Whooo, golly, is there a lot of silliness on this thread.
You are exactly correct: Asian Carp are NOT bottom feeders. In fact, a big part of the problem is that because they are filter feeders of plankton and such, and quickly occupy so much of the biomass in a body of water, they eat the bottom of the food chain away from the usual small fish and critters that then support the next level, and so on. They literally starve out their competition.
Out of decent water, cleaned and prepared correctly, they taste quite good. But, they are very bony.
Fish sausage made from Asian Carp can also be quite tasty. (I bought a couple pounds of such, to try, last year.)
Multiple operations now export processed Asian carp to Asia. So far, that harvest is only a drop in the bucket, but is growing. For example:
http://www.the-messenger.com/news/local/article_6e21c568-0216-11e7-a2ff-e74d37336db5.html
If one has ever visited the area below the spillway @ KY or Barkley dam, the numerous dead carp (yuck!) left there by fishermen attest to the size of the fish. A large “kill” there, in 2014, possibly by a virus* that attacked the carp, demonstrated the amount of protein available.
http://www.the-scientist.com/?articles.view/articleNo/39850/title/Something-Is-Killing-Asian-Carp/
http://fw.ky.gov/fish/pages/ky-barkley-fishkill.aspx
*I do not know if a virus was confirmed, as little information “followed up”.
I’d also point out that many bottom feeders, again out of decent water, can taste good. Channel catfish (again, properly prepared), come to mind. Granted that the channel catfish most people eat come from farms where they learn to eat commercial catfish feed, most consumed long before it might sink (if it ever does) to the bottom. Also granted that the very best catfish I’ve ever eaten were 3-4 lb. blue catfish out of the Buffalo River in Arkansas = Very good water, and, blues mainly prey on other fish.
I disagree with some of our posters when it comes to nature always finding a solution: Dutch Elm disease is but one example. In the case of Asian Carp, Mo Nature might very well find a solution, or at least an acceptable balance, but, it might take hundreds or thousands of years. I don’t think people dependent on the Great Lakes fisheries would be too happy about waiting around for a 1000 year “fix”.
That said, along that line, it would seem that very large blue and flathead catfish, though still rare, may be becoming more numerous. One might speculate that the relative few who do make it to be big enough to eat an average adult Asian Carp are having a field day. It also may be that slot limits are needed: Say, blues over 20 lbs. must be returned to the water they came out of.
As for a solution to keeping them out of the Great Lakes, the problem of eggs on birds’ feet, or predatory birds carrying a fish some distance, and then for whatever reason dropping the fish back into water, cannot be discounted at all.
My proposal is a series of 4 or 5 of those “electric fences” along the river, leading to a downstream dam: The “uppermost” fence would be 50 miles straight line distance from the dam, and normally, the lake is kept @ 1/2 of capacity. Overstock that baby and the “fenced” sections of river with predatory fish, and regulate fishing as needed to encourage their numbers and size. (Maybe NO fishing in the uppermost section.) If Asian Carp are ever found above the “lowermost” fence, close the dam during a low water-flow period, and apply Rotenone from it to the next-to uppermost fence. After a few days, the Rotenone will degrade, and the dam can be reopened. Desirable fish from the uppermost section will repopulate the lower sections with time. (It may be necessary to close fishing entirely, for a period.)
Notes / fine tuning:
Closing the dam will be harmful to fish downstream, and commercial traffic.
Potassium Permanganate can be used to deactivate Rotenone in water, to lower toxicity back down to acceptable levels, if the treatment period needs to be shortened. Normally, Rotenone breaks down fairly quickly: At 24 °C, the half-life in natural waters is ~1/2 day, at 0 °C it is 3-4 days.
A 2 dams & lakes setup could mitigate river level problems below the dams, and lake level problems as well. But, the cost is already very high. This is not exactly a deserted area...
There's been concern that the buffalo carp, and more importantly paddlefish along with smaller species such as gizzard shad (which are feed for larger game fish and pan fish) are undergoing deleterious effects wherever carp populations are highest (and of course, naturally enough, downstream from those locales0.
Of course you know that, already. I'm simply repeating it here to further publicize the information...
Which river? The Illinois? And what's with the "downstream dam" with electric fences "along the river"? I'm not seeing how that would work --- unless what you are thinking about is trapping the carp already in Lake Barkley?
If a dam or dams were to be built on the Illinois-- why not simply shut off the Chicago Sanitary and Ship Canal (aka; Chicago Drainage Canal)? If that were to occur, if there was no dam at some point built so as to provide a spillway to ensure water flow, one big problem could be need for large pumps to transfer water from Lake Michigan to the canal downstream of the dam blockage in order to keep the upper reaches of the Illinois to Corp of Engineer's specified channel depth (9 ft.).
That would shut off whatever barge traffic there is, and possibly make the upper reaches of the Illinois left high and dry part-time during the year.
Building dams would close off the barge traffic. Unless instead of locks, there were 'dry' lifts for barges, which I guess could be costly to operate. A system such as that, where barges would be hauled out and transited on, say, a dedicated railway from water to water, would be expensive to first; build, then maintain and operate. I'm sure it's been thought of and further investigated as to costs --- so has thus far been dismissed as impracticable.
Imagine if billions of dollars were spent in some way, and waterfowl still transported carp eggs in their feathers (and stuck in their bills) to the Great Lakes regardless of all the extra, and highly expensive efforts?
Not that this will cure or fix "the problem" of Asian carp menacing the Great Lakes; but I've already been scheming upon a net design where I could wrap 'em (round haul) but without using a purse line.
I've gotten to the point where I can start counting meshes (by the stretch measure foot) to then convert those numbers into lbs. of nylon webbing (which generally runs 9$-12$ per lb, sometimes less when purchasing large amounts of factory web). But I may switch to braided web, or else even polyethylene web for the middle "sack" or bunt portion of the net -- which portion would be no bunt at all as those are known in seine net terminology, transitioning instead to a "sock" as we called that when I was fishing on a seiner in Southeast Alaska.
The sock is like the body of a miniature trawl net. Trawls I really know, having fished those for many years, and worked in net shops too, along with regular repair, rebuild, and re-hanging a variety of those when not being part of a "net shop".
The reason for using a seine (instead of the gill and trammel nets most often presently used for commercial Asian carp harvesting) is that I think I'd want to catch the fish alive, so the fish could be bled while still alive. After which; chilled/refrigerated near immediately.
Both of those steps would raise the eating quality of the fish, which in turn could (hopefully) help lead to wider acceptance of the fish among American consumers, while also fortifying what export market demands presently exist.
But all that costs money, and would be challenging to accomplish on trailerable (8' 6" width) boats, and possibly purpose-built barges. Going bigger means a person would have to go through locks when transitioning from one segment of a river to another -- and -- would led to needing offload from the boat onto a truck instead of putting a boatload of fish on a trailer and taking that to whenever it would be offloaded and sold directly to a processor, or else processed by one's own company.
Whichever way -- a guy could not be fishing full-time and processing full-time without hiring many persons to assist, which raises the question === would it pencil out (be profitable after paying wages and taxes along with each and every other expense).
If they (dang those "they" people!) would just allow me to hit the Mega for about $200 million --- I could find out if it would be profitable, or not. It would keep me out of the bingo parlors, regardless, that's for sure. :^')