TPWD Continues To Fight Invasive Plants, Gears Up
for Zebra Mussels
In the ongoing battle biologists and managers face against
invasive species that impact America’s wild places, we hear word of
various efforts and campaigns. Getting the public on board with
prevention is a huge key. The following report, from Texas, makes
Austin, TX – 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
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