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Re: More questions on the Exotic Removal Program
J. L. Wiegert NFC at actwin_com List Admin
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On Tue, 30 Jun 1998 Phylesis at aol_com wrote:
> South Florida, over the past half century or so, has become a repostitory
> for naturalized exotic species, from trees and shrubs to birds, reptiles, fish
> and even primates.
The mention of primates surprises me. I wasn't aware that mamals (Which I
misspelled) were becoming a problem there. Save a racoon, eat a monkey?
> The most immediatly obvious are the trees and plants who's
> judging from the success of the exotics, it's not our natives carrying victory
> Are we making a dent in the problem we created by fishing them out and using
> them to fund further conservation efforts or by educating the public at large?
> Time will tell, but doing nothing is not an option.
> >1. How many individual exotic fish are there in the canals?
> One too many, honestly I have no idea, care to come down and count? : )
Well, lets get that one out! Seriously: The fishes have been stocked at
such levels through escapes from breeders/hatcheries, neglegent aquarists,
or, worse yet, people wanting to stock them (Possibly for harvest
whatever.) The trick here is to stop further ones from entering the
system. Lets face it: The only way to eradicate the natives is to either
find a predator to introduce (which brings its own dangers, see below) or
find the indigenous species, remove them to another area, and, bluntly,
nuke the system. Electrofishing, netting, whatever is going to miss some
of these guys. And its quite reasonable to assume that they will
repopulate, even without introductions. It only takes two, after all.
Down there, its cichlids. Up here, we have a rather nastier problem.
Brought in the ballast water of ships from Europe to the Great Lakes and
spread into every canal/river/klake/waterway up here are Zebra Mussels.
These are TINY sweetwater mussels. In many systems, they don't have
signifigant competition. Theres no other mussels or clams or bivalves to
compete with. Therefore, they just explode. Worse yet, since that niche
has never been filled, the one above it hasn't: That is, something that
eats bivalves. The mussels were never dealt with. Moreover, a lot of
people welcomed them. Ponds that were clogged with scum and filthy
riverways got clean. The Mohawk, for example, went from being a green and
grey waterway you could walk across to being pristine. However, the
mussels were also removing a lot of plankton that other animals relied on.
In the short run, they were a blessing, in the long run, fishereis are
suffering. They also brought with them another unforseen problem. They
invaded waterways that fed homes. They got into pipeways, and exploded so
quickly that they clogged them.
Apparently, a sculpin sp. eats them. (I'm not sure its a sculpin, if I'm
wrong, someone correct me.) This wasn't a native, though. Its since been
introduced. Yes, its controlling the mussels. But, whats going to control
it? Its outcompeting our own natives for other prey, such as small
fishes, crawdads, and so forth.
> >2. How many exotic fish have been removed so far? The messages seem to
> indicate no more than a few dozen.
> As a reminder, we are only a few weeks old. I am currently working on forms to
> be distributed among the ERP volunteers to begin recording this and other
> info. Ask this ? again in a year and be astounded.
To me, this is a rather silly question (no offense intended.) Removing
the natives will not have any effect in the long run. HOWEVER, selling
them does. It raises fund, and may increase awareness. The funds, in
turn, finance other conservation problems, some of which may result in
irradiaction of the natives, and better education.
> >3. What is the total annual demand for the species of exotics that live in
> the canals?
Maybe making people aware that these fish were taken in an effort to reduc
exotic populations would help: A note like: "This fish was taken from a
florida canal in an effort to reduce exotic populations and increase
natives. A portion of the proceedes goes to the NFC yadadada"
> >4. How quickly do the target species reproduce? The slower they reproduce,
> the more effective their removal will be.
Sadly, cichlids are some of the best breeders out there. They are
pugnacious, and very good parents. The only native I can think of coming
close to these would be sunfish. Unfortunately, some cichlids lay over a
thousand eggs, and a good pair will have a very high survival rate.
Herotilapia multispinosa, the Rainbow Cichlid (Not the Salvini, which is
often called the rainbow too), is a Mesoamerican cichlid. Its an algae
grazer very simlar to Archocentrus. This is a niche not often filled.
the fish has specialized teeth that rasp algae from rocks. Its also the
most prolific cichlid out there. I'd count it as the easiest to breed
fish out there. Its difficult to obtain, which is strange for such a good
breeder. No one wants to handle it. No one wants to breed it. I've bred
it. The fry, from a 4" pair (which is about 1/2-1/3 grown), numbered in
the thousands. I had less than 10%% loss. One of the few times I was
glad that I won an electric catfish. Fish like this are a VERY big
threat. Think about how rapidly a fish like this could populate a pond.
J. L. Wiegert