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Re: Current PA Brook Trout Population as Percentage of Original?

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I remember reading somewhere that old growth forests had deeper, more fertile soils than today's forests which translated to more fertile headwater streams. In those streams, not only were there more brookies but they were larger on average. I don't think it's a stretch to say that by biomass, brookies are at 1% of pre-logging levels.

Posted on: 3/7 10:10
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Re: Current PA Brook Trout Population as Percentage of Original?

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"I remember reading somewhere that old growth forests had deeper, more fertile soils than today's forests which translated to more fertile headwater streams. In those streams, not only were there more brookies but they were larger on average."

hemlock needles are quite acidic? hemlock forests have little ground level growth, so probably fewer terrestrials? if brookies evolved in fertile water, they sure like terrestrials? (see below)

http://www.paflyfish.com/forums/open- ... ent-appalachian-streams/6,33995.html

Posted on: 3/7 10:35

Edited by k-bob on 2014/3/7 10:57:35


Re: Current PA Brook Trout Population as Percentage of Original?

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Trout in all waters seem to really like terrestrials.

Point taken though. I just remembered where I read it. I believe it was an article in eastern fly fishing magazine about slate run. I'll try to find it when I go home tomorrow.

Also I am not sure about that EBTJV map. It shows them as "extirpated" in areas where there are still quite a few small, unnamed brookie streams. I would think the term extirpated means completely wiped out from those areas in gray.

Posted on: 3/7 11:13
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Re: Current PA Brook Trout Population as Percentage of Original?

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Quote:

k-bob wrote:
still not clear what you mean by top 5%? then? now? diff betwn then & now?


The top 5% of brookie streams now.

Add up their biomass.

Compare to their biomass pre-disturbance.

Posted on: 3/7 11:23


Re: Current PA Brook Trout Population as Percentage of Original?

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sorry my guess is that some pa streams may have more now than then... yes or no in your opinion?

for ex ebtjv map does not allow for the possibility....


Posted on: 3/7 11:33

Edited by k-bob on 2014/3/7 11:50:15
Edited by k-bob on 2014/3/7 11:51:04


Re: Current PA Brook Trout Population as Percentage of Original?

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we may be talking past each other. here's the question I have brought up:

me: "if we had data for all the PA streams pre euro & present, incl tiny steep mountain ones, almost none would have better brookies now?"

Posted on: 3/7 12:50


Re: Current PA Brook Trout Population as Percentage of Original?

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I don't know how I missed this thread. It seems only small wilderness mountain streams are in discussion in this thread.

One thing that is not put into play here is the small limestone streams that used to hold 18" brook trout. I can think of one stream less than a mile from where I'm typing. Plus larger freestones where brook trout used to migrate.

So that would put a kink in the total biomass question.

Posted on: 3/7 14:19
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Re: Current PA Brook Trout Population as Percentage of Original?

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Quote:

BrookieChaser wrote:
I don't know how I missed this thread. It seems only small wilderness mountain streams are in discussion in this thread.

One thing that is not put into play here is the small limestone streams that used to hold 18" brook trout. I can think of one stream less than a mile from where I'm typing. Plus larger freestones where brook trout used to migrate.

So that would put a kink in the total biomass question.


Not just small limers. Big ones too. Penns Creek, Fishing Creek, Spring Creek and Little Juniata.

Pcray did mention the big freestoners, Pine Creek in particular.

Posted on: 3/7 14:38


Re: Current PA Brook Trout Population as Percentage of Original?

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Exactly troutbert. I shouldn't have just mentioned small limestoners. Just the stream I referred to is small and I can think of one more not a quarter mile away.


Posted on: 3/7 14:57
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Re: Current PA Brook Trout Population as Percentage of Original?

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If we take all these small limestoners, large limestoners, large freestones, small mountain streams, displacement from invasives, deforestation, and any lakes that beavers, or natural causes, would've made, I'd say we're definitely less than 10% of historic biomass (probably less than 5%) across the state.

But since I have no data from pre-European settlement, I can't make a very accurate estimation.




Posted on: 3/7 16:17
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Re: Current PA Brook Trout Population as Percentage of Original?

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Quote:

k-bob wrote:
we may be talking past each other. here's the question I have brought up:

me: "if we had data for all the PA streams pre euro & present, incl tiny steep mountain ones, almost none would have better brookies now?"


Correct. I've explained the physical habitat reasons why already. Far fewer pools = far fewer trout.

Supposing you took even a smaller slice then 5% of the top streams, and took only the top 1% of streams.

The populations of even that top 1% would be not just less, but FAR less, than in the past. For the physical habitat reasons already explained.

Regarding the map shown earlier. It is not mapping populations. It is mapping miles of streams that have brookies now, as compared to the past in subwatersheds.

So there are a couple of things to consider when thinking about the answer to the original question:

1) The maps shows areas where brookies are totally extirpated in entire subwatersheds.

2) The maps shows areas where different percentages of stream miles have lost their brookies.

3) What the maps do not show, but which we've been discussing, is the percentage drop in population in the streams that still have brookies.


Posted on: 3/7 16:39


Re: Current PA Brook Trout Population as Percentage of Original?

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I agree that of course there is total biomass loss in all streams, big and small, that went from brookies to browns. 100% loss. And there must be large biomass losses also in many of the bigger streams that have brookies now.

But are there very small, very steep, cold streams with woody debris accumulated in the 100 years since they were logged, that have as many brookies now as they ever did? I think there could be, because the old hemlock forest might have blocked streamside brush more than the replacement mixed forest and thus reduced terrestrials. I also don't think that such very small and steep streams, 7+% grade, really have far fewer pools now from logging 100 years ago.

no way to know and interesting to consider.


Posted on: 3/7 17:02

Edited by k-bob on 2014/3/7 17:24:08
Edited by k-bob on 2014/3/7 17:26:58
Edited by k-bob on 2014/3/7 17:36:35


Re: Current PA Brook Trout Population as Percentage of Original?

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any map that shows brookies being "extirpated" where some brookies exist will mislead readers.


Posted on: 3/7 17:08

Edited by k-bob on 2014/3/7 17:25:22
Edited by k-bob on 2014/3/7 17:32:04
Edited by k-bob on 2014/3/7 17:32:26
Edited by k-bob on 2014/3/7 17:32:57
Edited by k-bob on 2014/3/7 17:34:13


Re: Current PA Brook Trout Population as Percentage of Original?

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There are some other factors that affect brookie populations in the streams where they still remain.

Competition with brown trout. In many forested freestone streams that still hold brook trout, long stretches of the lower parts of the creek are strongly dominated by brown trout. There are still brookies there, and they show up in the stream surveys, but their populations are greatly inhibited by the brown trout.

One example, among many, is the well known Cedar Run, tributary to Pine Creek. From the mouth far upstream up to around Leetonia, the brown trout population is far higher than the brown trout population. There are still many brown trout even well above Leetonia. The brookies only rule in the very upper end of the creek.

Acid rain (acid precipitation) has been mentioned briefly. But this had a very large impact on brookies. There are many miles of streams where the brookies are just gone, from acid rain. Some of that mileage would show up in the databases and therefore the mapping.

But many streams are surveyed in the lower and middle ends, and wild trout are found, and the stream is put on the reproduction list as "headwaters to mouth."

But in areas of the state with geologies with low buffering, very often there are brookies in the middle and lower ends, but the very upper ends are too impacted by acid rain, so support no trout at all, or fish of any kind.

And there is often a transition zone, where there are brookies at certain times, then they get pushed back downstream by heavy rain or melting snow dropping the pH.

Those lost miles of streams at the upper ends in many cases are not recorded so not shown on the mapping.

Also, in the lower and middle ends of the acid rain impacted stream miles where brookies are found year around, often the numbers of brookies are low. Because the food supply, i.e. the insects and other inverts are reduced by the acidification. You can simply turn of the rocks and see that there are not many bugs.

Posted on: 3/7 18:16


Re: Current PA Brook Trout Population as Percentage of Original?

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Quote:

k-bob wrote:
any map that shows brookies being "extirpated" where some brookies exist will mislead readers.



That would mislead readers, if that were the case. I think pcray made the same point. But I have not seen any examples given.

If anyone has examples, let us know.

Posted on: 3/7 18:28



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