Invasive species are 'waiting on the doorstep' of the Great Lakes, scientists say

Published: Friday, January 14, 2011
Howard Meyerson | The Grand Rapids Press

While public attention has been riveted on the Asian carp’s progress toward Lake Michigan, scientists are mapping out just what the next invasion might be and what, if anything, could be done to stop it.

A team of university and government researchers has identified 75 species that could find their way into the Great Lakes basin over time. Some of them are bad actors.

The next invasion could arrive in the murky ballast waters of ocean-going ships. It could come via the aquarium trade, sold at a pet store and later released. The next invader, experts say, could arrive in a truck selling bait, fish or water lilies for country ponds or urban water gardens. It could even arrive as live food at market.

“There are lots of other species waiting on our doorstep,” said Ed Rutherford, a research scientist with the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory in Ann Arbor.

Rutherford recently addressed a group of charter captains in Ludington about the subject. He is part of a group of scientists who did the research and is now collaborating with others from the University of Notre Dame and The Nature Conservancy to identify the species that are most likely to arrive, how they might affect the Great Lakes ecosystem, and the routes they would take to get here.

Their concern, among others, is what invading species might do to the food web in the lakes, which could harm Michigan’s native species and $7 billion fishing industry.

The scientists’ current hit list of several high-priority, if low-profile, rogue species, includes the northern snakehead, monkey goby, New Zealand mudsnail, killer shrimp, golden mussel and hydrilla.

The snakehead has gained particular attention from the scientists. Rutherford said it is a voracious predator from Asia that can grow to 33 inches in length, survive out of water, move on land and breathe air.

In 2001 it was unheard of in the U.S., but it is now established in Virginia, Maryland, Pennsylvania and New York waters, according to the U.S. Geological Survey.
The fish have also been found in California, Florida, Massachusetts, Arkansas and North Carolina.

The fish was discovered in a Maryland pond in 2002, having been stocked by a man who bought two adults in a New York market. Maryland officials that were notified about the fish drained the pond and found two adults and more than 100 young. Considered a threat to the Chesapeake Bay fishery, all were destroyed.

“I think this one is coming,” Rutherford said. “People will bring them in live for the aquarium trade. It’s also been found in live markets around Toronto.”

The snakehead poses no threat to humans, but fish biologists worry they could threaten near-shore Great Lakes sport fish populations. They could easily dominate drowned river mouths or inland lakes and ponds, experts say.

The snakehead is a prolific breeder, producing 40,000 eggs when it spawns. Young snakeheads enjoy a higher than average survival rate, Rutherford said. The adults zealously guard the young after hatching.

Experts also are concerned about a familiar aquarium plant — the hydrilla. Call it “oxygen weed,” the name under which it is often sold, said Lindsay Chadderton, a collaborator on the project and the aquatic invasive species director for The Nature Conservancy.

Chadderton called it a “well-known invasive around the world that is problematic in many countries.”

If it gets established in shallow wetlands or bays, it can choke out all other native vegetation, he said. That, in turn, can harm species that either feed on or live in the habitat that is destroyed.

Hydrilla was imported into the U.S. as part of the aquarium trade and sold to customers to keep their tanks healthy. But people eventually tire of it and dump it out in wet places, where it takes root. Or it gets moved on boats and outboard engine propellers. It has also been spread “as a contaminant” when water lilies are sold for backyard water gardens, according to Chadderton.

“This is one I want to add because we’ve recently detected a number of populations on the doorstep of the Great Lakes, Chadderton said.

Not every invasive species causes big trouble, Rutherford said. The ruffe and tubenose goby are two examples of species that arrived but didn’t flourish or cause as much trouble as was anticipated.

And ballast water isn’t the only route invasives take into the Great Lakes.

What the scientists’ research illustrates is which species are likely to arrive given their survival needs and capabilities, and the available means for their transport or spread. They are also examining loopholes or inconsistent regulations from state to state that, for example, allow people to buy a live invasive species at fish market or pet store and release it.

State fisheries officials said the research will be highly beneficial for Michigan, which invests heavily in its Great Lakes and inland fisheries.

“If we understand the pathways to stop their entry, or if they do come and we have some pre-knowledge of how to manage the situation, it will help,” said Kelly Smith, state fisheries chief with the Michigan Department of Natural Resources and Environment.

“The one that really troubles me is the snakehead. It’s scary how that thing has progressed across the U.S. I think it’s only matter of time (before it arrives) and I am not sure what we would do if it gets here.”

Smith said he has had his hands full dealing with the immediate threat of the Asian carp. Recent DNA testing found no evidence of their presence in the St. Joseph River below the dam at Berrien Springs. The St. Joe is the first Michigan stream Asian carp would encounter moving along the southern shore of Lake Michigan.

Testing was conducted for evidence of the bighead and silver carp. The work was funded by Great Lakes Restoration Initiative, part of the U.S. Environmental Protection Agency. Smith said he is waiting for test results from the Paw Paw and Galien rivers and the lower St. Joe River. The western basin of Lake Erie will be tested in the spring.

E-mail Howard Meyerson: hmeyerson@grpress.com and follow him on Twitter at twitter.com/HMeyerson

http://www.mlive.com/outdoors/index.ssf/2011/01/invasive_species_are_waiting_o.html