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Re: Collecting fears.......
Hello All,
I can agree with Jay here. Gambusia affinis tends to produce fry in large
numbers, but also tend to eat their fry in large numbers. They are quite
cannibalistic. They also have an accelerated growth rate compared to many
livebearers, believed to be an evolutionary adaptation responding to the
pressures of cannibalism. They help keep their numbers down themselves.
Add to that fact other predators in the system and you strike some sort of
balance. Unfortunately Gambusia affinis has been introduced outside it's
native environment, and thus high fecundity can become an aid to invading
these new territories. In it's native range it really isn't a problem.
Norm
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-----Original Message-----
From: Jay DeLong <jdelong at nwifc_wa.gov>
To: 'nfc at actwin_com' <nfc at actwin_com>; 'nanfa at aquaria_net'
<nanfa at aquaria_net>
Date: Monday, August 31, 1998 10:42 PM
Subject: RE: Collecting fears.......
>> while I can appreciate the person's concern, it certainly helps a wild
>> population in the sense that fewer mouths to feed mean a
>> healthier, more
>> dynamic population, especially in the case of our most prolific native
>> species who can quickly overcrowd and overcome their
>> environments; as in the case of the native mosquitofish, the Gambusia!
>
>Whoa-- this is an opening large enough to walk through! I disagree with
>this. I think the only times when we can help fish by removing them is
>when we humans have screwed up their environment or ecosystem first.
>There's no fish that we are helping by removing them from their native
>environment except when their environment is so degraded from habitat
>destruction or pollution that individuals are saved by removing them and
>rearing them elsewhere, as with some very rare fish.
>
>The most prolific fish evolved their high fecundity for reasons which
>are NOT detrimental to the survival of the population. Fish with high
>fecundity rates are generally ones with poor survival. They're like the
>mice of the fish world. Most are forage fish which receive little or no
>parental care. Their survival is dependent upon producing large
>numbers, not prevented by it.
>
>Any opposing thoughts on this?
>
>Jay DeLong
>Olympia, WA, USA
>
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