2021 and 2022 Snohomish River Basin Juvenile Outmigration Monitoring FY 2020

Installation of the Skykomish and Snoqualmie screw traps began on February 28th 2021 and full trapping operations commenced on March 4th on the Skykomish trap and March 16th on the Snoqualmie trap. Trapping operations were initially delayed by heavy floods, making roads inaccessible for staff and trap assembly. The 2021 season ended on May 5th on the Skykomish trap due to a large cotton wood tree getting lodged just upstream of the traps and making operation of the trap unsafe given that we did not know when or if the tree would continue to drift down river into the trap, so we erred on the side of caution and ceased operation of the Skykomish screw trap. The sampling season on the Snoqualmie trap ended June 17th. Operation of the traps was greatly reduced due to social distancing issues which effected our ability to effectively staff and operate the traps. Each shift was manned by a two person crew that would only work together so as to reduce the possibility of spreading Covid across multiple staff. A total of three scheduled sampling events were cancelled due to unfavorable sampling conditions (i.e. high debris and discharge levels). As a result, the Snoqualmie trap was operated for approximately 764.4 hours from Statistical Week (SW) 12 - 25. Of those 764.4 hours, 332.7 hours were fished at night, representing 44% of total trapping effort. On the Snoqualmie trap 1,722 salmon and trout were captured, counted and released on the Snoqualmie trap. Captured unmarked Chinook included 586 sub-yearlings and 0 yearlings. Catch per unit effort (fish/hour) of unmarked Chinook (0.77); project average CPUE is 0.61 (2001-2019). Project average catch of sub -yearling Chinook is 529. Captured unmarked Coho included 563 yearling and 602 sub-yearlings. Catch per unit effort of unmarked Coho (0.74); project average is 1.39. Project average catch of Coho yearlings is 1,136 fish.

The Skykomish trap was operated for approximately 287 hours over eight week period from Statistical Week (SW) 10 to 19. Of those hours, 141 were fished at night representing 49% of total trapping effort. On the Skykomish trap a total of 14,522 salmon and trout were captured, counted, and released. Captured unmarked chinook included 1,739 sub-yearlings (0+) and 4 yearlings (1+). Unmarked Chinook sub-yearlings 2004-2019 average: 2,045. Captured unmarked Coho included 106 sub-yearlings and 181 yearlings. Unmarked Coho yearlings 2004-2019 average: 4,204. During the trapping and handling process a total of 5 salmonid mortalities were reported, of which 0 were unmarked Chinook

Unspent FY20 funds were carried over to fund trap operations in 2022. FY20 PCSRF funds were utilized to pay staff on the smolt traps until mid April 2022.

Overlapping PCSRF project timelines occur due to the fact that we use several funding sources to operate the screw traps. The application and award announcements for these grants operate on different schedules. When we apply for the PCSRF funds we have to assume we will not receive these additional funds since they are competitive grants. More funds were rolled over than usual due to the shutdown of the smolt traps on March 14th 2020 due to the pandemic and the smaller crew used in 2021 to ensure social distancing.



All initially proposed funds for this project were spent towards the initial scope. The scheduled end date was not updated once the project began, but if it would have been it would have reflected a CY 2021 completion, which explains why the CY 2022 completion was actually later than usual for the reasons described in the actual description.

In May of 1999, the National Marine Fisheries Service (NMFS) listed the Puget Sound Chinook salmon as threatened under the federal Endangered Species Act (ESA). This listing included Chinook salmon from the Snohomish River Basin (Skykomish and Snoqualmie populations). The recovery of these species depends upon improving the effectiveness of habitat, harvest, and hatchery management across the basin. In order to achieve such improved effectiveness, additional information is necessary to fill important data gaps within the Snohomish system and to assess impacts of restoration efforts, including information on Chinook and Coho salmon abundance, productivity, spatial structure, and diversity (Snohomish Basin Salmonid Recovery Technical Committee, 2005) (. Information about the trends and inter-annual variability in these population parameters is critical to inform salmon recovery efforts, provides basic information on the productivity and capacity of the system, and can lead to significant improvements in harvest management modeling and run forecasting. Additionally, the monitoring of production and survival along with other physical, chemical, and biological conditions provides a means to evaluate recovery actions, habitat conditions, and potential ecological trajectories in the basin.



A key component to provide information on Snohomish salmon populations is the operation of two rotary screw traps in the Skykomish and Snoqualmie rivers. These projects involved trapping and enumerating juvenile Chinook and Coho salmon (as well as several un-targeted species) as they emigrate from the Snohomish River Basin to the Puget Sound. The goals of these trapping efforts are to estimate Chinook and Coho salmon natural production, migration patterns, and freshwater survival. The goal of this project is to track Chinook and coho production and survival information and migration timing within the Snohomish river basin, which can be used in part to evaluate salmon recovery efforts in the various portions of the watershed, to refine preseason run size forecasting by harvest managers, and used in combination with other monitoring and research efforts to better understand and identify priority restoration areas. These goals are accomplished through the direct quantification of juvenile salmon emigrations, evaluation of trap efficiency, and assessment of influential environmental attributes.