Gar (Lepisosteus spp.) 



Shortnose gar were taken infrequently in the three lower pools of 

 the river (Table 5). Other members of the gar family occur, or once oc- 

 curred, in the Illinois River, but were rare or absent from the electro- 

 fishing collections. Gar are not as vulnerable to electrof ishing as 

 other species and both shortnose and longnose gar are probably more a- 

 bundant in the river and backwaters than the collections indicate. A 

 few longnose gar ( Lepisosteus osseus ) were taken by electrof ishing before 

 1970. No spotted gar ( Lepisosteus oculatus ) have been taken by electro- 

 fishing, but two have been taken by a commercial fisherman at Havana. 

 One taken during a high-water period on February 26, 1973 at Havana was 

 the largest spotted gar reported for the state (7.5 lbs, 32.8 in. total 

 length) and was a female full of ripe eggs, indicating that she was ready 

 to spawn. Alligator gar ( Lepisosteus spatula ) were probably extirpated 

 from the Illinois River prior to 1970 (Starrett, 1972). 



Shortnose gar are found in areas where there is a current, such as 

 the main channel, or side channel, whereas the other species favor clear 

 weedy backwaters and bottomland lakes. Since most electrof ishing was 

 conducted in side channels, it was not surprising that more shortnose 

 than longnose gar were taken. 



Gar are generally considered a nuisance by sport and commercial 

 fishermen because they are not commonly used as food, become entangled 

 in nets, and prey on other fishes. Actually, such predation helps sta- 

 bilize the abundance of prey-species at a moderate level and is probably 

 advantageous to the prey-species. Gar are considered sight-predators, 

 and would thus be disadvantaged in turbid waters. Increasing turbidity 

 in the Illinois River and its lakes and backwaters probably accounts for 

 the decline in numbers of members of the gar family. Gar possess an air 

 bladder, open to the esophagus, and are capable of "air-breathing" when 

 dissolved oxygen levels are low, so low oxygen levels in the river and 

 lakes wouldnot be expected to have as drastic an effect on gar as on 

 other species. 



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