Each of the four Hs has had some significant effect on the health of wild salmon populations, to varying degrees in each river basin. Of course, in rivers like those on the Oregon coast, where there are no hydropower facilities, only the other three factors have been at work. Land use and development rarely have a direct effect on fish, but they can have a very profound effect on water quality and fish habitat. As such, DLCD and the coastal program's contribution to salmon recovery is in the area of habitat protection. In order to continue to survive from one generation to the next in sufficient numbers to guarantee survival of succeeding generations, salmon need several things throughout their lives.
All salmon spend part of their life in fresh water and part of their life in the ocean.
Salmon are unique among fish in that throughout their entire life cycle, they utilize several habitats that extend from narrow mountain streams that dry up in the summer all of the way to the depths of the Pacific Ocean. Different species, though, have different life histories , and prefer to use different parts of the watershed for spawning and rearing. For example, chum salmon spawn in the very lowest reaches of a river, just above salt water. Steelhead, in contrast, spawn in the very upper reaches of a watershed. Juvenile fish need to be able to migrate downstream and need places to feed and hide while migrating.