Prevention of Escapement of Genetically Altered Salmon in the United States Act This bill prohibits a person from shipping, transporting, offering for sale, selling, or purchasing a genetically altered finfish (e.g., salmon), or a food product containing those fish, in commerce; having custody, control, or possession of those fish or food products with the intent to ship, transport, offer for sale, sell, or purchase them in commerce; engaging in net-pen aquaculture (pens of fish contained by nets) of those fish; releasing those fish into a natural environment; or having custody, control, or possession of those fish with the intent to release them into a natural environment. Fish, fish parts, or products confined for scientific research or collected to enforce this bill are exempted from the prohibition. An additional exemption is established if the National Oceanic and Atmospheric Administration (1) prepares a finding of no significant impact in accordance with the National Environmental Policy Act of 1969 after reviewing an application requesting a federal agency to permit activity prohibited by this bill, or (2) finds the application to be consistent with an environmental impact statement that includes an environmental risk analysis and specified assessments of costs and potential economic damage.