The Science of Locating Carp

Transcript

Some Asian Carp are known for jumping out of the water -- the whopping fish smack boaters. But Researcher David Lodge says it's not always that easy to find them in the water.
When he started working with the U.S. Army Corp of Engineers there wasnít a good way to find Carp in the water -- to see if they were getting past the electric fence built to stop them:

LODGE: ONE OF THE DIFFICULTIES IN MANAGING THE RISK OF INVASION THROUGH THE CANAL WAS THE DIFFICULTY OF LOCATING WHERE SOME OF THE POTENTIALLY HARMFUL SPECIES WERE, INCLUDING THE SILVER AND BIGHEAD CARPS. [:16]

So Lodge adapted a method of collecting whatís called Environmental DNA to see if Carp were in the water beyond the electric fence. Lodgeís findings are the backbone of the lawsuit argued by Pennsylvania and the four other states that want to close the Chicago locks.

He says collecting environmental DNA is similar to forensic science, except instead of collecting fingerprints and cigarette butts, theyíre taking water samples:

LODGE: WEíRE DOING THE SAME THING IN THE CHICAGO CANAL ANSWERING REALLY A CRUDER QUESTION. NOT WHETHER JOE OR JANE CARP IS THERE, BUT RATHER WHETHER ANY SILVER CARP OR ANY BIGHEAD CARP IS PRESENT. [:18]

Lodgeís team has been collecting thousands of water samples around the Chicago waterways in Lake Michigan. They filter the water and capture small bits of tissue. They extract DNA from that tissue for any organisms present. And from that, Lodge says, they can pick out the environmental DNA -- called eDNA - specific to Silver and Bighead Carp.
He says theyíve found eDNA of both types of Asian Carp at and above the electric fence line:

LODGE: I THINK BY FAR THE MOST PLAUSIBLE EXPLANATION FOR THE EDNA RESULTS THAT WE FOUND IS THAT THERE ARE BOTH BIGHEAD AND SILVER CARP IN THE CANAL ABOVE THE ELECTRIC BARRIER OR AT LEAST THAT THE FISH HAVE BEEN THERE WHEN WE DETECTED DNA. [:19]

On the final day of testimony in the Carp lawsuit, U.S. District Judge Robert Dow focused on the reliability of Lodgeís science.

David Rieser is among those doesnít think Lodgeís evidence holds water. Rieser is an attorney with the coalition of business and agricultural groups that want to keep the Locks open.

RIESER: WE DONíT HAVE HIS DATA. OTHER THAN LITTLE POINTS ON A MAP WHERE HE SAID HE HAD POSITIVE FINDINGS WEíVE GOT NO DATA OF THOUSANDS OF SOME ODD SAMPLES THAT THEY TOOK. OR ANY INFORMATION ON THE QUALITY CONTROL PROCEDURES THAT HE WAS SUPPOSED TO HAVE USED. [:19]

This past May, the U.S. Army Corps of Engineers spent 1.5 million dollars to poison the Calumet River, in the northernmost Canal Lock, just below the entry to Lake Michigan. Rieser says they wanted to see if any Asian Carp had advanced that far into the Chicago waterways. They didnít find any Carp.

RIESER: THROUGHOUT THE SAMPLING THEY KILLED AND OBTAINED THOUSANDS AND THOUSANDS OF FISH AND NOT ONE ASIAN CARP. SO THE SAMPLING WASNíT REALLY SUPPORTING THE EDNA INFORMATION. [:12]

Rieser says a decision to close the locks would have a devastating impact on the regionís economy, so it must be based on sound science. But he says the poisoning showed that the environmental DNA testing is not verifiable.

RIESER: BECAUSE WE DIDNíT HAVE ANY DATA THERE IS NO ABILITY TO SAY THAT THE EDNA REPRESENTED THE BEST SCIENCE POSSIBLE, AND IT JUST LACKED ANY KIND OF VERFICATION OF THE SORT THAT YOU REALLY NEED TO MAKE A DECISION OF THIS SORT. [:15]

But the researchers doing the Environmental DNA testing testified that they told the Army Corps not to poison the Canal Lock last May. David Lodge says his own EDNA testing showed little chance of finding Asian Carp in the northernmost Lock at that time.

In addition, other Great Lakes researchers say the team testing for Carp EDNA has made much of its data available, and some say it is proving to be more reliable than other, more traditional methods of testing for fish. But the question still remains for Judge Dow: even if Carp enter the Great Lakes, will their populations really take hold -- and do the billions of dollars in ecological and financial damage feared by those who want to close the Locks?
Attorneys expect his decision before the end of the year.