AUSTIN, Texas — The Texas Parks and Wildlife Department (TPWD) reports a new mussel specie that has been detected for the first time in Texas.
According to a press release from the TPWD, Quagga mussels were discovered by National Park Service (NPS) staff at the International Amistad Reservoir in the Rio Grande basin along the Texas-Mexico border near Del Rio.
In addition to being the first detection of quagga mussels in Texas waters, this is also the first finding of any invasive mussel species in the Rio Grande basin. A close relative of the quagga mussel is the zebra mussel which was first introduced in Lake Texoma in 2009 has already invaded 33 Texas lakes across six river basins.
“This detection of invasive quagga mussels is a very unfortunate first for Texas,” said Monica McGarrity, TPWD Senior Scientist for Aquatic Invasive Species. “Quagga mussels can inhabit greater depths and are also able to settle on soft substrates like mud or sand in addition to hard surfaces like rock or infrastructure—unlike zebra mussels—meaning they can colonize more of the lake.”
The NPS staff monitor Amistad Reservoir for early detection of invasive mussels using sampling for plankton (microscopic organisms) to detect their larvae and conducts settlement and shoreline sampling to survey for juveniles and adults. In June 2021, a single quagga mussel larva was detected and confirmed by DNA testing at Diablo East. In May, August, and September, single quagga mussel larvae were detected at a second site, Rough Canyon.
“Quagga mussels are very prolific and can form larger populations that can have greater effects on the lake ecosystem overall, especially in deep lakes,” added McGarrity. “Even the lakes that already have zebra mussels are at risk of having quagga mussels introduced and monitoring of these lakes for signs of quagga mussels will be necessary.
The NPS staff have been actively monitoring Amistad Reservoir for zebra and quagga mussels since 2014. Early detection monitoring can assist in preventing spread to other water bodies as well as providing an early warning for mitigating impacts on infrastructure for facilities using raw surface water. Currently, NPS employees conduct monthly inspections from docks and structures at several sites on the reservoir.
Since July 2021, NPS staff have also conducted multiple shoreline surveys using mussel detection dogs. To date, the NPS has not detected juvenile or adult mussels that might indicate population establishment. NPS staff will continue monitoring for quagga mussel larvae as well as juvenile and adult mussels. Any future population establishment will be explored as potential opportunities for containment should a full infestation develop.
TPWD has stated the reservoir as “positive” for quagga mussels. Positive status indicates mussel larvae have been repeatedly detected, but no juveniles or adults have been found and there is not yet evidence of a fully established population. The detection of quagga mussel larvae underscores the critical need for lake users to follow TPWD’s prevention guidelines when visiting Amistad Reservoir.
In addition to reducing the risk of further introductions of quagga mussels that could contribute to establishment, there is a need to prevent the introduction of zebra mussels and other aquatic invasive species. The NPS and TPWD encourage all visitors to follow the “Clean, Drain, and Dry” actions for watercraft and equipment before entering and after leaving the lake.
Because quagga mussels are present in other areas of the U.S. in the Great Lakes region and some western states, there was already a risk that boats could transport them to Texas lakes. However, their introduction into a Texas reservoir significantly increases the risk they could be transported by boats and introduced into other waterbodies in the state. The TPWD and partners will continue monitoring at-risk waterbodies for early detection of both zebra and quagga mussels. Prevention signage will also be updated at Amistad Reservoir.
Quagga mussels, in the same manner as zebra mussels, are often transported to new lakes by boats. Therefore, TPWD and partners will continue public awareness outreach efforts to encourage boaters to take steps to clean, drain, and dry their boats which will help with decontaminating boats with attached mussels to prevent the spread of these invasive species.
"Unfortunately, invasive mussels have now spread to 34 Texas lakes, with 28 fully infested, but there are far more lakes that still haven’t been invaded and are at risk,” said Brian Van Zee, TPWD Inland Fisheries Regional Director. “Each boater taking the necessary actions to clean and drain their boat before leaving the lake and allowing compartments and gear to dry completely when they get home can make a big difference in protecting our Texas lakes.”
Invasive mussels are most often transported on or in boats, boaters play a critical role in preventing their spread to new lakes. Invasive mussels attach to boats and anything left in the water such as anchors, and can survive for days out of water and often hiding in crevices where they may not be seen easily. Their larvae are microscopic and invisible to the naked eye and can be unknowingly transported in residual water in boats.
Boaters are urged to clean, drain, and dry their boats and gear before traveling from lake to lake. Remove plants, mud, and debris, drain all water from the boat and gear, and then open compartments once you get home and allow everything to dry completely for at least a week if possible.
If you have stored your boat in the water at a lake with invasive mussels or purchased a boat that has been stored on one of these lakes, it is likely infested with invasive mussels and poses an extremely high risk for moving these invasive species to a new lake. Before moving your boat that has been stored on a waterbody known to have either zebra or quagga mussels or if you purchase a boat from out-of-state and have questions, call TPWD at (512) 389-4848 for guidance on decontamination.
Other equipment stored in infested lakes such as barges, docks, hoists, and pumps etc. are also potential vectors for spreading invasive species so those items also need to be fully decontaminated before transporting to another waterbody.
The transport of aquatic invasive species can result in legal trouble for boaters or transporters. Transporting prohibited invasive species in Texas is illegal and punishable with a fine of up to $500 per violation. Boaters are also required to drain all water from their vessel and onboard receptacles, including bait buckets, before leaving or approaching a body of fresh water.
Anyone who sees invasive mussels on boats, trailers or equipment being moved should immediately report the sighting to TPWD at (512) 389-4848.
