pounds per acre. Deletion of the adult gizzard 

 shad reduced the average weight per acre to 

 approximately 285 pounds. This figure also is 

 considered to be more indicative of the average 

 population of area B. 



4. To facilitate evaluation of the popu- 

 lation data the various spyecies were arranged 

 in the following groups: predators, game fish, 

 panfish, catfish, forage fish, and rough fish. 



black crappie, white crappie; 4) catfish -- 

 channel catfish; 5) forage fish -- gizzard shad; 

 and 6) rough fish -- carp, spotted sucker, and 

 freshwater drum. 



11 . Weight composition by species groups 

 in area B varied greatly from year to year. The 

 most stable comp)onent of the populations was 

 the catfish group while the rough fish group was 

 the most variable. 



5 . On the basis of adjusted average 

 weight per acre of 285 pounds, the mean 

 percentage composition of the various species 

 groups in area B was predators, 27; game fish, 

 12; panfish, 13; catfish, 11; forage fish, 1; 

 and rough fish, 38. On the same basis, average 

 composition in pounds per acre was: predators, 

 77; game fish, 29; panfish, 36; catfish, 30; 

 forage fish, 2; and rough fish, 112. 



6 . Average standing crops of the three 

 northern backwaters and of area B alone were 

 less than the mean weight per acre of four 

 backwater areas in the southern section of the 

 river but the predator and game fish components 

 were greater in the upper section. 



7 . The average standing crop of areas A 

 and B and Miller Lake exceeded that of inland 

 waters to the north, approximated that of waters 

 in the same general latitude, and was less than 

 the mean crop of inland waters to the south. 



8. The preponderance of species with 

 long food chains suggests that total standing 

 crops with the existing species composition are 

 comparatively high for the latitude. 



9. Production of game fish in area B 

 tended to exceed that in most waters of the 

 north-central States where comparison was 

 made. Weight per acre of panfish in the same 

 area tended to approximate that in northern 

 inland waters but was much less than that in 

 waters to the south. 



10. The most prominent species in the 

 backwaters in each of the species groups were: 

 1) predators -- bowfin; 2) game fish -- northern 

 pike and largemouth bass; 3) panfish -- bluegill. 



12. Very few fish over 5 years of age 

 were found in the four collections from which 

 fish were aged. The great majority of game 

 fish and panfish were less than 3 years old. 



13. Growth rates of most species were 

 faster than those of the same species in almost 

 all waters of the north-central States where a 

 comparison was made, including the Illinois - 

 Missouri section of the river. 



14 . Results of water analyses indicated 

 that chemical fertility of the upper Mississippi 

 River is high when comf)ared to that of other 

 waters producing heavy crops of fish . 



15 . Bottom soils of the backwater areas 

 have a higher organic content (7.49 percent) 

 than those of adjacent running channels (2.64 

 percent) and also a finer texture. 



16. CompKDSition of the bottom fauna in the 

 backwaters of the upper Mississippi River has 

 changed since the navigational locks and dams 

 were installed but production per unit area com- 

 pares favorably with that observed before 

 installation of those structures. 



17. Differences in standing crops in area 

 B during the 4 years could not be related to 

 changes in water level . 



ACKNOWLEDGMENTS 



The authors appreciate Dr. Raymond E. 

 Johnson's assistance in detailed identification 

 of fish and in field work. Dr. John Greenbank's 

 supervision of much of the early general field 

 work. Dr. John B. Moyle's identification of aquatic 

 plants, and to Mr. John Dobie's cooperation 



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