AUSTIN – The Texas Parks and Wildlife Department (TPWD) has designated Lake Buchanan, located west of Burnet and north of Inks Lake in the Colorado River Basin, as “infested” with invasive zebra mussels. Infested status signifies that there is an established, reproducing population of zebra mussels in the lake. The designation is a result of recent sampling efforts that revealed new evidence of a reproducing population of zebra mussels in the lake.
Lower Colorado River Authority (LCRA) scientists discovered zebra mussel larvae in plankton samples taken from three sites around the lake in October. TPWD then confirmed the identity through microscopic and genetic analysis. The LCRA analyzed samples collected in November and again found zebra mussels at two of the three sites. Then in early December, crews working on a floodgate project at Buchanan Dam discovered several settled zebra mussels.
Additional surveys for settled mussels were conducted by LCRA on the shorelines while Lake Buchanan Conservation Corporation volunteers also checked their installed settlement samplers. Zebra mussels were not detected at any of these locations. Although few settled mussels were found at the dam, the presence of both larvae and adults and detection of young larvae in samples taken a month apart indicate that a reproducing population is present in the lake.
“At this time, the results indicate that the population in the lake appears to be small,” says Monica McGarrity, TPWD Senior Scientist for Aquatic Invasive Species Management. “However, as we have seen in other Texas lakes, the population is likely to increase rapidly over the next few years.”
To date, zebra mussels have not been found in nearby Inks Lake, but due to its location immediately downstream from Lake Buchanan, it is likely to become infested in the near future. Shoreline surveys at Inks Lake conducted by LCRA and TPWD, as well as checks of settlement samplers by Boy Scout citizen science partners did not locate any settled mussels. Fall plankton samples were also free of zebra mussel larvae. However, zebra mussel environmental DNA was detected in fall samples from one site on the lake, which could be an early indicator of zebra mussel introduction.
TPWD is encouraging boaters and home owners on both Lake Buchanan and Inks Lake to keep an eye out for settled zebra mussels and report any suspected organisms with photos to email@example.com. Zebra mussels grow to approximately 1-1.5 inches in length and have triangular, typically striped brown/tan shells. Unlike native mussels or non-native Asian clams, zebra mussels adhere strongly to hard surfaces.
“Although zebra mussels are now found in 31 Texas lakes, there are still many other lakes in the state that they haven’t invaded. Boaters play a critical role in preventing them from spreading to new lakes. Before traveling from lake to lake, clean, drain and dry your boat and gear. Remove plants, mud and debris, drain all the water from the boat and gear, and then open up compartments once you get home and allow everything to dry completely,” advises Brian Van Zee, TPWD Inland Fisheries Regional Director.
If you have stored your boat in the water at a lake with zebra mussels, it is likely infested with zebra mussels and poses an extremely high risk for moving this invasive species to a new lake. Before moving your boat to another lake, call TPWD at (512) 389-4848 for guidance on decontamination. 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 boat and onboard receptacles, including bait buckets, before leaving or approaching a body of fresh water.
A status map showing all lakes where zebra mussels have been found in Texas is online at tpwd.texas.gov/zebramussels. For more information on how to properly clean, drain and dry boats and equipment, visit the TPWD YouTube channel for a short instructional video. TPWD and partners monitor for zebra mussels in Texas lakes, but anyone who finds them in lakes where they haven’t been found before should report them by emailing photos and location information to firstname.lastname@example.org to help identify new introductions. Anyone who spots them on boats, trailers or equipment that is being moved should immediately report the sighting to TPWD at (512) 389-4848.
To learn more about zebra mussels and other invasive species in Texas, visit tpwd.texas.gov/StopInvasives. Information for marinas and owners of boats stored in the water on lakes with zebra mussels can be found on the TPWD website.