All three scientific studies were critical of the region s continuing focus on the hydropower system as the single fix for salmon. While there is no doubt that dams have had significant impacts on Columbia and Snake River salmon stocks, the fact that significant problems exist for numerous coastal salmon populations is an obvious indicator that hydropower development is not the only factor of importance for successful recovery of endangered salmon. However, the region continues to concentrate most of its money and talent on measures to alter downstream passage. Concentration on downstream passage has left little of the region s resources for research or investments to improve survivals during the remaining 96 percent of the salmon s existence.
Mortality is high in each stage of the salmon s life cycle.
There have been several studies to measure the mortality of juvenile Snake River chinook salmon as they migrate from natal streams or hatcheries down to the first mainstem dam. It is not known what causes the high losses, but seems to be related to the distance the fish must migrate to the first dam, and little has been done to reduce these losses. Data on the salmon s survival only begins to reemerge when they are killed in ocean and river fisheries as immature or adult fish. Our understanding of the survival of adult fish as they migrate upstream past the dams in the Columbia and Snake rivers and into tributaries to spawn is being broadened by large scale radio telemetry studies currently underway. Similar intensive studies of migrations of tagged juvenile salmon in parts of the system are also underway, but the studies need to be expanded to include the full length of the river.