I really don't get it. "The abstract of the report states: Intensive annual stocking of Brown Trout could eliminate resident Brook Trout in less than a decade. Ecological differences, harvest behavior, and other habitat changes can exacerbate Brook Trout losses. Custom stocking scenarios with Brown Trout introductions at relatively low proportions of resident Brook Trout populations may be able to sustain healthy populations of both species within their present range." Note the key word "may" in the last sentence. When I was still working we called these 'weasel' words.
How can the premise of this study be so. There are many other studies showing not only the opposite but give the reasons why: Brook trout are 3 times more likely to be harvested than brown trout in waters where the two species are living in sympatry in similar numbers (Cooper); brown trout (because they tend to be a little bigger than brook trout) can displace brook trout from critical stream positions (Fausch & White); brown trout can carry diseases (Saprolegnia) to which they are pretty much immune, but brook trout and other salmonids are very susceptible (DeWald & Wilzbach); and many others.
I fish for brown trout lot and have a lot of respect for them. Brown trout, like brook trout, are an excellent sport fish. I'm an immigrant too and my ancestors came from the same places. Their introduction could have been much worse (think snakeheads and carp). Catching big browns in the Little J and Spring Creek is a fine experience that I enjoy immensely. But they have taken over and dominate all the waters where brook trout once averaged 9 inches; frequently reached a foot; and occasionally 20 inches - the big freestones and limestone stream of PA. "Although we have not lost the brook trout as a species, we have lost a lot." (Charles Gowan).
This is just another attempt to justify the widespread policy of stocking brown trout over brook trout and other native salmonids.