Bridge Magazine recently discussed the threat of Asian carp invading the lakes with Lindsay Chadderton, director of aquatic invasive species for The Nature Conservancy.
Chadderton worked with the University of Notre Dame as part of a four-person team that developed the environmental DNA (e-DNA) surveillance methods being used to track the spread of Asian carp in the Chicago Waterway System and western Lake Erie. He also co-authored a 2010 report to the U.S. Army Corp of Engineers that characterized the aquatic invasion risk that the Chicago Waterway System poses to both the Great Lakes and Mississippi River basins.
Bridge: Do you believe Asian carp are living in southern Lake Michigan and the western basin of Lake Erie?
A: The fact that we’ve detected e-DNA of both bighead and silver carp within the western basin of Lake Erie gives us some evidence that there are likely bighead or silver carp, or hybrids of Asian carp, living in Lake Erie. That should not have been too surprising, given that bighead carp have historically been taken in Lake Erie.
I think there are four catches of bighead carp on record; most of those fish were taken between 1996 and 2002. The analysis of two of those fish indicated they had been introduced in Lake Erie in the early 1990s.
Based on the results of the surveillance work we did in 2009 and 2010 in Lake Michigan and the (Asian carp) that was taken out of Lake Calumet, we (at Notre Dame) continue to argue that the most plausible explanation for the pattern of (Asian carp e-DNA) hits we’ve seen indicates the presence of live fish. There’s nothing we’ve seen in the past two to three years that has changed my mind on that.
Bridge: How will we know if Asian carp have established a reproducing population in any of the Great Lakes? Is it game over if boaters in the Great Lakes basin someday encounter flying silver carp?
A: If we start seeing flying silver carp we’re in big trouble, but I don’t think we’re anywhere remotely near there. I think there are a lot of things we can do now (to prevent Asian carp from establishing reproducing populations in the Great Lakes). The reality is there is a massive fishery within Lake Erie and if (Asian carp) were reproducing within the system, we would be seeing live carp there. We would be seeing Asian carp by-catch or seeing them picked up in bait. But we’re a long, long ways from seeing the types of things we’re seeing in the Illinois River.
Bridge: Does it concern you that government agencies have caught people smuggling truckloads of live Asian carp across Michigan?
A: I think that’s a serious concern and there’s a lot of interest in the bait trade. Many of the bait retailers (in the Great Lakes basin) continue to source their bait from the southern states, like Arkansas, where there are Asian carp reproducing. To me, the live fish haulers are just one of the other possible pathways. I think the fact that we’re starting to see these things picked up means we are looking at the whole problem. We need to tackle every potential avenue of introduction. I think there’s growing awareness of the problem and I think we’re starting to close down some of these pathways.
We’re still really coming to grips with the scale and nature of the problem, what are all of the pathways, what are the threats and what must we do to manage them. It’s an incredibly complex issue, in a large geographic area with lots of jurisdictions and lots of different players. It’s always going to be challenging but I think we’re making good progress.
Bridge: With Michigan sitting in the center of the Great Lakes basin, does it have more to lose than other states if Asian carp invade the Great Lakes?
A: The general consensus is that Asian carp will do very well in the likes of Lake Erie and some of the small bays (in the other Great Lakes) and some of the river mouths. Asian carp clearly have the potential to affect Michigan’s coastal fisheries, but I think the big impacts would be in Lake Erie. Michigan has a small portion of Lake Erie, but I think the economies in Ohio and Ontario are probably facing a bigger threat because these fish are likely to do very well in Lake Erie.
Bridge: Does climate change make the Great Lakes more suitable for Asian carp?
A: My understanding is that warmer lakes would likely benefit Asian carp, but I’m not a climate biologist.
Bridge: If you were a betting man, how would you assess the odds of keeping Asian carp out of the Great Lakes? Realistically, can we expect to keep these invaders out of the Great Lakes or is that a long shot?
A: I’m still optimistic. The best example of an aquatic pest program on the sort of scale that is required to manage Asian carp is the sea lamprey control program. We have the tools and we’ve demonstrated we can do it … with regards to sea lamprey. I think we’re doing the work necessary to figure out how to do that job (with Asian carp).
The challenge is going to be if can we maintain this commitment over the long haul. We have to be honest with the public and tell them that (preventing an Asian carp invasion) is going to be a 20- to 30-year program. I’m coming at this from the standpoint that there are probably a small number of Asian carp in the lower Great Lakes (Lake Erie and southern Lake Michigan) and we will probably continue to see a small number of fish coming into the lakes until we close off all of the pathways. The challenge now is to prevent those fish from establishing and (reproducing). That’s going to require vigilance and a lot of ongoing work.
Bridge: Studies have found that Asian carp are most likely to enter the Great Lakes via the Chicago Waterway System, the manmade canals that link Lake Michigan to the Mississippi River basin. Physically separating the Chicago Waterway System from Lake Michigan would cost several billion dollars. Is it worth the expense?
A: Absolutely and it’s not just because of Asian carp. The Army Corps of Engineers has identified 29 species that could use the Chicago canal system to move between the Great Lakes and the Mississippi River basins. (A physical separation) makes sound economic and environmental sense. We just need to get on with it. I am firmly of the belief that we can do this in a way that will allow the (Chicago Waterway System) to operate and provide the functions it does, in terms of transport, sewers and stormwater, as well as preventing the movement of organisms in either direction. The challenge is to come up with an effective solution that allows all of that to happen. But it’s just an engineering problem and we can solve it.
Jeff Alexander is owner of J. Alexander Communications LLC and the author of “Pandora’s Locks: The Opening of the Great Lakes – St. Lawrence Seaway.” He’s a former staff writer for the Muskegon Chronicle.