[env-trinity] Willow Creek Trapping Summary

Bill_Pinnix@fws.gov Bill_Pinnix at fws.gov
Tue Apr 22 14:48:14 PDT 2008


Willow Creek Downstream Migrant Trap Site
                2008 In-Season Trapping Update –April 22, 2008

   Synopsis: The 2008 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 13, 2008 with the
   installation of one trap.  A second trap was installed March 15, 2008,
   and a third trap was installed March 27, 2008.

   This summary includes data from March 13th, 2008 through April 16th,
   2008 and is presented as raw catch.  No expansions have been calculated
   at this time. Data entry is not complete for Julian Week 15 and 16,
   April 9th to April 22nd.  Heavy debris load from floating algae have
   occasionally resulted in null sets, causing less than 21 trap days (3
   traps x 7 days) in some weeks.  This accumulation of algae in the rotary
   screw traps is a relatively new phenomenon for the Trinity River, and
   has necessitated increased trap checks at night as well as during the
   day.  See attached catch summary for details of this narrative.

   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 a higher than normal catch of age 1+
   natural Chinook salmon.  Weekly mean Fulton’s K values of YOY Chinook
   salmon began the season lower than 1.0 with an increase in condition to
   greater than 1.0 in Julian Week 15.  Age-0 Chinook salmon being captured
   are quite small (< 50mm) and many are just buttoning up.

   Raw daily catches of steelhead (Oncorhynchus mykiss) smolts (age 1+)
   have been increasing as the season progresses.  Steelhead smolts
   captured JW 11-16 had weekly mean Fulton’s K values slightly higher than
   1.0.  Steelhead YOY have not shown up yet in the catches, as they
   usually emerge from the gravel later in the season.  Normal peaks in YOY
   steelhead catch occur in mid-June to early July.

   Raw daily catches of coho salmon (Oncorhynchus kisutch) are low compared
   to the past 5 years, especially for natural smolts.  Weekly mean
   Fulton’s K value of natural coho salmon smolts were higher than 1.0 in
   JW 11-16.

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

   (See attached file: WCT_CatchSummary_4_22_08.pdf)

William Pinnix
USFWS, AFWO
1655 Heindon Rd
Arcata, CA 95521
(707) 822-7201
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