[env-trinity] Trinity River In-Season Trapping Update -- Outmigrant Monitoring at Willow Creek

[Byron Leydecker]

From: Bill_Pinnix at fws.gov [mailto:Bill_Pinnix at fws.gov] 
Sent: Thursday, May 06, 2010 1:56 PM
Subject: Trinity River In-Season Trapping Update -- Outmigrant Monitoring at Willow Creek

Willow Creek Downstream Migrant Trap Site
2010 In-Season Trapping Update –May 6, 2010


Synopsis: The 2010 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 8th, 2010 with the installation of two traps. A third trap was installed March 9th, 2010. See attached catch summary for details of this narrative.

This summary includes data from March 9th, 2010 through April 15th, 2010 and is presented as raw catch. No expansions have been calculated at this time. Data entry is not complete for Julian Week (JW) 16, April 16th to April 22nd. 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 13-15 when spring rains coincided with high dam releases), resulting in variable effort over the season; therefore raw catch numbers should be interpreted with caution. 

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). Weekly mean Fulton’s K values of YOY Chinook salmon were greater than 1.0 for all weeks sampled except JW 11. Efficiency calibrations were conducted with freeze-branded hatchery Chinook salmon during all weeks sampled. 

Raw daily catches of steelhead (Oncorhynchus mykiss) smolts (age 1+) have been relatively steady since the beginning of trapping with hatchery steelhead showing up in JW 12. Weekly mean Fulton’s K values of Steelhead smolts were greater than 1.0 for all weeks sampled except JW 11 and JW 14. 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 lower than last year at this time but not significantly lower than other years prior. Weekly mean Fulton’s K value of natural coho salmon smolts has varied greatly from week to week due to low catches. Hatchery Coho smolts occurred in the catch beginning Julian Week 15. 

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_05_06_10.pdf)


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

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