> I'm pretty ignorant about the proper ways to go about eradicating exotic
> predatory fish from a watershed, but it seems to me that it could be
> accomplished piecemeal. You could start by fencing off sections of
> stream and eradicating whatever fish within that section and then moving
> the fence further on. If nothing else it seems like you could create
> refuges for the natives in this manner.
Once an introduced species is introduced it is virtually impossible to get
rid of them irrespective of what you do. You can do what you suggest for
headwater species, but not lowland ones. Even in limited habitats it is
very difficult. It was already mentioned that hey have already tried
this and failed in-in-least one small habitat of barrens topminnow. Many
eradication attempts fail. Sometimes this is because small pockets get
missed and/or people reintroduce them. Plus it is very controversial.
Look-in-the whole mess relative to poisoning pike in Davis Reservoir in
California. I believe it is currently impossible to use rotenone in that
state which is really screwing up native trout conservation efforts. The
legislature of New Mexico banned any application of fish toxins for any
reason for a little while which was a major headache for folks trying to
conserve Gila trout.
And electric barriers are good until the power goes out and the backup
fails to come on. :-) And this is documented for the barriers on the CAP
canals in Arizona.
And all of this costs massive amounts of money to setup and maintain and
must be done forever or else why do it-in-all. Far better and cheaper to
prevent further introductions.
Provo River, UT
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