Invasive mussels thwarted by Utah efforts


Thumbnail-size invaders from out of state, which could cause a handful of trouble, have yet to gain a foothold in Utah thanks to statewide efforts.

The Division of Wildlife Resources deemed the massive Utah campaign meant to prevent small quagga and zebra mussels from invading local water systems as a success, but warned that the fight is not over.

The small mussels, lacking local predators, could quickly take over local waters if they arrived.

Larry Dalton, aquatic invasive species coordinator for the DWR, said the program, which began in 2007, has the public to thank for its success.

“The reason for success is that the boaters in the state of Utah have listened,” Dalton said.

More personnel had been stationed at bodies of water checking boats and encouraging boaters to clean, drain and dry boats after each use. Such cleaning prevents mussels and other species from hitchhiking between water systems. Dalton said many boaters complied, reducing the risk of contamination from ‘suspect’ to ‘not detected.’

“We were very worried the mussel could enter into the water system,” Dalton said. “They grow by the hundreds of thousands when they get there.”

With Utah’s complex water system, the mussels could have plugged pipes causing millions of dollars in damage. Recreation areas would be unusable to the public due to the smell and the sharp edges of shells that can cut feet.The mussels also threaten native species by reallocating resources.

“Each mussel can filter a quart of water a day and steal plankton from fish,” Dalton said.

The mussels first entered the U.S. in the 1980s as hitchhikers on boats and quickly spread throughout the states.

Gene Shawcroft, assistant general manager of the Central Utah Water Conservancy District, said the mussel has already reached Colorado, California and New Mexico.

“It is much more cost effective to prevent rather than deal with them once they get here,” Shawcroft said.

Dalton said eight different waters in Utah showed evidence of quagga and zebra mussels, but after the fight against their spread, seven of the lakes and reservoirs now show no signs of the invaders.

The mussels, which are about the size of an average thumbnail, only live two to three years so water managers are confident their four-year campaign prevented an invasion.

Dennis Shiozawa, a BYU biology professor, said the efforts simply slowed down the spread of the mussels, not prevented it entirely. In Utah, the invaders do not have natural predators or parasites, so future growth is almost inevitable.

“It’s almost a losing battle,” Shiozawa said. “Eventually somebody will transport it.”

Shiozawa said biological control, by introducing natural predators, is a possible solution but also could cause a “cascading of unexpected effects.”

The new parasites and predators might negatively impact other organisms and animals if they are introduced into the environment. Laboratory tests would be needed to determine the effects of biological control.

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