Chinook/Coho Salmon Updates 2023-24

May 2024:  Since 2001, the California Department of Fish and Wildlife has operated rotary screw traps (RST) on the Scott and Shasta Rivers to estimate abundances of outmigrating Chinook Salmon (Oncorhynchus tshawytscha), Coho Salmon (Oncorhynchus kisutch) and rainbow trout/steelhead (Oncorhynchus mykiss). The Scott River RST’s are located approximately 7 river kilometers (RK) upstream from the confluence with the Klamath River, while the Shasta River RST is located approximately 0.2 RK from the confluence with the Klamath River. The data presented below are preliminary and subject to revision.

SHASTA RIVER The Shasta River RST has been operational since January 30, 2024. Preliminary population estimates are provided as data allowed. 

MARK RECAPTURE POPULATION ESTIMATES

When data are sufficient, weekly trap efficiencies are reported here, otherwise, the season-to-date trap efficiency is used to generate the 7-day estimate. Total season-to-date trap efficiencies are calculated by dividing the total recaptures to date by the total released to date.

 Chinook Salmon

• 1. Age 0+ Chinook Salmon weekly trap efficiency is 21% with a preliminary population estimate (Carlson et al. 1998) of 62,831 for JW17 ending on April 29, 2024. Year-to-date, age 0+ Chinook Salmon total trap efficiency is 11% with an estimated 4,753,602 age 0+ Chinook Salmon total having outmigrated from the Shasta River.

• 2. Due to no age 1+ Chinook Salmon observed in the trap this week we are not able to calculate a preliminary population estimate (Carlson et al. 1998) for JW17 ending on April 29, 2024.  Year-to-date, age 1+ Chinook Salmon total trap efficiency is 15% with an estimated 262 age 1+ Chinook Salmon total having outmigrated from the Shasta River.

Coho Salmon

•1. Age 0+ Coho were first observed on March 13, 2024. Mark recaptures trials have not yet begun for age 0+ Coho.

• 2. Age 1+ Coho Salmon weekly trap efficiency is 20% with a preliminary population estimate (Carlson et al. 1998) of 170 for JW17 ending on April 29, 2024.  Year-to-date, age 1+ Coho Salmon total trap efficiency is 16% with an estimated 672 age 1+ Coho Salmon total having outmigrated from the Shasta River.

For more information on the Scott River RST or other locations within the Klamath River Basin contact the CDFW Yreka Office.