8. Fish surveys conducted in 1934, 1942, and 1967 with hoop nets 

 show that the number of game fish caught in the Alton Pool of the 

 Illinois River declined by at least 78 percent between 1934 and 1942, and 

 declined further from 1942 to 1967. The catch of non-game fish 

 increased by 50 to 74 percent between 1934 and 1942, primarily as a 

 result of increases in gizzard shad, carpsuckers, and carp. 



9. Two major changes which may have affected fish populations in 

 the study reach of the Illinois River in the period 1934-1942 were: 



(1) Lock and Dam 26 at Alton was put into operation 1 May, 1938, and 



(2) diversion of water from Lake Michigan into the upper reach of 

 the Illinois Waterway at Chicago was reduced from 6,500 cubic feet 

 per second (cfs) to 5,000 cfs starting 31 December 1935 and further 

 reduced from 5,000 to 1,500 cfs starting 31 December 1938. Domestic 

 pumpage was allowed, in addition to these amounts of diversion. 



10. In a 1942 survey of fish populations in the Alton Pool of 

 the Illinois River, more game fish were taken in Meredosia Lake 

 (66.35 game fish per net-day) than in side channels or the main 

 channel of the river (greatest catch: 26.02 game fish per net-day 

 in the channel at Kampsville). Meredosia Lake has since been de- 

 graded by an accumulation of oxygen-demanding sediment, which probably 

 plays a role in occasional fish kills observed in the summer. 



11. The commercial harvest of fish from the study reach of 

 the Illinois River has been relatively constant since 1950, in 

 contrast to upstream reaches where the harvest has shown a steady 

 decline since 1950. Starting in 1962, the Alton Pool of the Illinois 

 River consistently has ranked second in production among four pools in 

 the Illinois River with commercial fisheries. Some commercial 

 fishermen report that they do not fish the main channel borders of 

 the Illinois River, because the currents and wave wash associated 

 with the passage of barges collapse their nets. 



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