Bilby's latest findings were presented at the first annual Willapa Science Conference sponsored by the Willapa Alliance and Columbia Pacific Resources Center and the Willapa Science Advisory Group. Bilby explained that Pacific Salmon are unique in that they die after they spawn. He and other researchers have been tracing the affect of the dead salmon on the future productivity of streams. By migrating back from the ocean to local streams, then dying after spawning, the carcasses of those salmon serve to transport nutrients from the Pacific Ocean to the stream ecosystems. Coastal streams usually have pretty poor nutrient loading, Bilby explained.
Oceans have a lot of nutrients.
The migration of salmon back to lay eggs in the streams of their birth is one way to return the nutrients of the ocean to the streams. The difficulty has been in determining how important they are. A process called stable isotope analysis was developed about 15 years ago which helps track nitrogen and carbon in isotopic form. That allows scientist to test the nutrients in the steams and track them back to the ocean. It also allowed them to start tracking the impact salmon carcasses have on the productivity of the river.