37 Mortality during incubation is believed to be a major factor limiting the recovery 38 of many salmon populations though direct field measurements of egg-to-fry survival are 39 rare or small in scale. To determine the effects of physical habitat (river reach, fine 40 sediment intrusion, scour), parentage (mating/source of gametes) on Chinook salmon 41 (Oncorhynchus tshwaytscha) egg-to-fry survival and developmental stage at emergence 42 across a basin, we constructed 324 artificial redds in

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... ne reaches over four years in the 43 Yakima River Basin, Washington, USA. Average egg-to-fry survival ranged from 49% to 44 69% among reaches from 2009 to 2012 brood years. Survival was significantly different 45 among reaches in 2010, but not 2009, 2011 or 2012, while mating was a significant factor 46 in all years but 2010. In contrast, developmental stage differed significantly among 47 reaches and matings in all four years. Percent of fines, days-in-gravel and median particle 48 size explained only small (<10%) additional amount of variation in survival or 49 developmental stages. Our results suggest that parentage and reach within a basin are 50 major factors influencing egg-to-fry survival, but their relative influence vary annually 51 presumably depending on the magnitude of high flows and scour during incubation. 52 53