2018 and 2019 Snohomish River Basin Juvenile Outmigration Monitoring

Installation of the Skykomish and Snoqualmie screw traps began on February 12th 2018 and full trapping operations commenced on February 8th. The 2018 season ended on June 15th for the Snoqualmie River trap and June 14th for the Skykomish River trap. The Skykomish trap was fished for approximately 836 hours over 85 days the Snoqualmie trap was fished for approximately 1,117 hours over 85 days.
For the Skykomish Trap the fishing effort consisted of 325 hours of night representing 39% of total trapping effort. A total of 18 sampling events (both schedule cancellations, and unscheduled potential sampling days) were ultimately cancelled due to unfavorable sampling conditions. During the sampling season 104,269 salmon and trout were captured, counted and released. Of those fish, Pink salmon totaled 78,314 accounting for 75% of the total salmonid catch for 2018. Captured unmarked Chinook included 4,407 sub-yearlings and 79 yearlings. The number of Chinook sub-yearlings caught at the Skykomish River trap has varied widely from year to year, with this years’ total approximately 227% higher than the project average (2004-20178 average; 1,938). Captured unmarked Coho included 239 sub-yearlings and 1,583 yearlings. The number of unmarked Coho yearlings caught in 2018 was 36% lower than the project average (2004-2018 average: 4,343).
For the Snoqualmie trap fishing effort consisted of 445 hours of night fishing representing 40% of the sampling hours. A total of 6 scheduled sampling events were ultimately cancelled due to unfavorable sampling conditions (i.e. high debris and discharge levels). During the sampling season 11,274 salmon and trout were captured, counted and released. Of that number, 7,374 were sub-yearling Pink salmon fry accounting for 65% of the total catch. Captured unmarked Chinook included 1,508 sub-yearlings and 97 yearlings. The number of Chinook sub-yearlings caught at the Snoqualmie River trap has varied widely from year to year, with the catch in 2018 being the highest documented in project history; over three times the project average (2001-2018 average; 523). Captured unmarked Coho included 1,517 yearlings and 521 sub-yearlings. The number of unmarked Coho yearlings caught is 23% higher than the project average (2001-2017 average: 1,165).
In February 2018 we were informed we would be receiving additional funds from the Pacific Salmon Commission (PSC) to operate the screw traps and collect juvenile Chinook DNA. We did not receive the award funds until the end of May 2018 and had to bill all trap operations for the remainder of the sampling season to this fund in order to spend it down. This resulted in a disruption of our planned spending schedule and resulted in carrying over of FY 2017 PCSRF funds into the next project year, 2019. We utilized the remaining FY 2017 funds to fund the first portion of the operation of the screw traps in 2019 which were expended by the end of March 2019.
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. When we receive these competitive awards we have to spend them within the award year and as a result our projected spending schedule for PCSRF funds is disrupted which result is shifting of the end date for the PCSRF project.

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 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.