A program in the Pacific Northwest attempts to feed and nourish insect larvae and small fish of the North Siam and little North Fork rivers, by tossing dead salmon back into the river. The Oregon Department of Fish and Wildlife gathers carcasses of spring Chinook salmon from its fish collection sites and puts them back in the river they came from.
The concern is that dead salmon may carry a parasitic worm known as Nanophyetus salmincola, containing Neorickettsia Helmint bacteria, which can be deadly to dogs. This salmon poisoning causes severe vomiting and diarrhea, and requires intensive veterinary care to prevent extreme dehydration and possible death. It is imperative to seek treatment expediently to avoid excess suffering and expense.
The nutrient-enrichment program, as it is known, is trying to replicate what happens naturally in the wild with native Chinook salmon. Their carcasses provide nourishment for the insect larvae, smaller fish, and young salmon.
The drop sites are often located where travelers stop to let their dogs run, rest and drink. It takes about a week for symptoms to develop, which makes it difficult to connect the symptoms with the cause if a dog eats the tainted salmon.
Warning signs are sometimes posted at these locations, but are often ignored or overlooked. Another concern is that if the salmon is undercooked, it might cause mild intestinal distress-like symptoms in humans as well, who may just chalk it up to the stomach flu. It is not deadly for humans to ingest this bacteria laden fish, as it is with dogs, but it should still be a cause for trepidation.