I’m not too happy about there being a wild brown population in there, but I’m sure they won’t take over as long as the rainbow stocking continues. Any wild trout is better than none, so I’ll try and find some more wild trout there in the fall.
This gets into the question of how do invasive trout species displace native trout. Short answer is we know some of the mechanisms with brook and brown trout when it
does happen. I have posted these many time on here(predation, displacing brook trout from prime feeding lies, displacing brook trout from thermal refuge(cool spots in summer), reducing brook trout’s ability to travel from thermal refuge to feed for brief periods before returning, excavating and destroying brook trout redds(nests), blocking movement/gene flow acting like a culvert of sorts, and there are many more.
However, whats interesting is we don’t really have a good understanding about what allows the invasive species to invade and establish themselves in the first place to cause all the above listed harms via the mechanisms listed above. The role of geographic distribution of brook trout(southern range vs. northern), evolutionary history(how recently did they break off from another population and isolate or evolve on their own, environmental resistance(stream flow characteristics among others), and biotic resistance(how many competitors or diseases did they evolve with) are all being looked at in assessing what allows invasion to successfully occur after introduction in the first place. Kurt Fausch has a really interesting paper on this published in 2008.
There are a tiny handful of certain streams relatively nearby where the scientific community just can’t figure out why invasion hasn’t occurred or what has caused the stream’s “resistance” to invasion. And its not temperature. This is an evolving part of invasion biology.
But with the rainbow stocking, stream born brown trout, and native brook trout in your stream one things for sure. It has a limited carrying capacity so the invasive species that do in fact take hold ultimately likely represent a loss of potential native brook trout population if the stream, or sections of the stream, they occupy are truly suitable for native brook trout or not.
The funny thing is if you have in fact found a small population thats some how holding on in a developed corner of the state with multiple invasive species, in what mike is indicating is not the coldest stream, this would be discarded by our current native brook trout management system simply because it cannot provide significant recreational opportunity for brook trout.
However, let me tell you what it potentially means for the fish, not us! Lol
If your a tiny population of native brook trout and your eeking out an existence on the front lines(development/impervious surfaces, deforestation, agriculture, invasive species ect.) you have survived alot. Natural selection(what kills brook trout) is different here than it is on say slate run in tioga county. These brook trout could posses unique genetic diversity or traits that are the reason their still somehow here( thermal tolerance genes or genes that help with other stressors).
If thats true these class C class D “marginal” streams need to share those important genes that represent adaptive potential with other populations to make them resilient.
So as you can see if this was about conserving the species themselves and helping them adapt to climate change alot of these class C and D’s could be a genetic goldmine. But its about the fishing right now not the fish.
All this assuming their not fingerling stockies lol