All the other wildlife or plant communities have, in some way, some dependency. Working on the Snoqualmie River, Bilby found that as much as 40 percent of the nitrogen in the bodies of young coho salmon and 60 percent of the nitrogen in young steelhead came from marine sources. When they dumped salmon carcasses on streams running into Willapa Bay, they found higher densities of young fish around the carcasses. The young fish were feeding on the carcasses and eggs laid in the river. The extra food meant juvenile fish grew bigger before migrating to the ocean.
Bigger fish survive better, so more fish come back to the river.
The Oregon Plan for restoring dwindling salmon populations recognized this research, and for the past two years volunteers have been tossing salmon carcasses from five hatcheries along coho rivers on the northern Oregon Coast. Washington now has a similar program. But there is a long way to go, the authors of the Fisheries article concluded. Research has indicated that between 93 and 155 carcasses per kilometer are needed to provide the maximum ecological benefit on coho streams. While Oregon's goal for coastal coho streams is 26 fish per kilometer, only two to seven fish per kilometer were found in 1997.