The problem was that they believed the hatcheries could replace the natural production, and that mass production would allow for sufficient genetic diversity. The genetic argument has been somewhat of a red herring in fisheries management circles for the last 10 - 20 years. Some times it is true that the hatcheries do lessen genetic variation however there are just as many cases where hatchery fish are more genetically diverse than the native fish, which is especially true in small systems. Mom Nature eliminates the fish with bad genes and allows those with acceptable genes to survive. The theory being that hatchery systems don't allow mom to do her job fully and we select too many of the bad genes, and flood the system with fish that won't survive, forcing out the good gened fish by simply overwhelming them with numbers, and not enough survive to produce more good gened fish to sustain the population. The problem I have with the theory is that genetic make up is only one part. Environment plays a huge role, and thats where the effect of the habitat both in FW and out in the ocean comes in. In addition, animal geneticists, the guys who breed animals and plants will tell you that some traits have a very high degree of inheritability, and other traits do not. In other words by selective breeding you may be able to affect the growth rate of a fish, but not its ability to find its native stream, or survive a seal attack. I would suggest the hatchery fishes ineffective oredator avoidance is nore a product of enfivronment than genetic make up. So I wouldn't be too hasty to place the blame solely on hatchery production, and eliminate its use. It is after all simply another arrow in the fish managment quiver.
The increased predation occurs in natural systems as well. Fox and lynx populations closely follow the snowshoe hare populations cycle of boom and bust.
Hatchery production in Alaska also has produced similar effects in the increased predation by seal and birds at the time of smolt release. I wonder if the bird populations were this large before the dams were built and now have simply recovered up to pre dam levels as the hatchery production replaced the natural production.