Current PA Brook Trout Population as Percentage of Original?

[Chaz]

And there are run-off events like some streams will experience this year due to the amount of snow on the ground and rain on top of that snow. Pushes the ph down to fatal levels.

 

[Chaz]

pcray1231 wrote:
The Little Ice Age is an interesting topic, and the same discussion could shed light on the long term effects of the current warming.

Generally speaking cooler = drier and warmer = wetter, streams. The ones that really aren't in danger of getting too warm in our summers.

Cooler=wetter, warmer=drier

 

[troutbert]

k-bob wrote:
tb: "So, how does the hemlock/hardwood hypothesis deal with these known impacts from acid precipitation, with all these miles of streams with no brook trout whatever, or very low pops, and very little invertebrate life? ... According to your theory, what was the situation with these streams pre-settlement? Did they have brook trout then? Was the pH higher or lower than now? Were inverts higher or lower than now?"

my ideas are about invertebrates not acid rain. acid rain is a tangent I already addressed. I have not suggested that there were massively different acidity levels in the distant past -- for any reasons.

for ex., as I wrote above (emphasis added): "2) A stream that shifts from hemlock- to hardwood- drained forest would see changes in multiple variables. Yes, a small reduction in water acidity based on things I have read, in one case of paired study of hemlock and hardwood draining streams, the one under hardwood had a pH .25 higher. The pH difference was attributed to fewer acidic hemlock needles. Hemlocks were harvested because of tannic acid, right they produce acid. However, the pH level only has to be appropriate for trout, they don't calculate some balance w/ acid rain or anything else."

so pH is a tangent to the basic point about invertebrates ..

pH is not at all tangential, to inverts or fish. pH determines whether or not brook trout exist in these stream sections. And it has also determines quantity and species diversity of inverts.

Maybe not all of you have been on some these acid rain impacted streams. You turn over the rocks and there are scarcely any bugs at all. The one stream was thoroughly studied by a college and they found no mayflies, no stoneflies, and only one species of acid tolerant caddis, and a few midge larvae.

You're theorizing that the hemlock/hardwood thing increases pH. But that effect would be in direct competition with acid precipitation in lowering pH.

You cannot separate the two things out. Either one effect is greater, or the other one is, and the result is that the pH is either higher or lower in the past. And the result of the pH change is that trout, other fish, and invert life is either greater or less than in the past.

I say the effect of acid precip is MUCH greater, and completely overwhelms any countervailing effect from the hemlock/hardwood thing. And the many miles of acid precip. damaged streams supports that.

 

[pcray1231]

Cooler=wetter, warmer=drier

Overall, wrong. Higher temp = more evaporation from the oceans = more rain. That's the general consensus, looking at it on a global basis.

How that pertains to PA specifically, and how it varies by season, well, I dunno, and not sure that anyone really does.

 

[pcray1231]

Maybe not all of you have been on some these acid rain impacted streams. You turn over the rocks and there are scarcely any bugs at all.

Yeah, I've been on them, and I don't disagree with you. But there are other ones, getting the same rainfall, sometimes in the next valley over, which aren't so negatively affected.

Nobody is arguing that streams, overall, haven't been harmed by man. We even agree that the vast majority have been negatively affected to various, sometimes severe degrees. But you're trying to say EVERY SINGLE ONE has. That out of 3-5 thousand of them, there's not a single one that by some freak occurance didn't benefit from the overall effects of man. I think that's foolish. We highlighted two variables. There are a bunch that affect pH, and a whole bunch more that affect the overall brook trout populations.

Anytime you have a complex system of competing interactions acting differently in a chaotic system, you're going to have a wide range of rather unpredictable outcomes. You can predict the most common, and we largely agree on the most common effects of man on brookies. We're bad for em. You cannot predict every circumstance universally. That's where we disagree.

You cannot separate the two things out. Either one effect is greater, or the other one is, and the result is that the pH is either higher or lower in the past.

The heck you can't. One can be greater on one stream, and the other greater on the next. Are you saying that acid rain effects the pH of all streams exactly the same? Even though each stream has different buffering characteristics, based on rock type, % of flow resulting from groundwater, and a host of other factors?

Do you really think any effect from forest/soil type wouldn't be equally as variable?

I say the effect of acid precip is MUCH greater, and completely overwhelms any countervailing effect from the hemlock/hardwood thing.

Think that's a bit of an overstatement, but still generally correct. Generally. Not 100% of the time. 85% of the time, 90%, 95%, 99%, 99.99% of the time? I don't know. I will say that I'm reasonably sure it's correct well over 50% of the time, and not fully 100%.

 

[k-bob]

tb my ideas work quite clearly through the mechanism of varying leaf litter fertility of hemlock v hardwood as in-stream invertebrate food. my ideas are about the food chain.

I think that acid rain effects are too variable to conclude that no stream in Pennsylvania could possibly have more trout now because of acid rain... particularly if some now have more inertebrates due to reforestation that has the potential to increase trout food.

yes I have seen amd streams. but I have also read about the food chain for trout in its complexity and allow for interactions w geology etc.

so you can learn by fishing and walking streams sure but you can also learn by reading relevant research.. I have repeatedly linked an experimental study on this thread showing a large log scale difference in the number of in stream invertebrates that grew per gram of hemlock versus maple. we just disagree on its significance.

 

[pcray1231]

TB, think of it this way. Most streams were originally slightly acidic, just like our rain is naturally slightly acidic. Agreed?

Now, we agree that man, via acidifying the rain beyond what nature intended, has, as a general rule of thumb, made BOTH the rain and the streams more acidic. Great.

Yet, we can dump a bunch of limestone sand in a stream, and negate that, even turn it slightly basic. Definitely a higher pH than nature intended. And we can watch as brookie populations improve as a result. We've done it.

Now, that's intentional, but still a man-made improvement of waterways, no? You're gonna say that never, in the white man's history, has he unintentionally done a single thing with a positive effect on a single stream?

 

[troutbert]

pcray1231 wrote:
TB, think of it this way. Most streams were originally slightly acidic, just like our rain is naturally slightly acidic. Agreed?

Now, we agree that man, via acidifying the rain beyond what nature intended, has, as a general rule of thumb, made BOTH the rain and the streams more acidic. Great.

Yet, we can dump a bunch of limestone sand in a stream, and negate that, even turn it slightly basic. Definitely a higher pH than nature intended. And we can watch as brookie populations improve as a result. We've done it.

Now, that's intentional, but still a man-made improvement of waterways, no? You're gonna say that never, in the white man's history, has he unintentionally done a single thing with a positive effect on a single stream?

I never said that. You are arguing against a position that has not been taken, by me or anyone else.

 

[troutbert]

What this discussion reveals is that people don't realize the extent and severity of acid rain. Acid rain greatly lowered the pH of rain and snow all across PA. In every watershed.

So, any countervailing effect in the upward direction from change in ratios of hemlocks & hardwoods has to not only match, but to exceed the effect of acid precipitation. That is a very high hurdle.

And this is the case in every watershed. So pick your watershed. Figure out how much the hemlock / hardwood ratios shifted and how much effect that would have on stream pH. Then look at the effect of acid precip by comparison.

The acid precip would overwhelm it in every case. Not even a contest.

And there is no getting away from pH in small mountain streams. Where acid precip made the pH too low, there are no trout.

Remember our topic. Brookie pops now / brookie pops then.

 

[k-bob]

sorry but I have clearly explained that the hemlock to hardwood mechanism I see would affect ST biomass via the food chain, rather than via minor streamwater pH effects...

have linked studies on reforestation, invertebrates, & food chain repeatedly and connected these to ST biomass...

sorry to say but your third & fourth paras above suggest that this is not clear

can't just be my writing since I have given several quotes from articles...

if my posts and the articles I linked are tl/dr that's fine

I see no one size fits all answer to the balance of possible positive food chain effect vs negative acid rain effect.

 

[pcray1231]

You are arguing against a position that has not been taken, by me or anyone else.

Then we both are. I'm agreeing that the overwhelming majority of PA streams have lower brook trout populations now than they did pre-European settlement. The reasons are variable and definitely include acid rain, which is devastating on some streams, bad on all, and overwhelms positive changes on most.

Just not every single one now has a lower population. There likely is a small number that have increased the population in that time frame.

How small a number? I dunno. Greater than zero.

Do you agree with that?

 

[pcray1231]

For example, there still exist freestone streams, in PA, which hold wild brook trout, with pH's ABOVE 7. Not the norm, but they exist.

 

[Chaz]

pcray1231 wrote:

Cooler=wetter, warmer=drier

Overall, wrong. Higher temp = more evaporation from the oceans = more rain. That's the general consensus, looking at it on a global basis.

How that pertains to PA specifically, and how it varies by season, well, I dunno, and not sure that anyone really does.

If that were true then why is most of California desert, over half of Oregon and Washington Desert? For that matter most of the west. All of the west is hotter and dryer than the east.

 

[Chaz]

pcray1231 wrote:
TB, think of it this way. Most streams were originally slightly acidic, just like our rain is naturally slightly acidic. Agreed?

Now, we agree that man, via acidifying the rain beyond what nature intended, has, as a general rule of thumb, made BOTH the rain and the streams more acidic. Great.

Yet, we can dump a bunch of limestone sand in a stream, and negate that, even turn it slightly basic. Definitely a higher pH than nature intended. And we can watch as brookie populations improve as a result. We've done it.

Now, that's intentional, but still a man-made improvement of waterways, no? You're gonna say that never, in the white man's history, has he unintentionally done a single thing with a positive effect on a single stream?

But only as long as there is money available for the limestone sand, but it doesn't improve the buffering capacity on the land, and that is the key. The buffering capacity has been stripped away so much that even with a higher ph in rain, let's say it's 5 instead of 3.7 it may not help the rest of the watershed land.

So the expected result is not necessarily what you'll get, i.e., more brook trout. Plus you can't treat all of the streams in PA. there are thousands of miles of streams that are freestone, all of them to a degree have been impacted by acid rain and become more acidic, it's dependent on the buffering capacity of the land.

 

[k-bob]

I see a steep little ravine brookie stream in reports with pH professionally tested at 6-6.5 in various points, good macros in the professional assessment, very good brookie fishing, and a hardwood canopy. just sayin,...

to be clear, my view is that the hardwood tree leaf litter could affect the invertebrate numbers, and thus the biomass of trout that eat the invertebrates. I am not suggesting that the hardwood canopy does much to change the pH... back in the day there may well have been hemlocks over the stream, whose leaf litter may have resulted in lower invertebrate density, and possibly, lower trout biomass.

 

[Chaz]

k-bob wrote:
I see a steep little ravine brookie stream in reports with pH professionally tested at 6-6.5 in various points, good macros in the professional assessment, very good brookie fishing, and a hardwood canopy. just sayin,...

to be clear, my view is that the hardwood tree leaf litter could affect the invertebrate numbers, and thus the biomass of trout that eat the invertebrates. I am not suggesting that the hardwood canopy does much to change the pH... back in the day there may well have been hemlocks over the stream, whose leaf litter may have resulted in lower invertebrate density, and possibly, lower trout biomass.

I view the ph as more important a measure of a streams health, and the buffering capacity as a measure of the environments health. If the ph is 7, and the rain is 4.5, and an inch of rain falls in that drainage, that rain is going to trump the vegetations around the stream, because now the ph takes a dive toward 4.5.
I'm not saying that in a healthy watershed the type of trees isn't important, it is, but just having a forested buffer is important, but acid rain can trump everything and it often does.
The trout move but the bugs not so much and not so fast.

"The pH scale measures how acidic or basic a substance is. It ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic. Each whole pH value below 7 is ten times more acidic than the next higher value. For example, a pH of 4 is ten times more acidic than a pH of 5 and 100 times (10 times 10) more acidic than a pH of 6. The same holds true for pH values above 7, each of which is ten times more alkaline—another way to say basic—than the next lower whole value. For example, a pH of 10 is ten times more alkaline than a pH of 9." EPA

 

[troutbert]

pcray1231 wrote:

You are arguing against a position that has not been taken, by me or anyone else.

Then we both are. I'm agreeing that the overwhelming majority of PA streams have lower brook trout populations now than they did pre-European settlement. The reasons are variable and definitely include acid rain, which is devastating on some streams, bad on all, and overwhelms positive changes on most.

Just not every single one now has a lower population. There likely is a small number that have increased the population in that time frame.

How small a number? I dunno. Greater than zero.

Do you agree with that?

I think it is possible that the number is greater than zero. Simply because of the very large number of streams, and because it is impossible to really know every possible factor: landslides? who knows?

But I think these cases would be extremely rare. And kbob also said such cases would be rare.

If the cases are very rare, on a very small percentage of the thousands of small streams, it wouldn't even budge the needle regarding the answer to the original question, IMHO.

So why has there been so much focus on side stories that really do not impact the answer to the question in any meaningful way, i.e. that are several decimal places out.

IMHO, it's a tactical thing. Trying to create the IMPRESSION that things are really not that bad, among readers not familiar with these topics, by focusing on, emphasizing trivial counter-examples that really have almost no influence on the overall situation.

And possibly a diversionary tactic. As long as you can get people to talk about deer, bears, hemlocks, they are distracted from the original topic, and aren't focused on what most who have ventured to make an estimate have characterized as a 90 - 95 - 97 - 99% reduction in native brook trout populations.

I tossed the "outlier." Statisticians do that, right? 🙂

That's the real story. And the point of it all is that if in fact the populations of brook trout in PA are off by ~95%, then that ought be given some consideration in conservation and management decisions regarding brook trout.

There has been some consideration given over the years. Namely the raising of the size limit from 6 to 7 inches, was done specifically for brook trout.

And quite a few of the brookie streams that were stocked "back in the day" have been taken off the stocking list, and that has helped on those streams.

But stocking over brook trout is still very widespread, particularly in central, NC, and NW PA. Both by the PFBC and coop hatcheries.

The creel limit is 5 fish per day for brookies. In many states it ranges between 0 and 2 fish.

So, there is still a lot of work to be done that could improve brookie populations.

 

[pcray1231]

Chaz, the rainforests are wetter and warmer than those places, and Antarctica is the driest continent on earth.

See, I can give examples too.

The truth is that temperature isn't the only thing that affects rainfall. In fact its one of the lesser causes. The places you mentioned are dry because of mountains and the rain shadow effect.

 

[pcray1231]

TB, I also said they were rare. And I guessed modern populations to be 5% of "original". And repeatedly said my only disagreement was in the assertion that ALL brookie streams got worse. When you kept dismissing that I gave numerous reasons the odd stream could improve.

I'm not into intentional mis-statements, over-exaggerations, or witholding any contrary info for tactical reasons, in fact I abhor it. I'm an engineer. If people can't comprehend competing variables without thinking I'm advocating something I'm not, then I need Farmer Dave's avatars. While giving reasons and situations where a stream can improve, I gave reasons why they get worse too, and stated that those were much more common.

Statisticians can't drop an outlier just because it's an outlier. They have a way of telling you the most about whats going on. You have to acknowledge them and try to explain them. And when you figure out the reason it's an exception, verry often you prove the rule. For instance, if an"outlier" was found to have had a bunch of limestone gravel laid in its headwaters to support a road bed, thats a good indication that what's hurting every "normal" stream is indeed pH, rather than, say, availability of terrestrial bugs.

 

[k-bob]

I found a lot of the subjects that came up -- biomass vs fish vs stream miles?; how many PA streams have brookies today?; is biomass down, or are water temps up, in all streams?; etc interesting... got me to read some good biology papers as well. Didn't know there were papers on some subjects related to the thread, such as hemlock loss and brookies in s Appalachia!