The only really good "straying" data on steelhead that I know of came from BC in the 70s. They tried a local program, reared in local pond. Released, but fortunately all marked. These fish showed up in streams all through the Straits and on up to the release pond. A very significant number went elsewhere. So, just because these fish are at Dungeness doesn't mean their siblings, at some level, are elsewhere.

Historically, hatchery steelhead were well known for straying, even when the stock used was local.