Re: NANFA-- Pike could devastate fisheries (article)

John Bongiovanni (bongi_at_cox-internet.com)
Fri, 07 Feb 2003 21:21:20 -0600

My hypothesis would be that in recent geologic times the ocean has risen
and receeded several times. I suspect that fish species that
established themselves along coastal estuaries and freshwater streams
would have found themselves forced into extinction due to loss of
habitat (due to natural forces). I am just a casual observer, but the
aquatic fauna looks to have been through a number of bottlenecks
resulting in reduced diversity (variation). Species survived by
developing strategies that included spending a large part of their lives
in the ocean where food resources are relative plentiful as opposed to
the resources available in the melting snowpack rushing down off the
rockies.

The ocean level is actually higher now than it was even as recently as
10K years ago. The geologic make up of the west coast doesn't lend
itself to diversity due to space limitations and the severe rise in
altitudes of many of the streams. The geology is very young and
dynamic. Conversley, on the Gulf coast, the rise is much more gradual
and indicative of a much older geology. The geology has been much more
stable and even as ocean levels rose many species were able to move
inland to avoid the approaching seas. This probably has something to do
with a number of the disjuct distribution of species in the midwest.

Or not.

John

Christopher Scharpf wrote:

>>I've been thinking about fish-eating fish and why there aren't
>>many in western US and Canadian freshwater habitats.
>>
>>
>
>Is this because it's a depauperate fish fauna to begin with?
>
>
>
>>We have lots and lots of birds here that eat fish-- herons, cormorants,
>>mergansers, terns, several species of kingfisher, eagles, and more-- but few
>>fish that eat fish.
>>
>>
>
>Maybe that's why -- because there aren't enough fish to feed birds *and*
>other fish (and bears).
>
>
>
>>I'm also wondering a few things about the threat of the northern pike in
>>Lake Davis:
>>Is it really a threat to the endangered salmonids or is it a threat to
>>lucrative fisheries there?
>>
>>
>
>According to Moyle's *Inland Fishes of California" (2nd ed.), pike in Davis
>Reservoir are a potential hazard to salmon populations.
>
>Chris Scharpf
>Baltimore
>/"Unless stated otherwise, comments made on this list do not necessarily
>/ reflect the beliefs or goals of the North American Native Fishes
>/ Association"
>/ This is the discussion list of the North American Native Fishes Association
>/ nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word
>/ subscribe, unsubscribe, or help in the body (not subject) of an email to
>/ nanfa-request_at_aquaria.net. For a digest version, send the command to
>/ nanfa-digest-request_at_aquaria.net instead.
>/ For more information about NANFA, visit our web page, http://www.nanfa.org
/-----------------------------------------------------------------------------
/"Unless stated otherwise, comments made on this list do not necessarily
/ reflect the beliefs or goals of the North American Native Fishes
/ Association"
/ This is the discussion list of the North American Native Fishes Association
/ nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word
/ subscribe, unsubscribe, or help in the body (not subject) of an email to
/ nanfa-request_at_aquaria.net. For a digest version, send the command to
/ nanfa-digest-request_at_aquaria.net instead.
/ For more information about NANFA, visit our web page, http://www.nanfa.org