On October 31st, the US Army Corps of Engineers released approximately 13,000 triploid (sterile) grass carp into Kerr Lake. The carp were released from three locations on the NC side of the lake near the areas of greatest hydrilla infestation. Here’s a picture of a few of the fish: https://plus.google.com/112448875899960197128/posts/T8YymEnJnoh
Grass carp, as you may know, eat aquatic vegetation and have a special fondness for hydrilla. It is hoped that, over the next couple of years, we will begin to see a decrease in the area of hydrilla infestation. I would NOT expect it to disappear completely, and infestations in a particular area may increase or decrease from year to year. Thus, dock owners would be well-advised to continue monitoring the area around their docks so that they can arrange for chemical treatment by approved applicators as needed/desired.
As the name implies, sterile grass carp are unable to reproduce. This is a good thing because it allows the population to be managed. Also consider that they consume more when they are young and growing rapidly. Thus, ongoing management of hydrilla will require periodic restocking of the grass carp. To state the obvious, the frequency and rate of future stockings will depend on the availability of funding.
It’s worth noting that, for the past couple of years, the US Army Corps of Engineers has commissioned NCSU to conduct a lakewide aquatic vegetation survey. Hopefully this can continue so that changes in the hydrilla acreage can be monitored. The results of each survey are posted on the web for those that may be interested. Here’s the link:
The grass carp stocking may sound like bad news to bass anglers, since targeting the mats of hydrilla is an effective bass-fishing strategy. However, the fisheries experts I’ve heard from indicate that reducing hydrilla does NOT reduce the total bass population, it just requires anglers to change tactics. Granted, that may be little consolation to a bass angler. However, perhaps the aforementioned survey would prove a useful tool (pure speculation on my part as I’m more of a catfish guy).
For more information, contact the US Army Corps of Engineers. All the contact information is available here:
http://www.saw.usace.army.mil/Locations/DistrictLakesandDams/JohnHKerr.aspx
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Paul McKenzie
Agricultural Extension Agent, Vance/Warren Counties
NC Cooperative Extension