The track record of hatcheries that did intensive selection on few traits such as size, age at maturity, and so on have gone down in flames. The most egregious was Doc Donaldon's super trout. Selected for fast growth, high fecundity, etc. One year they picked live eggs out of the trays rather than dead because inbreeding caught up big time.

The hatchery spawns what the managers let get through. The harvest rates are 90+%. Kinda narrows the gene pool.

In my experience, the long-term successful hatchery programs have been those that spawn and release large numbers of juveniles. The smaller the program the more problems.

The idea that "plant more" is really getting tested in the N Pacific as AK is pushing, I believe, mega millions of not billions of pink out. There are lots of correlations showing that more pinks give you less zooplankton, Chinook, sockeye, coho, SRKWs, and shearwaters (and probably other seabirds). More is not always the answer.