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Annual abundance of outmigrating salmonids has been identified as a key performance measure of the success of the restoration program being implemented in the Trinity River. The Hoopa Valley Tribal Fisheries Department (HVTFD) has monitored the outmigration of salmonids in the Trinity River since 1997, using rotary screw traps. The primary focus of this monitoring program is to track abundance and trends in abundance of Chinook salmon Oncorhynchus tshawytscha, coho salmon O. kisutch and steelhead trout O. mykiss naturally produced between Lewiston Dam, which forms a barrier to upstream migration of anadromous salmonids, and the North Fork of the Trinity River. Salmonid production in this section of river is of primary interest due to the river restoration activities there.

In 2022, HVTFD operated a rotary screw trap (RST) in the Trinity River at river kilometer (rkm) 118, about 1 km upstream of the confluence with the North Fork of the Trinity River near the Pear Tree Bar; this RST will be referred to as the Pear Tree rotary screw trap, PTRST. This report describes the methods used, brief description of the results, and plans for the future report. HVTFD operated the PTRST for a total of 34 weeks in 2022 between January 10 and August 27. During this time there was recorded catch of both naturally produced and hatchery produced steelhead, coho, and Chinook.

The analysis estimating season long outmigrant Chinook salmon, coho salmon, and steelhead will be conducted the US Fish and Wildlife Service (USFWS) office in Arcata, Ca., and reported in the report 2022 Juvenile Salmonid Monitoring on the Mainstem Trinity River produced by the USFWS. The HVTFD has reported a summary of the 2022 data to the USFWS; data is reported in a series of tables that will be included in the 2022 USFWS out-migrant report and can be found attached to this current report as Appendices I-VIII.

Net catch at the PTRST included 55,401 Chinook, 563 coho salmon, and 1,479 steelhead. Daily flow measurements at the trap were used to estimate weekly flow-based abundance indices for Chinook salmon, Coho salmon, and steelhead for the weeks the trap was operated. The season total estimate of Chinook salmon (hatchery and naturally produced) was 679,459, 10,169 coho salmon, and 15,357 steelhead. In order to estimate trap efficiency, a mark-recapture study using hatchery produced Chinook salmon from the Trinity River Hatchery was conducted during for 18 weeks between the 10th and 32nd weeks of the year. Overall trap efficiency during that period was estimated to be around 3.2%.

Condition factor of outmigrating salmonids is also calculated and reported here using Fulton’s body condition factor (K). The average condition factor for age-0 Chinook condition factor was 0.967 (s.d. = 0.146). Coho condition factor averaged 1.149 (sd = 0.476) across the weeks when it could be calculated and did not vary significantly across the sampling season. Steelhead condition factor averaged 1.088 (s.d. = 0.043) across the weeks when it could be calculated and did not vary significantly across the sampling season.