The Louisiana Department of Wildlife and Fisheries’ (LDWF) Office of Fisheries is moving large quantities of salvinia weevils into Lake Bistineau in northwest Louisiana as part of a multi-tiered treatment effort to slow the growth of giant salvinia. Lake Bistineau covers 17,200 acres just south of Doyline and is a popular fishing spot for bass and crappie.
“The process began this month and our long-range goal is to restore normal use and aesthetics of the lake for residents and visitors,” said LDWF Secretary Robert Barham.
LDWF biologists and technicians plan to place at least 50,000 pounds of weevil-infested salvinia into the lake by the end of June. Those materials contain over one million adult weevils and between two and three million eggs and larvae. The floating colonies will be deposited into areas around the lake where salvinia has been growing for at least two years.
Fifty LDWF biologists and technicians from around the state have been involved in the effort that entails harvesting materials from a nursery pond in Lafourche Parish and transporting the weevils to Lake Bistineau. The LSU AgCenter has been raising the weevils in Gheens, La., as part of a cooperative effort between the agencies to find a method to control giant salvinia.
The weevil stocking program is one part of LDWF’s $7.9 million Aquatic Plant Control Program for fiscal year 2008-2009 to aggressively combat aquatic plants in the state’s waterways. Additional control measures planned for Lake Bistineau include the application of EPA-approved herbicides by contract applicators and LDWF employees and a lake drawdown immediately following Labor Day.
Giant salvinia, a free floating aquatic fern native to Brazil, has the potential to double in biomass every three to five days. It was discovered in Lake Bistineau in February of 2006. The lack of severe winter weather since 2001, with temperatures seldom below freezing for extended periods, has allowed the steady growth of all aquatic plants in the state.
A drawdown from July 2008 through January 2009 reduced the salvinia coverage from 4,500 acres to 850. Subsequent re-growth has increased the salvinia presence back to 4,300 acres as of the first week of June 2009. An increased weevil population on the lake is designed to significantly reduce the long-term presence of giant salvinia.