On Aug. 19 and 20, an undetermined number (estimates range from 4,000 to 185,000) of farmed Atlantic salmon escaped into the waters around Cypress Island, just northwest of Anacortes, Washington. In a region where vast amounts of money and effort have been spent attempting to restore wild salmon runs, this mass escape of non-native fish has caused a public uproar. How could this happen? Will the Atlantic salmon spread disease to wild fish? Will they outcompete native salmon for food or freshwater spawning habitat?