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TPWD News,, 512-389-8030

April 18, 2011

Texas Giant Salvinia Effort Reaches Boaters, Raises Awareness

TPWD Continues To Fight Invasive Plants, Gears Up for Zebra Mussels

AUSTIN – Survey results show last year’s giant salvinia public awareness campaign by the Texas Parks and Wildlife Department reached more than half of boaters living within 60 miles of four East Texas lakes targeted in the effort and that 96 percent of those boaters said they were “more likely to clean their boat, trailer or gear as a result of seeing information or advertising.”

Giant salvinia is usually spread unknowingly by people moving their boats from lake to lake. The plant “hitches a ride” on boats, motors and trailers. The invasive plant was first discovered in Texas in a small pond near Houston in 1998. It has been reported in 17 Texas lakes, including some of the state’s most popular recreational water bodies: Toledo Bend, Sam Rayburn, Caddo Lake, Sheldon Lake, Lake Texana and Lake Conroe.

Last spring’s “Hello Giant Salvinia, Goodbye Texas Lakes” campaign media buy generated more than 28.5 million audience impressions amongst boaters, anglers and the general public. Efforts included floating messages on buoys near key boat ramps, fish measuring rulers with campaign messages, online web banner ads, social media, gasoline “pump toppers” and billboard ads near key lakes, and even an amusing TV ad featuring “salvinia monster” trying hitch a ride with a hapless boater.

Given the success of the salvinia awareness effort, the department is now considering a similar initiative for zebra mussels, another serious invasive threat that is not yet widespread in Texas. The non-native mussels multiply rapidly and attach themselves to boats, piers, cables and other objects. Zebra mussels can block water treatment plant intakes and pipes, as well as cause declines in fish populations, native mussels, and birds.

“We are actively seeking partners to help make a zebra mussel awareness campaign a reality,” said Carter Smith, TPWD executive director. “Although currently only established in Lake Texoma in Texas, this exotic invader is on the doorstep of the Metroplex region and could eventually spread throughout the Trinity River system toward Houston.”

Meanwhile there has been some good news in Texas regarding giant salvinia. Herbicide applications by TPWD and its partners, plus two cold winters that froze plants back, and a rainy high water year in 2010 that killed or flushed out invasive plants, have caused a decline in Texas lake surface acres infested by exotic plants.

On Caddo Lake, for example, giant salvinia increased from less than 100 acres in 2007 to almost 1,100 acres in 2008, reaching more than 3,000 acres by fall 2009.  Fortunately, giant salvinia coverage on Caddo dropped to approximately 600 acres in spring 2010. Similarly, invasive water hyacinth on Caddo was estimated at 1,354 acres in fall 2008, was near 2,000 acres in 2009, but decreased to 720 acres by 2010.

However, experts expect that eventually the exotic plants will come back and once again pose greater threats, possibly this summer when warmer weather creates ideal growing conditions.

While TPWD and others continue public awareness efforts, mechanical or physical controls and the application of EPA-approved herbicides to control invasive plants, potentially promising bio-control efforts are also underway.

That includes plans to raise large numbers of salvinia weevils to eat the plant on Caddo Lake and other affected Texas waters. This bio-control agent from South America has helped reduce salvinia populations on several continents. Through a U.S. Fish and Wildlife Service grant, salvinia weevil rearing facilities have been constructed in Karnack and Jasper to mass-produce the insects for ultimate release.

Funds made available through U.S. Sen. Kay Bailey Hutchison made possible the newly formed Center for Invasive Species Eradication to be managed by the Texas AgriLife Extension Service.  The center is a partnership between AgriLife, USFWS, TPWD, the Caddo Lake Institute, Louisiana Department of Wildlife and Fisheries, and Louisiana State University, among others. The facilities managed through this partnership should help increase the numbers of insects needed to control salvinia populations in Texas and Louisiana.

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TH 2011-04-18

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