To the original question, you can look at it this way. Wild salmon and steelhead represent the surviving offspring of fish that survived in wild surroundings, most relevantly the spawning and stream rearing habitat. Hatchery salmon and steelhead represent the surviving offspring of fish that were bred in concrete ponds with nets overhead to keep predators away, with food delivered at regular intervals and diseases controlled by antibiotics. Each one is the result of fish that survived, and therefore lived to pass on it's genes, traits, and characteristics to its' young. Compare it to a society where, if you killed off everyone who wasn't blond, in a few generations you would not expect very many blond children. In hatcheries, fish that get scared when people throw food at them become pretty scarce.

This is like asking why a a new York City Catholic High School freshman is going to have a harder time surviving in the Serengeti plains than an African Bushman. One is native to the territory, one isn't. Doesn't mean that the other is bad or wrong, just more likely to get eaten by a predator.

And, if you take the Bushman, and turn him loose in the Concrete Jungle aka hatchery, he is likely to do poorly as well.

Returning from the metaphoric frenzy for a moment, individual wild fish have often done poorly in a hatchery setting, which has resulted in the hatchery strains either intentionallly or accidentally having been bred for hatchery tolerance. This has meant that the hatchery strains don't get as stressed by the appearence of predators, they tolerate crowding, and they aren't as aggressive towards each other as wild fish. Thse traits contribute to survival in a hatchery, but they may not be the best traits for survival in the wild.

Now, to the geneticists saying that these fish (wild and hatchery) are indistinguishable. I must marvel at the statements I have recently seen quoted, that the biologists can't distinguish between the fish. Is this perhaps similar to saying that Ray Charles can't distinguish between a blonde and a redhead?

Biologists can't look at Ichiro's cells and tell us why he plays baseball so well. They can't tell us why Tger Woods plays good golf, or why he likes to wear red on Sunday. They can't look at Brittany Spears' genes and tell us why she's vapid. They struggle to locate the most basic of recessive and dominant genetic traits on our, people's, chromosomes. They can't tell the difference, genetically, between wild fish and hatchery fish, because they are blind as the proverbial bat in these matters. They conveniently omit this fact when trying to sway our opinions.

So, before you take that statement too seriously, think about whether these folks have told you that they can differentiate between a Holstein and an Angus cow genetically.

Because they can't.

What's the difference? Coupla minor things. One gives high milk production, low meat production, and looks like the Gateway commercial. The other hardens your arteries with great steaks and burgers, and is red or black. And they are indistinguishable by the folks who would tell you that wild and hatchery steelhead are indistinguishable.

Not everything that is worthwhile can be measured.

Not that I have an opinion or anything.