WBTE

[KenU]

Sasquatch said, "I should also be catching 15" brookies, no?"

Yes! In the more fertile streams this was once the case. It is said that brook trout in the limestone streams regularly achieved that size. They did until recently in big Spring and I think I have heard that they are again achieving that size. But now they have to compete with rainbows, so we don't know how that is going to end up.

In streams with mixed brown/brook trout populations brown trout grow at a similar rate to brook trout. And it is well known that trout must switch over to larger prey (minnows, crayfish, etc.) when they reach about 10 inches in order to continue growing. In relatively fertile streams the reproduction rate of brook trout would assure that there is a ready supply of small fish as prey, so growth rate might even increase once the switch occurs.

Salmon and steelhead go to sea at about one or two years. And time in the sea is typically less than 5 years . Salmonids can grow really fast if there is an abundance of food.

Another factor is the well-known difference in susceptibility to angling pressure of the two species. Brook trout are at least three times more likely to be taken as brown trout. This helps to explain why browns can dominate streams that are being regularly harvested. And stocking encourages harvesting. As Chief Seattle said: Life is like a spider web: " Everything is connected. When you pull on one strand, they all respond."

As for 20", keep in mind the world record brook trout was over 30 inches long and weighed 14.5 lb. Canadian brookies regularly reach 7 lb or more even today. So 20 inches ain't that big as trout go.

 

[Tups]

As Behnke points out, Canadian brook trout are a seperate strain, distinct from the generalist form we have here in PA. The size of PA's brook trout could be improved (increased) through selective breeding with the Canadian strains, but such a course would include additional stocking of PA's waters with the hatchery offspring. More pulling at Seattle's web. Behnke adds that the Canadian strains are even more susceptible to angling harvest than the generalist stock we have now.

 

[troutbert]

Brook trout in PA rarely exceed 12 inches in our freestone streams now.

But does anyone really doubt that they got much bigger back in the day? As in 18-20 inches, and sometimes bigger?

I think there is plenty of historical record showing that. And for other states in the region, such as West Virginia.

And it seems logical that they would have, when they were much further down in the big water in the freestoners. And when there were no browns causing competition.

There seems to be little or no historical record about how big brook trout got in the early days of settlement on the limestone streams. Probably because the limestone valleys were settled so early.

But consider the habitat of the limestone streams even now, and then what those streams would have been like when they were largely undamaged. And then consider that the brookies would have had these limers to themselves. No brown trout. How big would the brookies have got in the Letort, Big Spring, Spring Creek, Little J, Penns Creek?

No one knows for sure. But surely much bigger than 12 inches.

 

[Tups]

TB: Prior to the advent of scientific fisheries management in the late 19th and early 20th centuries, the historical record of the sizes of brook trout is anecdotal and comes to us through fishermen. Theodore Gordon was one of the best and most reliable of observers during the pre-brown trout era. He says in 1903: "Fifteen years ago, in many of our best New York trout streams, a one-pound native trout was a big fish. In all my experiences of waters easily accessible from New York, I took but one fish of sixteen inches. Since the introduction of the brown trout, all this has changed."

 

[lycoflyfisher]

brown trout have been proven to live up to 10 years, its rare for brook trout to live more than 5, maybe at most 6 years. especially in our infertile headwater streams where brook trout thrive, there 3-4 might be the maximum age. I would say that is the biggest factor in the size difference.

 

[salmonoid]

Interesting read, pages 67-71, particularly the end of page 71. The author provides at least one instance where anglers (The Oquossoc Fishing Club) had a major effect on the genetics of a population (and illustrated Seattle's statement) - they introduced non-natives and wiped out the bluebacks. "Unique gene-guided maximum size potential" is one term he used to describe that extirpated population of fish.

https://books.google.com/books?id=j35ZD6OS2JgC&lpg=PA67&ots=bEufASbCvt&pg=PA67#v=onepage&q&f=false

A one pound brookie would average about 13.5" (glaring typo on the PFBC weight/length estimator has a 12" fish at .68#, a 13" fish at 1.88#, and a 14" fish at 1.10#). Gordon's 16" fish would have been 2.26# and Karas opines that 4-5# was the maximum, so probably 18-20" would have been the max length of the "generalist" variety we allegedly have (assuming that classification is correct).

 

[k-bob]

on acid rain, ST, & BT... I looked at a paper, it's too technical on chemistry & environmental science for me to follow, on the lag between air pollution reductions and eventual stream acidity reductions in NE & SE USA. My nonspecialist take: acidity from air pollution can be retained in soils. While our thinner, rocky NE soils may retain less acidity than SE soils, even here in PA acidity reduction in streams will be a gradual process. So there should be changes over time, but no rapid BT invasion of ST streams -- or rapid ST invasion of trout-free streams, either. If someone who knows some chemistry, etc., can do more to summarize, I'd appreciate it.

Decreased Atmospheric Sulfur Deposition across the Southeastern U.S.: When Will Watersheds Release Stored Sulfate?
Karen C. Rice, Todd M. Scanlon, Jason A. Lynch, and Bernard J. Cosby
pp 10071–10078
Publication Date (Web): July 21, 2014 (Article)
DOI: 10.1021/es501579s

http://www.fs.fed.us/nrs/pubs/jrnl/2014/nrs_2014_rice_001.pdf

 

[troutbert]

I think on many streams things have shifted towards more brook trout, and less browns, rather than the other way.

For example on the headwater tribs to Slate Run: Francis Branch and Cushman Branch.

I think the upper half (roughly) of Cross Fork Creek has shifted that way also. Maybe Hammersely also.

Maybe upper Kettle also. A PFBC person also said this about upper Kettle.

A fisheries biologist said some streams in the Allegheny National Forest region are shifting towards more brookies, less browns.

In some of these streams the shift towards a higher brookie/brown ratio may be simply because the stream was stocked in the past, which favored the browns vs the brookies, and in the years since stocking ended, the brookies have rebounded.

 

[k-bob]

well the unassessed streams programs have found many little streams with ST. but since the streams were unassessed, hard to know whether the ST have spread out due to steam acidity reductions, or were always there...

 

[Chaz]

The buffering capacity is impacted for years after the acid precipitation is reduced, because there is little buffering left and it has to be built up again.
My guess in most of PA where these waters were un-assessed that more than likely the trout were always there, maybe in lower numbers or very thin populations. Nonetheless always there.

 

[troutbert]

k-bob wrote:
well the unassessed streams programs have found many little streams with ST. but since the streams were unassessed, hard to know whether the ST have spread out due to steam acidity reductions, or were always there...

They were always there.

I don't think there has been much change in the brookie distribution in the far headwaters and trickle tribs between the 1980s and 1990s and today.

In areas where the geology is at least moderately fertile, the little streams have brookies as far up as there is water. Both now and in the past. These streams are buffered.

In areas where the geology is infertile, the far headwaters have no brookies. Not in the early 1990s. And not now. I haven't seen any sign of brookies pushing further up. The "boundaries" seem to be at about the same place.

It may begin to happen gradually over time. But I don't think it's happened much yet.

This is just what I've seen from fishing. I don't know if anyone has really studied this.

One way to keep track might just be to fish the headwaters of Swift Run, Snyder County up in the "Tall Timbers" area once a year, and see if brookies ever start making their way up there.

It's a nice place for a hike, even if you catch no fish up there.

 

[k-bob]

TB that swift run's headwaters are in low-buffering tuscarora bedrock.

Look at this way: Places with good bedrock buffering (for ex., catskill bedrock) already have ST. I think some streams with buffering capacity that is higher than Tuscarora but lower than Catskill (for ex burgoon bedrock) may not have ST. I'd look for returning ST in those ones first.

 

[KenU]

I have seen no indication that brookies are moving upstream in acid rain impacted streams. But browns do seem to be doing so. My records show that browns are moving into streams previously occupied solely by brook trout. Browns could also be invading as the result of stocking in the lower reaches of these streams.

I wonder if it isn't time to consider making triploids out of our hatchery trout. It's not that difficult or expensive and would prevent them from interbreeding with wild trout. Triploid hybrids do grow faster than fertile trout, which would help to defray some of the cost.

 

[troutbert]

k-bob wrote:
TB that swift run's headwaters are in low-buffering tuscarora bedrock.

Look at this way: Places with good bedrock buffering (for ex., catskill bedrock) already have ST. I think some streams with buffering capacity that is higher than Tuscarora but lower than Catskill (for ex Pottsville bedrock) may not have ST. I'd look for returning ST in those ones first.

I'm very familiar with the bedrock stuff and have been for a long time. I helped Dr. Kirby with some angling field work for his study.

Swift Run is just one example. I have also not seen brook trout moving up in the infertile streams in other geologies either, i.e. in the Allegheny Plateau streams.

The "boundaries" seem just about the same as they were 20-25 years ago. The upper ends are still fishless, and the "transition zone" seems to be at about the same location.

It seems possible that it COULD happen, and hopefully will, but I just haven't seen it on the streams I've fished over a long time, and I have not heard it from other anglers or read any studies that indicate this is happening.

It may happen over a long time, but probably pretty gradually, for the reasons already stated.

 

[k-bob]

right ST could spread out over time due to a lagged impact from acid rain reduction, but you havent seen it happening. I have no idea whether it has happened.

I was just following up on your suggestion that: "One way to keep track might just be to fish the headwaters of Swift Run, Snyder County up in the "Tall Timbers" area once a year, and see if brookies ever start making their way up there."

as we both know, that's a tuscarora bedrock stream. as papers by students from that bucknell lab point out, several of these tuscarora streams have not just low alkalinity but zero alkalinity.

so that swift run would not be a good place to keep track, imho.

 

[Chaz]

Northkill is very low in buffering capacity and near 0 in T. Acl. but it has brookies, so what's different? In fact all three branches have brookies seems they are all the way through the drainage to where the water comes out of the ground.

 

[k-bob]

Chaz Here's a table from the Kirby study showing impaired streams. There are 21 streams, their pH ranged from 4.4 to 5.6 in 2005. 19 of these streams had zero ST caught. Ten years may not be enough time for air pollution changes to significantly affect the pH; there's a time lag due to acid retention in soils (Table 2 of article linked post 67 has projections for a few PA streams). But at some point in time, the pH of these streams may increase a bit.

There are six Kirby study streams where no ST were caught or detected and the pH was over 5. If someone wanted to look for returning ST, those steams might get them sooner than the ones with pH around 4.5.

(btw, I don't think the exact surveyed stretch location info is available, so can't reproduce what the Kirby study did).

 

[k-bob]

chaz northkill is different, it has shawangunk bedrock not tuscarora bedrock as in the imapaired kirby streams. one study says the upper northkill had a pH of 5.96 in 2003. (higher than pH of all kirby imapired streams)

http://www.coldwaterheritage.org/docs/2004-grantees/northkill-creek.pdf?sfvrsn=2

 

[Swattie87]

I've fished a fair number of the streams in the Kirby study that show no fish being caught, and ALL of the ones I've fished had Brookies in them...maybe not Class A type stuff, but I caught fish in them. Maybe they were surveyed closer to the headwaters than where I fished them? Even so, many of those streams showing no fish caught are on the nat repro list. They may be "impaired" and not up to their potential but many are capable of supporting Trout, Brookies anyway.

Edit: I even caught a wild Brown in one of them.

 

[troutbert]

Swattie87 wrote:
I've fished a fair number of the streams in the Kirby study that show no fish being caught, and ALL of the ones I've fished had Brookies in them...maybe not Class A type stuff, but I caught fish in them. Maybe they were surveyed closer to the headwaters than where I fished them?

Yes.

On many of these streams, the headwaters have no fish. Then further down the geology changes and therefore the water chemistry changes, and then brookies appear.

If you want to see this, go to Swift Run in Snyder County. The "boundary line" is where a small trib enters Swift Run, at the last parking area going upstream, where the forest road swings away from Swift Run, and continues up along the small trib.

Below that trib there are brook trout and the PFBC stocks it.

Once you get a little bit above that trib, there are no brook trout, from there to the headwaters, about another 3-4 miles of stream.