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Re: Sterility, Teratogenic Effects, and Other Improbabilities -- or - the Roe not taken

Kyle said, in part:

> As for the disease issue, that argument doesn't add up. 
> The only 
> diseases they could potentially have are ones that they
> picked up 
> in their native habitat. 

Well, if they have been out of one place and in another,
they might have been exposed to other things.  A germ or
virus can be spread by a number of different paths, not
jsut water contact.   Some things travel airborne.  Will a
new variation of algae be instroduced with reintroduction
of the fish -- some snail eggs -- and baby killi that came
from who knows where (see today's posts ;-)  )  ???

> That means the disease would
> already be at 
> that site (I very seriously doubt it would completely
> disappear in a
> year).  

A pathogen could mutate differently at two different

> Rereleasing fish with a disease that is already
> found at that
> location won't change anything.  Plus, this assumes that
> Tom's fish
> will still be diseased after a year in captivity,
> something that 
> seems unlikely.  

A fish needn't be diseased to carry a potentially harmful
pathogen.  For example, an animal can carry a virus that
can cause a disease without actually having the disease, or
without acutally having the disease yet.

If you catch a wild pond fish in a cup and put it back
right away -- not much chance of changing the pond.  But I
would guess that the longer you have the specimen in
another environment (tank or otherwise), the greater the
chances that changes to the pond can occur with
reintroduction.  How sterile and isolated are these fish? 
Hmmmm. . . How sterile and fastidiously isolated are these
fish?   Is there a protocol?  Is there a routine?  The
chance is probably small for changes but with any
reintroductions, the chance for changes is probably small
in almost all cases, anyhow.  It's not a matter of high
probability but of potentially large impact.  The
probability for a undesired effect is low but the effect
can potentially be large.  The two factors combined
represent the risk.

> In fact I would think that the threat of foreign disease
> introduction is much higher from people (probably most of
> us) who dump the water from their weekly water changes
> down the drain.  That water will eventually make it into
> lakes and streams.

Probably true, but it depends  a lot on which person and
what they dump.  Anyhow, disturbances in an environ aren't
a justification for further disturbances  -- in fact, they
might even be reasons to avoid even further disturbances.

Sure, lots of things are going on already.  No matter what
you do, you're going to change environs you go near.  But
you picks your paths and takes your steps and who knows who
ends up paying what bill.  You can't get anywhere if you
don't walk around, but don't imagine that your steps have
no impacts (both desireable and undesireable) on the path.

Scott H.

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