I didn't realize this but there is an annual Salmon Toss in Oregon right about now and the salmon are DEAD! So please read this article. Apparently it is good for the streams to toss salmon carcasses into certain rivers. But it IS NOT GOOD FOR US DOGS!
Lurking in the dead salmon can be a parasitic flatworm Nanophyetus salmincola. And on the worm is a bacteria, Neorickettsia helmint, that can cause sickness or even death if untreated in dogs that have eaten infected salmon.
I'd keep away from the rivers where they are tossing salmon if I were you! More Information.
Enough said. I'll stick to fresh salmon from now on!