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Asian Carp eDNA: New hits point to danger in Chicago Waterways delays

Henry Henderson

Posted October 10, 2012

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Silver carp image courtesy of Michigan Sea Grant

Over and over the Asian carp debate gets dumbed down into "fish vs. barges." Usually it relates to pushback against any changes being made to the Chicago Waterways System, but also pops up in the increasingly common occurrence of eDNA tests that show genetic material of the invasive Asian carp present in the river system that transects the Chicago region. The “status quo” enthusiasts assert that the evidence of a pervasive presence of invasives in the river does not require a change for the waterways.  The excuse for “no action”  usually goes, "we don't think there are actually fish here, but if they are in the system, they may very well have hitched a ride on a barge or gotten into barge bilge water tanks..." to explain away the tests.

That brings us to the most recent red alert. This one announced yesterday regarding n the North Shore Channel, which connects to the north branch of the Chicago River in the city and leads directly to Lake Michigan at an MWRD pump station and sluice gate in the suburb of Wilmette.

Here's the thing: barge traffic between the Chicago River and the drainage channel is almost completely nonexistent on that portion of the waterway system.

So the announcement of three straight batteries of tests showing the presence of silver carp genetic material in the area is troubling. Aside from birds dumping a half dozen plus fish (don't forget, these fish get really big!) into the channel after flying them from miles and miles away, there aren't any other particularly plausible explanations (and really, despite the fact it gets repeated ad nauseum, the bird thing just doesn't pass the laugh test).

So, it will be interesting to see what happens with the aggressive fishing that will occur in response to the hits next week. Of course, officials have compared these efforts to finding a needle in a haystack. And they are being conducted a couple weeks after the initial eDNA water samples were collected (fish do swim), but then the entire response to the movement of invasive species into the Chicago waterway system (and the Great Lakes for that matter) has been slow, late, reluctant, and lackadaisical...

We hope that there are not invasive fish in the North Shore Channel---or anywhere else in the river system. But this latest test results in the northern reaches of the waterway system, as well as the spate of recent eDNA hits in the main stem of the Chicago River by the Navy Pier and the Chicago Lock which also connects with Lake Michigan, is causes continuing concern. The increased rate of detection in distinct places beyond the barrier implies an increased threat that we cannot ignore.

But as I noted last week, the Army Corps of Engineers just released an interim report outlining their response to Congressional orders for a speedup in offering a solution to this issue that was passed over the summer. The Corps signaled that they will not meet the deadline.

The newest eDNA results once again illustrate why that delay in response is a problem and why more aggressive action that permanently closes pathway for invasive species must to be taken. This is not about fish vs. barges. It’s about fish vs. Heads in the Sand.


Silver carp image courtesy of Michigan Sea Grant via Flickr.

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Michael BerndtsonOct 10 2012 04:24 PM

I thought the issue has more to do with water dilution for the sanitary and shipping canals connected to the Illinois River, etc then principally barge traffic. I would like to see the Chicago river cut off from Lake Michigan for many reasons including carp control. But wouldn't we see a massive sanitation problem without the reverse flow the Lake Michigan/Chicago River lock provides? Really important issue given a populous around 5 to 7 million depends on a solution to a problem unforeseen over 100 years ago. Back then the Chicago river flow was reversed and connected to the IM canal to protect Lake Michigan drinking water.

Josh MogermanOct 10 2012 04:39 PM


Thanks for taking the time to read and comment. Henry is referring to one of the knocks on eDNA that we often hear---that fish cannot get past the electric barrier, but eDNA hits can be explained away with barge traffic. While that is in the realm of possibility for some areas we've seen hits, that does not seem to be the case for the most recent spate of eDNA hits due to the nature of this portion of the waterway.

As for separation, check out NRDC's initial evaluation from 2010 at

The report concluded that the two systems could be separated without creating the sanitation nightmare that some predicted early in this debate---with good feedback and engagement from a variety of stakeholders. This is a separation strategy, not a re-reversal, which would require significantly more work to get water up to quality for return to the Lake.

ThamusOct 10 2012 10:56 PM

I have taken up this question about eDNA and commented many times. There are many vectors that can lead to eDNA transmission. Recreational craft and sportsman are one of the very real vectors in play. They are finding eDNA in very shallow water in Lake Calumet. Lake Calumet and other parts of the CAW's have been a gathering point for fishing tourneys bringing fisherman in from all over the midwest and nation. Is anybody checking to see where the fisherman and their recirculating live wells have been last? Notice that they found no eDNA hits in Milwaukee and up Lake Michigan but, found eDNA hits in the western basin of Lake Erie... Another fisherman Mecca. Are sportsman trailering the eDNA in? States like Nebraska and Minnesota are getting tough on establishing inspection stations for pleasure boats. These stations and check points are established to make sure boats are cleaned (and live wells) and bilge plugs pulled. Also, what about the vessels actually taking the water samples? The procedure is clearly defined how the sample collecting vessel should be cleaned prior to gathering eDNA samples. This procedure is very rigorous and complicated. Are they powerwashing the sample collecting boats well enough? They do use the same vessels in carp invested waters! This procedure proves that genetic material CAN hitch a ride on various vessels. The bottom line here is that in a real world setting outside of a closed laboratory there are many variables to the vectors in play. The completion of the ECALS study can not come to soon!

Here is a summary of a few plausible vectors other than live, swimming fish. Look closer at why they are finding only silver carp hits. Silver carp have the weakest scale structure of the 4 Asian carps and are the ones that jump. When something jumps, it has to land. When something lands, it splatters:

1. Contaminated commercial fishing nets. The nets they use to try and find live fish, after positive eDNA have been found, are the same nets commercial fisherman use down river in carp infested waters

2. Recreational craft and the vessels of fisherman as explained above. Live wells that contain 30 gallons or more water that gets recirculated with surrounding local water. Some modern fishing, ie: "bassboats", have two or more recirculating live wells. Are fisherman cleaning and emptying their live wells while pulling their bilge plugs after fishing carp infested waters?

3. Dredge material. It is a known fact the movement of dredging operations and the trasportation of fill material occures on the CAW's... Almost seasonally! During the summer months dredges head south and dig at carp ground zero near places like Peoria. In the fall, they return north to their winter storage. ALSO, dredge material is brought north as it is currently been done now.

4. The actual contamination of the eDNA water sample taking vessel.

The list goes on and on. This whole process is tainted from head to toe.

ThamusOct 10 2012 11:17 PM

To specifically comment on the North Shore Channel. The two most plausible vectors there are:

1. Fisherman, live wells, dirty boats, bait, etc... Bassboats with electric trolling motors can access very, VERY shallow water as they do in the Lake Calumet region near the golf course.

2. Number one leads me to numeber 2. The actual sample gathering vessel is contaminated. Take a look at where the hits were found on the NSC. Read the procedure that they have to go through to decontaminate the vessel. This to me is the biggest "if." Maybe they should abandon water samples taken from a vessel and do shore based gathering?

3. The recent movement of northbound dredge operations from southern Illinois and the material used to nourish parts of the Chicago water front. This doesn't explain the North Shore Channel... BUT, the Chicago River past the north-south junction comes into play... EPSPECIALLY with the recent "reverse flow" conditions at the locks. Not all reverse flow conditons get full lock closure. There are times when water is even and/or slightly reversed back towards the lake.

Thank you for your time and thoughful discussion.

Michael BerndtsonOct 11 2012 03:05 PM

Thanks Josh for the info. I need to get up to speed on this issue for personal reasons: I drink the wonderful and tasty Lake Michigan water and contribute my share to the Stickney Works.

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