I got a survey in the mail from GA DNR and UGA asking my input on a few topics, mostly regarding hydrilla in Lake Thurmond and my opinion towards it. My knee-jerk reaction is I'm against the stuff and get rid of it. But one of the survey questions put me to thinking. It asked if I would support removal of hydrilla if it meant reduction in wildlife habitat. They also asked if I supported the use of sterile grass carp as hydrilla-b-gon.
Would native wildlife, flora and fauna, suffer long term if hydrilla was significantly removed? What impact do grass carp have on our native species, specifically other fish and aquatic plants? My rather naive view is kill off as much hydrilla as possible, with as little toxins as possible. Let the carp be a big part of the eradication, and when things are more manageable in the way of the hydrilla, let the ospreys, eagles, Father Time and what not take care of the carp.
I searched the forum, but only saw a couple passing mentions of this topic. I must have searched poorly, because I figure this has to have come up before. But, could people with more knowledge give me their opinions before I finalize mine? Or point me towards the right threads? I'd surely be remiss not to learn from you all!
Thanks!
Sterile grass carp
Started by
mattknepley
, Feb 20 2013 02:19 PM
9 replies to this topic
#2
Guest_Ken_*
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Posted 20 February 2013 - 02:59 PM
Here's a quote I found on this website http://www.weedscien...ds/hydrilla.PDF though I didn't look all that much. They also refer to mecahnical and chemical means of reducing hydrilla:
Triploid sterile grass carp
Ctenopharyngodon idella) have been used extensively in North Carolina and many other states to control hydrilla and other submersed aquatic weeds. Grass carp may live as long as 10 years and are usually very effective in suppressing hydrilla in ponds and small lakes, particularly if the fish are stocked in the fall. Their longevity makes grass carp very attractive alternatives to expensive herbicides, in spite of their seemingly high cost (about $7 per fish). Grass carp also eat hydrilla in preference to many other submersed plant species and usually do not feed extensively on desirable emergent vegetation such as arrowhead and bulrushes. Grass carp are generally stocked in ponds at 10 to 15 fish per acre. For larger impoundments, fish should be stocked at 20 fish per vegetated acre. A permit
from the Wildlife Resources Commission (919-733-3633) is required if the pond is larger than 10 acres or if the owner plans to stock more than 150 fish in the same body of water.
Biological Control
may be introduced into North Carolina waters, and these may be stocked only in relatively small
impoundments where the fish can be contained readily.
This limitation stems from concern about the impacts that escaped fish could have on fisheries and waterfowl habitats in public waters and on marine fisheries and shellfish habitats downstream. Policies on stocking of grass carp in large lakes and reservoirs in North Carolina and elsewhere can be expected to change as we gain more information about their impact on large systems and downstream resources. No other organisms are currently available for biological control of hydrilla in North Carolina. The progress of recent research in Florida indicates that one or more species of insects (including two species of flies, a tuber weevil, and a stem-boring weevil) may prove effective on hydrilla. The North Carolina Department of Agriculture has shown interest in these insects and others for hydrilla control in North Carolina. One or more of these insects may be available in the future.
Triploid sterile grass carp
Ctenopharyngodon idella) have been used extensively in North Carolina and many other states to control hydrilla and other submersed aquatic weeds. Grass carp may live as long as 10 years and are usually very effective in suppressing hydrilla in ponds and small lakes, particularly if the fish are stocked in the fall. Their longevity makes grass carp very attractive alternatives to expensive herbicides, in spite of their seemingly high cost (about $7 per fish). Grass carp also eat hydrilla in preference to many other submersed plant species and usually do not feed extensively on desirable emergent vegetation such as arrowhead and bulrushes. Grass carp are generally stocked in ponds at 10 to 15 fish per acre. For larger impoundments, fish should be stocked at 20 fish per vegetated acre. A permit
from the Wildlife Resources Commission (919-733-3633) is required if the pond is larger than 10 acres or if the owner plans to stock more than 150 fish in the same body of water.
Biological Control
may be introduced into North Carolina waters, and these may be stocked only in relatively small
impoundments where the fish can be contained readily.
This limitation stems from concern about the impacts that escaped fish could have on fisheries and waterfowl habitats in public waters and on marine fisheries and shellfish habitats downstream. Policies on stocking of grass carp in large lakes and reservoirs in North Carolina and elsewhere can be expected to change as we gain more information about their impact on large systems and downstream resources. No other organisms are currently available for biological control of hydrilla in North Carolina. The progress of recent research in Florida indicates that one or more species of insects (including two species of flies, a tuber weevil, and a stem-boring weevil) may prove effective on hydrilla. The North Carolina Department of Agriculture has shown interest in these insects and others for hydrilla control in North Carolina. One or more of these insects may be available in the future.
#3
Guest_centrarchid_*
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Posted 20 February 2013 - 03:14 PM
If grasscarp legal, then I would have no problem using the the sterile triploid version as a management tool. If breeding population already established in watershed then even diploids will not make a difference in feral abundance although laws still come first. They are a management tool that can be abused. Understock then work up to numbers needed to control hydrilla. Just because they have been found effective in one situation does mean they will work in all and dietary habits can change to target more valued macrophyte species. Take care to cull some grass carp if non-target plant species are negatively impacted. If carried out properly in a situation presently with excessive hydrilla, habitat could actually be improved by grass carp but again this must be monitored to prevent overshoot.
#4
mattknepley
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- Smack-dab between the Savannah and the Saluda.
Posted 20 February 2013 - 05:08 PM
Good info, guys, thanks. Does it influence your answers if I mention Lake Thurmond is a massive impoundment? It's one of the dammed up stretches of the Savannah River.
Matt Knepley
"No thanks, a third of a gopher would merely arouse my appetite..."
"No thanks, a third of a gopher would merely arouse my appetite..."
#5
Michael Wolfe
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Posted 20 February 2013 - 05:59 PM
I am not a professional and not experienced in proper technique. But I would be concerned. People do not have a great track record of doing this kind of thing well. We are not patient and not cautious and we almost never really think things through. There are too many bad outcomes that I have heard of and can think of.
I mean I can see where they could be a powerful tool, used properly... but so is a filet knife on a camping trip... and I wouldn't go handing that to just anyone that happened to walk by. Used improperly it could be dangerous and not yield the originally intended results. That would be my concern. Some combinations of abuse and unintended consequences.
Maybe like in the medical profession... first, do no harm.
I mean I can see where they could be a powerful tool, used properly... but so is a filet knife on a camping trip... and I wouldn't go handing that to just anyone that happened to walk by. Used improperly it could be dangerous and not yield the originally intended results. That would be my concern. Some combinations of abuse and unintended consequences.
Maybe like in the medical profession... first, do no harm.
Either write something worth reading or do something worth writing. - Benjamin Franklin
#6
Guest_fundulus_*
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Posted 20 February 2013 - 06:36 PM
Such campaigns have a good chance of backfiring in some fashion. Like Michael says, there's not a really encouraging record of this kind of work. Just trusting suppliers to supply 100% (yes, 100%) triploid stock is a major act of faith. It gets worse from there.
#7
Guest_Skipjack_*
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Posted 20 February 2013 - 07:59 PM
Bruce made a good point. If there are 1000 triploid grass carp going out to 300 farm ponds, the odds of two accidental diploids meeting up is probably fairly low. But stocking several thousand in one impoundment..... The odds of a spawn get quite a bit higher. Additionally it is directly linked to a river system. Are there currently Asian carp in the Savannah?
Homo sapiens has a nasty habit of not looking before it leaps.
Homo sapiens has a nasty habit of not looking before it leaps.
#8
Guest_gunner48_*
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Posted 20 February 2013 - 09:15 PM
We bought four sterile,triploid Grass carp for our quarter acre farm pond in Indiana. The fish worked has advertized and cleaned up a weed problem. I figured after awhile they would eat themselves out of a job and perish. That was 12 years ago. I see all four them every Spring when they start working the shallows eating the new growth. They are now about ten pounds each and if all goes well they may outlive me. While I don't know how they will do in a large impoundment I would assume they would be equally longed lived and I would assume that once they go in they will continue to be a factor in the impoundment for a long time. Once grass carp get big they really don't have many or any natural predators in North America. When we bought the farm and built the pond 21 years ago we stocked 25 flathead catfish. They have never reproduced but a few of those flatheads are stlll caught and released every year back into the pond. I would consider Grass carp a solution but they really have to make sure there sterile because it is really hard to get them out again.
#10
mattknepley
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- Smack-dab between the Savannah and the Saluda.
Posted 25 February 2013 - 07:14 AM
Thank you for all the input, folks. I feel better about my responses knowing I had insight from people with more knowledge/experience on such topics.
Matt Knepley
"No thanks, a third of a gopher would merely arouse my appetite..."
"No thanks, a third of a gopher would merely arouse my appetite..."
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