Salmon and Biodiversity

Recent research efforts have yielded the conclusion that salmon are a necessary component for the diversity of species in the terrestrial and aquatic environments found in the Pacific Northwest. Salmon have an effect far beyond their own species as their life cycle becomes inter twined with numerous mammals, birds, insects and various aquatic dwellers.

As salmon return to their natal streams to spawn a new generation and end their lives they become prey for not only humans but also birds such as eagles and hawks. Large terrestrial mammals such as cougar, bears, bobcats and coyotes depend on salmon carcasses to help carry them through lean winter months ahead. A myriad of aquatic insects will feast on the carcasses as well as the young emerging juvenile fish from the redds.

The effects of dead salmon are not just limited to the animal kingdom. The fish carry nutrients, such as isotopes of nitrogen, phosphorus and carbon that are not found anywhere except in the oceanic environment. These nutrients are broken down and utilized by the streamside vegetation, which in turn provide food for insects, shade for the stream and large woody debris essential for salmon and other fish species habitat. The carcasses that are dragged off also transfer nutrients into the adjoining upland environment. Without such inputs of nutrients the stream would traverse a much-simplified ecosystem that would contain lesser numbers of animal, insect, invertebrate, amphibian, plant and fish species. The salmon also help the stream by cleaning the gravel during redd excavation that helps provide more habitats for stream dwellers such as bottom living insects.

Young salmon that migrate to the sea also provide food for other predatory fish, mammals and birds along the stream. Without them there would be less species with smaller numbers present.

Thus salmon affect many other lifeforms beside themselves. They definitely contribute to biodiversity and the Pacific Northwest would be poorer with their absence.

Earl Emerson
Face of Salmon