Hoh River Steelhead Project 2016 Annual Report

The purpose of Hoh River Steelhead Project is to better explain steelhead abundance trends and how they are related to survival and diversity in marine and freshwater environment. The program is led by the Science Division at the Washington Department of Fish and Wildlife and is a collaborative effort with managers and stakeholders. In 2016, we conducted pilot studies and our work included sonar siting and operation and a volunteer angler study.

We surveyed the main stem Hoh River and identified multiple locations that may be suitable for sonar (adult monitoring) and smolt trap (smolt monitoring) operations. We further evaluated the feasibility of three potential sites with an ARIS Explorer 1800 sonar. One location was selected for future work based on the image quality, site access, site security, and ability to account for harvest above and below the location. A flow of ~4,500 cubic feet per second will be used as an upper threshold for sonar operation. Based on stream flows over the past decade, the highest frequency of sonar outages will occur between November and January (67 to 78% operational) whereas the sonar is predicted to be operational at least 85% of the time in the remaining months of the year. In 2016, the sonar was operated intermittently at three different locations and recorded data 59% of the time between February 10 and May 20, 2016. In total we observed 1,889 fish targets (> 55 cm fork length) moving upstream and 750 fish targets moving downstream. In the future, species composition sampling will be needed to apportion counts of the fish targets observed in the sonar imagery to specific species.

A volunteer angling program collected biological data including location, origin (hatchery or wild), gender, length, girth, and scales. Scales were used to describe steelhead residency in freshwater and ocean environments as well as repeat spawn rates. Steelhead averaged 73.0 cm fork length and 33.5 cm girth with males being slightly longer and wider than females. Residency of wild steelhead ranged between one and three years in freshwater and two to four years in the ocean. Five percent of females and no males were repeat spawners. Multiple years of sampling should improve understanding of how steelhead life histories are associated with time of entry and location of return. Recommendations developed for the 2017 field season include continual operation of the sonar between January and June, in-stream tangle netting to interpret species composition, continuation and expansion of the volunteer angling program with a focus on increasing the spatial coverage of the data collection to include the South Fork Hoh River and the Hoh River within Olympic National Park.