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Re: using bedrock geology info to fish in acidrain areas

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Quote:

pcray1231 wrote:
Further, another good question is that IF we were able to improve the acidity of the streams, would it really help the brookie?

I know that there are some very acidic streams with few or no brookies due to acid. And these streams would likely improve, to where they may hold relatively healthy brookie populations.

But alongside those, I think there are some streams with currently stable brookie populations that would switch over to primarily browns. Generally speaking, your brookie populations may merely get pushed even further to the headwaters, while browns take over the lower reaches of what are currently inhabited by brook trout. In some cases, slightly acidic streams could be regarded as the last bastion of brookie habitat, in that it holds off the onslaught of brown trout.

More trout is good, so I'm not suggesting we try to stop this from happening. Just musing out loud.


I think that both brookie and brown trout populations would improve.





Posted on: 7/6 14:27


Re: using bedrock geology info to fish in acidrain areas

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^ Right. I'd say that you'd have an overall increase of fish populations.

However, pcray, your musings are legitimate. If there is a limited food supply, and given all things ideal for a marine environment, the brown is going to push the brook out and in some special cases you might have a "zoning" of brooks and browns along the same watershed.

I'd think that it'd have to hit the "magic" pH values for each species.

Posted on: 7/7 19:42
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Re: using bedrock geology info to fish in acidrain areas

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I think that the brook trout and the brown trout would increase in roughly the same proportions.

And it's quite possible that the brook trout would improve at a higher proportion than the browns.

In the infertile watersheds, brook trout would re-inhabit the headwater stretches which presently hold no fish.

Below these headwater fishless stretches are commonly long stretches that hold brook trout but which are still very infertile. If pH of rainfall was returned to a normal 5.5, these stretches would still probably not support brown trout. The brook trout would improve here as a result of better food supply.

Further down, yes, there would be some increases in the range of brown trout in the upstream direction.

But I think the increases in brook trout would be as great or greater than increases in brown trout populations. In the infertile watersheds there would still be only brook trout for many miles down.

In the fertile watersheds, I'm not sure there would be much difference. Because the brown trout are not currently limited by pH in those watersheds. Often these streams have pH suitable for brown trout as far up as there is water. But the headwaters of these streams are still typically all brookies for a ways down. Then the brown trout appear, but they are still typically outnumbered by the brookies for a ways further downstream. Then you get to a zone where they run about 50/50, and the ratio continues to shift towards more browns / brookies as you continue down.

But this does not seem to be pH related. Because the pH is within the range for browns from right up where the streams originate the whole way down.

So, in fertile watersheds, why do the browns not totally displace the brookies in the upper ends? I don't know, but it's not about pH, IMHO.

It may be related to groundwater temps for spawning being more favorable for brookies than browns. Or it may be that brookies survive better in droughts in the small streams. Some PFBC survey reports during a severe drought stated that their data indicated that.


Posted on: 7/7 21:37

Edited by troutbert on 2014/7/7 22:16:29


Re: using bedrock geology info to fish in acidrain areas

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Came across this map while preparing a lecture for my environmental sciences class. I thought it would be relevant for this topic.

Resized Image



Posted on: 7/8 3:20
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Re: using bedrock geology info to fish in acidrain areas

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"So, in fertile watersheds, why do the browns not totally displace the brookies in the upper ends? I don't know, but it's not about pH, IMHO."

my guess: brookies feed more throughout the day, while browns feed less consistently, so brookies can hang on in smaller headwater stream sections?


Posted on: 7/8 9:49


Re: using bedrock geology info to fish in acidrain areas

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"So, in fertile watersheds, why do the browns not totally displace the brookies in the upper ends? I don't know, but it's not about pH, IMHO." ... " It may be related to groundwater temps for spawning being more favorable for brookies than browns."

maybe feeding, but in a different way? there is slightly colder water in the headwaters, and I think the rosenbauer small stream book says browns don't grow as well as ST in colder water

Posted on: 7/8 10:46

Edited by k-bob on 2014/7/8 11:07:14
Edited by k-bob on 2014/7/8 11:13:52


Re: using bedrock geology info to fish in acidrain areas

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I think browns may simply need/prefer a bit more space or slightly deeper water than the brookies. At least the adults anyway, since they tend to run larger than the adult brookies. Just a thought, I don't really know either.

Great info here btw, thanks.

Posted on: 7/8 11:40
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Re: using bedrock geology info to fish in acidrain areas

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Quote:

troutbert wrote:
I think that the brook trout and the brown trout would increase in roughly the same proportions.

And it's quite possible that the brook trout would improve at a higher proportion than the browns.

In the infertile watersheds, brook trout would re-inhabit the headwater stretches which presently hold no fish.

Below these headwater fishless stretches are commonly long stretches that hold brook trout but which are still very infertile. If pH of rainfall was returned to a normal 5.5, these stretches would still probably not support brown trout. The brook trout would improve here as a result of better food supply.

Further down, yes, there would be some increases in the range of brown trout in the upstream direction.

But I think the increases in brook trout would be as great or greater than increases in brown trout populations. In the infertile watersheds there would still be only brook trout for many miles down.

In the fertile watersheds, I'm not sure there would be much difference. Because the brown trout are not currently limited by pH in those watersheds. Often these streams have pH suitable for brown trout as far up as there is water. But the headwaters of these streams are still typically all brookies for a ways down. Then the brown trout appear, but they are still typically outnumbered by the brookies for a ways further downstream. Then you get to a zone where they run about 50/50, and the ratio continues to shift towards more browns / brookies as you continue down.

But this does not seem to be pH related. Because the pH is within the range for browns from right up where the streams originate the whole way down.

So, in fertile watersheds, why do the browns not totally displace the brookies in the upper ends? I don't know, but it's not about pH, IMHO.

It may be related to groundwater temps for spawning being more favorable for brookies than browns. Or it may be that brookies survive better in droughts in the small streams. Some PFBC survey reports during a severe drought stated that their data indicated that.


TB, Your last paragraph is probably spot on as to the reason why. I would add that if the upper reaches of those streams because of temps and droughts have different macros, then the macros may some how favor the brookies. I've never found anything on that aspect, but I never really looked either.

Posted on: 7/9 11:46


Re: using bedrock geology info to fish in acidrain areas

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Quote:

sarce wrote:
I think browns may simply need/prefer a bit more space or slightly deeper water than the brookies. At least the adults anyway, since they tend to run larger than the adult brookies. Just a thought, I don't really know either.

Great info here btw, thanks.


All things being equal, if you were to take 2 streams that were the same PH, the same temperatures throughout the years, and had all else equal except species, browns in one stream brookies in the other, the brookie stream would have the same size structure as the brown stream.

Again, all great stuff.

Posted on: 7/9 11:51


Re: using bedrock geology info to fish in acidrain areas

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Chaz, do you have any studies or other sources that came to that conclusion? I would be interested in reading them. I was under the impression that, all other things being equal, browns will grow faster and bully the brookies around, which is how they displace them. But I could also see brookies losing out simply because browns are more aggressive toward other fish.

Posted on: 7/9 13:25
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Re: using bedrock geology info to fish in acidrain areas

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There are a number of streams where its all browns way up to the headwaters. In those cases, yes, browns run small just like brookies in the same situations. And they act more like brookies too.

As for why they can't do that in all streams? I dunno, but suspect generalities doesn't cut it. Each stream is unique and may have a unique reason. I do suspect pH is a common reason. But temperature, structure, food base, availability of spawning beds, etc. are possibilities as well.

There's also simple opportunity. All else being equal, a habitat may be capable of supporting lots of browns. But all else is not equal. A few brown invaders may struggle to get a substantial foothold in the face of a healthy established brookie population. Introduce a temporary disaster to make both species re-establish from scratch, and all bets are off. This has happened in places.

Posted on: 7/9 19:41


Re: using bedrock geology info to fish in acidrain areas

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Quote:

pcray1231 wrote:
There are a number of streams where its all browns way up to the headwaters.


What are some examples?

Posted on: 7/9 22:11


Re: using bedrock geology info to fish in acidrain areas

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As for examples, I'm excluding true limestoners, or streams typically thought of as limestoners. But some of these likely may have a touch of limestone influence as some of the alkalinity values are in the upper teens and 20's. These are listed class A browns with headwaters as upper limit. It's not all of them listed like that, just what I picked out in a minute or two looking at the list. I've fished a couple, others I haven't.

Berks Cnty: Hay Creek, Beaver Run
Columbia: Mugser Run, Roaring Creek, Tenmile Creek
Centre: Rupp Hollow
Clinton: Shingle Branch, Spring Run
Lycoming: Mill Run
McKean: Lewis Run
Potter: Dingman Run, Bear Creek
York: Rambo Run

Posted on: 7/10 7:32


Re: using bedrock geology info to fish in acidrain areas

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I'd have to cogitate on some of the streams on that list in order to form an opinion as to why they present exceptions to the ST dominated headwaters/mixed middle sections/BT dominant lower sections model. In some cases, geology and its effects on Ph may be primary. In others, probably not. My guess is that most are a mix of factors and that in some cases, decent alkalinity may be contributory but a different factor is actually determinative. For example, the situation on Lewis Run is probably more indicative of the fact that it is directly accessible to the strong wild BT pop. in the EB Tunungwant Creek than anything to do with Ph. I don't know what Lewis Run's alkalinity numbers are, but my guess would be that even if they were no better than the average stream in its size class in that area, it would still be dominated all the way to the headwaters by BT.

Something similar may be the case with Dingmans, the difference being the replenishing factor could be large browns from the Allegheny who spawn in Dingmans. There probably aren't a lot of these fish, but it wouldn't take that many to do the trick.

There are probably a lot of streams in that same situation and probably quite a few as well where the chemical characteristics are perfectly fine for browns but ST remain dominant because they lack direct connection to a stream with a potent enough BT population to overwhelm the dominance of the brookies.

Posted on: 7/10 16:11


Re: using bedrock geology info to fish in acidrain areas

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Shingle Branch has a lot of brook trout, as well as browns.

In Mill Run also I've caught both browns and brookies.

Dingmans also has both browns and brookies.

So, I don't know why these would be considered exceptions. They fit the general pattern for fertile freestoners, i.e. the mix of brookies and browns strongly favoring the browns in the lower ends, then shifting more and more towards brookies as you go upstream. And up where the stream gets quite small, the population is dominated by brook trout.

This happens even where the streams are fertile the whole way up. For example Kettle Creek.

And the headwater branches of the Genesee River, which are flowing out of fertile glacial till. Further down it's mostly browns. But up where those streams get quite small, it's dominated by brookies. It's not a pH thing, it's some other factor(s).

Another example is where you have a fertile freestoner with a mixed population, but more browns than brook trout. Where a small, secondary channel splits off the main channel, that channel will have a greater percentage of brook trout than the main, unsplit channel.

That is definitely not a pH thing. Because it's the same water flowing through both sections. The brookies seem to have an edge over the browns in the smaller, shallower stream sections.

Posted on: 7/10 17:23



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