Current PA Brook Trout Population as Percentage of Original?

[k-bob]

... hemlock logging could have been a massive net negative for brook trout without being a negative in the case of every stream... put your savings into lottery tickets, and you'll lose money, even if a few $3 scratch tickets looked at individually pay back $5...

 

[Chaz]

No one has mentioned that the reduction of ground water flowing into streams has changed, wells all over tap into ground water for human use and draws that water off at the peril of stream flows. But that's not the question, and it does have an impact. I suspect that it's a major impact in the Piedmont geographic region of PA. it's the most developed region and it has the most draw off on the groundwater.
Look at the flow reductions of the streams in this region in the summer, most are even lower now then 30 years ago.
But if you look at where brook trout are being found in this region under the un-assessed streams program, a lot of new streams have been found, making the area that brookies were found in 1492 much larger than assumed by many.

 

[k-bob]

see below, emphasis added> good enough groundwater can allow for OK headwater stream temps even in thinned canopy... note the mention "at this site" below. streams will differ. for ex., forest changes could influence ph or water temp without pushing all streams into problem ranges.

"Changes in light levels and stream temperatures with loss of eastern hemlock (Tsuga canadensis) at a southern Appalachian stream: Implications for brook trout" Leigh A. Siderhursta, Heather P. Griscoma, Abstract

"The exotic invasive insect, hemlock woolly adelgid (Adelges tsugae Annand), is causing mortality in eastern hemlocks (Tsuga canadensis [L.] Carr.) throughout the eastern U.S. Because hemlocks produce dense shade, and are being replaced by hardwood species that produce less shade, their loss may increase understory light levels. In the southern Appalachians, increases in light could increase stream temperatures, threatening species such as brook trout (Salvelinus fontinalis). We studied changes in light and stream temperature with eastern hemlock decline at a headwater southern Appalachian brook trout stream. Our results indicate that stream light levels have increased significantly with adelgid infestation. Leaf-on light levels are currently significantly higher (P < 0.02) in plots containing high basal areas of hemlock (mean global site factor (GSF)(SE) = 0.267(0.01)) compared with plots containing no hemlock (mean GSF(SE) = 0.261(0.01)), suggesting that increases in light have occurred with hemlock decline. The Normalized Difference Vegetation Index (NDVI), a remotely sensed metric of vegetation density, decreased with hemlock decline from 2001 to 2008. In 2001, NDVI showed no relationship (R2 = 0.003; F = 0.14; P = 0.71) with hemlock basal area, but by 2008, there was a significant negative relationship (R2 = 0.352; F = 19.55; P < 0.001) between NDVI and hemlock basal area. A gap experiment showed that light levels may increase by up to 64.7% more (mean increase in GSF = 27.5%) as hemlocks fall, creating gaps in the canopy. However, stream temperatures did not increase with hemlock decline during the study period, and we found that ground water inputs have a stronger influence on water temperature than light levels at this site. Linear regression showed a significant negative relationship between water temperature and proximity to ground water sources (R2 = 0.451; F = 13.14; P = 0.002), but no relationship between water temperature and light levels (R2 < 0.02; P > 0.05). In addition, by comparing light levels between plots containing hemlock and those containing only hardwoods, we found that if hemlocks are replaced by hardwoods, light levels under an all-hardwood canopy (mean GSF(SE) = 0.240(0.005)) are unlikely to be higher than they are under the current forest (mean GSF(SE) = 0.254(0.007)). These results suggest that loss of hemlock along southern Appalachian headwater streams could have short-term impacts on light levels, but that long-term changes in light levels, increases in water temperature, and adverse effects on brook trout may be unlikely."

 

[Chaz]

k-bob wrote:
Chaz: "Well not necessarily, you may have lower trout biomass, but bigger trout.."

even if that is correct, from a conservation or preservation point of view, I think biomass is more important than the total number of bigger trout (a fishing issue?)

As to TB's original question yes it is. But the point is we have now according to PFBC est. 5000 brookie streams and they are probably as diverse as they were back in 1492 or more diverse, because among other things human changes.
Don't forget in 1492 it was colder then too. Colder isn't always better no matter where the trout stream is. The little ice age probably negatively impacted brookie populations in some streams making them too infertile to support fish.
Again, I think that some streams may have better biomass now then in 1492, but we'll never identify them.

 

[pcray1231]

wells all over tap into ground water for human use and draws that water off at the peril of stream flows. But that's not the question, and it does have an impact.

And within that, most of that water is put back into the stream in the form of sewage effluent.

It may be taken from upstream and put back in far downstream, but it does go back into the watershed. At what temperature, nutrient load, level of toxins, timing, etc. and other stuff is highly variable and depends on the local sewage treatment as well as what people put down their drains, and when they do it.

 

[k-bob]

chaz: "Again, I think that some streams may have better biomass now then in 1492, but we'll never identify them."

Ill find them Chaz some hints: steep and still full of boulders, so not altered to move logs. cold, lots of ground water. no brown trout, I bet we agree. maybe not under hemlocks, much as I like hemlock forests.

 

[pcray1231]

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, though I don't know if that's accurate for PA in particular, and I don't know if it's different by the season. It's another ying/yang trade-off that is likely to help some streams and hurt others, nomatter which direction you're moving.

My uninformed guess would be that warming would help the small streams. It increases the rate of composting and thus puts upward pressure on pH, more water = better flows, and slightly increased temperatures improve bug activity and trout metabolism without coming close to lethal temps.

And it'd hurt the larger streams which flirt with lethal trout temps in the summer.

Cooling would do the opposite, it'd hurt the small streams, but help the large ones.

i.e. yes, it's likely that global warming has HELPED some of our streams. The ones that really aren't in danger of getting too warm in our summers.

If that's true, it's the same old story. By % of streams, it'll help more than it'll hurt. By % of fish, the opposite is true, because the ones being hurt are our bigger, better ones.

 

[k-bob]

right water temps are interesting. I focus so much on the idea that trout need cold water that I am impressed by one tiny stream I know, which will be below 60 in the late Pm in the middle of the worst heat wave.

But brookies can handle higher temps than 60, and hypothetically, they might be better off with less groundwater in that little trickle?

 

[troutbert]

Here's an article about an acid precipitation impacted stream in PA.

http://tinyurl.com/mmrm7qu

And there is a very large mileage of similar streams. 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?

(I think the pHs were higher, the streams did have brook trout, and that inverts were much higher.)

 

[Chaz]

pcray1231 wrote:

wells all over tap into ground water for human use and draws that water off at the peril of stream flows. But that's not the question, and it does have an impact.

And within that, most of that water is put back into the stream in the form of sewage effluent.

It may be taken from upstream and put back in far downstream, but it does go back into the watershed. At what temperature, nutrient load, level of toxins, timing, etc. and other stuff is highly variable and depends on the local sewage treatment as well as what people put down their drains, and when they do it.

There are a lot of inter basin water transfers too.

 

[pcray1231]

Trout are probably best-off somewhere right around 60ish. The ideal scenario would be to stay there year round with solid flows.

That said, if you're PEAKING at 60ish in early August, you're spending most of the year well below that. If you hit 60 in early May, you're probably getting to lethal range by July.

That's one reason why many limestoners are so good, compared to freestoners of similar size. They vary less. The average may be still a bit on the low side. But you're ranging from 45-65, not 32-73. For 10/12 months of the year, you're closer to the ideal than their freestoner cousins.

Small freestoners have temperature profiles more like the limestoners. More steady. But they're small and with infertile water chems.

The overall picture here is that, while we're all merely speculating on the effects of this or that, it's clear there are a whole lot of different factors that are actually at play, acting in often opposite directions. Some of them are very natural, others are manmade. How it all weighs out is highly different for different streams. We can probably identify trends as well as anyone, based on categories of streams, but there will be streams which buck those trends. With such a large number of highly different streams, it's a statistical certainty. The situation is ruled by chaos theory, not by some fully predictable set of inputs and outputs.

Hence it's a really, really bold statement to say that not a single stream has improved since the white man settled North America.

Heck, when Columbus landed, I'm betting there was a large Indian camp on a brookie stream in PA somewhere, which harvested a crap load of fish from said stream. Imagine a team of bait fisherman trying to feed a village by fishing a little trickle nearly everyday with no size or creel limits. When our cruelty sent that camp packing for a reservation, we inadvertently helped that little stream.

 

[k-bob]

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 .. quoting myself to save typing:

"4) My real point is that the well documented switch from hemlock to hardwood with logging altered a food chain involving trout. Hardwood leaf litter is more productive for in-stream invertebrates than hemlock leaf litter. Invertebrates eat leaf litter, and trout eat invertebrates.

why do I think think hardwood draining streams will have more inverbrates than eastern hemlock draining streams?

"The conversion of forests from hemlock to deciduous species is predicted to impact the hydrology, chemistry, and biology of associated headwater streams. In this study, we examined the macroinvertebrate communities of two adjacent headwater streams with differing hemlock influence in central Massachusetts. Abundance, taxa richness, diversity, and unique taxa were generally greater in the deciduous stream.""

"Stream Macroinvertebrate Communities in Paired Hemlock and Deciduous Watersheds"

http://www.bioone.org/doi/pdf/10.1656/045.016.0108

(also higher aquatic invertebrate density in headwaters dwgnra streams drained by hardwood v hemlock, see Snyder et al above)

 

[pcray1231]

"According to your theory, what was the situation with these streams pre-settlement? Did they have brook trout then?

The vast majority, yes.

Was the pH higher or lower than now?

Some higher, some lower.

Were inverts higher or lower than now?

Some higher, some lower.

We CHANGED things. Just shook it all up. The results are highly variable.

 

[Chaz]

pcray1231 wrote:
Trout are probably best-off somewhere right around 60ish. The ideal scenario would be to stay there year round with solid flows.

That said, if you're PEAKING at 60ish in early August, you're spending most of the year well below that. If you hit 60 in early May, you're probably getting to lethal range by July.

That's one reason why many limestoners are so good, compared to freestoners of similar size. They vary less. The average may be still a bit on the low side. But you're ranging from 45-65, not 32-73. For 10/12 months of the year, you're closer to the ideal than their freestoner cousins.

Small freestoners have temperature profiles more like the limestoners. More steady. But they're small and with infertile water chems.

The overall picture here is that, while we're all merely speculating on the effects of this or that, it's clear there are a whole lot of different factors that are actually at play, acting in often opposite directions. Some of them are very natural, others are manmade. How it all weighs out is highly different for different streams. We can probably identify trends as well as anyone, based on categories of streams, but there will be streams which buck those trends. With such a large number of highly different streams, it's a statistical certainty. The situation is ruled by chaos theory, not by some fully predictable set of inputs and outputs.

Hence it's a really, really bold statement to say that not a single stream has improved since the white man settled North America.

Heck, when Columbus landed, I'm betting there was a large Indian camp on a brookie stream in PA somewhere, which harvested a crap load of fish from said stream. Imagine a team of bait fisherman trying to feed a village by fishing a little trickle nearly everyday with no size or creel limits. When our cruelty sent that camp packing for a reservation, we inadvertently helped that little stream.

According to Lenape lore, and some other tribes they didn't eat brook trout, they were touched by the hand of the creator, but what they did eat shad, they built wires and trapped them on the incoming migration. If Native Americans are to be believed, and I think they are, brook trout were sacred.
As for temps, they affect what invertebrates are in the streams to, the wider the range of temperatures the greater the diversity at least up to a point. As temps get higher a bunch of other things come into play that alters the diversity of bugs. So ideally trout would like temps to be between 50 and 60, but the inverts will be big hatches of a few species versus many hatches of diverse species.
So an ideal stream would be something like a fertile freestone stream in NC PS with a temp swing of high 30's to 72 degrees, with hemlocks along the banks and hardwoods in the uplands, it sounds a lot like Cedar Run, Slate Run and Kettle Creek, 3 of the best freestone streams in PA. Add to that a winter refuge and , maybe the pops. are better now then in 1492.

 

[Chaz]

Ill find them Chaz some hints: steep and still full of boulders, so not altered to move logs. cold, lots of ground water. no brown trout, I bet we agree. maybe not under hemlocks, much as I like hemlock forests.
Let's go together, we can reach middle ground.

 

[k-bob]

talkin to me? OK spring break around the bend

 

[troutbert]

pcray1231 wrote:

"According to your theory, what was the situation with these streams pre-settlement? Did they have brook trout then?

The vast majority, yes.

Was the pH higher or lower than now?

Some higher, some lower.

Some higher? How so?

Considering the greatly lowered pH of precipitation (rain and snow), how would some streams have a higher pH now than before acid precipitation?

 

[troutbert]

double post

 

[pcray1231]

The runoff has lower pH because of acid rain. The groundwater has higher pH on account of less conifer cover and more hardwood cover.

While there are exceptions, such as oak, most hardwood leaves have higher pH than pine needles. Even beyond that, they are much easier to compost, and thus the soil, even while thinner, holds a greater abundance of fully composted material and less incompletely composted material. Composting bacteria bring the pH back towards neutral.

So the final effect on the stream pH itself is a function of % of runoff vs. % of top groundwater (soil) vs. % of deep groundwater (bedrock). That's a function of geography, forest type, development, etc.

And that doesn't mention the effects of exposed pyrite, which may have been exposed, covered, or removed, by human activity, and small trickles and underground streams which may have been diverted into, or away from, such natural deposits. An extreme example is AMD, where large volumes of groundwater were diverted by mining shafts through pyrite veins. But smaller case examples surely exist, including some that were diverted AWAY from such veins.

Nor does it mention that in the extreme headwaters, there's a seasonal cabin on the most acidic trickle of a feeder. The guy's driveway crosses this little feeder, and instead of putting a pipe down to run the water through, he dumped a few truckloads of limestone gravel to support his road.

Estimates of # of brookie streams in the state range from 3000-5000 in number. You need every single one to prove your point. I only need 1. I like my odds.

 

[Chaz]

k-bob wrote:
talkin to me? OK spring break around the bend

Yes, I can go any time.