Here we go again. Blogosphere Google searches seeking information.
Q: Do hatchery fish spawn in wild
A: Why yes they do.
Sometimes hatchery fish simply die before they mature sexually and are therefore unable to spawn in the wild. Sometimes this death occurs as a consequence of actually being caught and “retained” by an angler, as intended. So that pretty much negates any possibility of spawning in the wild.
Sometimes the hatchery fish do not get caught, don’t die, and do in fact spawn, either with other hatchery fish or with wild fish.
Sometimes the offspring of the hatchery fish survive and themselves reach maturity and spawn.
Sometimes the offspring of hatchery fish live for a portion of their life cycle and then die before spawning. Studies of the effectiveness of hatchery fish spawning in the wild, compared to wild native fish spawning – a mouthful – usually show that the hatchery fish are not as productive (i.e., they express lower fitness) than the wild fish spawning in the same stream.
There are some examples where hatchery salmon or steelhead that escaped from net-pens have established “wild” naturally produced runs, but these are, to the best of my knowledge, principally in places where the salmon are exotic (not native) and in these places, and the exotic salmon have decimated any native fishes that were present in the streams.
Bedazzled and confused by my oversimplifications? You should be. The matter is complicated.
Beware of simple, one-size-fits-all answers.