Document Details Page

California Department of Fish and Wildlife's Trinity River Project conducted tagging and recapture operations from June 2022 through March 2023 to produce run size, angler harvest, and spawner escapement estimates of spring and fall Chinook Salmon (Oncorhynchus tshawytscha), Coho Salmon (O. kisutch), and fall steelhead (O. mykiss) in the Trinity River basin. Monitoring results inform the Trinity River Restoration Program’s adaptive management decision making process and help evaluate progress toward achieving fundamental objectives outlined in the Integrated Assessment Plan (TRRP 2009). Additionally, run size estimates are used in annual fishery management decisions, feeding into the Pacific Fishery Management Council’s Klamath River basin fishery regulation and harvest allocation process.

Using a Petersen mark-recapture methodology, we estimated 13,262 (95% CI 12,420 – 14,136) spring Chinook Salmon migrated into Trinity River basin upstream of Junction City weir. The run was comprised of an estimated 575 jacks (493 natural-origin [NOR] and 82 hatchery-origin [HOR]) and 12,687 adults. Using tags returned by anglers we estimate harvest of 0 jack and 185 adult spring Chinook, yielding a total escapement of 13,077 fish, including 4,151 spring Chinook that entered Trinity River Hatchery and 8,926 estimated natural area spawners. We had insufficient data to estimate the contribution of HOR adults to the total run because the 2019 brood year was not marked (ad-clipped and coded-wire tagged) due to COVID-19.

An estimated 14,179 (95% CI 12,909 – 15,511) fall Chinook Salmon migrated upstream of Willow Creek weir in 2022. The run consisted of an estimated 3,772 jacks (1,880 NOR and 1,892 HOR) and 10,407 adults. Using tags returned by anglers we estimate harvest of 144 jack and 173 adult fall Chinook Salmon, yielding an escapement of 13,862, including 4,938 that entered Trinity River Hatchery and 8,924 estimated natural area spawners. We had insufficient data to estimate the contribution of HOR adults to the total run because the 2019 brood year was not marked (ad-clipped and coded-wire tagged) due to COVID-19.

Coho Salmon run size and escapement in the Trinity River upstream of Willow Creek weir were both estimated at 6,551 (95% CI 5,995 – 7,135), as no harvest was reported. The run consisted of 617 jacks (25 NOR and 591 HOR) and 5,934 adults (550 NOR and 5,384 HOR). Escapement of 550 NOR Coho Salmon adults was 39.3% of the Trinity River Restoration Program (TRRP) goal of 1,400 fish.

Coho Salmon run size and escapement in the Trinity River upstream of Junction City weir were both estimated at 4,292 (95% CI 3,710 – 4,916), with no reported harvest. Escapement consisted of 282 jacks (28 NOR and 254 HOR) and 4,010 adults (356 NOR and 3,653 HOR), including 18 NOR and 12 HOR adults that were removed from the river at Junction City weir and trucked to Trinity River Hatchery as part of a broodstock collection project to implement the hatchery’s genetic management plan (CDFW 2017). There is no TRRP goal for this sector.

Using a Petersen mark-recapture methodology we estimated 10,597 (95% CI 7,962 – 14,780) adult fall steelhead returned to the Trinity River basin upstream of Willow Creek weir. Anglers harvested an estimated 322 (126 NOR, 196 HOR) adult fall steelhead upstream of the weir, leaving 10,274 (7,642 NOR and 2,632 HOR) fish as potential spawners. Of those potential spawners, 1,051 (53 NOR, 998 HOR) were recovered at TRH, and an estimated 9,223 (7,589 NOR, 1,634 HOR) escaped to natural areas. Escapement of 7,642 NOR adult steelhead is 19.1% of the 40,000 fish TRRP goal.