I enlarged an old stock pond on my farm about 5 years ago and stocked grass carp in it afterward. The carp have done a great job of controlling weeds, with the exception of one specie, ever since. Now after reading many posts I have some questions. Will weed infestation increase now that my carp are older and if so, how do I "catch" the old carp to replace. These things are huge and plentiful. Also, any help with the weed i.d.? It grows at the waters edge above and below the water. Has a yellow flower. In the autumn it turns a a reddish purple until it dies off. Simple enough! Any help appreciated.
Two difficult things to do. Remove older GC and take care of an invasive aquatic plant.
Grass Carp being as skiddish as a bonefish make it difficult to remove them once they have grown up. I have heard some people use the bow fishing method with the best results. This allows you to stand back far enough not to scare the fish yet catch them.
The plant without an actual picture sounds like Bladderwort. If you are okay with using an aquatic herbicide, I can make some recomendations on what to use after a firm identification is made.
PGC:
LOTS of discussion about GC here in the past. Here are three links to a few of the good threads:
Grass Carp Vote Grass Carp Problem Finally hooked a GC GC do tend to have a lower weed intake as they get older. You need to decide when you want to add fresh stock; two inputs to help figure it out are 1) how bad were your weed problems before adding GC and 2) are you willing to handle more weeds in a transition period between old GC losing effectiveness and eventually dieing and placing new GC.
If you decide to (try and) remove the older GC, some of the methods which have been listed here as being successful are bowfishing (as Cary mentioned), regular fishing (cherry tomatoes, pom-pom flies imitating floating fish food, earthworms, and mealworms have all been reported to work), and shooting. Older GC seem to really take to floating fish food pellets and my personal choice for removing some GC would be to get them used to eating pellets at a dock or rock outcropping and then pick them off with a gun while they are eating. Whether you can get more than one GC by any of these methods (in a short period of time) is a good question since GC tend to be very skittish around events that scared them in the past.
Your plant could also be Water Primrose. If so, GC will not eat it at all. It is also very difficult to control.
I suspect the plant to be creeping yellow water primrose, too. As it rears its head next spring, and you wish to eliminate it, glyphosate is a great choice. Be sure to use a good surfactant, follow the label, mist the mixture on the plant, and you can rid yourself of it. It won't be done with one application, though. Be prepared to treat it every two to three weeks during the growing season, until you are satisfied with the results.
h20fwlkillr said:
“Your plant could also be Water Primrose. If so, GC will not eat it at all. It is also very difficult to control.”
Perhaps GC are picky eaters?
They do control yellow water primrose in our ponds.
Interesting situation tho…. First limited numbers of GC were stocked in our ponds
two years ago and water primrose was only vegetation present and they cleaned it up.
Then bushy pondweed took over and they wouldn’t touch it.
Last year the pondweed was ugly and almost took over the pond, creeping further into the pond as water receded with drought.
Todd Overton recommended additional GC into main pond and it was absolutely amazing how fast they cleaned up the pondweed.
One GC in new 1/4-acre pond nearly starved to death until water primrose appeared and now he/she nibbles leaves and flowers to the stalk.
Amazing fish.
George Glazener
N.E. Texas 2 1/2 ponds
Thanks to all that replied. After looking at a few pictures I believe I have an increasing Water Primrose problem. While one poster tells of Grass Carp eating it, mine definitely do not. At least not enough to knock it back. As far as the "fishing" goes. Sounds like a whole lot of bad ways to solve the problem, if it is one. Anybody know what the life expectancy of a Grass Carp is? Perhaps knowing that would help!
Grass carp will eat primrose if they are stocked at high densities, like 10 per acre. I've seen large older grass carp consume primrose, but as you've read here on the forum, they don't eat as much (as a percentage of their body weight) when they grow old and large. You can try glyphosate, but soon realize that it is a pain in the butt to deal with spraying weeds. Primrose will return relatively quickly, wind can work against you, and spray equipment may not be sufficient to cover significant portions of infestation at a time.
I don't see the need, necessarily, to remove old grass carp unless you have soft water. In Lexington area you should have relatively hard water and thus may not have to worry about carp causing muddy water. Grass carp will live 10-15 years.
Another option is to use Sonar Q at 90 ppb concentration, which is a pelleted form of sonar that is quite environmentally friendly and will work for up to an entire season. It is easy to apply, but can be expensive. Contact me if you need more specific recommendations for Sonar Q.
We have GC here in a pond at work and they are at least 12 years old...we refer to them as "submarines". Pushing three feet now...be tough to talk anybody into letting me bowfish them. Half the office windows face the pond and the Holiday Inn sits 50 feet from the other side...and it's the dining room.
Might get the PETA folks all in an uproar...
Haven't had to add any to my ponds...yet.
PGC, which Lexington? Todd is thinking it's Lexington, Texas, but I suspect somewhere else, like Kentucky.
I have had great success with glyphosate on primrose, but have never dared stock grass carp at high enough densities for them to eat it. I have been fearful of other consequences of high stocking rates of grass carp.
You win Bob! It's Lexington, Ky not Texas but I assure you that Todd is correct in the fact that we have hard water. It's the limestone that builds that great bone in the thoroughbreds you know! Sounds like glyphosphate for the plants and archery lessons for me!
We have had great results with Rodeo at 3-4 oz/gal of water combined with Kinetic at .25 oz/gal of water as a surfactant/spreader.
If the plants are tall I would recommend spraying towards the pond so not to create drift burns on the bank.
Pinegrove,
Grass carp stocked correctly should control your weeds for 3 to 5 years. After this time you should start seeing weeds again. A minimum of 1/2 of what you stocked before should be replaced considering you are leave the old grass carp in. There really is no need to take the old grass carp out, unless you consider them a nuisance. They will eat to sustain there weight, but not as agressively as when they were younger. As the posters above stated they can live up to 10-15 years, however some do start dieing after 5 years.
I stocked additional Grass Carp in my pond in the spring of 2005, to support the earlier ones I stocked in 2003, that weren't having much of an impact or had possibly died. We can only re-stock Grass Carp in Pa. every two years. This spring (2006), I had an outrageous curly leaf pond weed bloom, which subsided naturally towards June. Since then, the weed control has been fairly good with the Grass Carp, although I did have to use chemicals in August as the coontail and milfoil were over-running the pond. The grass carp are now about three feet in length.
Since we haven't had any ice yet in NW Pa., I have been able to monitor my pond pretty well this winter season. I have several Bryzoan colonies (green blobs) and some more than desired sub-surface weed growth, along with the usual cold weather filamentous algae.
My question is do Grass Carp stop or severely slow down their eating of vegetation in the winter months? I don't even see them in the shallows like I did in the summer months, so I hope they didn't get eaten by a pesky blue heron we have around from time to time. Of course, none of the other fish are abundant in the shallows. I have a shallow pond and the bottom is pretty much weed covered most of the time. I just thoguht it would be pretty barren by now.
Thanks for your experiences.
GC metabolism ought to be slowed about as much as other fish by lower water temperatures. If so, their appetite could currently be just a few % of what it is in the Summer.
I've never seen mine during the Winter months.
Thanks, Theo. Despite having Grass Carp for close to three years, it is still a new experience for me and I want to learn from those who have had them for awhile.