Visiting a hatchery is fun and informative. One I went to told me they milk the hatchery fish that show up at the hatchery. Nates are moved to streams, river branches and such where fishing is off limits. Hatchery bucks are also moved there after milking the sperm because they can spawn again. Hatchery hens are released after the eggs are removed and they generally will head straight back to the ocean. It may be different at different hatcheries, dunno, but the visit was a lot of fun.