EVALUATION OF A BARRIER TO PREVENT TRANSFERS OF HARMFUL AQUATIC SPECIES BETWEEN 
THE MISSISSIPPI AND GREAT LAKES BASINS.

Traci L. Barkley 1, Richard E. Sparks 1, John M. Dettmers 2
1University of Illinois, Natural Resources and Environmental Science, Urbana, IL  
61801,
2Illinois Natural History Survey, Lake Michigan Biological Station, Zion, IL, 
60099.

The Chicago Sanitary and Ship Canal, located in northeastern Illinois, links two 
of the largest drainage basins in North America: the Mississippi and the Great 
Lakes-St. Lawrence and has become a gateway for the transfer of aquatic nuisance 
species between the two basins.  Nuisance organisms that have moved through the 
canal from Lake Michigan to the Mississippi drainage in the past decade include 
the zebra mussel (Dreissena polymorpha) and the round goby (Neogobius 
melanostomus).  Other nonindigenous fish are poised to enter the Mississippi 
River Basin by way of the canal, such as the European river ruffe (Gymnocephalus 
cernuus).   The ruffe is a small, spiny fish that is neither a desirable forage 
item for other fishes, nor a commercial or sport species and is likely to 
compete with highly-valued species.  The ruffe entered northern Lake Michigan in 
September 2002 and will eventually work its way south along the shoreline to 
Chicago and the canal system.   Kolar and Lodge (2002), using a modeling 
approach to assess risk to the Great Lakes from potential unintentional ballast 
water introductions from the Ponto-Caspian region, predict five more fishes will 
become nuisance species.   Currently moving in the opposite direction, two Asian 
fishes, the bighead carp (Hypophthalmichthys nobilis) and the silver carp 
(Hypophthalmichthys molitrix) are rapidly approaching Lake Michigan via the 
canal.  An electric dispersal barrier was constructed by the U.S. Army Corps of 
Engineers in the canal and activated 9 April 2002.  It provides an opportunity 
for rapid assessment and development of barrier technology. Because the barrier 
is experimental, its performance needs to be assessed promptly to optimize field 
strength, configuration, and the electric pulse rate before the impending 
arrival of the Asian carps and the European ruffe. A combined radio and acoustic 
telemetry system tracks movements of fish, implanted with transmitters, in the 
vicinity of the barrier.   The transmitters emit coded sonic and radio signals 
so individual fish can be identified and movements from one side of the barrier 
to the other can be detected. Barge traffic and high flow events, which may 
affect the electric field and the movement of fish, are monitored with a web-
accessible video camera, hydrophones, and several U.S. Geological Survey 
acoustic velocity meters mounted just downstream of the barrier.  If any tagged 
fish move through the barrier, barrier operators will be notified and the 
microprocessor-controlled electric field can be modified.  Each modification of 
the electric field is tested by the introduction and tracking of tagged fish.  
Once proven in the field, this electric barrier technology could be used to 
retard or prevent invasions of unwanted fishes, not only in the Chicago Sanitary 
and Ship Canal, but wherever there are interbasin connections. 

Keywords: aquatic nuisance species, Chicago Sanitary and Ship Canal, dispersal 
barrier, monitoring, telemetry.