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My experience with spawning ground surveys in northern Alaska included
several observations of fish densities so high that animals were forced
to accept marginal habitat and\or spawn without the opportunity to
construct suitable redds. Whether these broadcast eggs were fertilized
or viable is unknown as I was not sampling.
Brian Bigler
NW Region Biology Program Manager
Washington State Dept. of Transportation
15700 Dayton Avenue North, NB82-138
P.O. Box 330310
Shoreline, WA 98133-9710
Phone: 206-440-4519
Cell: 206-919-1610
Fax: 206-440-4805
email: [log in to unmask]
P Please don't print this e-mail unless you really need to.
Reduce, Reuse, Recycle..
-----Original Message-----
From: Scientific forum on fish and fisheries
[mailto:[log in to unmask]] On Behalf Of Sprague, Gary
Sent: Thursday, February 11, 2010 7:23 AM
To: [log in to unmask]
Subject: Re: Redd counts and construction
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Hello,
My experience with this is limited. I participated in a couple of
sockeye spawner surveys in southeast Alaska, in the primary tributary to
McDonald Lake. There were very few redds in the stream. The substrate
was mostly fist sized pieces of granite. The sockeye would spawn and
the eggs would drop down into the spaces between the rocks.
Gary
Gary Sprague
206.233-5108
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-----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 6:36 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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