or customs,
these protected species end up with us here.
Then, what we do with these non-native species
is we always try to send them back
to their natural habitats, to their places of origin.
Since the implementation of regulations for the trade and sale
of the Florida turtle
a few years ago, they have been
marketing other species of turtle
which, straight away, have ended up
in the lake
and in our traps
just before
we can start to consider them
a problematic
or invasive species but they are there
and it is important that we remove them from the environment.
Next chapter: Native turtles