Tuesday, Apr 16, 2013
Over the past month, park staff have found 14 adult quagga mussels attached to moored vessels and dock structures at the Wahweap Marina in Lake Powell. None of the adult mussels were close enough together to mate for successful reproduction.
Quagga mussels are an invasive species. They’ve spread rapidly over the United States over the past two decades, causing major impacts on lakes, rivers and other bodies of water.
The first four mussels were found when a local marine service business noticed the small shells on a boat that had been pulled for maintenance and then notified the National Park Service.
“We really appreciate the report of this finding since it will help in the removal of the adult mussels before they can reproduce,” said Mark Anderson, an aquatic ecologist at Glen Canyon.
The park’s dive team assessed boats, docks and cables in Wahweap Bay and found an additional ten adult mussels which were physically removed from the lake. Marina structures and vessels will continue to be monitored. The Antelope Point area was inspected beginning last December, with no mussels discovered.
Superintendent Todd Brindle remains hopeful that the monitoring results are not evidence of an established population of mussels.
“If it is an early detection, the mussels may not establish and reproduce”, said Brindle.
“It is important to note that we have not found a reproducing population,” Anderson said. “Prevention is still the most effective way to fight invasive species, so we will continue the boat inspections that are currently in place. Everyone needs to take this as a warning to continue to clean, drain, and dry your boat and equipment after every use.”
The NPS has operated a mussel prevention program at Lake Powell since 2000. Over a decade ago, scientists predicted that Lake Powell would be the first lake in the western U.S. to get mussels.
The number of high-risk boats coming to the park has increased exponentially in that time. Prior to 2007 and the discovery of mussels in the west, Lake Powell was threatened by about 50 high-risk boats per year from eastern states. In 2011 alone, that number was 17,000. 38 boats with mussels were stopped from launching in 2012, over twice the number in 2011.
The increased pressure has required the park to screen boats to determine the highest risks and focus our limited capability where it was needed most. At busy times, as few as 15% of boats may actually get inspected.
Additional monitoring information and updates are posted on the GLCA webpage at www.nps.gov/glca/.