There are several strategies like this that can be helpful. The issues that make them harder include:

1) There may not be carrying capacity in the stream, due to ecological issues. Planting the fry may just result in dead fry.

2) Hatchery 'races' of fish have been bred because some of the wild fish don't rear well in hatcheries. It takes some docility, something like the difference between cows and elk, to allow large numbers of fish to grow in a small space.

BC has done some neat things with spawning channels, which provide spawning baitat, without the crowding issues associated with a hatchery. There are definitely options out there.
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