COUTTS, Alberta – At an inspection station here on the border with Montana, a black dog in an orange vest briskly scoured the hull of a motorboat, his nose twitching as he investigated every crevice.
Suddenly he found the scent: a quagga mussel. Wicket sat and looked expectantly at his handler.
“Good dog,” said Aimee Hurt, who trained Wicket and is with a group called Working Dogs for Conversion. She tossed a red rubber ball on a rope to him, which he attacked with gusto. “He’s not just a seeker,” of mussels, she said. “He’s a destroyer because if he could, he’d chomp them.”
Exercises like these are fun for Wicket, but they are deadly serious to his handlers. Montana, Wyoming, Washington, Oregon and Idaho are the only states in the West still free of invasive quagga and zebra mussels. State officials want desperately to keep the mussels out of blue-ribbon trout streams and pristine mountain lakes.
Boat inspections are an important part of the effort. Along major highways in the Northwest, bright orange signs direct all travelers towing boats to pull over for a mandatory search for the two invaders, thumbnail-size creatures that have wreaked damage across the continent. Roving crews also travel to fishing derbies to search out mussels. National parks such as Yellowstone have their own inspection efforts.
Out of 10,000 boats inspected in Alberta this year, just nine have been found to have mussels affixed to their hulls. But even that is too many when just a couple could start a population surge.
“It’s an excellent effort,” Robert McMahon, emeritus professor of biology at the University of Texas, Arlington, and an expert on invasive mussels, said of the searches. But if the mussels evade detection, he added, “in three or four years, they take off and you’ll get massive populations. And they would greatly change the ecology.”
These search efforts are expensive for sparsely populated Western states, and surveillance will be needed for the foreseeable future. But the price of a mussel invasion would be far greater.
Invasive mussels cost the national economy at least $1 billion a year, though the real figure is likely much higher, McMahon said. In Idaho, officials estimate that turning back an explosion of zebra and quagga mussels could cost $100 million a year.
In the 1980s, a freighter from Europe discharged ballast water into Lake Erie, and with it, some mussels. From that humble start, the invaders colonized the Great Lakes and spread across the country on towed boats.
The quagga has already made its way into the West. California has battled its spread from the southern part of the state, largely successfully, with an ad campaign – “Don’t Move a Mussel” – that urges people to clean, drain and dry their boats.
Mussels are successful in large part because they spread by expelling clouds of wispy veligers – larvae, invisible to the naked eye, that float in a river current for weeks and perhaps hundreds of miles before attaching to rocks or pipes. With calcium in the water, they build their shells and grow into adults.
While mussels don’t thrive in cold streams, their numbers explode in lakes and large, slow-moving rivers. In the Great Lakes, multitudes of these filter feeders consume so much algae that the water has become crystal clear in places.
“That means less food for small organisms, small fish and then large fish,” McMahon said. More light is reaching the lake bottoms, too, increasing plant growth. The decay of these plants contributes to the increases in botulism, which has killed large numbers of fish and birds.
Tom Boos, head of the aquatic invasive program at the Montana Department of Fish, Wildlife and Parks, lived on a lake in Wisconsin when the mussels moved in, soon carpeting the lake bottom. “You couldn’t go into the water without shoes on because your feet would get cut up” on the sharp shells, he said.
Mussels also clog irrigation pipes and water intakes, and once established are impossible to permanently eradicate. That’s why surveillance has become so important.
If a mussel is found on a boat, it can mean quarantine, a meticulous search and decontamination with hot water, which for a large boat can take a full day. Some commercial boat haulers know they can sidestep mandatory inspections by traveling at night.
Enlisting public support is part of the program, and inspectors do their best to speed boaters on their way. A sign at the inspection points describes “what we’re looking for,” followed by a picture of a mussel. Below that is “what we’re not looking for,” followed by pictures of marijuana, a handgun and alcohol.
Beyond the inspections, biologists are testing lakes and rivers for mussel DNA. If it’s found, “we have a rapid response team in place,” said Cindy Sawchuk, who heads efforts to manage aquatic invasive species for the province of Alberta.
The goal? Keep the mussels at bay until a successful mussel-killer can be developed. “Every year we keep them out, new progress is being made,” she said.