Inseason harvest and effort estimates for the 2023 Kuskokwim River subsistence salmon fisheries during block openings

ABSTRACT: Management of subsistence fisheries for salmon (Oncorhynchus spp.) in the Kuskokwim River has historically been conducted with minimal inseason harvest information. Due to this lack of information, managers have faced challenges making well-supported and defensible inseason decisions regarding fishing opportunities that simultaneously achieve conservation and subsistence harvest objectives, particularly during years of weak Chinook Salmon (O. tshawytscha) runs. In response to conservation concerns for the 2023 Kuskokwim River Chinook and Chum (O. keta) salmon runs, as well as for Coho Salmon (O. kisutch) following weak returns in 2022, the Kuskokwim River Inter-Tribal Fish Commission (KRITFC), in collaboration with the United States Fish and Wildlife Service–Yukon Delta National Wildlife Refuge, the Orutsararmiut Native Council (ONC), and independent contractors collected and processed data to produce inseason subsistence salmon harvest estimates from the mainstem Kuskokwim River within the boundaries of the Yukon Delta National Wildlife Refuge, between and including the villages of Eek and Tuluksak. Input data included: drift and set gillnet counts from aerial surveys; subsistence harvester interviews by ONC at the Bethel boat harbor, and Bethel, Oscarville, and Napaskiak area fish camps, and by USFWS and KRITFC at the Bethel boat harbor; and subsistence harvester interviews by KRITFC community-based harvest monitors from the Lower Kuskokwim River villages of Eek, Tuntutuliak, Napakiak, Napaskiak, Kwethluk, Akiachak, Akiak, and Tuluksak. Using methods developed and refined during 2016–2018, the best minimum estimate of total subsistence salmon harvest in the study area was 69,350 (95% confidence limits [CL]: 64,350–74,800) during 18 fishing opportunities with data collection between June 1 and August 12, 2023. Most salmon harvested were Sockeye Salmon (O. nerka; 28,940; 25,500–32,760), followed by Chinook Salmon (21,050; 95% CL: 19,240–23,040), Chum Salmon (11,930; 10,770–13,230), and Coho Salmon (7,420; 6,660–8,240). These estimates do not include harvests that (a) occurred in tributaries of the lower Kuskokwim River, (b) occurred downriver of the lower river boundary of Eek Island or upriver of Bogus Creek, (c) arose from non-gillnet capture methods, or (d) occurred during fishing opportunities on July 1, 5, 6, 7, 8, 21 and 26. While the sampling and analytical methods remained standardized and generally consistent with previous years, harvest and effort estimation for the 2023 season, similar to 2022, was facilitated by a customized software package (termed ‘KuskoHarvEst’) for program R that provides an intuitive, menu-driven workflow. This allowed the coauthors to independently execute the estimation model and confer on results. This software will be useful for future seasons in which inseason harvest and effort estimates are desired for the lower Kuskokwim River subsistence salmon fishery and during which similar sampling occurs.