Snakehead Impact Study

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poopdeck

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Actually I have been contradicting Fred's "Facts" since the beginning of his love, appreciation and promotion of snakeheads.

To suggest the snakehead is just a fish with similar diet restrictions as any other fish is another flat out rejection of the facts. To suggest this is the essence of hyperbolic sensationalism. I am not suggesting Fred and his buddies are lying or misrepresenting for nefarious reasons. I am suggesting that angler defense of snakeheads is an emotional cherry picking of perceived facts born out of angling passion.

From Columbia University:

"Ecological Role: Though little is known about specific ecological impacts do to their recent introduction, as previously gauged from past Northern snakehead invasions outside of the United States. The species has the potential to wipe out a small pond and stream ecosystem, moving from failed ecosystem to failed ecosystem as the available prey becomes exhausted in the area as noted when the Northern Snakehead was introduced into the Syr Dar’ya, river in Uzbekistan. C. argus fed on 17 species of resident fishes (juveniles through adults), including prey up to 33 percent of the predator’s body length (Dukravets and Machulin, 1978).

In addition to other fish, the Northern Snakehead’s carnivorous diet includes crayfish, dragonfly larvae, beetles, and frogs giving it the ability to consume large percentages of indigenous animal biomass, thereby potentially depleting many different key sectors of these relatively small aquatic ecosystems.

The Northern snakehead also has high reproduction rates with adults producing between 1,300 and 15,000 eggs per spawn at a frequency of 1-5 spawns per year (ISSG, 2004). Snakeheads can breathe air, surviving up to four days on land as long as their skin remains moist and has the ability to survive colder or dry temperatures by burrowing into the mud (Hilton, 2002).

Threat(s): C. argus is a rapacious primary predator consuming a wide variety of prey besides other fish whose predacious nature, lack of natural predators, high fertility, and adaptability to a wide range of environmental conditions qualify it as a potentially dangerous invader in climatologically-favorable and resource-rich U.S. ponds, lakes, and streams (Courtenay and Williams, 2004; ISSG, 2004; Okada, 1960). Also, given that C.argus has a geographic range of native range (24-53º N) and temperature tolerance (0-30 ºC) and was established in Maryland in 2002 and possibly in Florida around the same time, the probability that the C. argus will become more widely established is quite favorable (Courtenay and Williams, 2004). "

Clearly they will destroy an ecosystem as proven in other countries where they have been established for a long time. Clearly the studies in the USA are showing they are beginning to destroy the eco systems in the USA where they have been introduced. What more needs to happen for snakehead aficionados to understand the true impact? My guess is nothing but a total destruction of a fishery.

RA-PA-CIOUS - Aggressively greedy or grasping
 
krayfish2

krayfish2

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Sorry Fred but if I ever see one, it will be killed and I haven't killed a fish in 30 yrs or so.
 
jifigz

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Poopdeck, first of all the use of the word rapacious in what you have quoted means that the snakeheads are predatory and like to capture and eat live prey and not subsist on carrion. And, as I pointed out, there isn't a whole lot of contradicting or counteracting anyone with "facts." If you say that all of these studies show where they have destroyed ecosystems within the U.S. then please link them/show them or give direct reference where the information can be cross checked. And some of that quoted material from Columbia is from the 70's. Not that species change in 50 years all that much or anything, but people's opinions and, more importantly, our prowess in scientific endeavors and our ability to be more precise with our gathering of scientific facts HAVE IMPROVED.

If you're going to quote part of Columbia, why not the rest of the page? It's funny how you left out the part that doesn't blatantly support what you're saying ....
 

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D-nymph

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Fredrick wrote:

Anyone that fishes for snakeheads knows that they are not ravenous eaters that just gorge themselves on prey all day . If that was the case I would be having 30 fish days.

Would you be having 30 fish days?

Maybe you should be having 30 fish days but... suck? ;-)
 
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poopdeck

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Jifigz,

I never said there was data in the USA. It's pretty clear the USA lags behind in snakehead studies because of their newness to our eco system. However the Columbia university study makes it clear their is substantial data from other places of the world. I ask you, why is this source of available data completely ignored?

I did not include the entire article because it was long in the tooth so I only covered the heavy hitters so the post wasn't crazy long. Your piece of the article is equally alarming so I'm not sure where your coming from on that point. Did you read your snippet? It simply rehashes the lack of data in the USA while ignoring worldwide data. The part about govt. regulations being adequate to stop their spread has proven itself wrong. Perhaps it was effective on Asian importers but it failed to take into account angler participation in their spread. Don't you find it curious that only anglers see no harm in the snakehead invasion even while the experts, at a very minimum, are issuing dire warnings. The fact that there is any question as to their impact is stunning to me.

I simply provided the definition of rapacious. You may put your own spin on it if you like. Perhaps I should have simply highlighted that it eats everything it can eat up to 1/3rd of its size. That's most of the bass, trout, panfish, sucker, catfish population as well as everything the various migratory spawns produce.

 
jifigz

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I think you're misunderstanding my take on the situation. I think the snakeheads pose a threat to changing the ecosystem but certainly not destroying it. And what does destroying it mean, anyways? After all, we see it fit to stock species that aren't native all over the place and it is perfectly fine for them (the species that people are used to) to change an ecosystem? This has been done long before people cared or realized what they were doing but would we be happy as anglers if they weren't stocked? Did the smallmouth bass change the Susquehanna watershed? Absolutely, it became the dominant fish but we aren't complaining about that invasive these days and how it's displaced/reduced native fish populations.

I listed the part of the Columbia piece because it says that the ecosystems aren't being overrun yet. Sure, the fish are spreading, that's only natural. They will find and fill all areas that are suitable habitat that they can reach, but it clearly states they aren't overrunning the systems and John Odenkirk has agreed with that. We have quite a bit of data and history within the Potomac system now.

And I'm not putting any spin on the word rapacious. That is the definition of the word that applies to the situation. It has multiple definitions and when pertaining to animal behaviors that is what is meant. Not greedy.

So, yes, I don't want Snakeheads spread by boneheads that think it's okay to do what they please. But I also don't think that they are causing as much harm and disruption as people are making it out to be. In the end it doesn't matter. It is what it is, it's done, and we can't get rid of them. They are in the watershed to stay and in another 20 years they might be all through the Susky too. Who knows.
 
Carpo

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After the initial scare and hysteria, people have let their children and large pets roam their grounds without being armed any longer.

Their another invasive species that will fit into our eco system just like the carp,brown trout and many others.

For those who see an opportunity to fish for a very agressive predator who doesn't sip size 36 blue winged dingoasparian bufus from the film, you should be delighted.

An hours drive south from Lanc,York, and chester countys will land you in snakehead heaven.

Wet wading chuking meat and an 8 wt. it don't get any better than this.
 
afishinado

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Carpo wrote:
After the initial scare and hysteria, people have let their children and large pets roam their grounds without being armed any longer.

Their another invasive species that will fit into our eco system just like the carp,brown trout and many others.

For those who see an opportunity to fish for a very agressive predator who doesn't sip size 36 blue winged dingoasparian bufus from the film, you should be delighted.

An hours drive south from Lanc,York, and chester countys will land you in snakehead heaven.

Wet wading chuking meat and an 8 wt. it don't get any better than this.

How can you be so sure the snakehead will not effect other species since they come from Asia and their impact in US waters is unknown?

You don't know and neither do the fisheries biologists studying the snakehead introduction.

Just as an example, The Chesapeake and Delaware Bays are the spawning grounds and nursery waters for the Atlantic Striper.

How will the addition of a predator fish effect the striper population in the northeast US Atlantic waters in the long term?

Again, no one knows.

There's more to the story than just all the other species introductions have worked out and they're sure fun to fish for....
 
Carpo

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I did not say they would not make an impact, they will as any predatory species will in any eco system.
They are here, all the hand wringing and whining wont change that fact.
It probably will take decades to realize their impact , so if you want to help instead of crying wolf, then grab a rod kill what you catch and help instead of crying havoc!!!
Heat up the grill, cover with your favorite BBQ sauce and onions, great eating and you wont feel guilty either.
 
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Mike

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POTENTIAL negative impacts of snakeheads and other exotic fish are not just through predation. Exotic fish species introductions can also bring with them other exotic biota, such as disease causing bacteria and viruses, along with parasites, to which resident organisms may not be adapted. The negative impacts of these may not be realized for quite some time (decades) when individuals within other species populations or the populations as a whole may become more susceptible due to changing immunity or environmental conditions. Don’t believe it? Follow the history of Largemouth Bass Virus.

 
Fredrick

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Here is a video of John Odenkirk discussing Northern Snakehead diet and feeding habits

https://www.youtube.com/watch?v=dzjlNOihR6o&feature=share
 
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Mike

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There are seasonal and habitat related variations in fish abundance. That killifish are a prime forage organism in Virginia streams because of very shallow water, weedy habitat overlaps with snakeheads and because the killies are very abundant does not mean that small yellow eels are not a prime forage organism in the deeper and relatively weed-free areas of the tidal Delaware and Schuylkill. In fact, a follow-up discussion with another biologist who samples the tidal Schuylkill revealed that as I had properly recalled, snakeheads there were full of small yellow eels during spring sampling.

As for Pa’s concern about eels and why they are allowed to be sold in Pa, please note that Pa does not permit commercial fishing for eels, has removed more dams than any state in the country, and, to my knowledge, has been involved in pressing for eel passage facilities and/or capture & transport around some major dams, thus Pa is doing its part.
 
Fredrick

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Not mine but here is something to think about the recent study .



The study by Joseph Love and Joshua Newhard is being touted as proof that snakeheads are the reason for declining species in the Blackwater Wildlife refuge.

It contradicts the findings by John Odenkirk on the Potomac River that concludes that snakeheads have had no negative impact on that fishery.


https://youtu.be/lceYaOj8P9M


What stands out are the big declines in many species in Blackwater BEFORE snakeheads ever showed up there.

Northern Snakeheads were first reported from the Blackwater River drainage in 2012 and may have shown up as early as 2010.

A few notable species that declined before snakeheads arrived in that area are as follows

Banded Killifish 2006: 169 2007: 3
Black Crappie 2006: 3329 2007: 2665
Bluegill 2006: 2127 2007: 1955
Brown Bullhead 2006: 4365 2007: 3776
Pumpkinseed 2006: 3227 2007: 1310
White Perch 2006: 11,538 2007: 4548

Fisheries are complex systems and the factors that impact them are many. It looks like the trend of declining fish populations was set in motion before snakeheads ever showed up there. I believe snakeheads are being used as a scapegoat to what may be deeper problems in Blackwater.
 

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taimen

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The Northern snakehead is native for my home water, the Amur River. During the open water period (April-October) its habitats are limited to swamps, shallow lakes and backwater; it is impossible to meet this fish in large channels or in the main stem of the Amur. Here it comes only in winter - but snakeheads are not feeding in cold water.
At one of the videos in my thread you could see the habitats of this fish:
https://www.youtube.com/channel/UCGtt4Hxj6y84eDyhZALldCg
GOPR1459
 
Fredrick

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The Northern snakehead is native for my home water, the Amur River. During the open water period (April-October) its habitats are limited to swamps, shallow lakes and backwater; it is impossible to meet this fish in large channels or in the main stem of the Amur. Here it comes only in winter - but snakeheads are not feeding in cold water.
At one of the videos in my thread you could see the habitats of this fish:
https://www.youtube.com/channel/UCGtt4Hxj6y84eDyhZALldCg
View attachment 1641224387
Nice looking Channa , I'll try to watch your video later on today
 
RisenFly

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The most destructive non-native fish species in the country is.....

The brown trout.
Change my mind.
 
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Mike

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The Common Carp, but what’s your point?
 
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moon1284

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Definitely the carp. Brown trout are pretty low on the list.

Rainbow trout are more of a problem than brown trout. In the east they displace brook trout. In the west (outside of their native range) they displace and hybridize with cutthroat. Brook trout are also a problem in the west.

Off the top of my head Idaho encourages catch and kill and may even have a bounty on rainbows in the south fork of the snake River. I know it's the same for Brook trout a lot of places out west. I can't think of any place where that is the case with brown trout.
 
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lycoflyfisher

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Definitely the carp. Brown trout are pretty low on the list.

Rainbow trout are more of a problem than brown trout. In the east they displace brook trout. In the west (outside of their native range) they displace and hybridize with cutthroat. Brook trout are also a problem in the west.

Off the top of my head Idaho encourages catch and kill and may even have a bounty on rainbows in the south fork of the snake River. I know it's the same for Brook trout a lot of places out west. I can't think of any place where that is the case with brown trout.
Just because a species isnt under catch and kill regs in certain states does not mean that there are scenarios where there are negative impacts. One could certainly make the case that brown trout and smallmouth bass for that matter have had a significant influence on fish community composition in the Susquehanna River drainage. More so than the major dams and anthropogenic impacts? I am not sure I want to make that argument
 
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moon1284

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Just because a species isnt under catch and kill regs in certain states does not mean that there are scenarios where there are negative impacts. One could certainly make the case that brown trout and smallmouth bass for that matter have had a significant influence on fish community composition in the Susquehanna River drainage. More so than the major dams and anthropogenic impacts? I am not sure I want to make that argument

What fish species have been extripated from the Susquehanna watershed due to brown trout?
 
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