The effect of spawning time and incubation temperature on meristic variation in chum salmon (Oncorhynchus keta)

Abstract

Variability in the number of dorsal, anal, caudal, pectoral, and pelvic fin rays, vertebrae, and gill rakers of early and late spawning stocks of Chehalis River chum salmon (Oncorhynchus keta) incubated under controlled water temperatures of 4, 8, and 12 °C was examined. The early spawning stock had fewer dorsal fin rays, more anal fin rays, fewer pectoral and pelvic fin rays, and fewer gill rakers than did the late spawning stock. Chum salmon originally incubated at 4 °C had the lowest number of dorsal fin rays, but the highest number of vertebrae and gill rakers. Chum salmon originally incubated at 8 °C had the highest number of anal fin rays, and those incubated at 12 °C had the highest number of pectoral fin rays. Meristic phenotypes had both a genetic and an environmental component.