Age and Length Composition of Columbia Basin Spring and Summer Chinook Salmon at Bonneville Dam in 1994
Representative samples of the 1994 Columbia Basin spring and summer adult Chinook Salmon populations were collected at Bonneville Dam. 1994 was the eighth year spring Chinook Salmon, and fifth year summer Chinook Salmon were sampled in this study. Fish were trapped, anesthetized, sampled for scales and biological data, allowed to revive, and then released. The scales were examined to estimate the age composition. Based on scale analysis, five-year-old fish were estimated to comprise 40% of the spring Chinook and 50% of the summer Chinook population. Four-year-old fish were estimated to comprise 57% of the spring Chinook and 34% of the summer Chinook population. Two-, three-, and six-year-old fish were estimated to comprise the remaining 3% of the spring Chinook, and 16% of the summer Chinook population. Difference in age class returns were used to predict spring Chinook population sizes for 1995.
Fryer, J.K., D.R. Pederson, and M. Schwartzberg. 1995. Age and length composition of Columbia Basin spring and summer Chinook Salmon at Bonneville Dam in 1994. Columbia River Inter-Tribal Fish Commission Technical Report 95-1. Portland, OR. 37p.