Sterile grass carp and herbicide applications are the preferred ways to reduce hydrilla, and, by extension, the death of bald eagles at Lake Strom Thurmond (Thomas Hill) on the Georgia/South Carolina border, according to a draft management plan from the U.S. Army Corps of Engineers.
Since 1998, at least 81 eagle deaths there have been attributed to avian vacuolar myelinopathy (AVM). Scientists believe that the birds of prey contract the fatal disease from eating coots, which feed on hydrilla tainted with a toxic blue-green alga.
For five years, the Corps and other agencies have considered control measures for Thurmond, which seems to be Ground Zero for AVM-related eagle deaths. Other options included mechanical harvest and periodic drawdowns.
Of course, anglers are concerned that carp will eat not only invasive hydrilla, but beneficial native vegetation as well. "What about the loss of fish habitat and the potential damage to the bass fishery and economic impact it has on the region?" said Gene Gilliland, National Conservation Director for B.A.S.S.
Public comment for the plan opened in late April, with public meetings scheduled for May in both Georgia and South Carolina.
AVM was first documented in 1994 at Arkansas' DeGray Lake. Since then, it has been the prime suspect in the death of hundreds of eagles, as well as thousands of geese, ducks, coots, and other birds. It's been confirmed at hydrilla-infested fisheries from Texas to the Carolinas.
“In places where dead eagles are found, invasive aquatic vegetation --- primarily hydrilla --- and the blue-green alga are always present,” said Susan Wilde at the University of Georgia, adding that the number of deaths likely is much higher than can be confirmed because scavenging animals eat the carcasses before they can be checked for the disease that seems to affect only birds.