Another dust-up about Asian carp
Written by Southtown Star   
Sunday, 24 January 2010 06:03
Lindsay Chadderton used this perfect analogy for eDNA sampling for Asian carp around Chicago waterways: "It is like cars driving along a gravel road and throwing up a dust cloud. We are sampling the dust cloud."

The latest find in the dust cloud is not good. Word came Tuesday of silver carp eDNA found past the O'Brien Lock and out to Calumet Harbor.

"We think fish have probably got into (Lake Michigan)," he said.

The formal announcement of that find came just hours after the Supreme Court denied the injunction requested by Michigan to shut the Chicago-area locks to prevent the advance of Asian carp into the Great Lakes.

Let me backtrack. The early release of the results of eDNA sampling (before peer review) profoundly troubled me.

It felt as if the eDNA information in the fall was quickly released to rush the public to judgment - the bludgeon to justify the Great Fish Kill, the poisoning of a 6-mile stretch of the Sanitary & Ship Canal in early December so routine maintenance could be done safely on the electric fish barrier at Romeoville. For that $3 million exercise, one bighead carp was killed.

All in all, it was like another piece in the tale of the greatest boondoggle in Chicago outdoors, the electric barrier.

The effort to stop the advance of Asian carp has been botched from early on. We've had more than a decade to figure this out, and suddenly eDNA evidence of Asian carp past the electric barrier rushed the bizarre decision for the Great Fish Kill.

It was suggested I talk with Chadderton, the aquatic invasive species director of the Nature Conservancy's Great Lakes Project. He developed the technique for sampling for the presence of Asian carp DNA with TNC partners, including the University of Notre Dame and the U.S. Army Corps of Engineers.

I'm glad I did. Glad because it reassured me on the science end. Chadderton understands this is not the normal, accepted procedure.

He also noted that EPA quality control/quality assurance teams check their work.

The result of their work is not reassuring: If eDNA is found, it means "there probably was a fish present within the last 48 hours," Chadderton said. In other words, positive results signal a live fish had been through that stretch of water (a car leaving a dust cloud).

"We have complete confidence that it's showing the presence of fish," he said.

He thinks finding the plume of DNA is simply a better method for indicating the presence of Asian carp than the traditional methods of netting or electroshocking.

The process begins with the collection of 100 two-liter samples at a time, usually with multiple samples at each spot. The samples are taken back to Notre Dame, where they are filtered with a very fine glass filter within 12 hours of collection. The DNA is extracted from the filter. Species-specific markers are then used.

Chadderton said the basic techniques have been used for 20 years with ''some tweaks in the meter.''

''We would like to get to the point to (know) what it means about abundance,'' he said.

So far, they have collected samples from nearly all Chicago-area waterways with one gap of about 5 miles. If they get a positive, they usually take additional samples.

''We are increasingly discouraged about what we found,'' he said.

Yet, he believes it important to push on for three reasons: to understand what is in the lake already; to prevent more Asian carp from getting into the lake, and to prevent more from getting above the barrier.

To see where the dust settles.
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