The overall goal of this proposed work is to quantify the density of ichthyophonus infections from foursample locations along the mainstem yukon river, including fort yukon, and opportunistically…

The overall goal of this proposed work is to quantify the density of ichthyophonus infections from foursample locations along the mainstem yukon river, including fort yukon, and opportunistically evaluatechinook, chum, and prey fish species captured in the northern bering sea (NBS) and southern beringsea (SBS) surveys. Lastly, funds would be used to directly test samples collected from the fourth location, fort yukon, and marine fish in the NBS and SBS.objective 1: use qpcr and histopathology to assess ichthyophonus infection and disease in yukonchinook salmon samples collected from fort yukon. Funds for the fish pathology lab to process thesesamples are currently lacking and this sample location is a vital site for the study at-large.objective 2: use qpcr to screen for ichthyophonus and quantify infections in immature chinook andchum salmon, walleye pollock and forage fish species opportunistically captured in the 2024 NBS andsbs surveys. Qpcr positive samples will be confirmed with histopathology. Funding support forcontinued assessment of ichthyophonus infections in chinook salmon from the NBS and SBS surveys andexpanded testing to chum salmon from these platforms. We hypothesize that ichthyophonus infectionswill occur in chinook and chum salmon at an unknown prevalence and intensity that may differ by hostage, size, or SEX. We also hypothesize that ichthyophonus infection will occur in walleye pollock andforage fish species at an unknown prevalence and intensity that will provide insight into possibleinfection sources for yukon river chinook and chum salmon. The vision of this project beyond this current funding year is to support the intended long-term annualmonitoring program for ichthyophonus in yukon chinook salmon collected from the pilot station testfishery performed inseason to assist managers with estimating EN route mortality for their managementdecisions. Research is needed to develop this program by comparing infections from different riverlocations. Monitoring infections from marine samples collected from the NBS and SBS surveyscomplements this work by providing information on infections in salmon used for future run forecasts asheavily infected fish may indicate a source of variation in estimates for forecasting. This could beextended to the key prey species if determined from this research. Anticipated outcomes include: 1) vitalinformation about infection and parasite-associated mortality by testing fish upriver (i.e., fort yukon)where survivors will be compared to infections lower in the river, 2) determining infection levels insalmon from the NBS and SBS surveys to provide managers with infection and disease information thatmay be qualitatively considered in the context of preseason run forecasts, and 3) an initial determinationof key prey species that infect NBS and SBS salmon. The work will benefit the U.S. Fish and wildlifeservice, alaska department of fish and game (ADF g), and department of fisheries and oceans canadatasked with assessing population abundance and fishing opportunities. IT will also directly benefit thesubsistence fishery via better informed management and may aid in postseason assessment canadianorigin chinook salmon fates, as required to address U.S. Canada treaty obligations. ADF g intends tocontinue operating an ichthyophonus monitoring project for the foreseeable future if sufficiently funded.laboratory reports and any peer-reviewed manuscripts will be available to agency staff and the public. This project involves a partnership with local fishers and yukon river residents contracted to collect fishwith opportunities to learn about fish anatomy, necropsy, and disease during sample collection. Allsampled fish from the yukon river will be provided back to the communities where sampled so residentscan use them for cultural and food security needs. This work is of interest to both alaskans andcanadians.