Snakeheads in Philly area

[lycoflyfisher]

Pcray, that is an excellent description in laymans terms. I would also add impacts to connectivity such as barriers at road stream crossings and old, obsolete low head dams as significant contributing factors to isolated populations.

Shannon White's research showed that brook trout still move down into the mainstem loyalsock and travel to different tribs. The mainstem loyalsock is heavily stocked, there is a notable brown trout population that utilizes the mainstem and larger tribs. In that watershed, I personally would have more concern with stocking on tribs and physical connectivity barriers as there is evidence that brook trout are already and continuing to utilize the mainstem for movement.

 

[afishinado]

In simple terms, clearcutting forests back in the 1700's - 1800's decimated the streams and thus the native brook trout disappeared from our streams. In the late 1800's brown trout and rainbow trout were stocked to replace the lost brook trout populations. Brown trout began to reproduce and thrive in PA streams as they slowly began to mend.

A pipe dream, but if brook trout were reintroduced and/or left to repopulate on their own, instead of stocking non-native browns and rainbows, we would all be fishing over a thriving population of native brookies right now in the since recovered major streams and like Penns, Spring, Little J, Pine, Kettle, etc. as well as their tribs, which historically held brook trout.

So the overriding factor why native brook trout do not exist at all where they once did or are a small minority in the population in our largest streams is because of the stocking of non-native trout, brown trout from Europe and rainbows from the northwest US.

I accept the reality that brown trout and rainbows have displaced our native brook trout in PA. We cannot turn back time and unscramble the egg, but I do believe we should do more to assure native brook trout survive and thrive in what is left of their range.

 

[silverfox]

Pcray, that is an excellent description in laymans terms. I would also add impacts to connectivity such as barriers at road stream crossings and old, obsolete low head dams as significant contributing factors to isolated populations.

Shannon White's research showed that brook trout still move down into the mainstem loyalsock and travel to different tribs. The mainstem loyalsock is heavily stocked, there is a notable brown trout population that utilizes the mainstem and larger tribs. In that watershed, I personally would have more concern with stocking on tribs and physical connectivity barriers as there is evidence that brook trout are already and continuing to utilize the mainstem for movement.

I've had a lot of discussions about barriers lately. Mostly revolving around the idea of genetic rescue as a tool to introduce genetic diversity into an isolated population where other AOP barriers prevent the ingress of nonnative salmonids.

It's an interesting dilemma. Should we improve AOP through barrier removal and risk ingress which could lead to extirpation for the sake of genetic diversity and other ecosystem benefits, or do we try to improve diversity through manual methods to protect them from extirpation due to displacement?

Which is more damaging long-term? Inbreeding depression or displacement? The displacement issue might happen anyway through bucket-biologist introductions of nonnative species over barriers or even natural expansion past barriers due to flooding or avian transplant. Maybe the population is resilient to invasion due to gradient, pH, temperature, etc.? As Pcray said, also, if a population is isolated by a physical barrier and that population blinks out due to drought, disease, or whatever, then the genes are gone anyway. So repopulation might be the most important factor?

I guess it depends entirely on the circumstances to a pretty granular level. All compounded by the presence of nonnative species.

 

[lycoflyfisher]

With the extreme storms we have been experiencing the past decade, I would advocate for connected systems almost 100% of the time. A major flood in the fall and winter can kill adult fish and wipe out a year class at the same time. Some other work in the loyalsock drainage showed st population response to floods in 2011 and 2016. Populations in systems without barriers responded much quicker post flood in terms of yoy the next spawning season and stabilization of adult population.

 

[silverfox]

With the extreme storms we have been experiencing the past decade, I would advocate for connected systems almost 100% of the time. A major flood in the fall and winter can kill adult fish and wipe out a year class at the same time. Some other work in the loyalsock drainage showed st population response to floods in 2011 and 2016. Populations in systems without barriers responded much quicker post flood in terms of yoy the next spawning season and stabilization of adult population.

I agree. Allow me play a little "Phil's broken record". 😀 The upper savage is a good example of how a large connected watershed (above the impoundment anyway) provides a much more stable brook trout population.

As much as I hate to admit it, I've been convinced the stocking (rainbows and yellow rainbows) that still takes place in the USR has limited to no impact on the ST population. Interestingly, SMB seem to turn up further and further up the tribs. I think brook trout have such critical mass there that even with some predation, and competition, it really isn't going to impact the population any more than any other natural predation would.

To be fair, S. Trutta are almost entirely nonexistent in the USR though. I'd love to see somethign like that in PA. Ahem, Avlin Bush...

 

[Fish Sticks]

K you

I agree. Allow me play a little "Phil's broken record". 😀 The upper savage is a good example of how a large connected watershed (above the impoundment anyway) provides a much more stable brook trout population.

As much as I hate to admit it, I've been convinced the stocking (rainbows and yellow rainbows) that still takes place in the USR has limited to no impact on the ST population. Interestingly, SMB seem to turn up further and further up the tribs. I think brook trout have such critical mass there that even with some predation, and competition, it really isn't going to impact the population any more than any other natural predation would.

To be fair, S. Trutta are almost entirely nonexistent in the USR though. I'd love to see somethign like that in PA. Ahem, Avlin Bush...

Yea great points guys! I agree kettle is the most natural candidate due to its intact habitat, and large connected network of streams. Stocking/invasive trout associated damages to the brook trout population there make it an exciting potential candidate for cesssation of stocking, C and R, combined manual XYY supermale removal, and even possibly genetic rescue. Also from my conversations with a prominent herpetologist if there were no browns rainbows or stockers a hellbender reintroduction would make sense there, he thinks the habitat there is still fine for them it’s just the non native fish population and sheer bulk of fish with the stockings.

 

[Mike]

I don’t know where this idea that there aren’t hellbenders in Kettle Ck above Kettle Ck Lk is coming from. (which I think is Alvin Bush Dam). In general they are between there and Ole Bull S P and there are multiple sampling/study points in that stretch. I was just speaking with one of the former field crew this week as well as another biologist about the population. Additionally, a sampling site that is also a popular stocking point and has been for decades is one of the best sampling sites for these critters. Just as with fish there are preferred habitat limitations in some portions of the stream, but I’m not getting into any additional detail.

 

[lycoflyfisher]

How we have completely abandoned the snakehead in philly discussion to hellbenders in Kettle creek is comical. Here is a recent article on hellbender research, by arguably the leading hellbender researcher in the region. Population decline has been noted in many watersheds, but if I recall various presentations kettle creek has remaimed a stronghold.

Feature: Hellbent For Hellbenders In The Kettle Creek Watershed

By Dr. Peter Petokas, Lycoming College Clean Water Institute I first began searching for the giant Eastern Hellbender salamander in Ket...

paenvironmentdaily.blogspot.com

 

[Fish Sticks]

How we have completely abandoned the snakehead in philly discussion to hellbenders in Kettle creek is comical. Here is a recent article on hellbender research, by arguably the leading hellbender researcher in the region. Population decline has been noted in many watersheds, but if I recall various presentations kettle creek has remaimed a stronghold.

Feature: Hellbent For Hellbenders In The Kettle Creek Watershed

By Dr. Peter Petokas, Lycoming College Clean Water Institute I first began searching for the giant Eastern Hellbender salamander in Ket...

paenvironmentdaily.blogspot.com

I don’t know where this idea that there aren’t hellbenders in Kettle Ck above Kettle Ck Lk is coming from. (which I think is Alvin Bush Dam). In general they are between there and Ole Bull S P and there are multiple sampling/study points in that stretch. I was just speaking with one of the former field crew this week as well as another biologist about the population. Additionally, a sampling site that is also a popular stocking point and has been for decades is one of the best sampling sites for these critters. Just as with fish there are preferred habitat limitations in some portions of the stream, but I’m not getting into any additional detail.

I did not know they were still above the Alvin bush dam in the upper watershed. I will call that herpetologist and make sure I did not misunderstand them. The concern about stocking and non native trout comes from this article showing hellbenders cannot chemically detect invasive brown and rainbow trout the same way they can with predatory fish they evolved with. The concern for invasive species/increased predation seems to be at the larval stage.

(PDF) Innate Predator Recognition and the Problem of Introduced Trout

PDF | Innate predator recognition typically only occurs when there is an evolutionary history between predator and prey. Predator introductions thus can... | Find, read and cite all the research you need on ResearchGate

www.researchgate.net

 

[moon1284]

In simple terms, clearcutting forests back in the 1700's - 1800's decimated the streams and thus the native brook trout disappeared from our streams. In the late 1800's brown trout and rainbow trout were stocked to replace the lost brook trout populations. Brown trout began to reproduce and thrive in PA streams as they slowly began to mend.

A pipe dream, but if brook trout were reintroduced and/or left to repopulate on their own, instead of stocking non-native browns and rainbows, we would all be fishing over a thriving population of native brookies right now in the since recovered major streams and like Penns, Spring, Little J, Pine, Kettle, etc. as well as their tribs, which historically held brook trout.

So the overriding factor why native brook trout do not exist at all where they once did or are a small minority in the population in our largest streams is because of the stocking of non-native trout, brown trout from Europe and rainbows from the northwest US.

I accept the reality that brown trout and rainbows have displaced our native brook trout in PA. We cannot turn back time and unscramble the egg, but I do believe we should do more to assure native brook trout survive and thrive in what is left of their range.

I don't agree with this at all (the we would be fishing over a thriving population of brook trout part). Unless your definition of thriving is different than mine.

Here is what I would consider a thriving ST population , and I'll stick with Penns specifically. A thriving ST population in Penns to me means equal biomass and size distribution compared to the current brown trout population.

What are some big rivers that had their ST population decimated, do not have BT or RT populations, then recovered and now have a large ST population including ST over say 15 inches?

There are plenty of rivers in ME that meet the criteria (decimated ST population due to habitat loss, no RT or BT, and now restored habitat), but very, very few with ST populations returned to anything close to what they were pre habitat loss.

 

[silverfox]

How we have completely abandoned the snakehead in philly discussion to hellbenders in Kettle creek is comical. Here is a recent article on hellbender research, by arguably the leading hellbender researcher in the region. Population decline has been noted in many watersheds, but if I recall various presentations kettle creek has remaimed a stronghold.

Feature: Hellbent For Hellbenders In The Kettle Creek Watershed

By Dr. Peter Petokas, Lycoming College Clean Water Institute I first began searching for the giant Eastern Hellbender salamander in Ket...

paenvironmentdaily.blogspot.com

I do think this is all related and the discussion headed in the directions it has because of a fundamental problem in the way species are viewed based on how some have been handled over the years.

It gets harder to convince the public of the dangers of introducing invasive species when we're also protecting or even proliferating species technically considered invasive. Even across the state with different species that might be native in one part of the state and technically invasive in the other.

I see this all the time in a social media group. There are a decent number of people who defend snakeheads and often use other species that we've accepted or even protect as justification for why we should just leave the snakeheads alone. Mixed messaging.

 

[lycoflyfisher]

I don't agree with this at all (the we would be fishing over a thriving population of brook trout part). Unless your definition of thriving is different than mine.

Here is what I would consider a thriving ST population , and I'll stick with Penns specifically. A thriving ST population in Penns to me means equal biomass and size distribution compared to the current brown trout population.

What are some big rivers that had their ST population decimated, do not have BT or RT populations, then recovered and now have a large ST population including ST over say 15 inches?

There are plenty of rivers in ME that meet the criteria (decimated ST population due to habitat loss, no RT or BT, and now restored habitat), but very, very few with ST populations returned to anything close to what they were pre habitat loss.

We don't know what a thriving st population would like.... there are very few scientific records that show evidence of 20in brook trout. We all know anglers may stretch the truth from time to time.

Would the size of average adult brook trout be larger than what we currently see if logging and the industrial revolution didn't happen and without the introduction of brown and rainbow trout? Probably, but its a question we can't definitively answer.

I often dream about what fishing in the Susquehanna drainage would have been like in colonial times... big brook trout, abundant american shad and eel runs...

I enjoy fishing for brown trout on Penns as much as anybody, but I hate to see brook trout devalued because soneone thinks they couldn't or can't provide the same angling experience as brown trout.

You might as well be saying bring on the flathead catfish, they grow bigger than bullheads and channel catfish.

 

[silverfox]

I don't agree with this at all (the we would be fishing over a thriving population of brook trout part). Unless your definition of thriving is different than mine.

Here is what I would consider a thriving ST population , and I'll stick with Penns specifically. A thriving ST population in Penns to me means equal biomass and size distribution compared to the current brown trout population.

What are some big rivers that had their ST population decimated, do not have BT or RT populations, then recovered and now have a large ST population including ST over say 15 inches?

There are plenty of rivers in ME that meet the criteria (decimated ST population due to habitat loss, no RT or BT, and now restored habitat), but very, very few with ST populations returned to anything close to what they were pre habitat loss.

I think part of the problem here is you're basing your definition of "thriving" on an artificial fishery. i.e., Penns never existed in its current form without human intervention/introduced nonnative species, so it's unnatural and unfair to say that its current state is the only acceptable form. I think there's a distinction between "thriving" and "healthy".

If you're comparing what would've been possible without nonnative fish to what we have today comprised of nonnative fish, I don't think it would ever be equal. Expand that concept to any number of warmwater/coolwater fisheries across the state. Native assemblage would've likely been suckers, eels, shad, chubs, catfish, pickerel, and numerous minnow species. Not exactly angling nirvana, but I'd argue more "healthy" because it's a native assemblage of species that co-evolved and are better suited to find balance. To be fair, the modification of the river systems (dams) plays a bigger role here than species composition.

I think our view on a species' "value" is skewed as anglers to begin with, but then that's compounded by what man has created today as recreational fisheries that we now use as a baseline. Where do we draw the line on this? Do we devalue any species that doesn't reach >15 inches and is considered a sportfish? If it ain't good on a fly rod, who cares what happens to it? Is the baseline now whether it has trout or not?

I think the inclusion of fish size is based on an altered perception of importance which is driven by the unnatural fisheries we have today. The maximum possible size of ST is driven by access to large water bodies (lakes or large rivers) and the connectivity of the system among other things. Outside of PA, there are places that do routinely turn out >15 in brook trout. Some with a more southern latitude than PA.

My concern with devaluing any native fish, but especially brook trout, is it implies we should just give up on trying to do anything. When we say "can't turn back the clock" or "can't unscramble the egg", we're conveying a sentiment that we shouldn't even try. That's reckless in my opinion.

 

[Striperbobby]

Sorry guys I was just honestly looking for some established snake head populations closer to home. I did not intend to start a whole “ kill the snakeheads” and “bass and brown trout are invasive “ crap. I now have learned there are two subjects you should never talk about, politics and snakeheads! Lol hope everyone has a great fishing season no matter what you enjoy catching!

 

[Fish Sticks]

How we have completely abandoned the snakehead in philly discussion to hellbenders in Kettle creek is comical. Here is a recent article on hellbender research, by arguably the leading hellbender researcher in the region. Population decline has been noted in many watersheds, but if I recall various presentations kettle creek has remaimed a stronghold.

Feature: Hellbent For Hellbenders In The Kettle Creek Watershed

By Dr. Peter Petokas, Lycoming College Clean Water Institute I first began searching for the giant Eastern Hellbender salamander in Ket...

paenvironmentdaily.blogspot.com

Sorry guys I was just honestly looking for some established snake head populations closer to home. I did not intend to start a whole “ kill the snakeheads” and “bass and brown trout are invasive “ crap. I now have learned there are two subjects you should never talk about, politics and snakeheads! Lol hope everyone has a great fishing season no matter what you enjoy catching!

I don’t blame anyone for fishing for any species unless it’s threatened endangered or too warm out ect. I separate the conservation and the fishing since they have two different goals so I hope I didn’t give the impression it’s my belief that it’s wrong to fish for brown trout our snakeheads where you find them. Maybe I’ll even see you out there striperbobby! Tight lines.

 

[tomgamber]

Sorry guys I was just honestly looking for some established snake head populations closer to home. I did not intend to start a whole “ kill the snakeheads” and “bass and brown trout are invasive “ crap. I now have learned there are two subjects you should never talk about, politics and snakeheads! Lol hope everyone has a great fishing season no matter what you enjoy catching!

Let me assure you, you did not start anything. You're late to the party on this. All these same people with differing viewpoints on all these topics get along just fine in May at the Jam too. Better to talk about this than not.

 

[Fredrick]

Mike actually gave some unbiased info in another thread . Start here
"Plus snakeheads in Manayunk Canal!"


Or you can join my facebook group links in signature

 

[Mike]

Pcray, that is an excellent description in laymans terms. I would also add impacts to connectivity such as barriers at road stream crossings and old, obsolete low head dams as significant contributing factors to isolated populations.

Shannon White's research showed that brook trout still move down into the mainstem loyalsock and travel to different tribs. The mainstem loyalsock is heavily stocked, there is a notable brown trout population that utilizes the mainstem and larger tribs. In that watershed, I personally would have more concern with stocking on tribs and physical connectivity barriers as there is evidence that brook trout are already and continuing to utilize the mainstem for movement.

Lyco,
That is exactly right and supports what I said elsewhere regarding the surveys that I did on the Loyalsock in the Forksville/Worlds End area when all of those tribs and the Loyalsock were more heavily stocked (in total) than they are today. Wild ST were still utilizing the Loyalsock, perhaps seasonally, but that’s the point with respect to 1) trout finding “new frontiers;” ie streams that have improved enough to now support trout, and 2) the exchange of genes among populations occupying different streams where there are no physical barriers to prevent it. Despite the much heavier stocking, including the stocking at that time of what are now Class A, unstocked streams, the ST gene exchange system still functioned, as witnessed by this recent research in the Loyalsock basin. The whole idea of stocked trout or wild BT populations restricting the movement of wild ST and, thus, genes flowing from one population to another is in my view being overplayed, which is not uncommon with newer ideas within the scientific community or the public until research matures (more studies conducted that reveal the nuances). Think of how the Covid recommendations changes as research progressed.

An example of how the trout angling community went a bit wild in the past is when whirling disease was discovered out west. Suddenly the sky was falling, not just in the west, but more importantly to my point among some Pa trout anglers who had to no clue that it had been in Pa for a few decades, that the PFC had done some of the lead research on the topic, and that it was being managed appropriately in the hatchery system and in fish distribution. Fast forward: Now you don’t hear about it.

As with many things in life that cause an uproar, this too shall pass.

 

[Mike]

As for the impact of stocked trout on forage fish populations, I had only once seen a clear negative impact and that was a comparison of forage fish numbers within and immediately upstream from a FFO area that was being overstocked by a cooperative nursery on top of the good numbers of trout being stocked by the PFBC. The forage fish population was depauperate. Immediately above the FFO area in the area stocked under statewide regs the forage fish population was quite healthy. To their credit, the coop nursery backed off on its stocking rate and may have stopped entirely once this was pointed out. Still, it remained a scientific curiosity to me and later on in the journals that I receive I ran into two papers that scientifically evaluated the impacts of trout stocking on forage fish abundance and in both cases there was no measurable impact. I suspect that the impact of trout stocking on forage fish populations is stocking rate specific and, furthermore, there may be some threshold value of stocking rates in a given stream beyond which impacts are felt.

 

[Fish Sticks]

Lyco,
That is exactly right and supports what I said elsewhere regarding the surveys that I did on the Loyalsock in the Forksville/Worlds End area when all of those tribs and the Loyalsock were more heavily stocked (in total) than they are today. Wild ST were still utilizing the Loyalsock, perhaps seasonally, but that’s the point with respect to 1) trout finding “new frontiers;” ie streams that have improved enough to now support trout, and 2) the exchange of genes among populations occupying different streams where there are no physical barriers to prevent it. Despite the much heavier stocking, including the stocking at that time of what are now Class A, unstocked streams, the ST gene exchange system still functioned, as witnessed by this recent research in the Loyalsock basin. The whole idea of stocked trout or wild BT populations restricting the movement of wild ST and, thus, genes flowing from one population to another is in my view being overplayed, which is not uncommon with newer ideas within the scientific community or the public until research matures (more studies conducted that reveal the nuances). Think of how the Covid recommendations changes as research progressed.

An example of how the trout angling community went a bit wild in the past is when whirling disease was discovered out west. Suddenly the sky was falling, not just in the west, but more importantly to my point among some Pa trout anglers who had to no clue that it had been in Pa for a few decades, that the PFC had done some of the lead research on the topic, and that it was being managed appropriately in the hatchery system and in fish distribution. Fast forward: Now you don’t hear about it.

As with many things in life that cause an uproar, this too shall pass.

So because their class A, an arbitrary PA fish and boat amount of kg/hectar, their doing ok huh. Hey Mike, what’s the rate of inbreeding depression in those class A tribs? Is the gene exchange via the current minority of brook trout moving enough to encourage genetic adaptive capacity to deal with warming temperatures? I’m sure you must have the data on this to dispute some of the most knowledgeable brook trout conservation genetics researchers in the world?

Pointing to the fact that there is still some movement left despite stocking the bejesus out of the sock and that there are still enough brook trout to meet at the arbitrary kg/hectare in some places that says nothing about the population’s genetics/fitness is a pretty weak argument to try to seep this under the rug. The problem is Class A is not the greatest measurement of brook trouts population’s health, they could be class A and so inbred from connectivity issues that they are going to blink out in the coming decades. And again, even these class A “sections” make no sense because it would be like going into someone’s house and saying “we found them in the kitchen they must only live in the kitchen”. The only thing that will pass is “the buck” at the fish commission when it comes to science based fisheries management taking a back seat to social programs like stocking.