Interannual variability in the effects of physical habitat and parentage on Chinook salmon egg-to-fry survival

Roni, Philip, Johnson, Christopher, De Boer, Trenton, Pess, George, Dittman, Andrew and Sear, David (2016) Interannual variability in the effects of physical habitat and parentage on Chinook salmon egg-to-fry survival. Canadian Journal of Fisheries and Aquatic Sciences, 73 (7), 1047-1059. (doi:10.1139/cjfas-2015-0372).

Abstract

Mortality during incubation is believed to be a major factor limiting the recovery of many salmon populations, though direct field measurements of egg-to-fry survival are rare or small in scale. To determine the effects of physical habitat (river reach, fine sediment intrusion, scour), parentage (mating, source of gametes) on Chinook salmon (Oncorhynchus tshawytscha) egg-to-fry survival and developmental stage at emergence across a basin, we constructed 324 artificial redds in nine reaches over 4 years in the Yakima River Basin, Washington, USA. Mean egg-to-fry survival ranged from 49% to 69% annually from 2009 to 2012 brood years. Survival was significantly different among reaches in 2010, but not in 2009, 2011, or 2012, while mating was a significant factor in all years but 2010. In contrast, developmental stage differed significantly among reaches and matings in all 4 years. Percentage of fines, days-in-gravel, and median particle size explained only small (<10%) additional amount of variation in survival or developmental stages. Our results suggest that parentage and reach within a basin are major factors influencing egg-to-fry survival, but their relative influence varies annually, presumably depending on the magnitude of high flows and scour during incubation.

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Contributors

Author: David Sear

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