ADFG 2022 3 Rivers Index Letter
On September 22, 2022, the Alaska Department of Fish & Game (ADF&G) submitted its annual 3 Rivers Index letter to NOAA Fisheries with preliminary 2022 total Chinook salmon run estimates, harvest levels, and spawner escapements to the Unalakleet, Yukon, and Kuskokwim Rivers. The combined Chinook salmon run sizes from these three rivers determine the Chinook salmon bycatch cap set by the North Pacific Fishery Management Council (NPFMC) for the following year’s Bering Sea commercial pollock fishery.
According to ADF&G, “The 2022 three-system index of inriver adult Chinook salmon run sizes from the Unalakleet, Upper Yukon, and Kuskokwim rivers is 158,646 and is below the threshold level of 250,000.” This means the Chinook salmon bycatch cap in the 2023 Bering Sea-Aleutian Island pollock fishery will be 45,000 Chinook salmon.
ADF&G’s analysis of the Kuskokwim River fishery reads:
“The preliminary postseason run size estimate of Kuskokwim River Chinook salmon is 143,622 fish (95% CI: 106,565–193,565), based on preliminary results of a maximum likelihood model. The total run estimate was informed by direct observations of escapement and an expectation of drainagewide harvest. The preliminary escapement estimate (105,774) is uncertain (95% CI: 68,717–155,717) because the model was informed by only three weir projects. Poor weather conditions prevented the department from flying aerial surveys during the 2022 season, and those indices of escapement were not available to inform the model. The total harvest of Kuskokwim River Chinook salmon is expected to be 37,848. No commercial harvest of Kuskokwim River Chinook salmon occurred during the 2022 season. Nearly all harvest occurred in the subsistence fishery, and minimal harvest occurred in test fisheries operated by the department and collaborators. Subsistence fishing restrictions were implemented throughout the Chinook salmon run in 2022. U.S. Fish and Wildlife Service (USFWS) estimated that approximately 29,300 Chinook salmon were harvested within a portion of the Yukon Delta National Wildlife refuge during subsistence fishing openings announced by Federal Special Actions. A preliminary estimate of drainagewide subsistence harvest was generated using a six-year relationship between partial harvest estimates developed inseason by USFWS and drainagewide estimates developed postseason by the department. The preliminary total run size of Kuskokwim River Chinook salmon was within the preseason run forecast of 99,000–161,000 fish and is consistent with an independent partial run estimate of 144,997 (90% CI: 114,988–175,006) Chinook salmon, based on a sonar project operated near Bethel, Alaska.”