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Depending on the complexity of the habitat (large wood, undercut banks
etc.) spawning can occur where it is extremely difficult to observe.
Additionally if spawning occurs during periods of turbidity or high
flows redds and spawning fish may be unobservable. I guess my point is
the absence of observed spawning (or redds) is not in itself evidence of
broadcast spawning.
-----Original Message-----
From: Scientific forum on fish and fisheries
[mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Thursday, February 11, 2010 7:36 AM
To: [log in to unmask]
Subject: Redd counts and construction
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In the recently published AFS book _Standard Methods for Sampling North
American Freshwater Fishes_ there is the following statement in one
section
re: the use of redd counts (p. 122):
"In some cases, eggs could be broadcast directly into the substrate with
no
redd construction. To our knowledge, this behavior is not well
documented
for stream-living salmons and trouts, but field observations (e.g., lack
of
observable redds in streams with high juvenile recruitment) indicate
that
this is a distinct possibility."
The field observations mentioned in this quote are consistent with some
of
my (albeit limited) observations (or interpretations) in some local
streams.
Does anyone have a reference for this behavior or, in the lack of that,
does anyone have an observation or opinion about this quote.
Thanks in advance for any help or discussion.
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