An Experiment in the use of Derris Root (Rote-None) on the Fish and Fish-Food Organisms of Third Sister Lake

Sufficient powdered derris root (guaranteed rotenone content of 5 per cent) to make a concentration of 1:500,000 parts of water was applied to Third Sister Lake on May 6, 1941. Temperatures were unfavorably low and the treatment was not successful in the complete removal of fish. A second application on August 18, 1941 of a slightly greater concentration was sufficient to eradicate the remaining fish. There seemed to be little or no difference in the toleration of the different species of fish, however minnows and the young of game fish were killed in larger numbers at the beginning. It is believed this was the result of their location in shallow water rather than a difference in susceptibility to the poison. Not all fish came to the surface after death. Live fish taken from the lake before poisoning were placed in traps at different points and at various levels in the lake at the time of each poisoning in order to test vertical and horizontal distribution of the poison. In the first poisoning al...