Update on the Asian Carp Threat: What Can We Expect Going Forward?

Today I attended a subject matter hearing at the Thompson Center regarding the Asian carp issue. Moderated by Illinois State Senator Susan Garrett and Senate Environment Committee, the hearing featured presentations and discussions by the following organizations and panelists:

U.S. Army Corps of Engineers: Colonel Vince Quarles (Commander of the Chicago District)
The Nature Conservatory: Lindsay Chadderton (Aquatic Invasive Species Director)
Illinois Department of Natural Resources: Marc Miller (Director), John Rogner (Assistant Director)
U.S. Environmental Protection Agency: Bill Bolen (Great Lakes National Program Office)
Metropolitan Water Reclamation District: Ed Stadacher (Waterways Operations)
Alliance for the Great Lakes: Joel Brammeier (President)
Illinois Commercial Fishing Association: Kirby Marsden (President)
Schafer Fisheries: Mike Schafer (Owner)
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The hearing also had a short “Open Forum” section featuring the following additional stakeholder organizations and representatives:

Metropolitan Planning Council: Josh Ellis
Natural Resources Defense Council: Henry Henderson (Director)
Sierra Club: Jack Darin (Director)
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There was a lot of really good, in-depth discussion on the current status of the Asian carp threat and what might happen in the future were it to successfully establish a presence in the Great Lakes. I’ll try to distill the key points of the hearing down to the essentials. So here goes…

1) There are two non-indigenous “Asian Carp” species that threaten the Great Lakes – the bighead carp (Hypophthalmichthys nobilis) and the silver carp (Hypophthalmichthys molitrix).

Both of these species are native to the large rivers and associated floodplain lakes of Northern and Eastern Asia (primarily China), and both feed by filtering plankton from the water. Because they are so good at this, the bighead carp and silver carp were imported to the U.S. in the 1970’s to help control algae growth and improve water quality in sewage treatment plants and aquaculture facilities. The silver carp is infamously known as the “jumping carp” due to its proclivity for leaping out of the water when startled.

2) The bighead carp is already in the Great Lakes.

Bighead carp have been reported in Lake Erie as early as 1995. Since then, other large adult bighead carp have been either captured or spotted in Lake Erie. However, there is no indication that they have established a breeding population (more on that below). Here is a very recent map by the U.S. Geological Survey indicating the current territory of the bighead carp.

3) The Illinois River is heavily infested with both bighead carp and silver carp – and there is pretty strong evidence that they are both very close to entering Lake Michigan through the Chicago water system.

The fish kill conducted last December in the Chicago Sanitary and Ship Canal uncovered the presence of a bighead carp near the Lockport dam. However, environmental DNA (eDNA) testing of the Chicago waterways has indicated the potential presence of both bighead and silver carp as far up as Calumet Harbor and the Wilmette Pumping Station. Previous tests had only indicated a positive presence of the Asian carp eDNA as far upstream as the Calument Sag Channel:

The eDNA findings are significant. The tests are designed to detect the specific cellular debris (mucus, feces, urine, and remains) of only the bighead carp and the silver carp. And more importantly, ratios of eDNA between the two species varies by the location tested. This makes it highly unlikely that the eDNA was carried upstream in the ballast water of barges.

4) If either or both Asian carp species enters Lake Michigan via the Chicago waterways, they may or may not be able to develop a self-sustaining population.

This is the wildcard issue that we cannot yet address with 100% certainty. Both the silver carp and the bighead carp are certainly quite capable of surviving in the Great Lakes. In their natural setting, both species are big lake fish. However, both species need river systems to reproduce successfully. And therein lies the rub.

Both Asian carp species rely on long stretches of river currents (up to 100 kilometers) to keep their eggs in suspension during spawning. Without such currents, the eggs sink to the riverbed (or lake bed) and become inviable. So even if the bighead carp and silver carp manage to invade Lake Michigan, it is questionable as to whether the water dynamics of the Great Lakes can provide such lengthy and constant currents.

Nevertheless, these two carp species are quite adaptable. Despite being lake fish by preference, both the bighead carp and silver carp can live in slower moving rivers or in low velocity habitats in rivers. And they can also adapt to – and thrive in – large lakes with limited river systems feeding into them.

Hungary’s Lake Balaton is often cited as a comparable case study for what we might see in the Great Lakes. Lake Balaton is a fresh water lake about 1/5 the size of Lake Erie with a similar climate and water chemistry. The silver carp was introduced into Lake Balaton in 1972 and has since become a thriving, self-sustaining species – all without needing 100 kilometers of free flowing, undammed river water to reproduce.

So where do we go from here?

As you can see, this is not an easy issue to address. And there’s millions of dollars on all sides of the issue at stake which further complicate us finding a simple and elegant solution.

Many conversationalist groups advocate sealing off the canal system altogether and restoring the Chicago water system to its natural pre-canal ecosystem. But these ideas are quickly dismissed as unfeasible by the water reclamation district which warns of catastrophic flooding and water contamination that might result.

And while these various stakeholders polemic their respective causes, the INDR and USACE keep stepping up their efforts to contain the silver carp and bighead carp before they breach the electric barriers – provided they haven’t done so already.

So I’ll continue to stay on top of this and keep you all informed on any new updates as I hear about them. In the meantime, my recommendations would be to heed the timeless wisdom of Douglas Adams – Don’t Panic.