Linked from
The 7 pages that link to Fish hatchery, each with the reason it gives.
SpawningRelated: Hatcheries induce or collect spawning to produce eggs and young fish.
Fish larvaRelated: Hatcheries manage larval feeding and water conditions to improve survival.
WalleyeRelated: Hatcheries supply juvenile walleye for managed fisheries.
MilkfishRelated: Hatcheries produce milkfish fry for stocking ponds and cages.
Murray codRelated: Hatcheries produce juvenile cod for some population-recovery efforts.