Study just completed: stream restoration likely only beneficial to native brook trout when non-native trout are not present.

[Fish Sticks]

A lot of you may remember a while back I had shared a case study on pine creek in Wisconsin that showed the following results post restoration:

“Beneficial project outcomes included: a decrease in stream temperature, a reduction in stream width, greatly reduced stream bank heights and erosion potential, and increases in water depth, stream bank cover, presence of coarse stream bed substrate, and macrophyte presence. Unanticipated project outcomes included: no change in canopy cover, a decrease in water velocity, no significant improvement in macroinvertebrate metrics, and a significant increase in brown trout abundance and decrease in brook trout abundance. Within eight years post-restoration, numbers of brook trout per mile decreased by 70% (3,800 to 1,200), while numbers of brown trout per mile increased by 3,150% (175 to 5,600). A continuation of this trend may lead to the loss of the brook trout fisher”

https://www.kiaptuwish.org/wp-conte...tion-Manuscript_Wild-Trout-Symposium_0917.pdf

The above case study decreased water temperature and increase water quality yet could be the loss of death to that population eventually. Clean cold water wasn’t the panacea it’s made out to be in lay person/ PAFB circles for brook trout. This observed displacement is explained by research from Faust and White/hoxmier and deiterman showing that brown trout exclude brook trout from favorable habitat and that especially deep pools are associated with larger brown trout presence respectively


So the new hot off the press research that confirms this and has BIG TIME implications for on going stream restoration for brook trout…..




Dr. Brock Huntsman Et al. Just concluded this study on shavers fork(March 2022) in WV confirming that stream restoration likely only benefits native brook trout if non-native trout are not present. They also cited concerning evidence for projects where native and non native trout exist having a detrimental effect on native brook trout in the discussion section, much like the above pine creek study. These projects do seem to benefit brook trout when non native trout are not present though.

-Link to study:

https://doi.org/10.1111/rec.13678

Quote from article:

“Collectively these results indicate that habitat restoration was only beneficial for native brook trout when non-native trout were absent from the restored sampling area. Proactive approaches to restoration will be integral for supporting resilient ecosystems in response to future anthropogenic threats (e.g. climate change), and we have shown that such actions will only be successful if non-native competitors do not also benefit from the restoration actions.”



I will try to find and post a not behind a pay wall version, I read whole article but can only link to abstract. This could have a HUGE impact on the stream restoration community because the vast majority of projects for brook trout have atleast some invasive salmonids present in or in close proximity to project reaches. Even though people doing the projects may or may not care about the replacement of brook trout by invasive species, it will be really interesting here to see what the grant funders do with this information. For example, when people name brook trout as a target species in their grant restoration objectives to get prioritization for funding/increase chances of winning regardless of what they value personally, if invasive brown and rainbow trout in proximity to the project will they still fund it or move on to focus on all allopatric?

There are a lot of j-hooks, deflectors, and lunker bunkers out there with brook trout written all over their past grant applications that are now just invasive trout hotels from what I have seen, heard, and read. Wonder if PAFB will do anything differently based on this? I am still for improving water quality with these projects obviously. However, I guess another interesting question would be if the brook trout are harmed from the invasive trout expanding/thriving in this restored habitat, would the same thing not happen to other sensitive species that have evidence of harm/likely harm from invasive trout such as sculpins, macros, hellbenders, native darters, native crayfish, certain suckers ect? The restorations are about more than native brook trout obviously and the Chesapeake bay wins no matter what but there is going to be more focus on these questions in the future.

 

[troutbert]

It probably on what type of restoration is done. If you are using the term "restoration" to refer to cross vanes, then the results that it favors brown trout over brook trout is not surprising.

But cross vanes are not restoration. The stream/floodplain system was not originally structured that way.

In PA's forested streams with mixed populations, what you see is that the sections with the most natural habitat have higher populations of both brook trout and brown trout than the channelized sections.

Natural means the stream is unrestricted, so is able to flood the whole floodplain, is able to freely move laterally across the floodplain, is free to form channel splits and rejoinings, has natural vegetation which influences the structure via tree roots, leaning trees, fallen trees, and log jams. Beaver dams also play an important role.

This type of system is physically complex, so has a very wide variety of habitat niches. It won't get rid of brown trout. But it increases the population of both brookies and browns compared to the typical straightened single channel that is flat and shallow because of past alterations.

And the restored more complex system benefits many other animals, and plants, in addition to the trout.

 

[Classicriver]

They needed to do a study to figure that out? Brown trout have been outcompeting brookies since they were introduced well more than a century ago.

 

[Fish Sticks]

It probably on what type of restoration is done. If you are using the term "restoration" to refer to cross vanes, then the results that it favors brown trout over brook trout is not surprising.

But cross vanes are not restoration. The stream/floodplain system was not originally structured that way.

In PA's forested streams with mixed populations, what you see is that the sections with the most natural habitat have higher populations of both brook trout and brown trout than the channelized sections.

Natural means the stream is unrestricted, so is able to flood the whole floodplain, is able to freely move laterally across the floodplain, is free to form channel splits and rejoinings, has natural vegetation which influences the structure via tree roots, leaning trees, fallen trees, and log jams. Beaver dams also play an important role.

This type of system is physically complex, so has a very wide variety of habitat niches. It won't get rid of brown trout. But it increases the population of both brookies and browns compared to the typical straightened single channel that is flat and shallow because of past alterations.

And the restored more complex system benefits many other animals, and plants, in addition to the trout.

So you bring up an interesting point, I didn’t mention this because I was talking about restoration in the traditional sense. And what I mean by traditional sense, is a lot of the parameters of brook trout habitat that projects target are sourced from studies of allopatric(just brook) populations.

The aspect of the complexity of habitat you speak of that allows brook trout to persist better is related to two things as per my conversations with the fisheries scientists helping me with the restoration I volunteer with. One: minimal to less large deep pools that develope/favor larger brown trout that will harm brookie population. Two: shallow habitats that favors smaller fish/young of the year decreasing predation and competitive effects on brook trout. That being said just because you don’t use armored structures doesn’t mean your not at risk of tipping the scales to brown trout. Large woody debris that creates very deep holes will likely do the same thing. It’s frustrating because if brown trout were not there brook trout would be getting great benefit from these structures.

It seems if you are going to do flood plain/wetland creation by legacy sediment removal, how far down you excavate may have a bearing on how deep you can make some of these pools/structures in talking to restoration professionals because you can only lower the stream bed so much, esp with culverts/bridges up and downstream acting as stream channel height constraints. Will be interesting to see if this has a positive effect for brook trout in areas where removal is not an option and sympatric(both brown and brook) populations exist. Now that we know these traditional approaches help brook trout (operative phrase here, when done correctly) but likely are no benefit to harmful when invasive trout present, it will be interesting to see more research into possible solutions where removal is not feasible. There are likely some small actionable things/changes suggested from observational data that can be piloted and then studied based on my conversations with fisheries scientists, but none of its proven.

 

[Fish Sticks]

They needed to do a study to figure that out? Brown trout have been outcompeting brookies since they were introduced well more than a century ago.

I think hey knew brown trout were out competing Brookies but I think the authors of the study had the goal of either confirming or debunking what we now know is the false notion that brown trout strictly outcompete brookies because of water quality/habitat loss/human activity. That’s why they chose shavers fork because all habitat and water quality issues and connectivity had been addressed to a very significant level already.

So the studies importance is basically, this water quality/habitat carrot on a stick we have been chasing in some cases is not always the limiting factor for brook trout and helps us focus efforts on pioneering new restoration protocols to use this information that may not always have to do with changing the stream itself. Knowing that browns aren’t outcompeting brookies in all cases due to habitat and water quality issues as previously thought is valuable to know and could help us use our funding more effectively essentially.

 

[pcray1231]

I get what you are saying regarding funding. But I can't see past:

Number of trout per mile before: 3975

Number of trout per mile after: 6800

Plus improved flood control, better water added to whatever watershed is downstream, and the bay. Willing to bet if decreased stream temperature in the study zone was a result, then you've extended the trout water farther downstream as well, so not just better water, but more of it. It is a success story and should not be looked at as a failure.

Most likely the reason it benefitted browns more would be the limestone sanding they did in the tributaries and lowering the culverts in them for fish passage. Just invited the browns up the tribs to spawn where the brookies always have.

 

[Fish Sticks]

I get what you are saying regarding funding. But I can't see past:

Number of trout per mile before: 3975

Number of trout per mile after: 6800

Plus improved flood control, better water added to whatever watershed is downstream, and the bay. Willing to bet if decreased stream temperature in the study zone was a result, then you've extended the trout water farther downstream as well, so not just better water, but more of it. It is a success story and should not be looked at as a failure.

Most likely the reason it benefitted browns more would be the limestone sanding they did in the tributaries and lowering the culverts in them for fish passage. Just invited the browns up the tribs to spawn where the brookies always have.

Oh yea I agree that it definitely was not a failure from a fishing standpoint and I think there will be a continuation of these grants that improve fishing opportunities because the TMDL grants focus on pretty much just that. Don’t think those kinds of fishing projects that benefit the bay too are going away, I’m just talking about grants where the funder specifically trying to steer money to the native fish assemblage, macro, crustacean, or amphibian population, and they are the main goal from a conservation standpoint. Would be more of a NFWF, eastern brook trout JV grant or potentially all this recovering americas wild life act money that could be coming.

 

[pcray1231]

It is clear that if brookies are your stated goal, you have to adopt a pH "target". It's not about cover or velocity or even temperature really, those favor more trout period, but browns will eventually outcompete brookies where they are able to do so. It's about pH. The only advantage brookies have is a tolerance for slightly more acidic water. Want to favor brookies in a stream overrun with browns? Make it more acidic.

I am not advocating that.

But I do think you get a handful of browns in nearly allopatric brookie water because there's SOMEWHERE the pH is right for browns to breed. A trib, coming up from below. That one spot distributes a smattering of browns here and there and they travel. And the same is true in reverse. You tend to get a few brookies in mostly brown trout water because there's a trib somewhere that's too acidic for browns, and it distributes a smattering of brookies here and there.

But when the water is cold and the pH is good, brown trout eventually win.

Note that in a common scenario, with more browns downstream and more brookies upstream, the "boundary" fluctuates year to year. All of us have seen that. It is my belief that it has a lot to do with snow cover. Snow gets more acidic as it sits on the ground. It's melting and entering streams in winter/early spring when there are eggs. Get a big, long lasting snowfall and you lose a year class of browns in the boundary area.

 

[silverfox]

I get what you are saying regarding funding. But I can't see past:

Number of trout per mile before: 3975

Number of trout per mile after: 6800

Plus improved flood control, better water added to whatever watershed is downstream, and the bay. Willing to bet if decreased stream temperature in the study zone was a result, then you've extended the trout water farther downstream as well, so not just better water, but more of it. It is a success story and should not be looked at as a failure.

Most likely the reason it benefitted browns more would be the limestone sanding they did in the tributaries and lowering the culverts in them for fish passage. Just invited the browns up the tribs to spawn where the brookies always have.

Shavers fork empties into the Ohio (via Cheat>Monongahela) so the only bay involved is the Gulf of Mexico.

In the area where the study was conducted, a lot of the channel would've been fairly restricted historically due to terrain (narrow valley with steep banks). I'm not sure it's really that disconnected from its floodplain as it is. I'm sure there are places where it should have better access, but the floodplain in that system, in that area is pretty narrow.

It's important to note also that there is very little BT natural reproduction in that area. All of the nonnative trout numbers are from stocking. What you're seeing in trout per mile is that the stocked trout are better able to survive due to improved water temps/habitat. It's not that the wild BT numbers increased naturally. So they increased stocked trout numbers at the expense of wild native brook trout.

It's also important that the macro life is not great in that stream and so small brook trout become an important food source for the stocked trout. It's easy to see how this was a double whammy to the ST population.

 

[Fish Sticks]

It is clear that if brookies are your stated goal, you have to adopt a pH "target". It's not about cover or velocity or even temperature really, those favor more trout period, but browns will eventually outcompete brookies where they are able to do so. It's about pH. The only advantage brookies have is a tolerance for slightly more acidic water. Want to favor brookies in a stream overrun with browns? Make it more acidic.

I am not advocating that.

But I do think you get a handful of browns in nearly allopatric brookie water because there's SOMEWHERE the pH is right for browns to breed. A trib, coming up from below. That one spot distributes a smattering of browns here and there and they travel. And the same is true in reverse. You tend to get a few brookies in mostly brown trout water because there's a trib somewhere that's too acidic for browns, and it distributes a smattering of brookies here and there.

But when the water is cold and the pH is good, brown trout eventually win.

Your deff correct the acidic PH is a big Boone to the brook trout to a point when it comes to keeping the browns out. There are some streams that never had mines and are naturally acidic due to geology and tannins from trees. It’s always saddening to see limestone sand applied to these systems where they are not likely that much drastically different from historic photos in most likelihood, esp with Ohio valley air pollution on the decrease from an acid rain perspective.

However it is more complicated than ph scientists will tell you they are not even sure what all is in play and brook trout out compete brown trout in some cold spring influenced streams even in karst areas like the driftless. Check this study out, the brookies all but extirpated the browns in a groundwater rich stream.

(PDF) Natural replacement of invasive brown trout by brook charr in an upper Midwestern United States stream

PDF | Competition with invasive species and a warming climate have threatened brook charr (Salvelinus fontinalis) populations throughout their native... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

Now oddly relevant to this discussion, the study mentions the restoration improved hydrologic function(base flow) which is separate from habitat restoration(it’s hydrology). So conservation practices that increase buffers and increase aquifer recharge( or the not as sexy to our community Ag BMP’s like cover crops, grass strips, ect) can benefit brook trout. But this just goes to show we don’t have it figured out yet, this too is an area of active research.

 

[silverfox]

Your deff correct the acidic PH is a big Boone to the brook trout to a point when it comes to keeping the browns out. There are some streams that never had mines and are naturally acidic due to geology and tannins from trees. It’s always saddening to see limestone sand applied to these systems where they are not likely that much drastically different from historic photos in most likelihood, esp with Ohio valley air pollution on the decrease from an acid rain perspective.

However it is more complicated than ph scientists will tell you they are not even sure what all is in play and brook trout out compete brown trout in some cold spring influenced streams even in karst areas like the driftless. Check this study out, the brookies all but extirpated the browns in a groundwater rich stream.

(PDF) Natural replacement of invasive brown trout by brook charr in an upper Midwestern United States stream

PDF | Competition with invasive species and a warming climate have threatened brook charr (Salvelinus fontinalis) populations throughout their native... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

Now oddly relevant to this discussion, the study mentions the restoration improved hydrologic function(base flow) which is separate from habitat restoration(it’s hydrology). So conservation practices that increase buffers and increase aquifer recharge( or the not as sexy to our community Ag BMP’s like cover crops, grass strips, ect) can benefit brook trout. But this just goes to show we don’t have it figured out yet, this too is an area of active research.

This is exactly what is proposed in a watershed to my West. Naturally acidic, no mining history in that area, mostly inert substrate, somewhat infertile stream declining in richness from source to confluence. Wild BT in the larger stream, small class b,c,d brook trout from headwaters to confluence. The CD got approval to lime the headwaters. I voiced my concern about them making it more conducive to BT moving in and got an angry response that it would improve the fishery by making more BT water.

I hate our class system. If it isn't class A it isn't worth investing in the ST population apparently. Anything less than class A ST is ripe for stocking or BT conversion therapy.

Class C brook trout:

 

[wildtrout2]

I hate our class system. If it isn't class A it isn't worth investing in the ST population apparently. Anything less than class A ST is ripe for stocking or BT conversion therapy.

Class C brook trout:
View attachment 1641224995

Nice brookie. Where was it caught?

 

[troutbert]

So you bring up an interesting point, I didn’t mention this because I was talking about restoration in the traditional sense. And what I mean by traditional sense, is a lot of the parameters of brook trout habitat that projects target are sourced from studies of allopatric(just brook) populations.

The aspect of the complexity of habitat you speak of that allows brook trout to persist better is related to two things as per my conversations with the fisheries scientists helping me with the restoration I volunteer with. One: minimal to less large deep pools that develope/favor larger brown trout that will harm brookie population. Two: shallow habitats that favors smaller fish/young of the year decreasing predation and competitive effects on brook trout. That being said just because you don’t use armored structures doesn’t mean your not at risk of tipping the scales to brown trout. Large woody debris that creates very deep holes will likely do the same thing. It’s frustrating because if brown trout were not there brook trout would be getting great benefit from these structures.

Yes, the complex habitat creates many smaller pockets and pools which are favorable to the brook trout. And channel splits divides the stream into 2 or more smaller channels and that also favors the brook trout.

I have seen this many times while fishing these streams, and also from observing electrofishing.

These complex habitat sections have lots of large woody debris. The LWD is what most often creates the channel splits. The LWD triggers channel avulsions. The LWD creates many small protected niches, which allows the brook trout to escape predation from the larger browns.

And in these mixed population systems, the beaver dams are dominated by brook trout, not browns. I'm not sure of the reason, but this is definitely the case. And where there are channel splits caused by LWD, there are more beaver dams. Because beavers are more successful at damming small streams than large ones, because floods on the large streams blow out the dams.

Beaver restoration may be one of the main keys to improving brook trout populations in PA's forested lands. Have any of you caught brown trout in beaver dams? I have only one time, and that beaver dam was mostly broken down, so the water was flowing through, not really ponded.

 

[silverfox]

Have any of you caught brown trout in beaver dams? I have only one time, and that beaver dam was mostly broken down, so the water was flowing through, not really ponded.

Yes. Last year in a Class A brook trout stream. The brown trout was stocked and the stocking point was downstream.

 

[Fish Sticks]

I believe there is also a stream in Maryland that brown trout just can’t seem to invade for no obvious reason and researchers are kinda s

Yes, the complex habitat creates many smaller pockets and pools which are favorable to the brook trout. And channel splits divides the stream into 2 or more smaller channels and that also favors the brook trout.

I have seen this many times while fishing these streams, and also from observing electrofishing.

These complex habitat sections have lots of large woody debris. The LWD is what most often creates the channel splits. The LWD triggers channel avulsions. The LWD creates many small protected niches, which allows the brook trout to escape predation from the larger browns.

And in these mixed population systems, the beaver dams are dominated by brook trout, not browns. I'm not sure of the reason, but this is definitely the case. And where there are channel splits caused by LWD, there are more beaver dams. Because beavers are more successful at damming small streams than large ones, because floods on the large streams blow out the dams.

Beaver restoration may be one of the main keys to improving brook trout populations in PA's forested lands. Have any of you caught brown trout in beaver dams? I have only one time, and that beaver dam was mostly broken down, so the water was flowing through, not really ponded.

i have read the brook trout may have a passage advantage to beaver dams compared to brown trout. Random large woody debris that redirects the channel into historic bed or out of historic bed or causes island formation/side channel is deff good from what I’ve heard like you said. But the non random ones designed to make deep scour holes /pools often. I have never caught a brown in a beaver pond. Beaver ponds have good benefits on hydrologic function as well often. I would be interested to see a study in pa looking at similar brook trout streams with beaver introduction matched against controls surveyed pre and post introduction with additional endpoints of study being effects on baseflow, thermal conditions, and non native species presence.

 

[lycoflyfisher]

Yes, the complex habitat creates many smaller pockets and pools which are favorable to the brook trout. And channel splits divides the stream into 2 or more smaller channels and that also favors the brook trout.

I have seen this many times while fishing these streams, and also from observing electrofishing.

These complex habitat sections have lots of large woody debris. The LWD is what most often creates the channel splits. The LWD triggers channel avulsions. The LWD creates many small protected niches, which allows the brook trout to escape predation from the larger browns.

And in these mixed population systems, the beaver dams are dominated by brook trout, not browns. I'm not sure of the reason, but this is definitely the case. And where there are channel splits caused by LWD, there are more beaver dams. Because beavers are more successful at damming small streams than large ones, because floods on the large streams blow out the dams.

Beaver restoration may be one of the main keys to improving brook trout populations in PA's forested lands. Have any of you caught brown trout in beaver dams? I have only one time, and that beaver dam was mostly broken down, so the water was flowing through, not really ponded.

There is a watershed in Potter thats full of brown trout in beaver dams. There are some brook trout around there, but the biggest browns seem to be associated with the beaver ponds in my angling experience.

In other watersheds, I would agree that brook trout seem to do well with beaver activity. Improved floodplain connectivity and habitat complexity will benefit all aquatic organisms. Streams by nature are dynamic systems.

 

[Acristickid]

Who? Who didn’t know that?

 

[Fish Sticks]

There is a watershed in Potter thats full of brown trout in beaver dams. There are some brook trout around there, but the biggest browns seem to be associated with the beaver ponds in my angling experience.

In other watersheds, I would agree that brook trout seem to do well with beaver activity. Improved floodplain connectivity and habitat complexity will benefit all aquatic organisms. Streams by nature are dynamic systems.

Agreed about the complexity, in the past there have been stream projects that have been predominantly single channel deep pool habitat which has limited macros and yoy trout due to lack of riffles/side channels/ shallow flats ect. I’m sure you have seen those as well.

 

[Fish Sticks]

Who? Who didn’t know that?

It seems obvious but there are unfortunately tons of restorations out there where a stream with no infrastructure or nearby constraints have been armored to high heaven and channelized.

 

[Fish Sticks]

I think in some places hydrology and biotic interactions are ignored while solely habitat and water quality are prioritized. This is the 5 factor component framework, it’s used to describe the factors that govern the size and health of salmonid populations.

Five factor components model: in no particular order of importance because will vary stream to stream.

1.hydrology
2. Biotic interactions
3. Habitat/geomorphology
4. Water quality
5. Connectivity

John hoxmeir and Doug Deiterman have a great review article on habitat requirements on brown vs. brook trout I reference at least one a week. Link below.

https://www.tu.org/wp-content/uploads/2019/02/TroutHabitat_Dieterman_Mitro_DASymp_Final.pdf

One quote from this article in reference to stream restoration considering the five factor component frame work of variable governing salmonid populations is.

“An important implication of the five-component approach is that management empha- sis on only one component, such as restoring physical habitat/geomorphology, may still fail to protect and enhance fish populations if other components, such as water quality or biotic interactions, are also limiting to a population.”

The more you address the better out of those factors, this is why a lot of these past projects aimed at one or two things that may have left spring seeps perched on legacy sediment or just put armored structures in places failed( that and not recognizing streams as dynamic).

Getting back to my opening sentence unless your in Lancaster county, hydrology likely not getting as much consideration as it should. And biotic interaction threats recognition is obviously in its infancy in this state atleast because we still stock them. Other interesting potential projects that deal with hydrologic processes are all these cess pool nutrient ridden spring ponds warming in the sun. Will remind everyone the ONLY successful brook trout reintroduction that will count toward the 2025 goal of 8-% reintroduction was done by bunch of volunteers in bucks county Tu after one of these nasty spring ponds was restored after dam ripped out. That could be duplicated in so many places.