Two billion and counting
Yes, that’s two billion hatchery fish that have been released over time in California. Yet things have not always worked out well. There is an immense mortality of hatchery fish. The release of hatchery fish has masked the decline of wild salmon populations. “Beginning in 2007, the Central Valley fall-run Chinook salmon population suffered a large-scale collapse (Lindley et al. 2009), which resulted in an emergency closure of the commercial and recreational fisheries from 2008-2009 and limited fishing in 2010.”
All this and more is detailed in a report from FishBio which explores the efforts to compile a comprehensive picture of hatchery releases and explore solutions. Read the complete article at the link below, which also has links to primary source material.