In hatcheries, fish live in more crowded conditions and eat different food than wild fish do. Genetic change in hatchery populations would be no surprise. What was a surprise was the sheer amount of change found after only one generation of hatchery fish in a
study conducted by the Oregon State University and the Oregon Department of Fisheries and Wildlife. They found that first generation hatchery
steelhead trout and wild steelhead trout had differences in the activity of over seven hundred genes. Many of these genes were involved in wound healing, immunity, and metabolism. According to Mark Christie, the study's lead author, these changes are consistent with what is expected in the early stages of domestication, when animals adapt to more crowded conditions. The researchers hope that by better understanding the genetic changes caused by the hatchery environment, the methods of raising fish can be changed so as to maintain a closer degree of similarity to the wild fish.
It makes sense that the genetic changes associated with living in captivity would involve metabolism, because of the change in diet, as well as wound healing and immunity, because with more crowded conditions the incidence of injury and disease increases. The number of genes involved in so short a period of time is surprising, but more understandable when you consider that a sudden change in environment will probably kill off individuals unsuited to the new environment more quickly than will a slow change. That's not accounting for any epigenetic changes or artifical selection of the healthiest fish that may be going on at the same time.
As far as raising captive fish to be more like wild fish is concerned, it follows that if they are raised in conditions more similar to those that wild fish live in, they will be more like wild fish. What genetics has to do with it, I don't know.
