The Effect of Yakima River Spring Chinook Salmon Sire Life History Type on Emergence Timing and Size of Progeny

Abstract

Two sets of half-sib families of Chinook salmon Oncorhynchus tshawytscha were generated by crossing four full-size anadromous males and four early-maturing males with each of two full-size anadromous females (eight males × two females) obtained from the Cle Elum Supplementation Research Facility on the Yakima River. Emergence timing differed by up to 5 weeks between families, with a highly significant difference between females. Within females there was no significant effect of male life history type on either median emergence timing or fry size; however, there was a suggestion of a relationship between individual sire and progeny emergence timing. There were significant differences in fry weight at emergence between the two females, but sire did not influence fry weight at emergence within females. This study demonstrates that ecologically significant differences in emergence timing may be generated solely through genetic and maternal affects, as all parents were spawned on the same day and all progeny were reared within a common thermal regime.