Wild Trout (trout camps 2.0)

[silverfox]

Since the other thread got somewhat contentious pretty quickly and then turned into a discussion about something else, I figured I’d start a new thread here to reboot the conversation. I think it’s an important conversation for both sides.

There are a lot of common threats to native brook trout and wild nonnative trout. I think identifying the two camps that way is a better description, as wild brook trout are wild “trout.” I also think it’s important to clarify that I believe wild nonnative trout do have value. For example, in some cases, management decisions are made predominantly to improve wild brown trout, which also benefits native brook trout. The Freeman Run issue, which should never have been an issue in the first place, is an example where it makes sense to support a management change brought about by brown trout, but brook trout will benefit.

To clarify the other points, the concept of studying the movement of brown trout and adjusting management to favor those fish is also a case where a management change spurred by improving wild brown trout populations also helps protect brook trout. Something that I don’t think has been addressed enough is that the regulation change to limit extended season harvest, while directed at large migratory brown trout, also protects brook trout under the same regulation.

Taking this a step further, the petition to study the movement of brown trout and the effects of stocking over wild brown trout also has value in that wild brown trout are highly valued in the fishing community and are a driver for license sales. If the state were convinced that adjustments in stocking or adjustments to the range of how regulations are applied would improve angling opportunities, again, that change might have a positive impact on brook trout as well.

The last point on focusing on migratory brown trout as a trigger for management changes is that I’ve argued for some time that the “section” based approach to management is outdated. We need to be managing by watershed or species, not by some small subset of a single stream based on estimated biomass acquired via surveys conducted at the same time every year. The concept of studying the movement of brown trout gets at this same issue: if you need to protect a certain type of fish, rather than simply the biomass of a stream, management has to move with the fish rather than imaginary lines on a map. This is one step closer to species-level management, which I believe is needed for brook trout.

As was addressed in the other thread, the above is far beyond the scope of anything NFC would ever get involved in. At least where any of the above concepts are presented with no mention of the impact on native fish. This isn’t because NFC has a general disdain for nonnative fish, but rather simply because it is outside the scope of the organization's mission.

As for some of the other concepts discussed in that thread, it’s important to note that barriers are successfully used in fish conservation in the west to isolate native trout from nonnative (brook) trout. Additionally, on the east coast, several states other than Pennsylvania have effectively conducted successful removal and reintroduction efforts. Even in one case where the project was sabotaged by individuals reintroducing rainbow trout, the NPS communicated with the offenders and got them on board with the project in the end. So there is precedence for successful species separation outside of Pennsylvania. If people want to classify that type of management approach as a pipe dream, it’s because of something other than the technique's effectiveness.

This should all be about common goals, collaboration, and support for one another. We’re all in this because we’re passionate about fish and the resources. We all have far more in common than differences. The adversarial approach to discussing these topics is unproductive. It’s the compound vs crossbow debate of the fishing world. It’s silly to argue about these things, and it serves no function other than to cause further division.

 

[Mike]

In an ideal world, reclaiming a ST stream from a BT population would be effective and a once and done affair. Without even getting into the problem of trying to get environmentalists/public on board with the use of piscacides, electrofishing in complex habitats is unlikely to remove all individual BT from a population even with year after year of EF runs. A SE MN paper that described just such a difficulty was provided in prior threads. Furthermore, we’re not talking about a 300-500 m sampling site; we’re talking about an entire stream. In the real world without full removal, BT will just return on their own over time.

And then there is the problem of reintroductions by anglers. Maybe the NPS got lucky and found those responsible for reintroduction, but that’s not the usual scenario. Those responsible for introductions are usually long gone. If introductions were not a problem in Pa, then Pa would not have the species introduction problems that it does with those species and more that I mentioned above. Imagine this, with all of the negative publicity over the course of many decades, anglers were still introducing carp, not to mention the spread from impoundment to impoundment, up to 50 miles apart, of snakeheads within the past 5 yrs or so.

 

[silverfox]

In an ideal world, reclaiming a ST stream from a BT population would be effective and a once and done affair. Without even getting into the problem of trying to get environmentalists/public on board with the use of piscasides, electrofishing in complex habitats is unlikely to remove all individual BT from a population even with year after year of EF runs. A SE MN paper that described just such a difficulty was provided in prior threads. Furthermore, we’re not talking about a 300-500 m sampling site; we’re talking about an entire stream. In the real world without full removal, BT will just return on their own over time.

And then there is the problem of reintroductions by anglers. Maybe the NPS got lucky and found those responsible for reintroduction, but that’s not the usual scenario. Those responsible for introductions are usually long gone. If introductions were not a problem in Pa, then Pa would not have the species introduction problems that it does with those species and more that I mentioned above. Imagine this, with all of the negative publicity over the course of many decades, anglers were still introducing carp, not to mention the spread from impoundment to impoundment, up to 50 miles apart, of snakeheads within the past 5 yrs or so.

So how do you propose the state achieves TRACS Action 10.0 for brook trout in the action plan? Or did PFBC write that just to make it look like we're addressing an issue without actually doing anything? That was established almost 10 years ago. How long until they actually do it? 10 more years? 20? 50? Meanwhile, our neighbors have been doing it for a decade. Other states in the east are already and have been, doing what you're explaining is impossible.

Here are the success rate numbers. Antimycin-86%. Rotenone-79%. Annual Removal Electrofishing-55%. Multiple Removal Electrofishing-65%. Translocation-73%

 

[Fish Sticks]

Yea Mike, you gotta understand people dumped rainbows back in lynn camp prong and they did not take the brook trout population held and its now considered one of the most successful removals in the east despite a sabotage event. So its great they caught them but if they did not, they never took anyway. Phaedra Budy has described a density dependent biotic resistance for native trout that out number invasive ones. A lot of these populations with invasive trout had the balance shifted by wiping out the brookies with logging 100 years ago and the invasive trout used their absence to proliferate. Now alot these streams have dense forrest and that initial destabilization is no longer there. If your saying its impossible how are there well over a hundred projects in the eastern states alone???

How do you explain all these “pipe dreams” that materialized?

Eastern Brook Trout restoration summary table — EBTJV

Compilation of brook trout restoration projects and outcomes from across the EBTJV member states and agencies.

easternbrooktrout.org

 

[pcray1231]

Agree with just about everything in silver's post.

As for barrier + removal, I understand and share the feeling that it would be difficult, and also understand the argument that it may even harm the poulation by removing access to the stream below and limiting genetic diversity. But would like to see it attempted in a limited capacity as a test. Choose the subject stream wisely, and I favor the multiple shock method over chemical methods.

 

[Fish Sticks]

Agree with just about everything in silver's post.

As for barrier + removal, I understand and share the feeling that it would be difficult, and also understand the argument that it may even harm the poulation by removing access to the stream below and limiting genetic diversity. But would like to see it attempted in a limited capacity as a test. Choose the subject stream wisely, and I favor the multiple shock method over chemical methods.

so your absolutely right

Barriers are terrible TERRIBLE for native brook trout. I am always talking about managing for them at watershed scale right? The importance of connectivity, gene flow, and adaptation.

Well,

As it turns out we found out a barrier was the lesser evil conpared to brown trout in 78 northwestern Pennsylvania streams in this study that showed if a barrier was present between where Pa fish and boat stocks their invasive brown trout it was 12x more likely to be a brook trout stream!! Thats a powerful relationship demonstrating barriers are bad brown trout stocking downstream of brookies MUCH worse.




But this should make sense right, we know from casey weather Thomas’s dissertation and David Kayzak’s presentations that brown trout are ALREADY at least a partial barrier to gene flow. So if you put in a total barrier on-top of a brown trout barrier your not blocking a totally effectively clear and free segment anyway if gene flow is already being decreased by invasive species.

So in tiny little streams we may use a barrier to keep those uniques genes around. But if you have a huge connected waterway managed for brook trout with C and R brookies, no stocking, and harvest of invasive trout, you could use that diverse connect population to create artificial gene flow above that barrier in the tiny stream if the form of the occasional translocation of fish from the big connected system( called a genetic rescue). These large brook trout management zones with high gene flow and diversity can serve as reservoirs for adding gene flow above manmade barriers to minimize their effects that the brown trout are partially causing already.

https://easternbrooktrout.org/science-data/science-publications/evaluating-the-trade-offs-between-invasion-and-isolation-for-native-brook-trout-and-nonnative-brown-trout-in-pennsylvania-streams

 

[TimMurphy]

Dear silverfox,

I'd suggest 12,500.000 people move out of the State and take their extractive industries with them.

That ought to work. Anything less is just whizzing in the wind.

Regards,

Tim Murphy

 

[Swattie87]

You guys lose me, and a lot of others I think, when you start talking about chemically killing a stream. Just a point of constructive feedback. I’m not saying it wouldn’t work, or it wouldn’t be the most likely to work, I don’t know. I’m just saying it won’t be popular. And that is part of this deal…Promoting and advocating for conservation/management practices that can and will be supported. Otherwise we’re all just a bunch of spincasters pissing each other off on an internet board.

A good test study IMO would be to pick a tiny Class A Brookie stream, above an already existing barrier, that has a token population of Browns. Say one of those that is listed Class A Brookies, but has like 0.XX kg/ha Browns when last surveyed. Shock it, once/year for 10 years at the dead low flow of Summer/early Fall. Remove all the Browns. Repeat. After 10 years, note the changes…Are the Browns gone, or at least are there less of them? Has the Brookie biomass increased? Are the changes statistically significant versus the natural population fluctuations? (You’d also need a similar nearby control stream or streams that you’re not shocking.) You want a small, controlled as best as you can environment to test the viability of this. Can they actually be removed (and prevented from returning) from a situation where it’d be theoretically easiest to remove them, and prevent their natural return? If you can’t in this “ideal” test environment, you’re sure as snot not gonna be able to do it in larger streams/watersheds with more Browns to start with, and more places from which they can repopulate from.

Surely, the answer cannot be shocking every wild Trout stream in the state once a year and culling the Browns, simply from a resources standpoint.

I think two, obvious, easy starts that could most easily be supported are:

1. No stocking over streams that are currently listed as being more than 75% by biomass (Or so. Someone smarter and with more by biomass data can better assess what the tipping point number is.) Brook Trout when last surveyed. Period. No stocking on “Brook Trout streams.” All classes, not just Class A. No PFBC stocking, no club stocking, no rodeos for the kiddos, do it somewhere else. And enforce it. Make it public that you’re enforcing it. Streams that are “mixed”, or are predominantly Brown Trout are lost causes. Punt, and take the field position to fight on other fronts.

2. Make it catch and release statewide for Brookies. Everywhere. This is more for getting the word out and changing mindsets, than actually trying to limit the harvest of wild Brookies…It just doesn’t happen to a population meaningful level. The public should know that Brookies are native, are our state fish, and should be protected.

Short n’ Sweet version:
1. “We don’t stock over our state fish in PA.”
2. “We don’t kill our state fish in PA.”

^Not implying the above will be easy, only that it will be the easiest place to start and garner support IMO. And neither of the above cost anything, assuming the PBFC is shocking many streams/year already as it is. And the more complex you make it, the more people fall off the bus with each addition. (Again, you lose me at chemically killing streams.)

 

[silverfox]

Dear silverfox,

I'd suggest 12,500.000 people move out of the State and take their extractive industries with them.

That ought to work. Anything less is just whizzing in the wind.

Regards,

Tim Murphy

Now we're really getting to the meat of the problem! I suppose to prevent a complete psychological breakdown; it's best to focus on smaller issues rather than face the reality of the bigger ones we all face.

I had a lengthy, humbling conversation with Bob Bachmann about this very issue not too awful long ago. I think the older we get, the more we experience, and the more we come to terms with (or not) the level of impact we've had on the environment.

 

[silverfox]

You guys lose me, and a lot of others I think, when you start talking about chemically killing a stream. Just a point of constructive feedback. I’m not saying it wouldn’t work, or it wouldn’t be the most likely to work, I don’t know. I’m just saying it won’t be popular. And that is part of this deal…Promoting and advocating for conservation/management practices that can and will be supported. Otherwise we’re all just a bunch of spincasters pissing each other off on an internet board.

A good test study IMO would be to pick a tiny Class A Brookie stream, above an already existing barrier, that has a token population of Browns. Say one of those that is listed Class A Brookies, but has like 0.XX kg/ha Browns when last surveyed. Shock it, once/year for 10 years at the dead low flow of Summer/early Fall. Remove all the Browns. Repeat. After 10 years, note the changes…Are the Browns gone, or at least are there less of them? Has the Brookie biomass increased? Are the changes statistically significant versus the natural population fluctuations? (You’d also need a similar nearby control stream or streams that you’re not shocking.) You want a small, controlled as best as you can environment to test the viability of this. Can they actually be removed (and prevented from returning) from a situation where it’d be theoretically easiest to remove them, and prevent their natural return? If you can’t in this “ideal” test environment, you’re sure as snot not gonna be able to do it in larger streams/watersheds with more Browns to start with, and more places from which they can repopulate from.

Surely, the answer cannot be shocking every wild Trout stream in the state once a year and culling the Browns, simply from a resources standpoint.

I think two, obvious, easy starts that could most easily be supported are:

1. No stocking over streams that are currently listed as being more than 75% (Or so. Someone smarter and with more by biomass data can better assess what the tipping point number is.) Brook Trout when last surveyed. Period. No stocking on “Brook Trout streams.” All classes, not just Class A. No PFBC stocking, no club stocking, no rodeos for the kiddos, do it somewhere else. And enforce it. Make it public that you’re enforcing it. Streams that are “mixed”, or are predominantly Brown Trout are lost causes. Punt, and take the field position to fight on other fronts.

2. Make it catch and release statewide for Brookies. Everywhere. This is more for getting the word out and changing mindsets, than actually trying to limit the harvest of wild Brookies…It just doesn’t happen to a population meaningful level. The public should know that Brookies are native, are our state fish, and should be protected. We don’t kill Brookies in PA.

^Not implying the above will be easy, only that it will be the easiest place to start and garner support IMO. And neither of the above cost anything, assuming the PBFC is shocking many streams/year already as it is.

I didn't really intend to go down that road, or at least for that to be the thing people keyed in on, to be honest. On the public perception issue, reclamation is favorable to highly favorable on most projects (outside of PA). The key is that managers need to communicate with the public about why they're doing it and why it's necessary (not my words).

The barrier discussion in the other thread prompted that topic in my post, and while I brought the reclamation angle into the discussion, my point was that barriers, or even the issue of deliberate reintroductions, or introductions, are something that is being successfully dealt with in other places by other agencies already.

I agree with your 2 point plan. Especially number 2, and especially the point about the psychological impact of regulations.

 

[Fish Sticks]

You guys lose me, and a lot of others I think, when you start talking about chemically killing a stream. Just a point of constructive feedback. I’m not saying it wouldn’t work, or it wouldn’t be the most likely to work, I don’t know. I’m just saying it won’t be popular. And that is part of this deal…Promoting and advocating for conservation/management practices that can and will be supported. Otherwise we’re all just a bunch of spincasters pissing each other off on an internet board.

A good test study IMO would be to pick a tiny Class A Brookie stream, above an already existing barrier, that has a token population of Browns. Say one of those that is listed Class A Brookies, but has like 0.XX kg/ha Browns when last surveyed. Shock it, once/year for 10 years at the dead low flow of Summer/early Fall. Remove all the Browns. Repeat. After 10 years, note the changes…Are the Browns gone, or at least are there less of them? Has the Brookie biomass increased? Are the changes statistically significant versus the natural population fluctuations? (You’d also need a similar nearby control stream or streams that you’re not shocking.) You want a small, controlled as best as you can environment to test the viability of this. Can they actually be removed (and prevented from returning) from a situation where it’d be theoretically easiest to remove them, and prevent their natural return? If you can’t in this “ideal” test environment, you’re sure as snot not gonna be able to do it in larger streams/watersheds with more Browns to start with, and more places from which they can repopulate from.

Surely, the answer cannot be shocking every wild Trout stream in the state once a year and culling the Browns, simply from a resources standpoint.

I think two, obvious, easy starts that could most easily be supported are:

1. No stocking over streams that are currently listed as being more than 75% (Or so. Someone smarter and with more by biomass data can better assess what the tipping point number is.) Brook Trout when last surveyed. Period. No stocking on “Brook Trout streams.” All classes, not just Class A. No PFBC stocking, no club stocking, no rodeos for the kiddos, do it somewhere else. And enforce it. Make it public that you’re enforcing it. Streams that are “mixed”, or are predominantly Brown Trout are lost causes. Punt, and take the field position to fight on other fronts.

2. Make it catch and release statewide for Brookies. Everywhere. This is more for getting the word out and changing mindsets, than actually trying to limit the harvest of wild Brookies…It just doesn’t happen to a population meaningful level. The public should know that Brookies are native, are our state fish, and should be protected. We don’t kill Brookies in PA.

^Not implying the above will be easy, only that it will be the easiest place to start and garner support IMO. And neither of the above cost anything, assuming the PBFC is shocking many streams/year already as it is.

I can understand your feelings about the concept of chemical reclamation. I do wish there was some more public communication in the form of videos from agencies doing it about what does get removed, what doesn’t, how safe it is, how it’s inactivated and how quickly the entire stream bounces back with its newly gained reintroduced inhabitants. I wish these agencies did a better job sharing with anglers that we have kept multiple native trout from serious threat or complete extinction in the west(goldens, appaches, Gilas, and others) But I understand where your coming from and totally agree that stocking reform and catch and release statewide are logical very meaningful first steps and that I would be ecstatic about and support strongly. I agree that they are the places to start because pretty much every wild native brook trout watershed gets stocked with browns and rainbows in the mainstream with a few exceptions. If ya stop stocking it some browns might revert to a micro population in the face of stream characteristics or biotic resistance offered by a higher ratio of brook:brown trout. Removal may not even be needed in that case

To be honest stocking reform is the number one goal for us right now for native brook trout because its harm we (forced collectively) are paying to inflict and would be free to cost saving as you mentioned to eliminate. Out of roughly 8 million non private fish we know about state wide, stopping the ones stocked right over or in major high priority brook trout watersheds would almost be like doing a huge super effective removal because you would be taking next years hatchery trout that were supposed to be stocked, out of competition with native brook trout.

 

[silverfox]

What gets me is, how many brook trout populations have we manually removed in this state over the last 100 years? Apparently about 99% of them.

 

[pcray1231]

I think I said that one in a past thread. hehe. Although mine was.

1. Don't stock brook trout.
2. Make brook trout C&R statewide.

Same point, you can make my #1 Swattie's #3. And yeah, that's about changing mindsets. I'll also say, brookies or browns, the state's class A biomass bar is waaayyyyy too high. I'm not suggesting ending stocking altogether, or even on any stream that once had a wild trout pass through. You can argue fish move and all that, that surface area is not representative, and I won't disagree, but there's no great way to measure it, and the actual concept of establishing a biomass threshold and not stocking streams that come in over it is sound. It's just that threshold should be like, half, or 1/3, of where it's currently set. If you can go catch 30+ wild fish in a day on a class B or C stream, that's a quality wild trout fishery, I'm sorry.

 

[sarce]

A good test study IMO would be to pick a tiny Class A Brookie stream, above an already existing barrier, that has a token population of Browns. Say one of those that is listed Class A Brookies, but has like 0.XX kg/ha Browns when last surveyed. Shock it, once/year for 10 years at the dead low flow of Summer/early Fall. Remove all the Browns. Repeat. After 10 years, note the changes…Are the Browns gone, or at least are there less of them? Has the Brookie biomass increased? Are the changes statistically significant versus the natural population fluctuations? (You’d also need a similar nearby control stream or streams that you’re not shocking.) You want a small, controlled as best as you can environment to test the viability of this. Can they actually be removed (and prevented from returning) from a situation where it’d be theoretically easiest to remove them, and prevent their natural return? If you can’t in this “ideal” test environment, you’re sure as snot not gonna be able to do it in larger streams/watersheds with more Browns to start with, and more places from which they can repopulate from.

I see what you're getting at (testing whether it's even feasible to remove a small # of browns). But in that situation some of the other benefits won't be realized because the # of browns was too low to have a detrimental impact on the brookies. I think you'd want to test it on a more mixed stream. Otherwise it becomes like the WBTEP where the PFBC sees no benefit from the action because the streams selected weren't ever going to see a benefit no matter what the policy.

MD DNR did this on a stream section above a natural barrier that DID have a significant and growing brown trout population and a declining brook trout population. Reminds me I should reach out to someone there and see if they're seeing brookies rebound.

 

[pcray1231]

showed if a barrier was present between where Pa fish and boat stocks their invasive brown trout it was 12x more likely to be a brook trout stream!!

Thats interesting. Would love to read more about that.

Controlled for stream size and alkalinity? (in the ANF area, its plateau, so elevation and stream size correlate pretty well. Higher elevation streams do not cut richer bedrock and tend to have poor buffering, and tend to be brookies with only token populations of browns. Larger streams cut deeper bedrock, have more fertility and you get a transition to brown trout dominated. Elevation is an excellent predictor of what species will dominate. At least so long as the stream in question cut its own valley. It goes a little haywire near confluences, when smaller waters ener valleys cut by bigger waters.)

There's also an east/west thing going on. West of the Allegheny is lower elevation, lower gradient, more fertile, and pretty brown trout dominated overall. As you go east of it there's a lot more brookie water (with token brown populations), with much lower akalinity numbers.

Not discounting study, want to see it. Just as an engineer I'm trained to check for correlation vs causation stuff.

 

[TimMurphy]

Now we're really getting to the meat of the problem! I suppose to prevent a complete psychological breakdown; it's best to focus on smaller issues rather than face the reality of the bigger ones we all face.

I had a lengthy, humbling conversation with Bob Bachmann about this very issue not too awful long ago. I think the older we get, the more we experience, and the more we come to terms with (or not) the level of impact we've had on the environment.

Dear silverfox,

You'll get no argument from me about the effects of people on the environment.

But honestly, what is the next logical step in restoration? It must include extirpation. I'm old, I'll go first, but likely have no volunteers to follow me.

So, in the meantime I'll play the cards I have and try not to toss away a good one, or fold just because of a side-eye.

I'd respectfully suggest you do the same.

Regards,

Tim Murphy

 

[Mike]

Yea Mike, you gotta understand people dumped rainbows back in lynn camp prong and they did not take the brook trout population held and its now considered one of the most successful removals in the east despite a sabotage event. So its great they caught them but if they did not, they never took anyway. Phaedra Budy has described a density dependent biotic resistance for native trout that out number invasive ones. A lot of these populations with invasive trout had the balance shifted by wiping out the brookies with logging 100 years ago and the invasive trout used their absence to proliferate. Now alot these streams have dense forrest and that initial destabilization is no longer there. If your saying its impossible how are there well over a hundred projects in the eastern states alone???

How do you explain all these “pipe dreams” that materialized?

Eastern Brook Trout restoration summary table — EBTJV

Compilation of brook trout restoration projects and outcomes from across the EBTJV member states and agencies.

easternbrooktrout.org

If I examined the 2022 summary table closely enough, ten of the stream projects were Brown Trout removals and five of those ten were successful (50%). I saw no info on the lasting success of the projects without the need for additional removals, if any. Maybe they lasted; maybe they didn’t. Am I missing something in the BT data?

 

[Fish Sticks]

Thats interesting. Would love to read more about that.

Controlled for stream size and alkalinity? (in the ANF area, its plateau, so elevation and stream size correlate pretty well. Higher elevation streams do not cut richer bedrock and tend to have poor buffering, and tend to be brookies with only token populations of browns. Larger streams cut deeper bedrock, have more fertility and you get a transition to brown trout dominated. Elevation is an excellent predictor of what species will dominate. At least so long as the stream in question cut its own valley. It goes a little haywire near confluences, when smaller waters ener valleys cut by bigger waters.)

There's also an east/west thing going on. West of the Allegheny is lower elevation, lower gradient, more fertile, and pretty brown trout dominated overall. As you go east of it there's a lot more brookie water (with token brown populations), with much lower akalinity numbers.

Not discounting study, want to see it. Just as an engineer I'm trained to check for correlation vs causation stuff.

https://easternbrooktrout.org/science-data/science-publications/evaluating-the-trade-offs-between-invasion-and-isolation-for-native-brook-trout-and-nonnative-brown-trout-in-pennsylvania-streams

 

[troutbert]

Thats interesting. Would love to read more about that.

Controlled for stream size and alkalinity? (in the ANF area, its plateau, so elevation and stream size correlate pretty well. Higher elevation streams do not cut richer bedrock and tend to have poor buffering, and tend to be brookies with only token populations of browns. Larger streams cut deeper bedrock, have more fertility and you get a transition to brown trout dominated. Elevation is an excellent predictor of what species will dominate. At least so long as the stream in question cut its own valley. It goes a little haywire near confluences, when smaller waters ener valleys cut by bigger waters.)

There's also an east/west thing going on. West of the Allegheny is lower elevation, lower gradient, more fertile, and pretty brown trout dominated overall. As you go east of it there's a lot more brookie water (with token brown populations), with much lower akalinity numbers.

Not discounting study, want to see it. Just as an engineer I'm trained to check for correlation vs causation stuff.

The best correlation is with the bedrock geology. I've dug into this quite a lot.

In the Allegheny Plateau region, you can look at the geology maps and make pretty good predictions about whether you will find: no fish, or dominated by brookies, or plenty of browns.

The layers often do correspond to elevation pretty well, but there are places where anticlines and synclines shift the layers up or down. The anticlines are good for brown trout. The synclines are more favorable for brookies.

 

[Fish Sticks]

If I examined the 2022 summary table closely enough, ten of the stream projects were Brown Trout removals and five of those ten were successful (50%). I saw no info on the lasting success of the projects without the need for additional removals, if any. Maybe they lasted; maybe they didn’t. Am I missing something in the BT data?

Yea the majority of those you highlighted were electrofishing, the few times antimycin was used for brown trout it worked very well. The other thing is the reason there are so many more rainbow projects as you pointed out is likely more of a social factor than a logistical factor as far as species goes. NPS who does alot of these projects just happens to have the great smokeys where there is a ton of rainbows. States to the south of PA do this more than to the north, so you get a lot more rainbows.
50% for electrofishing(many were single pass) is not bad and is about on par with silver foxes original bolded success rate numbers for the technique considering. If you were to include out west you would have a lot mote successful antimycin projects for brown trout because this technique gets used often and effectively out there and they just chose to do it more where there are brown trout.