50 years ago is that all.
The first report I know of bringing in the Coturnix coturnix Japonica is that they were brought to America by bird fanciers around 1870. That is from the University of California - Davis. Evidently they keep records. So if you want to argue with someone on the proper nominclature for the bird contact the University of California - Davis and tell them they have it all wrong. I am sure they will want to know that their records are wrong and that Marsh farms named them differently. Around 80 years after they had already been in the country.
Didn't say he was the first, just that he import the common quail in the 60s, and started mass producing them. just because the japanese where here first doesn't prove his were japanese, because they where the common quail.