Many plants and animals may cause a nuisance to boaters and other recreational users, but invasive species actually impact the environment and threaten native species, he explained.
Invasive species typically have no natural predators and reproduce rapidly once established in a river, lake or pond. They will typically out-compete native species for food and often produce toxins that are deadly to the native species.
Boats provide a common form of transportation for invasives, but they also move into new areas through gardening — the sale of purple loosestrife, for example — and when set free from home aquariums or released through illegal stocking, Malchoff said.
“Sometimes it’s intentional; sometimes it’s unintentional,” he said. “Releasing small bait in New York and Vermont is illegal, but it still goes on.”
NUMBER OF SPECIES
Lake Champlain is currently home to 49 exotic species, including such invasives as zebra mussels, water chestnuts and Eurasian milfoil.
By contrast, more than 180 exotic species can be found in the Great Lakes, 87 in the St. Lawrence River and 91 in Hudson River — all water bodies that have physical connections with Lake Champlain.
“We’re relatively low in comparison because there’s not as much through traffic (in Lake Champlain),” Malchoff said, referring to the ocean vessels that enter those other water bodies.
“We’re trying to maximize that to our advantage” in keeping new species from entering the lake basin.
ON THE LOOKOUT
Malchoff reviewed several lesser-known species that have found their way into Lake Champlain, including white perch, rudd and tench, which are fish species that have already impacted local fish populations.
The Asian clam is an invasive species that surrounds Lake Champlain but has not yet been identified in the lake. Officials are asking the public to keep an eye on the mollusk, which looks more like a fresh-water clam than the zebra mussel.