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Joel,
Interesting dilemma, but there's some information missing that's important
for full understanding. First, are these animals introduced as eggs to the
mid and upper tribs and the females you mention have made the migration?
What do you mean by "acclimated release site"?
If these animals were introduced as eggs to the upper river tribs, your
thoughts on energetics is likely the single largest contributing factor in
spawning success. There're reams of information on size-selective pressures
on salmon populations, and an animal genetically and energetically adapted
to a short migration won't easily transition to a long one.
One other factor that you may consider is that the average size among
Columbia River coho has gone through a period of decline up to about four
years ago, though I'm unfamiliar with any subsequent studies. If the brood
source is affected by reduced average size, the progeny is likely to reflect
reduced survivorship.
Brian S. Bigler
NW Region Asst. Biology Program Manager
Washington State Department of Transportation
> * 206-440-4519
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-----Original Message-----
From: <Joel Hubble [mailto:[log in to unmask]]
Sent: Friday, April 05, 2002 7:07 AM
To: [log in to unmask]
Subject: hatchery coho incubation survival
Dear Fish List Colleges,
First alittle background information. We are conducting a coho
reintroduction study in the mid and upper tributaries (Yakima, Wenatchee,
Methow) to the Columbia River using a lower river broodstock (since all mid
and upper river stocks are extripated). Last fall in the 3 tributaries we
are reintroducing coho we noticed females (primarily) dropping out and
spawning well short of their acclimated release sites, suggesting that
there's an energenics issue. Essentially a stammina issue in that a lower
river stock fish is "being asked" to upmigrate a much greater distant than
normal. We have noticed less than ideal or normal egg-to-fry survival in
the hatchery from these hatchery broodstock in all 3 subbasins. I'm
wondering if the poor incubation survival rate is somehow related to poor
egg quality that is related to upmigration stress? Is there methods to
measure egg quality (i.e. amounts of lipids, protiens, etc)?
Water quality tests have have shown nothing to suggest that the water source
is the problem, as well as, the pathological results.
Thanks for your ideas and thoughts.
Joel Hubble
Yakama Tribe
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