Age and Length Composition of Columbia Basin Chinook, Sockeye, and Coho Salmon at Bonneville Dam in 2000
Five-year-old fish (BY 1995) were estimated to comprise 2% of the spring Chinook, 26% of the summer Chinook, and 40% of the fall Chinook salmon population. Three-year-old fish (BY 1997) were estimated to comprise 14% of the spring Chinook, 42% of the summer Chinook, and 17% of the fall Chinook Salmon population. The Sockeye Salmon population sampled at Bonneville was predominantly four-year-old fish (95%), and the Coho Salmon population was 99.9% three-year-old fish (Age 1.1). Length analysis of the 2000 returns indicated that Chinook Salmon with a stream-type life history are larger (mean length) than the Chinook Salmon with an ocean-type life history. Age classes 0.3 and 0.4 have no significant change over time and age 0.1 Chinook Salmon had a significant decrease in mean length over time. Based on three-year- old returns, the relationship predicts four-year-old returns of 325,000 (+ 111,600, 90% Predictive Interval [PI]) spring Chinook and 27,800 (+ 29,750, 90% PI) summer Chinook Salmon . Based on four-year-old returns, the relationship predicts five-year-old returns of 54,300 (+ 40,600, 90% PI) spring Chinook and 11,000 (+ 3,250, 90% PI) summer Chinook Salmon.
Kelsey, D.A., and J.K. Fryer. 2001. Age and length composition of Columbia Basin Chinook, Sockeye, and Coho Salmon at Bonneville Dam in 2000. Columbia River Inter-Tribal Fish Commission Technical Report 01-1. Portland, OR. 50p.