洄游鱼是宝贵的水产资源。美国在兴建水资源工中,十分注意对鱼类资源的保护。美国太平洋沿岸河流中,盛产鲑鱼和其他洄游鱼。游鱼经过2～4年生长成熟,其重量大的可达28.5g,一般在2.5k以上。近40年来在这些河流上建坝水,对洄游鱼的生存,产生不利影响。这种不利影表现在下列6个方面:(1)水位和流量的变动; Migratory fish is a valuable aquatic resource. In building water resources workers in the United States, great attention has been paid to the protection of fish resources. The Pacific coast of the United States is rich in salmon and other migratory fish. Fish after 2 to 4 years of maturity, its weight up to 28.5g, generally above 2.5k. Dam water has been built on these rivers for nearly 40 years, adversely affecting the survival of migratory fish. This adverse video is now the following six aspects: (1) the water level and flow changes;