too much to cut and paste but alot of good info on everything here.

Factor for Decline: Competition with Hatchery Reared Fish

http://www.oregon-plan.org/archives/steelhead_additions/sec4st2a.html

In addition to the potential for genetic risks to wild fish from hatchery fish discussed above, hatchery fish can also compete with wild fish, particularly if they are stocked at a larger size than wild fish at the same time or stocked before they have smolted and thus remain in freshwater until ready to migrate to the ocean. This could be detrimental to wild fish if resources, particularly food and cover, are limited. However, most hatchery salmon and steelhead are stocked as smolts that tend to migrate immediately to the ocean (partly because they are larger than wild juveniles), minimizing the amount of time hatchery and wild fish will be in direct competition for limited freshwater resources. Hatchery salmon and steelhead stocked as unfed fry may compete with wild juveniles over an extended period, but they appear to survive particularly poorly and may be less fit than wild fry. All releases of unfed fry by ODFW have been eliminated or reduced to very low numbers. In addition to hatchery-reared fish, juveniles produced by hatchery adults spawning in wild fish habitats can create competition for wild populations, as in the case of wild winter steelhead facing potential competition from summer steelhead juveniles produced by hatchery adults spawning naturally in the Willamette Basin where summer steelhead were not indigenous. Also, hatchery salmon and hatchery trout can impact wild steelhead through competition and other ecological interactions in some situations, so this concern is also addressed in this supplement to the OCSRI plan.