Introduced species 



Two introduced species have entered the Illinois River recently 

 and will probably become more abundant, just as the introduced carp, 

 goldfish, and white catfish have. It is difficult to predict whether 

 the latest arrivals will increase explosively, as carp and goldfish 

 did, or whether they will barely maintain themselves, as white catfish 

 have. White catfish are only occasionally taken from the Illinois River 

 and do not seem to reproduce abundantly in the river. 



The white amur ( Ctenopharyngodon idella ) , a plant-eating fish in- 

 troduced from Asia, is now being taken regularly by commercial fishermen 

 from the Mississippi River at Crystal City, Missouri, and from the 

 Missouri River (Personal Communication, October 1974, William L. 

 Pflieger, Fishery Biologist, Missouri Department of Conservation, 

 Jefferson City, Missouri; and Peter Paladino, District Fishery Biologist, 

 Illinois Department of Conservation, Aledo, Illinois) , and has probably 

 entered the Lower Illinois River. If rooted aquatic vegetation could be 

 restored to the Illinois River and its bottomland lakes by the lake 

 restoration techniques discussed above, or by a reduction of silt loads 

 in the river as a result of improved soil conservation practices in the 

 basin, the white amur might have a detrimental impact. On the other 

 hand, white amur from the Mississippi are being marketed in small quan- 

 tities commercially and their flavor is reported to be excellent. White 

 amur in the Mississippi grow to a large size (10 to 14 lb) in 2 years 

 (Personal Communications, October 1974, Pflieger and Paladino). They 

 might become useful commercial species in the Illinois River. 



Another exotic species, the Asiatic clam ( Corbicula manilensis ) was 

 found at three locations on the Illinois in the course of the 1974 

 electrofishing survey: at Kampsville (river mile 32.0), Bath Chute 

 (mile 106.7), and Turkey Island Chute (mile 148.4). Judging by the 

 size of the shells, the oldest clams were four years old. Asiatic clams 

 probably first occurred in the Illinois River in 1970-1971 (Thompson 

 and Sparks, in press). The Asiatic clam is a serious nuisance, because 



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