Species like zebra mussels and giant salvinia threaten not just Texas ecosystems, but economies as well. And the best way to prevent their spread is for boaters to clean, drain and dry.
Invasive species are defined as any organism introduced to an environment that overpopulates, resulting in the damage of the original wildlife. Two of the most common invasive species in Texas are zebra mussels and giant salvinia, according to the Texas Parks and Wildlife Department.
Zebra mussels are small, freshwater, shellfish that originated in the Caspian and Black Seas of Eastern Europe and Western Europe. They are now widespread in the U.S. and Europe, after likely being spread by ships unknowingly carrying them. Once they become established in a body of water, there isn’t much that can be done to remove them.
With that in mind, the Brazos River Authority’s environmental team, in cooperation with the Texas Parks and Wildlife Department, has taken an active role in the surveillance and monitoring of BRA System reservoirs for zebra mussel infestations.
Giant salvinia, or the Kariba weed, is a species of aquatic fern native to south-eastern Brazil brought to the U.S. as a part of the imported plant trade, first appearing in 1995. The weed is free floating, attaching to buoyant surface remnants. Once established, Giant salvinia can clog waterways making navigation difficult, damaging motors and discouraging fishing and recreation. It can also be deadly to swimmers as they can become entangled in the weed. The result is fewer visits to infested lakes and less commerce for local businesses.
But how are they getting around?
As zebra mussels were first brought to the U.S., boats are the major transporters of these species. These hitchhikers can survive for days in water-filled, or wet, areas of a boat, in eager anticipation of their new destination. Once these invasive species are introduced to a new territory without natural predators, they overpopulate and choke out the native species in the area, leaving lakes and rivers without the fish and other aquatic life that visitors love.
Without everyone cleaning their watercrafts these species will continue to spread throughout Texas’ lakes and rivers, damaging ecosystems and economies. Economies suffer when invasive species like zebra mussels become firmly attach themselves to hard surfaces like boats, docks or water supply intake pipes. This becomes an economic issue once these surfaces become encrusted in zebra mussels and they must be cleaned or replaced. Boaters are also impacted, if they fail to drain water from their motors, species like zebra mussels can root themselves there and clog the machinery.
“There’s no doubt that Texans love their lakes,” said John Findeisen, TPWD Brookeland Aquatic Habitat Enhancement team lead in a news release. “We also need Texans to take action to help protect their lakes. It only takes a tiny fragment of an invasive plant to create a new infestation and preventing aquatic invasive species introductions avoids costly, long-term efforts to manage these species once they infest a lake.”
These invasive species are easily spread by boats and other recreational equipment, especially since they are not always visible to the naked eye.
“Zebra mussels and quagga mussels can be attached to boats or even carried by anchors or attached to plants clinging to boats,” said Monica McGarrity, TPWD Senior Scientist for Aquatic Invasive Species Management in a news release. “Microscopic zebra mussel larvae can be transported in residual water in the boat. Taking just a few minutes to clean, drain, and dry boats can make a huge difference in our efforts to prevent further spread of this highly damaging species and harm to Texas lakes.”
There are already many lakes in Texas that have tested positive for zebra mussels, as of 2022 the list of positive lakes totals 32, with 27 being fully infested. Check this TPWD map that shows the locations of these lakes. There are currently three lakes in the Brazos River basin that are infested with zebra mussels they are, lakes Belton, Georgetown, Granger and Stillhouse Hollow. Currently, zebra mussels have not been found in the three Brazos River Authority reservoirs: Possum Kingdom Lake, Lake Granbury and Lake Limestone.
All it takes is one trip between an infested lake and a noninfected lake with an unclean watercraft to do irreversible damage.
It is necessary to clean, drain, dry anytime you take your boat or recreational equipment in or out of a body of fresh water. These invasive species can attach to more than the boat hull, they can attach to trailers, motors and even float planes. They are also found in other parts of the boat like the live wells and engine cooling water. Since there are so many places for these hitchhikers to hid it is critical to clean, drain, dry.
“The best way to prevent the spread of many destructive aquatic invasive species is to clean, drain and dry your boats and equipment – every time,” said Brian Van Zee, TPWD Inland Fisheries regional director in a news release.
To clean, drain, dry follow these steps:
Clean - Inspect your boat, trailer and gear and remove all plant material, mud and foreign objects.
• Wash, scrub using high pressure, hot tap water 140 degrees F – avoid doing this in areas with storm drains, ditches and waterways
• Inspect the watercraft, trailer and vehicle
Drain – All on-board water from the motor, livewell tank, bilge and ballast tanks
• Flush with hot tap water away from storm drains, ditches and waterways
• Leave plugs out during transport and tilt watercraft when stored to allow the bilge to both drain and dry
Dry – Proceed to dry all your watercraft equipment and all related gear completely and let air dry for five to seven days with all compartments left open
“We want to protect our waters and I know boaters and fishermen, and everyone want to keep these waters clean, but we just want you to remember that it is a requirement of state law to have your vessel clean, drained and dried,” said Kyle Lewis, project manager and program coordinator the BRA’s Lake Granbury Office during the BRA’s bimonthly Brown Bag on the Brazos presentation.
Not cleaning, draining and drying is not just potentially bad for aquatic environments, it is also against state regulations. The possession or transporting of zebra mussels is classified as a Class C misdemeanor and you could find yourself paying a $500 fine. A repeat offense could cost you up to $2,000, and /or up to 180 days in jail.
There is also a newly emerging invasive species called the quagga mussel that was detected in Lake Amistad in 2021. This mussel is like the zebra mussel, but without the signature striped markings. Quagga mussels present many of the same issues of zebra mussels. As invasive species like the quagga mussel are introduced to Texas lakes it is becoming more important for everyone to do their part by cleaning, draining and drying to prevent the destruction of Texas wildlife.
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By Ariel Wright
ariel.wright@brazos.org