tions in physical, chemical, and hydrological conditions such as the re- 

 placement of old style wicket dams, increased water pollution control, and 

 augmented stream flow from reservoirs during the low-flow period. The 

 changes appear to parallel and substantiate physical and chemical water 

 quality trends noted during the same period. 



In the 1957-60 period the 10 most abundant species of fish in the popu- 

 lation samples were in descending order: the emerald shiner, gizzard shad, 

 freshwater drum, mimic shiner, channel catfish, silver chub, black bullhead, 

 threadfin shad, blue catfish, and sand shiner. The 10 species that contri- 

 buted the greatest total weight in the samples were gizzard shad, carp, 

 channel catfish, freshwater drum, emerald shiner, skipjack herring, 

 flathead catfish, blue catfish, black bullhead, and river carpsucker. 



In comparison, the 1968-70 sampling revealed that six of the 10 most 

 abundant species in the population—the gizzard shad, emerald shiner, fresh- 

 water drum, channel catfish, bullhead, and the drum--were retained from the 

 1957-60 sampling period. The remaining species were replaced by the carp, 

 black crappie, yellow bullhead, and river carpsucker. Of the 10 species 

 that contributed the greatest total weight in 1957-60 the gizzard shad, 

 carp, channel catfish, freshwater drum, river carpsucker, flathead catfish, 

 and black bullhead continued in that category. The three new species were 

 bigmouth buffalo, white crappie, and bluegill. 



The species composition also varied throughout the river as it did in 

 1957-60. In the upper third the most abundant species were carp, channel 

 catfish, gizzard shad, emerald shiner, and brown bullhead; in the middle 

 third, the carp, gizzard shad, channel catfish, mimic shiner, and skipjack 

 herring; and in the lower third, the gizzard shad, channel catfish, emerald 

 shiner, freshwater drum, and bigmouth buffalo. 



Among the changes noted during the 10-year period was the marked in- 

 crease in the carp population, which had not been so predominant in the 

 earlier studies, and the increased abundance of species sought by both 

 sport and commercial fishermen - largemouth and smallmouth bass, sauger, 

 crappies, and sunfish. It is believed that the new deeper pools with de- 

 creased velocities and more lake-like settings probably account in large 

 measure for the increased carp population. The re-emergence of significant 

 numbers of the so-called sport and commercial species is probably due to 

 the decreased water pollution loads going to the river. Such a conclusion 

 is supported by ORSANCO appraisals of water quality conditions. Of the 21 

 water quality characteristics routinely monitored by ORSANCO, all except 

 four are now meeting established criterial goals for streams in the compact 

 area. 



SUMMARY 



A review of historical and recent information concerning fish in the 

 Ohio River during 1957-60 and 1968-70 indicates that the composition of the 

 fish population has changed during the period. In large measure, the 



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