Maybe some people would consider the drop in arthropods to be minimal, but
think of all the other native species that depend on the same food types,
just because there is a larger fish which has a higher biomass to maintain,
means there is less prey (i.e. arthropods) for other native species. Just
because there is more predation, doesn't mean that there is going to be a
corresponding increase in the available arthropods, so someone is going to
come up short, either the native fish and amphibians, as well as those that
feed on them.
I am not saying that the brown trout fishery has not given many of
naturalists the incentive to do good things, only that it seems slightly
skewed to think that a stream would be better off with an introduced
species, than a clean stream with it's indigenous ones.
> -----Original Message-----
> From: owner-nanfa_at_aquaria.net On Behalf
> Of NATURNUT_at_aol.com
> Sent: Sunday, May 27, 2001 6:34 PM
> To: nanfa_at_aquaria.net
> Subject: Re: NANFA-- Spawning in high water/non-point
>
>
> In a message dated 5/27/101 5:10:18 PM EST, fundulus_at_hotmail.com writes:
>
> << I'll leave it at saying brown trout would not have to reduce any
> population
> to "concern" levels to have a negative impact; I refer to changing local
> abundance of usually obscure animals such as aquatic insect
> forms, which can
> have indirect effects on other species down to the phytoplankton
> level. Some
> research has been done on these types of effects. One EPA group
> studied the
> presence/absence of various minnow species in northern New
> England lakes, in
> which some of these lakes have had bass introduced, some have had pike
> introduced, some have had both introduced and some were spared such
> introductions. The lakes without such introductions had more
> minnow species.
> That's not brown trout in Michigan, but I'd bet half a peach
> that you could
> find similar effects with aquatic arthropods. Not a glamorous
> group to most
> people, but... >>
>
> Well we would be talking very obscure changes that would occur with any
> organism in any ecosystem anywhere. Slightly changes in arthropodan
> populations are natural in many systems naturally, and things
> have a way of
> balancing out. Thats the way a natural system works, and I still beleive
> brown trout are not a problem in any way, shape, or form. Don't
> get me wrong
> on one thing, though. Other introduced (or exotic) fish that are more
> predacious, environmentally tolerant, ect do pose a threat.
> Brown trout, in
> their nature, cannot pose such a threat. Long live browns...
> ___Dan McConnell Marshall, MI
>
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