Pink salmon (Oncorhynchus gorbuscha) from a single introduction to Lake Superior in 1956 have reproduced naturally and expanded into all the Great Lakes. Pink salmon feed at or near the surface as they approach spawning streams and some can still be found with food in the stomach on the spawning bed. Spawning behavior of these freshwater pink salmon is similar to that of marine stocks. Fecundity was 1060 ± 229 (24) per fish and total weight averaged 0.68 kg. Total mortality of embryos to 50% hatch ranged from 67 to 87% at five test temperatures (7, 9, 11, 13, 15 °C); 15 °C is considered to be the upper limit for freshwater pink salmon incubation. Juveniles moved downstream only at night and all juveniles usually took a month to complete this movement. Mean preferred temperature for pink salmon up to 36 wk old was 10 °C. Substantial numbers of pink salmon progeny of the 1975 year-class, which entered the Michipicoten River on Lake Superior to spawn in 1977 survived to, and matured at, each age from II to IV yr in a freshwater laboratory environment.Key words: pink salmon, feeding, spawning behavior, fecundity, incubation, emigration, preferred temperature, early life history, age IV, late maturation
Patterns of Growth of the Pink Salmon Oncorhynchus gorbuscha in Year-Classes with Different Survival Rates during the Marine Life-history Phase
