Several lower Columbia River salmonid fish stocks are federally listed. Of these, coho, chinook and chum salmon (Oncorhynchus kisutch, O.tshawytscha and O. keta) and cutthroat trout (Oncorhynchus clarkii clarkii) have been found in park streams and sloughs.
Estuarine restoration projects are restoring former tidegated lands to tidal influence, increasing and improving salmonid rearing habitat.
Approaching, feeding, hunting or removing wildlife from the park is illegal. A current state fishing license is required to catch fish in the Lewis and Clark River, and Oregon Department of Fish and Wildlife established fishing seasons must be observed.