Same outcome after the eruption of Mt St Helens. Perfect situation to understand how wild fish populations recover into former habitats. Scientists pleaded to set aside at least a portion of the area for research and wild fish recovery without hatchery intervention. Policy makers vetoed that idea and broadcast hatchery fish into every possible stream to support restoration of harvest opportunity, even above natural barriers where species never occurred previously. Non native stocks persist above those barriers today, to the detriment of native species.