> Even with much worse mortality many aquarium escapees still become
> established out of their natural range.
Obviously it is hard to generalize, but many aquarium escapess become
established in altered aquatic habitats (frequently urban ones) which may
have reduced species diversity and other issues. Sometimes this may make
survival easier, but it can also make it more difficult too. But in less
disturbed systems there are typically fewer established introduced
species. You also have to keep in mind how many fish get released that
never make it? It has been moderately well documented that many initial
introductions fail, and the number of introductions can be an important
factor in determining success. In Australia the first release of rabbits
failed. The second time they took over a large proportion of the
continent!
Also, many species which do establish are pretty tough. Wimpy species
don't establish very often, or for very long.
Tootles
Peter Unmack
Provo River, UT
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