Abundance and Run Timing of Adult Salmon in the Gisasa River, Koyukuk National Wildlife Refuge, Alaska 2022: Alaska Fisheries Data Series Number 2024-2

A resistance board weir was operated by the U.S. Fish and Wildlife Service, Northern Alaska Fish and Wildlife Field Office to collect information on abundance, run timing, and biology of returning adult Chinook Salmon Oncorhynchus tshawytscha and summer Chum Salmon O. keta in the Gisasa River. The weir has been operated at this location since 1994 except for 2018, 2020, and 2021. This is the fifth year video technology has been incorporated into the project since 2015. In 2022, the weir was operated from the end of the day on June 29 through the morning of July 29 during which an estimated 503 Chinook Salmon and 3,300 summer Chum Salmon passed through the weir. Other species enumerated through the weir, in order of abundance, were Northern Pike Esox lucius (N = 22), Longnose Sucker Catostomus catostomus (N = 10), Broad Whitefish Coregonus nasus (N = 9), Sockeye Salmon O. nerka (N = 5), Humpback Whitefish Coregonus pidschian (N = 3), Arctic Grayling Thymallus arcticus (N = 1), and Pink Salmon O. gorbuscha (N = 1). A total of 42 Chinook Salmon and 294 summer Chum Salmon were sampled for age, sex, and length (ASL) data. The sample size goal was not met for Chinook Salmon and ASL analyses could not be performed for this species. The summer Chum Salmon run was composed of four strata (July 4 through 13, July 14 through 17, July 18 through 24, and July 25 through 28). The percent female for all strata combined was 55. There were two primary age classes identified for summer Chum Salmon, 0.3 and 0.4. Length-at-age of male summer Chum Salmon was larger than females.