Results of a stakeholder survey about hydrilla at Thurmond Lake, and the possible use of grass carp to control it, should be available sometime in May.
“We have received over 40 percent of the surveys back so far, and this is actually quite good for a mail survey,” said Susan Wilde, an assistant professor at University of Georgia’s Warnell School of Forestry, who is managing the survey.
Questionnaires were sent in February to about 8,000 lake stakeholders – including landowners, dock permit holders and hunting/fishing licensees – as part of an effort to gauge opinions about aquatic weed control and its link to bald eagle mortality.
Hydrilla was discovered in the reservoir in 1995 and has since expanded to almost 5,000 acres, including about 640 miles of shoreline.
Although it provides cover and shade for fish, it also harbors a microscopic algae bloom that forms a neurotoxin that is fatal to bald eagles that nest along the lake’s shorelines.
The condition, known as avian vacuolar myelinopathy, or AVM, creates brain lesions that infect small waterfowl known as coots, which are a preferred food of eagles.
Biologists have documented at least 60 eagle deaths at Thurmond Lake alone, including a case this past winter in which a female eagle was found dead, still sitting in her treetop nest.
The main solution under study involves introducing sterile grass carp into the lake, in hopes that the fish will eat enough hydrilla to stop its spread and reduce eagle mortality.
Officials in South Carolina seem to favor the idea, while Georgia authorities have voiced concerns that the carp would also consume native vegetation in the lake, further altering its environment.
The Army Corps of Engineers, meanwhile, wants to get as much data as possible.
“We hope to have a preliminary summary of the results by mid-May,” Wilde said. “I was just glad to see that people took to time not only to complete the survey, but also to add comments for consideration on management plans.”
The next step, she said, will be to schedule informational public meetings.
“The Corps of Engineers needs to find out what people already know and have opinions on concerning hydrilla management,” she said. “They also want to make sure that everyone become informed on all aspects (ecological, economic, regulatory) that need to be considered when developing a management plan.”