[env-trinity] Mainstem Trinity River spawn survey update for November 24 to 26, 2014

[Chamberlain, Charles]

Happy Turkey weekend, Trinity River friends!

The US Fish and Wildlife Service along with the Yurok Tribe, California
Department of Fish and Wildlife, US Forest Service, and Hoopa Valley Tribe
have another weekly update for our Trinity River mainstem spawn survey
posted on the Arcata Fish and Wildlife Fisheries webpage.
http://www.fws.gov/arcata/fisheries

Our crews mapped 86 redds in the Reaches from Lewiston Dam to Bucktail
River Access, Round House to Pigeon Point, and Big Bar to Cedar Flat.
Chinook Salmon spawning activity in the up river reaches is begging to slow
as it normally does this time of year. Conditions permitting, we'll get a
look at the river downstream of Hawkins Bar next week where the spawn
timing of Chinook Salmon is later and should still be going strong.  The
graph below is clipped from our weekly report (limited to the river
upstream of Cedar Flat).


[image: Inline image 1]

*Did you know*.... Egg size is a trait passed from spawning female salmon to
their offspring and has been shown to be related to thermal tolerance of
juvenile salmon?  Large eggs produce juvenile salmon with greater thermal
tolerance to warm waters (Muñoz et al. 2014
<http://rspb.royalsocietypublishing.org/content/281/1789/20141082>).
Natural selection in wild salmon populations favors large egg size.  In the
wild, large fry hatch from large eggs and have a competitive advantage over
small fry hatched from small eggs.  In a hatchery setting, fry size offers
little advantage compared to fecundity (the number of eggs produced by a
female) and selection favors females that produce eggs that are smaller but
higher in number (Heath et al. 2003
<http://www.sciencemag.org/content/299/5613/1738.full>).  Maintaining and
improving the integrity of wild Trinity River salmon populations is
important to the long-term ability of our populations to endure changing
climate.  Incorporating favorable wild traits like egg size into Trinity
River Hatchery populations is important too, and will improve the fitness
of the integrated wild and hatchery population.


Talk to y'all next week,
Charlie

Charles Chamberlain
Supervisory Fish Biologist
U.S. Fish and Wildlife Service
1655 Heindon Road, Arcata, CA 95521
http://www.fws.gov/arcata/fisheries
(707) 825-5110
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