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A load of carp


Fear the Asian carp. The fish jump several feet into the air. And they are big—up to 80 pounds. They’ll slap a fisherman in the face with their tails, and leave him with a black eye…if he’s lucky. They’ve been known to break jaws.

But it isn’t for their man-slapping prowess that Great Lakes ecologists fear the Asian carp. They are more worried that the fish will out-compete native fish and destroy economies based on commercial and recreational fishing. (No one much likes the taste of the Asian carp in the United States, except this guy.)

In their fervor to stop them, US government scientists have been using cutting-edge techniques to detect the carp. In fact, one technique—the detection of the fish by “environmental DNA”—hadn’t even been published in the peer-reviewed literature.

Environmental DNA detection works something like amniocentesis. When a pregnant woman gets an amnio, doctors look for fetal DNA that has sloughed off the fetus and is floating around in the fluid inside the womb. Here, scientists look for DNA sloughed off of carp floating around in the fluid of Chicago’s canals, and in nearby rivers and lakes.

When government scientists using the unpublished environmental DNA method said that carp had made it to Lake Michigan, past electrified barriers set up to stop them, the results were questioned. According to Lindsay Chadderton, Aquatic Invasive Species Director at the Great Lakes Project of The Nature Conservancy, among the most skeptical were those shippers and barge operators who stand to lose money if locks are closed between the lake and the Mississippi River–where the carp is rampant.

Now the peer-reviewed paper has arrived in Conservation Letters.

However, the paper may not be the end of the matter. The Associated Press quotes a lawyer for lock-closure opponents as saying that “Just because the data is published in a peer-reviewed journal doesn’t make it gospel.”

Chadderton is one of the people behind the technique, and he says he doesn’t mind the questioning. “It is fair and appropriate that they would be questioning the validity of the science, because there is so much at stake,” he says. But when introduced species are threatening native ecosystems, he says, “there is an urgency. If we waited until the work was published, we would be too late.”

Chadderton says that he previously worked on an algae species introduced to New Zealand with the appealing moniker of “rock snot,” using similar techniques. “We used the tool well before it was published,” he says.

Perhaps his team’s use of the environmental DNA method can be equated to emergency use of unapproved drugs.

Check out this CBS news report for film of the fish jumping. Yowza.

Photo Credit: Department of Fisheries and Allied Aquacultures, Auburn University, Alabama, USA.


  1. Report this comment

    arvind mishra said:

    Here Ganges in India is badly infested with Tilapia and common carp both of exotic origin and their containment is an open challenge as its very difficult to eradicate these creatures completely from the vastness of aquatic domain/habitat. And they are prolific breeders too !

    THhe environmental DNA TECHNIQUE what i apprehend may be just a placebo trick!

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