Salmon carcasses are a nutrient rich fertilizer. Beyond simply the nutrients they bring to the stream itself, they have been found to benefit nearby trees, Eagles, Bears, Insects and many other streamside species. 

Salmon, as an ocean-going fish, bring nutrients from the ocean deep into the hills and forests of Coastal areas. 

This article talks about the studies that led up to the practice of placing salmon carcasses streamside intentionally, in order to benefit fry, smolt, insects and other wildlife.

This was originally featured in the 1996 Aug/September issues of Salmon Trout Steelheader.