Elwha River Salmonid Assessment: Adult Weir Project 2012 Annual Report

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 2012, which was the third summer/fall season and the second winter/spring season for the floating weir on the Elwha River, a 59.4 meter wide resistance board floating fish weir and multiple fish traps were operated at river kilometer 5.9 (river mile 3.7). Biological information was obtained from all salmon, trout, and char species collected at the weir. The weir was fished for a total of 140 days in 2012: 59 days in the winter/spring from February 16 to April15, and 81 days in the summer/fall from August 2 to October 21. A total of 370 salmonids were collected (upstream and downstream) in 2012, representing seven different salmonid species: 174 (47%) Chinook salmon, 76 (20.5%) pink salmon O. gorbuscha, 45 (12.1%) steelhead (20 in winter and 25 in summer), 35 (9.4%) coho salmon O. kisutch, 33 (8.9%) bull trout Salvelinus confluentus, 4 (1%) sockeye salmon O. nerka, and 3 (0.9%) chum salmon O. keta. For all salmonids except Chinook salmon carcasses, the weir collected a greater number of fish in 2012 than the average of the previous two years (2010 and 2011). A total of 79 (45.4% of all) Chinook salmon captured at the weir in 2012 were held for brood stock purposes.