Chapter 13. The Salmon Smolts Spring Migration

The declining salmon runs on the Snake and Columbia River system is one of the most serious environmental problems in the Pacific Northwest. The salmon have disappeared from 40% of their historical breeding ranges despite a public and private investment of more than $1 billion. The annual salmon and steelhead runs have dwindled to 2.5 million, less than a quarter of the run sizes of 100 years ago. This chapter describes a model which may be used to simulate one piece of the complex and threatened salmon system. It focuses on the spring migration of hatchery smolts to the ocean. It may be used to test the relative merits of barging fish or drawing down the reservoirs to help the smolts reach the ocean.