Current PA Brook Trout Population as Percentage of Original?

[k-bob]

General significance of in-stream large woody debris for pool formation understood. However, for a high-gradient stream (7+% gradient, for example), boulders can be big enough to provide pools even at very low flow levels -- as in the very low-flow brookie-stream image below. btw, this ravine stream stays cool, probably due to groundwater input. it might have had lower fertility and lower trout biomass 125 years ago when it had a hemlock ravine, due to the relatively poor food hemlock needles provide to invertebrates. today, it's in a mixed forest whose leaf litter may well produce more macros (article post 57 above)... it def has the brookies!

this sort of steep cold stream may be unusual... but that's the point, really. I agree that most PA streams that have brookies today had more brookies in the past... but some small percent may have more brookie biomass now... if the hemlock forest of this ravine could be restored, the steep little run might look great, but I am not sure it would have more brook trout biomass.

 

[troutbert]

troutbert wrote:

pcray1231 wrote:

I'm not so sure it's true that old growth results in more LWD than modern successional forests, though. There's certainly more woody debris in your typical 80-130 year old mixed forest than there is in the pockets of virgin, mostly Hemlock, forests I've been in.

Where were you seeing this? (The streams flowing through pockets of mostly hemlock old growth forest?)

BTW, this question is not just for pcray. I'd be interested in any stretch of stream people have seen flowing through old growth forest in PA. There are probably very few such stream stretches, but I'm interested to go see the ones that exist.

 

[k-bob]

never been there but jakey hollow natural area? info on web....

or

http://www.nativetreesociety.org/fieldtrips/penna/old_growth_forests_in_pa.htm

 

[k-bob]

here's a study of "coarse woody debris" in an old growth PA stream,,, they looked at East Fork Run, Tionesta?

http://www.nrs.fs.fed.us/pubs/gtr/gtr_ne267/gtr_ne267_216.pdf

https://tinyurl.com/lsruko6

https://tinyurl.com/kxh82qj

 

[k-bob]

also

https://tinyurl.com/m3vt6v2

 

[pcray1231]

As far as virgin stands, there's an area in Rickett's Glen, with a small stream flowing through it. Another at Heart's Content, but no streams there. It is the extreme headwaters of a stream that is largely dead, though I've never figured out exactly why, as the other trib in the same drainage have brookies.

Probably the best is the Tionesta area, and that stream there does not have much LWD. Not sure how representative it is of ancient forests in other areas. Lots of beech and Hemlock.

Also a region in Cook's forest I believe.

Yes, they are very limited examples, as virgin timber is very limited in PA. Hence this is likely to remain conjecture.

K-bob, In your links. I'll have to give it a close read when I get the chance.

 

[sarce]

Allen Seeger natural area has old growth forest along Standing Stone Creek. Almost creepy how dark it is there.

Btw, I can't find that slate run article. Must have tossed it. Oh well.

 

[k-bob]

the second study linked above, "Forest seral stage and large woody debris abundance in an Allegheny High Plateau forest-stream system," Charles E. Williams and Rachel Cook, mentions old and second growth on Henry Run in Cook Forest? I have never seen it:

"This study was conducted along Henry Run, a low-gradient, second-order stream located in Cook Forest State Park (CFSP), Forest County, Pennsylvania. CFSP contains some of the best remaining old-growth eastern hemlock-eastern white pine forests in the northeast, with many hemlock trees exceeding 400 years in age(Smith 1989; Abrams and Orwig 1996;Cook 1997; Orwig and Abrams 1999). The upper portion of Henry Run is flanked by old-growth hemlock-dominated forest that may have had some light selective cutting. The lower portion is bordered by second-growth forest with trees that range from approximately 60 to 80 years in age."

 

[k-bob]

alan seeger pictures, some of streams:

http://tinyurl.com/kfpa3ul

does look interesting

 

[k-bob]

LWD & old growth ideas are interesting. but a steep stream with biggish boulders has pools even at low flows, so LWD isn't as important vs. a flatter stream. moreover, the articles I linked above show that hemlock canopy is a minus for stream fertility/ invertebrates versus later mixed forest. I agree with pat: logging greatly reduced total brookie biomass, but some brookie streams are probably better now than pre-logging.

trout eat invertebrates; invertebrates eat leaf litter. see chart below from Maloney study: maple leaf litter is much more productive for in-stream invertebrates than hemlock needles.

http://www3.nd.edu/~underc/east/publications/documents/Maloney_94AMN.pdf

 

[Chaz]

From EBTJV--Intact stream populations of brook trout (where wild brook trout occupy 90-100% of their historical habitat) exist in only 5% of sub watersheds.
that said, during the glacial period there may have been ST in the southern tier of the Commonwealth but the northern tier wouldn't have had any because of the glaciers. They moved into the northern tier at the end of the glacial period.
What we do know is they are still found in the southern tier, mostly in headwater streams, but all of the limestone streams had them almost into the 20th century. Some like Fishing Creek and Big Spring still have them, and they grew big in the limestone streams. We also know they are all over the northern tier.
There is a book Named "Pioneer Life- 30 years a hunter" Phillip Tome recalled he and his father building weirs in Pine Creek to catch fish to take to the market, and they did this during the summer at Slate Run, and they were capturing brook trout in the weirs even in the summer. Early records indicate that there were brook trout in streams in and around Philadelphia, in the records of the Schuylkill River Fly fishing club. They were the top predator in many more streams we find them in now.
So What I get from that is that there would have been solid populations in all of the big freestone streams, all the way to the 20th century, because the historical record talks about them, in Vanishing Trout Charles Lose writes about catching a big trout near a dam that was 5 lbs. before the stocking period began.
Now I've never caught a 5 pound brookie, which would be about 20 inches, but in the big freestone streams and the limestone streams they would have been there. Probably not in big numbers, but we're talking about virgin streams, that the native americans didn't fish for trout according to there history.
I wouldn’t be accurate in guessing the biomass except to say by todays standards, all stream that had brook trout in the pre-Columbian period would have been Class A or more. So if out of 86,000 miles of streams 85% had brook trout, and they had over 30 kilos per hectare that a lot of biomass.
Add to that the leaf little would have made streams more fertile, but there still would streams with low ph because of geology and the types of trees. Mixed forests are more prevalent now then back then, though we can only use fossil evidence to figure out the mix of plants and trees. Chestnuts and elms are all but gone. Vast expanses of Pine/Hemlock are gone. So the soils would all have been different. I suppose maybe the sediments can be tested for ph and that would give use an idea, but I haven't seen any studies on that.

 

[Chaz]

definition of a basin from wikihttp://en.wikipedia.org/wiki/Drainage_basin

 

[Chaz]

Some of you are thinking about the pasting terms of the present, i.e., brookies are limited to where they exist today and that is not the case. Brookies were in every region and county in PA then, they are not now. They were in large streams and small streams. It is entirely possible that in some cases streams would have been more acidic then than they are now, because of volcanic eruptions, throwing sulphur gases into the atmosphere. As I stated earlier the leave debris in the forests was estimated as being 2 to 3 feet deep pre-Columbian and in many cases it is no where near that now. But I still think the populations then as opposed to now is so far above what we see in even our best streams as to make the argument simply a bad comparison.

 

[Chaz]

k-bob wrote:
nice bad news table 🙂. imho biomass ain't everything. by numbers of fish, and numbers of streams, you'd get much less gloomy numbers. pat for example
guessed that a majority of streams that had brookies then have brookies now -- which tells a different and more relevant species preservation story than biomass?

seems that Brook trout have been relegated to several thousand smaller PA streams without being truly endangered

100% of the streams that have brookies now would have had brookies then, but the biomass would be very different, it would have been much higher then .

 

[k-bob]

chaz: "100% of the streams that have brookies now would have had brookies then, but the biomass would be very different, it would have been much higher then ."

I agree on the 100%part: yes streams with brookies now would have had them pre-euro. But I doubt that all the PA streams with brookies now would have had higher biomass pre-Euro.

I wrote that pat "guessed that a majority of streams that had brookies then have brookies now ..." which he did. He guessed that 70-80% of PA streams that had brookies in pre-Euro times ("then") still have them now ("now"). see his post near start of thread.

If Chaz assumes that all PA streams that have brookies now had higher brookie biomass in pre euro times (that right?), both pat and I have disagreed. see his posts above for his logic.

my logic: yes, brown trout, deforestation, acid rain, etc., have greatly reduced total PA statewide brookie biomass. but despite deforestation, acid rain, BT etc., there are still thousands of pa streams with brookies, in part because of cooling groundwater (for ex, nat repro list). some of these streams were switched from less productive hemlock to much more productive mixed hardwood canopies, which imho could lead some streams to have more brookie biomass now.

I provide a very clear chart above from research. It shows that hemlock needles are associated with lower in-stream invertebrate levels than leaf litter from tree such as maples, that often replaced hemlocks. I also give the link to a DWGNRA study showing much higher macroinvertebrate levels in mixed versus hemlock forest headwaters streams.

PA streams went from hemlocks to mixed forests in many cases, and there is very clear research showing mixed forest makes more aquatic bugs than hemlock. TB feels that there may be more LWD in old growth such as hemlock, and some papers agree with this. But I have argued that for steep streams the LWD issue matters less, because the boulders form pools even at low flow levels.

So I guess that some exceptional cold steep PA streams that have brookies now did have brookies in the past, just not as many as right now.

Do I think that every PA stream that has brookies now had them pre-Euro? Yes. Do I think that every PA stream that has brookies now had a higher biomass of them pre-Euro? No I suspect there some exceptions.

 

[Chaz]

Can we all agree that all trout streams on todays list would have been broke stream pre-Columbian? And add to that the stocked streams,i.e., marginal streams were also broke stream?

 

[pcray1231]

Quick and concise, my view:

1. We totally lost some brookie streams. Warming/brown trout/pollution/etc.

2. MOST (as in by number, not by miles or biomass) streams that used to have brookies still do, but in somewhat reduced populations/biomass.

3. A rare few probably actually improved. Hence troutbert's 5% question. Our top 5% may indeed be better than ever. The other 95% aren't.

Overall, the picture is pretty dire. Category #1 may be a relatively low % of the streams, by number, but they tend to be best ones. i.e. by mileage we've lost a much greater %, and by fish numbers and biomass, an even greater %. By those measures, we may have indeed lost >95% of the fishery.

 

[k-bob]

first chaz question yeah I think so.

second chaz question, yes I think so, again.

 

[k-bob]

I agree with all 3 of pat's points. pat: '3. A rare few probably actually improved. Hence troutbert's 5% question. Our top 5% may indeed be better than ever. The other 95% aren't.'

I agree with this also, have described reasons above.

I do think it EZ to just assume that every current PA brookie stream had more brookie biomass in the past. Changes are too many and interact too much for that imho...

imagine; take a really strong current brookie stream with good groundwater input. now blast out its mixed forest and put back hemlocks, which are less productive for instream bugs (see clear chart post 71). in some cases imho, you'd wind up with lower brookie biomass by restoring the old growth. particularly in steep streams w/ boulders which don't really need LWD to have pools. so some streams may be better now than in 1492... just a guess of course, and yes these would be rare exceptions...

 

[pcray1231]

Can we all agree that all trout streams on todays list would have been broke stream pre-Columbian?

For all intents and purposes, yes. I don't discount that there could be an extremely rare exception, but it'd be extremely rare and not the norm.

And add to that the stocked streams,i.e., marginal streams were also broke stream?

Most, but not all. Look back at the map on page 1. Brookies never occurred in regions of extreme western PA, yet some streams in those areas are stocked today.