Snakehead impact on other species of fish

afishinado

afishinado

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Sobering article about the introduction of snakeheads in our region >

http://www.middlesusquehannariverkeeper.org/blog/specialist-invasive-snakehead-impacts-aquatic-ecosystem-on-many-levels?fbclid=IwAR1VfQnt9SlMBqD2X1O54NUBCoZtr0Y3Za0EXjIXGPwe34hi9OjkDW4I05c


Report on results of snakehead infestation in MD >

http://www.middlesusquehannariverkeeper.org/uploads/7/8/8/1/78814684/final_blackwater-fish-community-comparison.pdf
 
Dave_W

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Thanks for linking to this.

I've long been skeptical of some of the doom and gloom predictions of the impact of snakehead (SH) where they have been introduced. However, this study shows strong evidence that the presence of SH has a negative impact on native fishes. Obviously, more studies like this are needed but this is a good start and suggest strong correlation between the presence of SH and decline of other fish.

 
Fredrick

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Ah Dr. Joe Love snakeheads are Joe's white whale . I wonder why Joe isn't getting this research published hint hint . Also I'd like to add that all fish populations were in a big decline in BW before snakeheads were introduced, that's why they completed the studies in 2006 and 2007. Look at the difference in fish numbers between 06 and 07 . Even John Odenkirk is quoted as saying that Dr. Loves study is inconclusive .

I honestly like to see some studies of the effects of blue cats and flatheads but they are not as juicy of a topic as snakeheads .

Tom and Dave i'd like to take both of you out sometime for snakeheads let me know if you are interested .
 
afishinado

afishinado

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Fredrick wrote:
Ah Dr. Joe Love snakeheads are Joe's white whale . I wonder why Joe isn't getting this research published hint hint . Also I'd like to add that all fish populations were in a big decline in BW before snakeheads were introduced, that's why they completed the studies in 2006 and 2007. Look at the difference in fish numbers between 06 and 07 . Even John Odenkirk is quoted as saying that Dr. Loves study is inconclusive .

I honestly like to see some studies of the effects of blue cats and flatheads but they are not as juicy of a topic as snakeheads .

Tom and Dave i'd like to take both of you out sometime for snakeheads let me know if you are interested .

The study was first done in 2006-2007 when snakeheads were not yet established. Because of minimal habitat changes owed to protection by Blackwater National Wildlife Refuge, this dataset enabled the study to document changes in the fish community that could be attributed to the establishment of Northern Snakehead. The same study was done in 2018-2019. Summary of the study is below.

Summary
Northern Snakehead is an invasive species initially discovered in the Potomac River in
2004, but has since spread to most major river systems of the Chesapeake Bay. In 2012,
Northern Snakehead was first reported from the Blackwater River drainage on the eastern shore
of Maryland. Fish community surveys were conducted in Blackwater River and Little
Blackwater River in 2006 and 2007, before the establishment of Northern Snakehead there.
Because of minimal habitat changes owed to protection by Blackwater National Wildlife Refuge,
this dataset enabled us to document changes in the fish community that could be attributed to the
establishment of Northern Snakehead. We replicated the 2006 and 2007 surveys (preSnakehead) over a year from 2018-2019 (post-Snakehead). Over all sampling periods we caught
35 species (32 fish species and 3 invertebrate species) totaling over 50,000 individuals. Of 21
species that were captured both pre- and post-Snakehead, 17 declined in relative abundance with
percent reductions ranging from 30%-97%. We found that five of six sites had significantly
different fish communities when comparing pre-Snakehead and post-Snakehead surveys. The
main difference in fish communities was a reduction in overall biomass of most fish. Species
dominance during the post-Snakehead period was significantly higher for both Blackwater and
Little Blackwater River. Pre-Snakehead surveys were more evenly distributed and dominated by
White Perch, Black Crappie, and Brown Bullhead, while post-Snakehead surveys were less even
and dominated by Common Carp and Gizzard Shad. This study is the first to document major
shifts in a fish community following establishment of Northern Snakehead. Further investigation
into ongoing fish community changes and continued vigilance in minimizing spread and
population growth of Northern Snakehead is warranted.


All I can say is don't let your love for snakehead fishing get in the way of your judgement of fact from a scientific survey from qualified fisheries biologists.
 
Fredrick

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So did the fish populations stop declining after 2007 ? Then start back up after the snakeheads were introduced that's the question . And Joe Love is far from what I'd call a unbiased biologist . And why not state what the habitat changes were and what causes the changes had on the fish populations were they felt they needed to complete a survey . Why isn't he being transparent on this because it definitely has a great significance on the outcome of the data for the study .
 
afishinado

afishinado

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Fredrick wrote:
So did the fish populations stop declining after 2007 ? Then start back up after the snakeheads were introduced that's the question . And Joe Love is far from what I'd call a unbiased biologist . And why not state what the habitat changes were and what causes the changes had on the fish populations were they felt they needed to complete a survey . Why isn't he being transparent on this because it definitely has a great significance on the outcome of the data for the study .

"Because of minimal habitat changes owed to protection by Blackwater National Wildlife Refuge, this dataset enabled the study to document changes in the fish community that could be attributed to the establishment of Northern Snakehead."

You turned it around completely above. The lack of habitat changes makes the study more valid.

Since we can't unscramble the egg, I've always had a "wait and see" attitude about the effects on our streams, rivers and lakes with the introduction of snakeheads.

Why can't you accept a legit survey to study the effects of snakeheads? It appears the only study that would be valid to you would be one that shows minimal effect on the ecosystem. I wish you were right, but your not; at least in this case. I know you love snakeheads, but most of us can only continue to hope for the best, which is minimal damage to our stream and rivers in the future.
 
Fredrick

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My point was that they fail to tell why they conducted the initial surveys in 06 and 07 .It was because of complaints of declining fish populations .


Tom if the fish were declining prior to the arrival of snakeheads and then you surveyed those same areas 11 years later and then blame the decline on snakeheads because minimal habit changes were made to combat the fish decline . Makes your research inconclusive .

Tom maybe you're the one that wants the cause for the fish decline in BW to be on snakeheads. You never accepted the study's conducted by Odenkirk that were published (18 years worthof research). And is over looking that the biologist hates snakehead and is definitely biased . Or that this shows a decline in fish populations which was happening before the snakeheads arrived. This study is not enough to blame the decline of fish populations on snakeheads. If Mr. Love would stand by this research he would of had it published because Mr. Love knows that if another biologist conducted this same study, that person would not be able to duplicate the results .

I bet Genbeam and Larkmark would be less bias than Love with this study .
 
Fredrick

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The reason they completed the studies in BW in 06 & 07 was due to raising salinity in the watershed

https://link.springer.com/article/10.1672%2F07-238.1

We used the Little Blackwater River as a reference system to test the hypothesis that remnant freshwater-dependent fish populations of transitional areas in the Blackwater River may have declined as salinity levels increased. Upstream habitats of Blackwater River were brackish, while such habitats of Little Blackwater River were more persistently freshwater. As salinity increased seasonally in the Little Blackwater River, the abundance of freshwater-dependent fishes declined at two sites. Differences in species diversity and composition between Blackwater River and Little Blackwater River are likely associated with higher salinity and connectivity in upstream portions of the Blackwater River.
 
GeneBeam

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Seems to me that John Odenkirk is stated as being the Virginia Department of Game and Inland Fisheries one of the nation’s foremost expert on the snakehead, and after reading some things from Joe Love my take is that Joe Love detest the snakehead and John Obenkirk admires and maybe loves the snakehead. John has spent so much time with the snakehead he might affected with Stockholm syndrome.

So I’m thinking that John Obenkirk might be a member of Fred’s “We Love The Snakehead” facebook group page and Joe Love would never join the “We Love The Snakehead” facebook group.


Whatever is your take I would hope as a Pennsylvania licensed fisherman\sportsman you would following the Pennsylvania Fish and Boat Commission (PFBC) statement of urging anglers to report and dispose of any invasive Northern Snakehead fish that may be caught.

Anglers are reminded that possession, transport, and importation of a live snakehead is unlawful in both Pennsylvania and Maryland. Any of these invasive fish that are caught should be killed and disposed of properly or consumed.
 
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AndyP

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The world and the ecosystem, which we are a huge part of, is always changing and adapting to those changes. Of course nobody would rightly want to destroy an ecosystem just to introduce their favorite new fish to catch. But this has all occurred by accident and by ignorance... BUT it has happened and cannot be undone. Mother Nature will sort it all out with or without some help from mankind. Fred, I live in Delco near Montco, and I would be interested in experiencing a "snakehead" outing someday. For what it is worth, all of the areas that I have fished for many many years in SEPA have declined in quality and numbers and that was happening before the snakehead was found in this area...
Is it invasive ...yes but technically so is the brown trout... I don't think there is much we can all do about it so lets keep fishing : )
 
P

poopdeck

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odenkirk is often cited by snakehead aficionados. He does say snakeheads are misunderstood. He says this in response to concerns of snakeheads walking on land and eating small children and pets as has been portrayed in movies. Interesting enough is the fact that I've never actually heard that about snakeheads until I watched a snakehead aficionado doing YouTube interviews of odenkirk. When it comes to the impact snakeheads have on a fishery odenkirk simply states he doesn't know, there isn't enough information, they are still looking into it and only time will tell.

Odenkirk is an expert in Virginia. He is the guy tasked with providing the state of Virginia with a game plan on what to do about snakeheads. The state of Virginia actually follows his direction and advice on snakeheads based on his training, experience and scientific research. Currently Virginia still asks anglers to kill snakeheads if encountered. If the state of Virginia's actions doesn't clearly sum up Odenkirk's thoughts at this moment on snakeheads I don't know what will.

To call another biologist suspect because his research states openly what Odenkirk must tell his bosses in private is disingenuous.
 
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