September 8, 2012 at 1:00 am

Lake Erie carp evidence puzzles researchers

DNA tests raise concerns invasive fish has made way into shallowest Great Lake

Sunnie McCalla loads extracted DNA from a water sample into a 96-well plate to determine whether DNA from Asian carp are present. (U.S. Geological Service)

As they worked their way north through the Mississippi River system over the past decade, Asian carp — with their feats of eating, leaping and reproducing — made a name for themselves.

Yet it took a team of scientists wielding a new technology to literally put the invasive species on the map here in the Great Lakes region.

In 2009, researchers with the University of Notre Dame and the Nature Conservancy used environmental DNA, or eDNA, testing to detect traces of Asian carp much closer to Lake Michigan than previously believed.

That sparked mayhem, including calls for closing the waterways connecting the Mississippi River and the Great Lakes, demands for new electric barriers, lawsuits between the states and the federal government, and rising panic over what might happen if Asian carp were allowed to reach the lakes.

Similar eDNA results have now turned up in Lake Erie this summer for the first time.

U.S. Fish and Wildlife Service researchers weren't specifically looking for carp when those samples were taken a year ago as part of a broader investigation into invasive species.

But genetic material linked to the silver carp species was identified in samples collected from the Sandusky River and Sandusky Bay.

The reaction, however, has been far different this time: no closures and no lawsuits.

The reason may have to do with a different perception of what eDNA results mean. The testing has not yet led to the discovery of any live fish in the Great Lakes region. People are no longer sure what a positive eDNA test means.

"We recognize that this is an indication of the presence of eDNA in the water," said Rich Carter, executive administrator of fish management and research for the Ohio Department of Natural Resources.

"There is an uncertainty about the source of that eDNA. The potential sources could include live fish or some other source that we don't know at this point."

The continued absence of live Asian carp in eDNA testing areas has scientists looking at what else might account for the findings. Possible transfer routes of the genetic material include bird feces, fish carcasses or genetic material transported by barges, or sewage overflows that contain the material after it has been ingested by residents who consider the carp a delicacy.

The Michigan Department of Natural Resources announced this week it would begin testing water in bait shops to see if that is the possible point of entry for the eDNA in Lake Erie.

State officials will also be on the lookout for Asian carp that may have been included in other shipments to the stores.

"At this point, we're not saying there is definitely not live fish in those areas," said Kelly Baerwaldt, eDNA program manager for the U.S. Army Corps of Engineers. "We are saying: Let's look at all of the other things it could be.

"We're starting to realize there are lots of ways this material can move through a system other than being attached to a live fish."

'We're very concerned'

Along Lake Erie, those who make their living off the water are concerned about the future.

Should Asian carp establish a reproducing population in the Great Lakes, their voracious appetite and ability to reproduce could push out many of the native species and hurt the region's $7 billion sport fishing industry.

In addition, the carp's propensity to leap from the water when startled by passing boat motors poses a threat to recreational activities.

Many residents believe Asian carp could reach all of the Great Lakes once they gain a foothold.

Bob Witt, who is based in Port Clinton, Ohio, along Lake Erie and has been in the charter fishing business for 30 years, said the findings could represent a major threat.

"My understanding is (the eDNA results) could mean a number of things," said Witt, 50. "That the carp are here, that they're not here. We're very concerned. The one thing that's for sure is no good can come from this."

Late last year, the Asian Carp Regional Coordinating Committee — a group of federal, state and local agencies funded by the Great Lakes Restoration Initiative — decided to try to get a better handle on what the new testing technology means with a two-year study.

Questions about eDNA inevitably arise when samples show signs of Asian carp, but no live fish are found.

After the analysis of the Lake Erie samples, Ohio officials followed up with electro-fishing and netting in and around Sandusky Bay, but did not find any live carp. It's similar to the pattern that took place in Lake Michigan starting in 2009.

To many, the eDNA found in the Chicago Sanitary and Ship Canal, then in the Chicago River, and finally in Lake Michigan meant Asian carp were already there.

Researchers and government officials always couched their announcements with warnings against that kind of thinking, but many opined that the test results indicated the fish had infiltrated those locations, just not in large numbers.

In three years since the first samples were taken in the waterways south of Chicago and Lake Michigan, only one fish has ever been found. A single bighead carp was pulled from Lake Calumet in June 2010.

Constant testing takes place at hotspots such as the Chicago locks, the North Shore Channel and the O'Brien Lock at Lake Calumet. Any time eDNA samples for Asian carp come up positive three times in a row, crews move in with electro-fishing to search for live fish.

The Army Corps' Baerwaldt recalled the domino effect that the first set of tests produced in the Chicago area three years ago.

"At first, we thought there were live fish," she said. "We went in and applied rotenone (a pesticide) and closed sections of the waterways leading to Lake Michigan."

Few options for Lake Erie

Instead of starting off with a flurry of similar emergency actions, Lake Erie appears to be skipping that step. The announcement that Asian carp eDNA had been found in water samples has been greeted with plans for more testing.

Unlike Lake Michigan, Erie presents few clear-cut options for preventive action. USACE officials have identified a trio of potential routes for the fish to reach Lake Erie. Those include two central Ohio locations: Killbuck Creek and the Oho-Erie Canal area — where carp could possibly move from the Ohio River system to a pair of rivers that reach Lake Erie.

The most worrisome area is Eagle Marsh, near Fort Wayne, Ind. In this wetlands area, the Wabash and Maumee rivers are near enough that Asian carp could move through flood waters into the Maumee, which leads to Lake Erie.

In October 2010, Indiana officials had a 1,177-foot chain-link fence built between the two waterways to keep carp from moving from one river to the other.

And that will be one more problem residents like Joe Weiss don't need.

In recent years, Weiss has watched as the economy helped reduce his Monroe-based fishing charter business from three boats to two. Throw Asian carp into the Lake Erie mix:

"If they get in here, it's not going to be pretty," he said. "It's just going to be a mess."

jlynch@detnews.com

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