When we domesticate animals, we alter their evolutionary development to favor the traits that we find most desirable. Usually, that process takes hundreds, even thousands of years. But fish hatcheries can scramble a species' genetics in a single generation.
A reader who works at large turkey hatchery in Minnesota sent an update about her experience there, along with some truly horrible pictures. You can see the update here. Warning: Not for sensitive people. Heck, not for anyone with a slice of empathy in them. [The Technology of Turkey Harvesting Uncovered]