[env-trinity] 2009 Trinity River Outmigrant Monitoring Update -- Willow Creek Trap Site

[Bill_Pinnix at fws.gov]

Hello Everyone,

Here is the most recent 2009 Trinity River Outmigrant Monitoring Update for
the Willow Creek Trap Site. See the attached pdf for catch table and text.

                  Willow Creek Downstream Migrant Trap Site
                2009 In-Season Trapping Update –July 17, 2009

   Synopsis: The 2009 Downstream Migrant trapping season at the Willow
   Creek Trap Site (river kilometer 34) is being conducted jointly by the
   USFWS Arcata Fish and Wildlife Office (AFWO) and the Yurok Tribal
   Fisheries Program (YTFP) on the mainstem Trinity River near Willow
   Creek, California.  The season began March 12, 2009 with the
   installation of two traps.  A third trap was installed March 14, 2009.
   See attached catch summary for details of this narrative.

   This summary includes data from March 12th, 2009 through July 9th, 2009
   and is presented as raw catch.  No expansions have been calculated at
   this time. Data entry is not complete for Julian Week (JW) 28, July 9th
   to July 15th.  Heavy debris load and high flows have occasionally
   resulted in null sets, causing less than 21 trap days (3 traps x 7 days)
   in some weeks (particularly weeks 18-23 when spring rains coincided with
   high dam releases).

   Raw daily catches of Chinook salmon (Oncorhynchus tshawytscha) have been
   captured each day sampling has occurred and most have been
   young-of-the-year (YOY), with  more age 1+ natural Chinook salmon than
   in past years.  Raw catch to date is almost twice the raw catch of the
   previous yearly high….and the season is still underway! Weekly mean
   Fulton’s K values of YOY Chinook salmon early in the season were lower
   than 1.0 with an increase in condition evident over the first 4 weeks
   and stabilizing at slightly higher than 1.0 in the later weeks.
   Efficiency calibrations were conducted with freeze-branded hatchery
   Chinook salmon during all weeks sampled, with numerous batches of fish
   to address assumptions and recommendations of the downstream migrant
   monitoring review.

   Raw daily catches of steelhead (Oncorhynchus mykiss) smolts (age 1+)
   have been steady since the beginning of trapping with hatchery steelhead
   showing up in JW 13 and peaking in JW 17, while natural steelhead peaked
   in JW 14.  Steelhead smolts began the season with weekly mean Fulton’s K
   values slightly higher than 1.0, which has dropped to lower than 1.0 as
   the season has progressed; this drop in condition is typical for smolts
   as they ready for ocean entry.  Steelhead YOY numbers are present in the
   catch, but have yet to show signs of a peak.

   Raw daily catches of coho salmon (Oncorhynchus kisutch) are low compared
   to the past 6 years, especially for natural smolts.  In addition, it
   appears that the emigration period is later for natural coho smolts
   compared to previous years. Weekly mean Fulton’s K value of natural coho
   salmon smolts have been higher than 1.0 with a slight drop in later
   weeks indication that the smolting process is underway.  Hatchery coho
   smolts occurred in the catch beginning Julian Week 12 with a somewhat
   later peak in catch compared to previous years.

   If you have any questions regarding this summary, don't hesitate to
   contact Bill Pinnix at (707) 822-7201.



(See attached file: WCT_Catch_Summary_07_17_09.pdf)
William Pinnix
USFWS, AFWO
1655 Heindon Rd
Arcata, CA 95521
(707) 822-7201
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