Lummi Nation Nooksack River Basin Salmonid Population Assessments, FY23

Two rotary smolt traps will be operated in the Nooksack River, one in the lower mainstem (which has been operated since 1994) and one in the South Fork. The additional smolt trap in the South Fork will expand our ability to calculate outmigration survival and aid in expanding mark/recapture estimates based on PIT tagging data. Fishery biologists and technicians will operate both traps during the principal outmigration period from approximately January to August. Additional beach seine sampling at various sites across the basin will be conducted to increase sample sizes for DNA collection to enumerate differences in population and origin productivity (i.e. hatchery vs. natural origin; North Fork/Middle Fork vs. South Fork population). Production estimates will be made for Chinook, steelhead, coho and other salmonids from modeled expansion of trap catches. These data are used for pre-season run forecasting and run reconstruction efforts with co-managers.



Field staff will participate in co-manager spawning ground surveys in South and Middle Forks of the Nooksack River with emphasis on Chinook salmon. River water temperature, turbidity, discharge, and stage height are monitored to help interpret survey results and to assist with field scheduling. Spawner survey data will be shared with other co-managers to develop Chinook escapement estimates using a traditional approach based on visual redd and fish carcass counts. Ongoing genetic mark-recapture escapement techniques using DNA data collected from spawner carcasses and smolt trap outmigrants will be compared with methods that rely on visual counts.



Additionally, LNR staff will conduct salmon harvest sampling, including commercial harvest and spring tangle net fisheries. The tangle net fishery is a mark-selective fishery with 100% catch sampling of all directed and bycatch species. These activities generally occur between April and June and regulations are outlined in the Chinook resource management plan.

The expected benefits of providing more accurate and complete population estimates and habitat use for adults and juveniles are: 1) evaluation and identification of restoration activities that will have or could have the largest impact on recovery, 2) improved ability to identify factors limiting recovery, such as predation or toxicity that habitat restoration cannot address and that may require other actions or solutions.