100 each of smallmouth black bass (3.1 inches), largemouth black 

 bass (2.6 incnes), and bluegills ^2.4 incnes). On August 26, three 

 of these ponds were sprayod with suspension formula 3; and a second 

 group of them with suspension formula 4, both at the rate of one 

 pound of DDT per acre; while a third group of them served as a con- 

 trol. Fish survived well in both treatments except in one pond (1-4) 

 which had been visited periodically by a heron (table 7). Formula 4 

 was apparently somewhat less toxic than suspension formvila 3« An 

 inventory of the ponds on September 4 showed tnat the survival rate 

 was generally lower in ttie sprayed ponds than in the controls, in- 

 dicating some effect from DDT. 



Summary and Conclusions 



A series of experiments v;ith DDT formulations used in field 

 applications for forest insect control were performed- in dirt- 

 bottomed ponds, concrete raceways, concrete daphnia ponds and aquaria 

 at the Fisheries Experimental Station, Leetown, West Virginia, to 

 test the toxicity of DDT to different species and sizes of fish. 



Small bluegills, largemouth black bass, and smallmouth black 

 bass one inch in length were killed by DDT in both suspensions and 

 oil formulations in applications ranging from 0.25 to 1.0 pound per 

 acre. Golden-shiner fry were killed by oil sprays in excess of 0.25 

 pound per acre in dirt-bottomed ponds . 



Young black crappies 1.2 inches in length were killed by 0.5 

 pound per acre of DDT in both suspension and oil formulations. 



Fingerling fish 2 inches or more in length were better able to 

 withstand the higher rates of application. In some instances large 

 fingerling or adult fish were able to withstand spray applications 

 of as much as 1.0 pound of DDT per acre in both suspensions and oil 

 formulations . 



Fingerling bluegills, smallmouth black bass, and black crappies 

 were found .-nore sensitive to DDT than largemouth black bass, ^.olden 

 shiners, and trout. 



In raceways with a continuous flow, brook and rainbow trout, 

 smallmouth bass, and golden shiners were relatively unaffected by a 

 1-pound per acre application of DDT in a suspension formula. 



In general, mortality with DDT suspensions occurred later and to 

 a lesser extent ttian witn oil sprays. Two commercial brands of 

 wettable DDT, advertised as the same strength, showed a difference 

 in toxicity. 



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