Newaukum Adult Salmon and Steelhead Spawner Abundance, 2021-22

The Newaukum River basin was selected as a “pilot watershed” in 2015 by Chehalis Lead Entity to help guide and monitor salmon recovery projects in the Chehalis River basin with the goal of assessing limiting factors, data gaps, and restoration targets (http://www.chehalisleadentity.org/our-work/). Since then, both an adult and juvenile monitoring program have been implemented in the basin, allowing for adult and juvenile in-stream production estimates. This report covers the 2021-2022 survey season of intensive adult spawner monitoring in the Newaukum basin for spring and fall Chinook Salmon (Oncorhynchus tshawytscha), Coho Salmon (O. kisutch), and steelhead trout (O. mykiss).

A census redd (salmon nest) survey was conducted for all salmonids for the 2021-2022 season in the Newaukum basin (total escapement for Chinook and Coho Salmon in the 2021 run year and steelhead escapement in 2022 run year). However, due to the high flows and broad distribution of Coho Salmon in small creeks and tributaries with many private landowners, we were unable to completely survey all spawning habitat. The majority of spawning habitat was surveyed, and either a supplemental survey or a redd mile-1 estimate was used to expand redds for un-surveyed spawning habitat to generate a total estimate. Major findings for the 2021-2022 season were:

• Spring Chinook adult abundance of 545 spawners in 2021 was less than the 20-year average.
• Fall Chinook abundance in 2021 was 423 adult spawners, less than half of the previous year’s abundance (1,063 spawners) and the 20-year average (995 spawners). Also of note is the fall Chinook abundance estimate was less than that of spring Chinook.
• Genetic analysis of run timing markers of opportunistically collected salmon carcasses showed hybridization between fall and spring run types; 23% of the samples came back as heterozygotes with the majority of those from downstream of Onalaska on the South Fork Newaukum.
• Spring and fall Chinook spawning distribution overlapped spatially and temporally however, there appears to be some separation between early Spring Chinook spawners in the upper South Fork above Onalaska. The fall Chinook spawners that reach these upper reaches appear to do so after most of spring Chinook have spawned. This is observed in both the redd timing information combined with live observation and the genetic testing from carcasses sampled.
• Both fall and spring Chinook distribution and spawning were greatly reduced in the North Fork Newaukum when compared to the previous year’s distribution. Likely, a combination of lower run size and reduced flows during migration and spawning.
• Coho Salmon nearly doubled in escapement when compared to 2020 and was the most abundant salmonid species in the Newaukum basin with 5,594 spawners.
• Hatchery Coho Salmon spawning in the Newaukum Basin quadrupled to 833 spawners in 2021 from around 200 spawners in the previous two years.
• Steelhead spawner abundance was 766 adults, 15% lower than the 20-year average.
• Steelhead were mostly distributed in the upper North and South forks of the Newaukum River with few spawning in the lower parts of the forks or the Middle Fork Newaukum. Only one steelhead redd was observed in the main stem Newaukum River below the confluence of the North and South forks.

On average (run years 2000 to 2020), the Newaukum River contributed between 18% and 45% of the Chehalis River spring Chinook spawning population, yet both Newaukum River and Chehalis River basin populations have declined since 2000. In 2021, the Newaukum contributed 21% to the overall spring Chinook total spawner abundance, yet this was lower than the average (28%) for the time series indicating that Newaukum River spring Chinook contribution is still below the long-term average. Through long term monitoring of the Newaukum River, our program will generate a time series of species distribution, spawner abundance, life history diversity, and other population-level metrics (e.g., productivity) that will be valuable as restoration projects are implemented throughout the Chehalis Basin.