these has been rotenone because of its high degradabil ity, freedom from 

 such problems as precipitation and persistent toxicity, and above all, the 

 relative safety for the user. Rotenone, which is obtained from the derris 

 root ( Deguelia elliptica , East Indies) and the cube root ( Lonchocarpus 

 nicour , South America) has been used extensively since 1934 in fishery work 

 throughout the United States and Canada. The chemical is toxic to man and 

 warm-blooded animals (132 mg/kg), but has not been considered hazardous in 

 the concentrations used for fish eradication (0.025 - 0.050 mg/liter active 

 ingredient). Therefore, it has been employed in waters used for bathing 

 and in some instances in drinking water supplies. Activated carbon removes 

 rotenone very effectively, as well as the solvents, odors, and emulsifiers 

 present in almost all commercial rotenone formulations. The rotenone used 

 in lock-chamber studies is a 5% active ingredient in an emulsion base. 

 Best results are obtained with water temperatures above 13 C (55 F). It is 

 a relatively fast-acting toxicant which decomposes in 24 hr or less. The 

 toxicity threshold, however, differs only slightly among fish species, and 

 for this reason rotenone cannot be used as a selective toxicant for certain 

 species. 



LOCK-CHAMBER APPLICATION 



The lower gate of the lock chamber is left open approximately 4-6 hr 

 before the sampling. Personnel move into the lock chamber in boats, and 

 the lower gates of the chamber are closed. The rotenone emulsion is then 

 pumped and sprayed from a boat into the water within the lock chamber until 

 a concentration of 1 mg/liter is attained. The chemical is then rapidly 

 dispersed through the water inside the chamber by means of the ouboard 

 motors on the boats. The fish begin rising to the surface 5-10 min after 

 the rotenone has become well mixed. As the fish surface, personnel in 

 boats pick them up with dip nets and place them in large tubs. Because of 

 the size of the chambers, i.e., 100 ft by 1,000 ft, approximately five 

 boats and 10 men are required to conduct the work. Additional personnel 

 spot the fish as they surface. After all the fish have been picked up and 

 placed in receptacles, the lock-chamber gate is partially opened, and the 

 water is permitted to bleed out slowly. The fish are then taken to a 

 central location near the lock and are sorted, weighed, identified, and 

 catalogued. Appropriate species, such as the channel catfish, are frozen 

 in dry ice, shipped to laboratories, and analyzed for heavy metals and 

 pesticides. Recently, the U.S. Food and Drug Administration has cooperated 

 in analyzing the fish for these constitutents . The fish are also inspected 

 for parasites and other pathological indications possibly attributable to 

 adverse water quality conditions. Fish not used in the additional studies 

 are disposed of by burying. 



SAMPLING RESULTS 



A comparison of lock-chamber sampling results for the 1957-60 and 

 1968-70 periods reveals that a number of changes have taken place in the 

 composition of the fish population in the Ohio River, reflecting altera- 



163 



