Link to Fish species in the Potomoc river

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warmouth said:
A study was done and was concluded that Snakehead were a bigger threat to certain species of native fish than LMB or Blue catfish. I can no longer find the results of this study online......but here they talk about the study, in the link above they discuss how Snakehead have a higher percentage of fish in them from gut analysis than LMB and how Snakehead will go into brush and weeds to feed and ambush prey where other Piscavores like Blue and Flathead catfish will not go this plus the fact that they are fast growers, eat a lot and are hardy makes them a triple threat to our native fish fauna. Its not just theyre teeth and aggressive guarding of the young that makes them dangerous to native centrarchids.
http://fishwild.vt.edu/snakeheads/diet.html
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Where is the studies about the largemouth bass and other "native" predatory fishes has a negative effect on the native sunfish and other native forage fish of Potomac River before the snakehead arrival? Funny thing is that catfish and bass LOVES the brush and weeds. Snakeheads are not only one piscavores of Potomac River. Last time I check, bass, catfish, walleyes and pikes have higher percentage of fish in them, not just snakeheads. Also there are studies that snakeheads have varied diet, no different from the bass and pikes.
 
warmouth said:
I agree that Pollution and siltation have a huge impact on the Potomoc also, as well as introduced natives......but my opinion based on the research available to me is that the biggest threat to native centrarchids and Killifish/ topminnows in that part of the east coast at this time is the Northern Snakehead due to the fact that once grown they have no natural predators and they are very hard to catch with traditional fishing methods.
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Based on the research available to me, the biggest threat to the native centrarachids and killifish/topminnows are the pollution, siltation and habitat destruction..not mentioned to the huge numbers of non-native predatory fishes (not just snakehead) as well. There are evidence that non-native mosquitofish pose a threat to native centrarchids and killifish/topminnows.

As for the snakeheads do not have any predators, you are dead wrong. Snakeheads have found in the stomachs of bass, catfish and pikes/muskellunges.
 
Article on Blue and Flathead catfish in the James and Raph. rivers, http://www.dnr.state.md.us/fisheries/catfish/pdfs/Invasive_Catfish_ Fact_Sheet.pdf " Impact of Introduction: Introduced bass usually affect populations of small native fishes through predation, sometimes resulting in the decline or extinction of such species (Minckley 1973). Species that have suffered such effects include relict dace Relictus solitarius, Clover Valley speckled dace Rhinichthys osculus oligoporus, Independence Valley tui chub Gila bicolor lethoporus (U.S. Fish and Wildlife Service 1985b), a distinct population of Gila chub G. intermedia, Monkey Spring pupfish Cyprinodon sp. (Minckley 1973), White River springfish Crenichthys baileyi, Pahranagat roundtail chub Gila robusta jordani (U.S. Fish and Wildlife Service 1985b), Owens pupfish Cyprinodon radiosus (Miller and Pister 1971), wild brook trout Salvelinus fontinalis (Boucher 2003), and White River spinedace Lepidomeda albivallis (U.S. Fish and Wildlife Service 1994e). Jenkins and Burkhead (1994) speculated that introduced largemouth bass may have contributed to the demise of an isolated population of trout-perch Percopsis omiscomaycus in the Potomac River in Virginia and Maryland. Introduced predatory centrarchids are likely responsible for the decline of native ranid frogs in California, California tiger salamander Ambystoma californiense populations (Hayes and Jennings 1986; Dill and Cordone 1997), and the Chiricahua leopard frog Rana chiricahuensis in southeastern Arizona (Rosen et al. 1995). In Squaw Creek Reservoir in northcentral Texas, introduced Florida largemouth intergrade with native northern largemouth (Whitmore and Hellier 1988). Nonnative predators, including largemouth bass, have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Hughes and Herlihy 2012)." USGS website. Eastern Mosquitofish are native to the Potomoc, and its juvenile Snakeheads that have been found in the stomachs of other fish; I clearly stated that adult Northern Snakeheads have no natural enemies in the Potomoc and that they are not as easy to catch on rod and reel as Bass or Northern Pike are, if you take the time to look at studies of gut content analysis they show that Bass eat a lot of Crawfish, Insects, as well as many types of fish, whereas percentage wise Snakeheads were found to eat predominately fish and it seems that they favor Centrarchids, Mummichogs and Killifish in the Potomoc.....I have already provided the links in posts above where this is stated. I fish for Bass here in Mo and usually catch them around stumps, logs, lilly pads, and around Brush and vegetation, I have never seen them or Blue or Flathead catfish in the middle of thick water weeds hunting other fish near the shoreline.....they always seem to be hiding on the edge of the brush and open water or near or behind rocks in open water. I must ask you, do you believe that LMB's are as aggressive and as efficient as a predator as the Northern Snakehead?
 
"Abstract

The feeding habits and diet of northern snakeheads were studied in 2007 and 2008. Fish were captured by boat electrofishing at all times of the day. Diet was compared to that of North American species, including largemouth bass, yellow perch, longnose gar and American Eel. Data are currently being analyzed, and results will be reported here and published in a scientific manuscript. Over 500 adult snakeheads were captured and dissected. Initial results suggest that snakeheads feed more actively during the morning hours and on outgoing tides. Feeding activity was also highest in May after water temperatures warmed and before spawning began in June. Over 20 prey items (mostly fishes) were detected, with banded killifish as the most common prey item by number, and bluegill as the most important prey item by weight. Diet was most similar to largemouth bass; however, bass had a wider diet breadth and a much stronger preference for crayfish. A few schools of juvenile northern snakehead were captured and dissected, and were found to consume a wide variety of macroinvertebrates." This talks about the study which I swear used to be found online a couple of years ago, and that I can no longer find....the study was done by Virginia tech.
 
Yes I believe the largemouth bass are aggressive and efficient as northern snakehead based on their diet. But I'm glad that your links are actually support my arguements that the non native fishes were already altered the ecosystem and changed the native fauna before the snakehead arrival. I've caught catfish and bass near shoreline, weeds and brushes before. Guess what is popular bait using for the catfish fishing. You don't clearly stated that adult snakehead have no natural predators as some adult snakeheads have found in larger cat fishes.

So far I do not see any evidence that northern snakeheads pose a threat to the ecosystems.
 
MN_Rebel said:
Yes I believe the largemouth bass are aggressive and efficient as northern snakehead based on their diet. But I'm glad that your links are actually support my arguements that the non native fishes were already altered the ecosystem and changed the native fauna before the snakehead arrival. I've caught catfish and bass near shoreline, weeds and brushes before. Guess what is popular bait using for the catfish fishing. You don't clearly stated that adult snakehead have no natural predators as some adult snakeheads have found in larger cat fishes.

So far I do not see any evidence that northern snakeheads pose a threat to the ecosystems.
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I agree with you on the danger posed to the Potomoc by siltation and pollution, but I do not and cannot agree that Large Mouth Bass and Catfish are as dangerous to native Centrarchids ,Killifish and Topminnows as the Northern Snakehead is for the following reasons 1. with Northern Snakehead both the Male and Female guard the nest and they also guard the young longer than LMB's and they do so very aggressively and have big teeth to do so with, 2. Northern Snakehead are designed (long and slender with a flattened head)like an eel or snake where they can get into weeds and brush where a fat LMB,Blue or Flathead catfish cannot and will be able to get to or ambush Roanoke Bass, Bluespotted Sunfish,Blackbanded sunfish and YOY Bass where they hide, 3. Northern Snakehead can live in waters that are more polluted and have less dissolved oxygen than LMB's and Blue catfish, so when condtions get bad and you have a huge Bass and Blue cat dieoff the Northern Snakehead well be having thanksgiving and the 4th July picnic all at once and will be able to survive while others die off 4. Man you gotta whatch the videos on youtube of Snakehead eating Bass, Catfish and whatever else they want to eat.......in a fight between any native and a Northern Snakehead of the same weight only the Alligator gar or Flathead catfish because of the way theyre built could possible survive. Northern Snakehead get 4ft long and can weigh up to 20+ pounds (a man caught a 18 1/2 pounder in the Potomoc on rod and reel) that's too big for even the biggest native catfish to eat. Minnesota Im now gonna rest my case and will let my fellow MFKers be the jury :D
 
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