Close the navigation locks? It’s a question of risk.

In the past two weeks I’ve talked to a lot of people, including many officials on the Rapid Response Team, and I haven’t found anybody who disagrees with this statement: any Asian carp beyond the electric fence have an open path to Lake Michigan unless the navigational locks are closed.

So if there are Asian carp beyond the fence, then the agencies really have no choice. No matter what the drawbacks, they have to close the locks until they can find other ways of cutting off those monster fish from the Great Lakes. The consequences of their invasion would be too devastating, ecologically and economically. And I think you’d find that the agencies would agree.

So why is it so hard to get the Corps and the other agencies to close the locks?

I think it’s their perception of risk.

People see risk very subjectively, and the folks in the agencies are no different. In this case, their perceptions are colored by what they have described as some very harmful consequences from closing the locks: lost materials, lost jobs, maybe even flooding in Chicago. Now, there’s a real question about how many of these consequences are real and how many could be avoided, but that’s an inquiry the agencies would rather not pursue. So instead, they engage in a little wishful thinking about how likely it is that Asian carp are present beyond the electric fence in the Cal Sag channel.

What’s the risk that there Asian carp in the channel?

Nobody knows for sure, but here’s what the evidence says.

On the one hand, we know that DNA tests taken in the water in the Cal Sag channel contain Asian and silver carp DNA. How many are positive? Not one, not two, but 32 tests found Asian and silver carp DNA in various places along the channel.

On the other hand, sampling in the river hasn’t turned up any Asian carp fish. That sampling included electroshocking and extensive netting by commercial fisherman in parts of the channel. It caught 800 other fish, but no Asian carp. Now, we don’t know how extensive that sampling was. The Illinois DNR is due to put out a report soon that will tell us. But based on what we know, the sampling caught only a fraction of the total fish in the channel.

So what does the evidence mean? To understand it better, look at what happened at the other stretch of canal where DNA testing and sampling was done, the 6-mile stretch between the Lockport Lock and the electric fence. There, DNA testing only had one positive sample. There, the agencies did extensive electroshocking and netting. And there, they found no Asian carp…. until they killed all the fish in that stretch of the canal with poison. Only then did they find an Asian carp (dead by that time). And they now believe there are probably more dead Asian carp at the bottom of the canal.

So based on that experience, it’s reasonable to expect that there are Asian carp in the Cal Sag channel. There’s much more Asian carp DNA in the channel than there was in the canal, and the sampling techniques used in the Cal Sag channel were the same ones that failed to reveal the Asian carp that was present in the canal. Bottom line, the presence of carp in the canal is a strong indicator of carp in the channel, even though the channel sampling hasn’t found them yet.

Asian carp jumping

Asian carp | Photo: Jason Lindsey

I suspect that this is where the agencies have gone wrong. They don’t want to close the locks unless there’s solid proof that there are populations of Asian carp in the channel, and to them, that means finding live fish.

But they’ve missed the point. Sure, close the locks if they find hundreds of Asian carp. But also close the locks if there’s a significant risk of Asian carp in the channel. And the way the evidence looks now – in fact, the way it’s looked for the past three weeks since the Asian carp DNA tests were first released – there’s a high risk that Asian carp are in the channel.

If the agencies have evidence they haven’t shared, let’s see it. Otherwise, no more delay. It’s time to close the locks.


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