Bowfin (Amia calva) 



Bowfin is a commercial species that was not common in the Illinois 

 River collections (Table 6) . Bowfin were taken as far upstream as Peoria 

 Pool only in 1961 and otherwise were taken in collections from LaGrange 

 and Alton Pools. Bowfin numbers have been drastically reduced. Forbes 

 and Richardson (1908) reported that bowfin were abundant in sloughs and 

 lakes adjoining the Illinois River. In 1903 commercial fishermen took 

 1,097,050 lbs of bowfin from the Illinois River and its tributaries; 

 at the time the Illinois River furnished nearly all the bowfin marketed 

 in the United States (Forbes and Richardson, 1908). 



Bowfin have a cellular air bladder, connected to the esophagus, 

 which can be used for "air-breathing" when dissolved oxygen levels in 

 the water are low. In addition, bowfin can use their highly vascularized 

 gill covers as an accessory respiratory organ (Lagler, et al . , 1962). 

 Bowfin construct nests for spawning on silt-free bottoms, often in beds 

 of vegetation. 



Increasing turbidity, sedimentation, and the gradual loss of aquatic 

 vegetation in the Illinois River and backwaters were probably responsible 

 for the decline of this species. Trautman (1957) writes about the bow- 

 fin in Ohio: 



"The bowfin was not adverse to waters made cloudy by the 

 abundance of plankton but normally occurred sparingly or 

 as strays in waters habitually turbid with clayey silts. 

 It displayed the greatest decreases in abundance in those 

 Ohio waters which formerly were clear and contained much 

 vegetation, but which during the survey had become silty 

 and almost vegetationless. " 



American eel (Anguilla rostrata) 



American eels were rarely taken. One was taken from Alton Pool at 

 mile 19 and two from Peoria Lake in 1974. None were taken in 1973. A 

 few were taken prior to 1973. Forbes and Richardson (1908) reported 

 that eels were taken regularly in small numbers from the Illinois River 

 at Havana. 



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