Here is a study about chinook and coho recolonizing newly open water above Landsburg. It only one study on one body of water. They allowed the hatchery strays to spawn with the wild fish. This was done by city of Seattle with multiple partners. They have no dog in this fight.
This is the powerpoint presentation.

http://www.rco.wa.gov/documents/SalmonConference/presentations/WednesdayAMAnderson.pdf
Overall, allowing the hatchery females to spawn in 2003 - 2005 more
than doubled (2.7x) the total number of second generation recruits

The actual paper is Anderson et al 2012

Maybe the most important thing here is this is a very small population of fish and the wild males outnumbered the hatchery males about 3 to 1 and all males outnumbered the females about the same margin.

So a male chinook swam up the river to spawn and the only females left were those scrawny hatchery females. Sort of like you on a bar after last call.