post-construction years, the fish populations had been reduced to ex- 

 ceptionally low levels in 1931 as a result of successive drouths in 

 1929, 1930, and 1931 (Department of Registration and Education, 1931: 

 25 and 1932: 33). Consequently, we decided to use the year 1922 as the 

 pre-construction year. 



The total harvest of 2.9 million pounds of fish in 1950 was greater 

 than the harvest of 2.5 million pounds in 1922, and 1.3 million in 1931. 



Tables 12-20 also show the market value of the commercial catch. All 

 monetary values were converted to 1977 dollars by using conversion factors 

 given in Table 21. The corrected values for 1894-1970 show that a 

 relatively stable amount of about $600,000-900,000 of fish per year were 

 harvested by Illinois fishermen from the upper Mississippi River. The 

 highest value of the fishery was reported in 1894 at $946,000, whereas 

 the lowest value was in 1931 at $427,000. The market value decreased 

 by 6 percent, from $785,489 prior to construction of the navigation 

 system in 1922 to $735,000 following construction in 1950. 



The total number of Illinois commercial fishermen engaged in the 

 upper Mississippi River fishery fell from a high of 1,149 in 1899 to 

 only 152 in 1970 (Tables 13-20). It can be seen that since 1931, the greatest 

 number of fishermen have been employed on a part-time basis. 



Changes in Species Composition, 1894-1970. In preparing Tables 12-20 

 it was apparent that major changes had taken place in the species compo- 

 sition of the commercial harvest from the upper Mississippi River. For 

 ease of discussion of these changes, the following fish groupings were 

 used: sturgeons, paddlefish, American eel, carp, suckers and carpsuckers, 

 buffalo, catfish and bullheads, freshwater drum, and other fish. At 

 this point, only historical quantitative changes are outlined. A dis- 

 cussion of these changes as related to the navigation system follows in 

 a separate section. 



Sturgeons: The lake sturgeon ( Acipenser fulvescens ) was included in 

 the commercial harvests of 1894 and 1899, when 37,000 and 31,000 pounds 

 were taken, respectively. No lake sturgeon were reported in the 1922- 

 1970 statistics. 



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