Re: NANFA-L-- Re: Chinese Sturgeon on AquaBid

anutej-in-loxinfo.co.th
Fri, 12 May 2006 01:16:13 +0700

Sorry to make it a bit generalized, but in Thailand even with large
number of species some exotics do show up in natural waters. Recently
we get silver arowana, tiger shovelnose catfish and peacock bass in
fishermen catch [and these species are from pet trade]. Hope they are
escapees and not naturally born ones. I agree with the notion of
alteration of habitat [that reduce number of native species] as one
factor for success in introductions. I've seen Nile tilapias in huge
numbers mainly in areas with strong human influences, while in less
altered rivers and streams there are much less common. Interestingly
ones in less altered habitat tend to grow bigger and healthier.

Off topic but does anyone know how do the Clarius [walking catfish]
and Asian Swamp eel become established in the US? The same species of
Clarius is in trouble in Thailand due to escape/release of hybrid
walking catfish used in aquaculture.

Tony

Peter Unmack wrote:
>
> On Thu, 11 May 2006 anutej-in-loxinfo.co.th wrote:
>
> > 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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