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Whatever their route into the state, their potential for spread and damage is unsettling. Grass carp are extremely mobile, fecund, and voracious. Biologists have documented them migrating 1,000 miles in one season. Like zebra and quagga mussels, they can produce millions of eggs in a year. And they're pigs. They can increase in size by 45 percent in one month. The intestine of an adult grass carp is two and a half times the size of its body.
"The grass carp eats all the vegetation in a system," said Ryce. "So in terms of habitat, they are very destructive...You can end up with a sort of pea green soup of algae left over."
Grass carp only process about half of what they eat, however. The rest is expelled as feces, which can contribute to toxic algal blooms. After the introduction of grass carp into Devil's Lake, in Oregon, toxic algal blooms linked to the fish resulted in a "Red Level" alert in 2009 in which "contact with the water by people and pets" was not advised.
Asian carp and VHS are scary, but the poster creatures for an aquatic invasive species apocalypse are the zebra and quagga mussels. At the Crown Conference, discussion of invasive mussels focused on Flathead Lake, both because of the lake's susceptibility to an infestation and because the lake–the largest natural freshwater lake in the American West, and one of the cleanest large lakes in the world–is an ecological and economic keystone of western Montana.
Lakes with lots of calcium are vulnerable to an invasion because mussels need calcium for their shells. Chris Downs, a fisheries biologist in charge of Glacier National Park's aquatic resources, showed that most of the park's lakes had 15 to 20 milligrams of calcium per liter of water. That's a moderate level for mussels, but not necessarily prohibitive. According to Bonnie Ellis, Flathead Lake's calcium level is about 25 to 35 milligrams per liter—which probably makes it good real estate for zebra and quagga mussels. "Zebra and quagga mussels would definitely alter the entire food web," she said. "Every square meter, if it was loaded with mussels, would be filtering the zooplankton and phytoplankton out of the water column at the rate of 100,000 liters per day. So they're removing food for the young fish. Not all fish eat the plankton, but many of the juvenile fish do."
Such dire predictions are born out by research elsewhere. In the Hudson River, for example, biologists found that mussels reduced phytoplankton abundance by 85 percent. The removal of such large quantities of food would dramatically affect any fish that feed on plankton. That would include many native fishes such as the pygmy whitefish and northern pike minnow, and also the lake whitefish, a popular sport fish. The severe competition for plankton would also reduce Mysis numbers, which in turn could cause the lake trout fishery to collapse.
"Basically almost all fish would decline except maybe those that feed in the littoral zone," the area close to shore, said Ellis. "So we might get a lot more suckers, mountain whitefish, pike, bass, and black crappie—meaning more shallow-water angling opportunities for non-native fish."
More beach fishing then?
"The shoreline experience will be really pretty bad," she said. "There will be bacterial mats, green algal mats, toxic algal blooms, and rough, sharp mussel shells."
A mussel invasion in Flathead Lake could also easily spread into the Flathead River. Rhizomes of flowering rush have been steadily dispersing downstream from Flathead Lake since 1964 and have now reached Lake Pend Oreille, in Idaho. Zebra and quagga mussel larvae can likewise float free in the water. It's likely that the downstream drift of these larvae from Lake Mead, for example, is responsible for mussel invasions at several other spots on the Colorado River. This all makes protecting the Crown of the Continent Ecosystem from invasive species even more important. "We have the triple divide here," said Ryce, referring to the point in Glacier National Park where drainages flowing to the Pacific, Atlantic, and Arctic Oceans converge. "And all this crap flows downstream."
Even more than the ecological effects, it's the physical presence of invasive mussels–the coating and the clogging–that worries some people. "Mussels are probably different from the other aquatic invasive species because they have that ability to impact more than the ecosystem," said Ryce.
At Parker Dam on the Colorado River, for example, mussels have fouled the dam's spillway, its generator seals, and its domestic water lines. In the East, attempts at mussel control give a sense of what long-term attempts can cost. Ontario's hydropower utility has spent between 15 and 18 million dollars retrofitting its power plants after mussels encrusted them. Between 1993 and 1999, invasive mussels cost the entire North American power industry an estimated $3.1 billion. The broad impact on communities, businesses, and industries was estimated at more than $5 billion.
Downstream from Flathead Lake is some expensive water-related infrastructure. Directly below the lake is Kerr Dam and the Flathead Irrigation Project, and beyond the Flathead Valley there are dozens of other dams, irrigation projects, and municipal water systems, all the way down the Columbia River to the Pacific Ocean.
Make sure the eggs are killed
Montana Representative Verdell Jackson is something of an aquatic invasive species crusader. In 2009, he sponsored the state's first Aquatic Invasive Species (AIS) Act. This year, he's introduced a revision to the 2009 AIS Act. Not otherwise known for supporting environmental issues, Jackson has pushed hard for better funding and policy for invasive species. So far, he's had success. His new bill passed the state senate by a landslide and passed a first hearing in the state house more narrowly. Still, even if Jackson's bill is signed into law, Montana will lag behind many other western states in terms of funding and capacity to deal with aquatic invasive species.
Since 2002, Montana has had an aquatic invasive species plan, which includes coordination between agencies and education. The plan received federal approval and funding that was matched by state funds and bolstered by various grants. Jackson's 2009 bill secured more funding to combat aquatic invasive species and gave more power to agencies to regulate boating and recreation activities that could spread them. It also resulted in a large education and outreach campaign that included signs, radio spots, and billboards instructing boaters to inspect, clean, and dry their boats after use.
Jackson's new bill would extend funding and strengthen agencies' ability to regulate activities that could spread invasive species. "This special program is setting up check stations around the perimeter of Montana, around the border, and on the roads especially that come in from other states that are infected," he explains. "Last time these were voluntary check stations and this time they are going to be mandatory check stations...When anything is found [on a boat], inspectors would use the power washer to clean it off. If it's a big boat, and we can't adequately clean it, then it will be impounded. In fact, probably if it has a live mussel on it, it will be impounded because we want to make sure the eggs are killed."
Erik Hanson helped write Oregon's invasive species act, which served as a template for Montana's 2009 AIS Act. He supports Jackson's revision, with a qualification. While the bill allows for mandatory inspections and quarantine, it requires agencies to declare an invasive species management zone first. "Nobody in the state has that authority now unless they declare a statewide management area," says Hanson. "That needs to happen."