Endocrine responsiveness in Chinook salmon

Ichthyophonus hoferi is a parasite infecting various fish species, including Chinook salmon. While the parasite is not harmful to humans, the effects on the fish host can be devastating and include reduced endurance and fecundity, in addition to pre-spawning mortality. Poor returns of Arctic-Yukon-Kuskokwim (AYK) salmon stocks are a concern to both managers and fishermen and introduce uncertainties about the involvement of pathogens and their impacts on fish populations. This study will address effects of Ichthyophonus infection on Yukon River Chinook salmon egg and milt quality (as determined by proximate analysis) as well as hatching success, morphometric parameters, and stress hormone levels in yolk-sac and swim-up fry. Current management regimes do not take into account potential detrimental effects of disease on spawning fish and their offspring once they pass counting towers or weirs. The proposed research will therefore not only provide information on escapement quality, but also advance knowledge of physiological impacts of disease effects on spawning success.