You need to understand evolution to know the difference. It is little about their instinct and more about natural selection. The weaker genetic fish have been allowed to get to a place in their life cycle that they would not have been allowed by nature had they been raised 100% wild . They would have died. So you are increaseing the likelyhood of passing on traits that have been removed from wild fish breeding naturally. It can only mean a weaker fish strain. Conditioned responses like coming to the surface to look for food because thier food is broadcast into the pen and holding in open water regardless of bird predation have not been proven to be passed on gentically. Imune response,genetic abnormalities,etc are transfered. More hatchery fish surrvive right now that wild fish so they are more likely to breed with wild females. Also current research in Ore ( salmon not steelhead) shows that the wild males will move out of breeding areas when hatchery fish are present.