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Elwha River Salmonid Assessment: Adult Weir Project 2011 Annual Report

Category: Fish/Shellfish Research and Management

Date Published: May 30, 2012

Number of Pages: 27

Publication Number: FPA-12-05

Author(s): Kent Mayer and Mara Zimmerman

EXECUTIVE SUMMARY:

Removal of the Elwha and Glines Canyon Dams in the Elwha River began in September of 2011. Enumerating returns of adult salmon and steelhead trout in the Elwha River is necessary to assess fish responses to dam removal and to adaptively manage the recovery of salmonid populations. The main goal of the Elwha weir project is to evaluate trends in abundance and diversity of Chinook salmon Oncorhynchus tshawytscha and steelhead trout O. mykiss before, during and after dam removal. In 2011, a 59.4 meter resistance board floating fish weir and fish traps were operated at river kilometer 5.9 (river mile 3.7). Biological information was collected from all salmon, trout, and char species captured at the weir. The weir was fished for the winter season (April 27 to May 13, 2011) and the summer/fall season (August 18 to October 20, 2011). The August 2011 weir installation occurred in flows of more than 1,640 cfs. A total of 647 salmonids were captured in 2011: 438 Chinook salmon, 184 pink salmon O. gorbuscha, 14 steelhead (12 during the winter and two in the fall), 6 sockeye salmon O. nerka, 3 bull trout Salvelinus confluentus, 1 coho salmon O. kisutch, and 1 chum salmon O. keta. Of these, a total of 175 fish were captured for the Washington Department of Fish and Wildlife (WDFW) and Lower Elwha Klallam Tribe (LEKT) brood stock programs: 62 Chinook and 113 pink salmon. The majority (67.7%) of the female Chinook salmon captured in 2011 were 4 years of age. The majority (59.8%) of males were age 3. A combination of scale, otolith, and coded-wire tag data indicated that most (94.1%) of the spawning Chinook salmon were hatchery origin and released from the WDFW Rearing Channel as sub-yearlings. Mean fork length of male Chinook salmon was longer than the females within each age class. Coded wire tags (CWT) were recovered from 21 Chinook salmon. Sixteen of the CWT’s were from fish released from the WDFW Rearing Channel. Five CWT’s were recovered from fish with origins outside the Elwha basin: Four from the Dungeness River, and one from Grovers Creek, Vancouver Island, British Columbia.