THE ROUND GOBY:  AN UNWELCOME INVADER TO THE MISSISSIPPI RIVER BASIN

Mark T. Steingraeber and Pamella A. Thiel.
U.S. Fish and Wildlife Service, Fishery Resources Office, 555 Lester Avenue, 
Onalaska, WI 54650.  

The round goby (Neogobius melanostomus) is a small, benthic-oriented fish native to 
the Black and Caspian Seas of Eurasia that was introduced to North America in Lake 
St. Clair a decade ago.  Round goby are now present at shoreline sites in all of the 
Great Lakes.  Members of the southern Lake Michigan population have also expanded 
their range at least 43 miles inland along the Illinois Waterway System (IWS) at an 
annual rate that appears to have increased dramatically since 1998.  The goby-
inhabited reach of the IWS in metropolitan Chicago now comprises the uppermost 
13% of this 333-mile navigation corridor that flows diagonally across Illinois from 
Lake Michigan to the Mississippi River.  The round goby is thus poised to spread, 
perhaps rapidly, to other states in mid-America via the Mississippi River and its many 
tributaries.  This aquatic nuisance species (ANS) has the potential to upset riverine 
food webs, out-compete native species for preferred habitats, increase contaminant 
bioavailablity, and adversely impact recreational and commercial fisheries.  To slow 
the further downstream movement of round goby and other nuisance species of fish 
from Lake Michigan to the Mississippi River basin, as well as to serve as an 
impediment to other nonindigenous fish moving upstream from the Mississippi River 
drainage to the Great Lakes basin, Congress appointed the U.S. Army Corps of 
Engineers to lead an interagency advisory panel in selecting and implementing the 
most appropriate ANS dispersal barriers for the IWS.  A non-lethal, vertical gradient 
electrified barrier was chosen for the first phase of a round goby demonstration 
project here and will be installed at a site on the Chicago Ship and Sanitary Canal 
(river mile 296.5) near Romeoville, Illinois by mid-2000.  Since 1996, the U.S. Fish 
and Wildlife Service has also led interagency efforts to determine the downstream 
leading edge of the round goby's distribution and its relative abundance in the IWS. 
Theses annual surveillance efforts will continue after the barrier is operational to 
evaluate its efficacy.  Once an ANS becomes locally established, as the round goby 
has in the Chicago area, an integrated ecosystem management approach with agency 
and public cooperation is required to address the multi-faceted issues that can arise in 
tying to contain these unwelcome invaders.

Keywords:  aquatic nuisance species, dispersal barriers, Illinois Waterway System, 
range expansion, round goby
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