The Northern Snakehead amphibian has been here over a decade now.
If their was going to be a negative impact, we would very likely know by now.
In fact the bass population exploded in the years after they were introduced, now things have leveled off somewhat.
This is what I have read in local stories and fish and game articles over and over.
Yes, we essentially dodged a bullet and got lucky, but I would consider it a win at this point.
The reasons for this are fairly simple to understand from what I have read.
1) They spawn 3 times per year, and have 10k to 40k fry per spawn.
Our game fish eat the hell out of these fry, giving a food boost to our native game fish.
Where our native fish spawn once per year. This increases the available food supply tremendously for our native fish.
2) The adult ones do not seem keen to eat our game fish as our fish are fast and tough, where as the snakeheads have fairly tender skin and are easily torn up by our game fish. They also seem to prefer other amphibians instead of other fish for food.
3) They are not as aggressive or dangerous as we have been lead to believe.....unless you are a frog that is lol.
Yes they have scary teeth, but like pike and musky are just not that bloodthirsty. If they were, we would have a problem.
4) They are not able to migrate on land, this is a myth. Yes, they can sorta of wiggle around, but there is no documented case of them walking to a new area. They breath air, and can survive out of water for about 48 hours if they can stay moist, that's it. This is probably an adaptation to survive dry seasons, and low oxygen environments in SE Asia where they came from.
5) Asian immigrants brought them here to eat, and they probably stocked them in some local waters thinking they would die in the winter, but somehow they can survive by going into a sort of hibernation. Then people also had them as pets, and some one released them into other waters for various reasons, and they are unstoppable breeders.
Florida is full of invasive fish from all over the world, so far, the native fishery world has not ended there either.
6) They prefer warm, dirty, dark, muddy, low oxygen, and shallow water. I don't see them getting much further up the Potomac, or surviving in any of our more pristine waters inland. This means our Smallmouth are safe, and definitely our trout. I have not heard of much if any as far north as point of rocks MD, let alone any further norther or inland other then a few muddy lakes and ponds where some one stocked them.
At the end of the day, they are an illegal immigrant fish, but they are here to stay now, no way to stop them all due to their rapid breeding, and luckily they have not caused any negative effects to our native fisheries, and have instead provided extra fun, and food for our citizens to enjoy.
They should never have gotten loose here, but it seems now we just have to make the best of it.
Considering in 40 years fishing this area I have never even seen a pike or musky let alone caught one, I welcome the chance at a toothy fresh water fish lol.