Some chronic effects of DDT on cutthroat trout /

Effects on cutthroat trout (Salmo clarki lewisi) of periodic exposure to different levels of DDT in bath and in food were determined over a 20-month period involving one spawning cycle. High dosages produced a marked increase in mortality, probably by reducing the resistance to nonspecific stressors; survivors fish in high-dosage lots were significantly larger than those in control and low-DDT lots. Intermediate and low dosages of DDT generally did not measurably affect mortality, growth, or reproductive potential, indicating that a threshold level exists around 0.1 p.p.m. monthly in contact form and around 0.3 mg. DDT per kg. of fish weekly in the diet for the toxic effects of DDT.Research supported by the United States Department of the Interior, Fish and Wildlife Service.Other authors on title page: Burton J. Kallman, Oliver B. Cope and Charles Van Valin.Includes bibliographical references (p. 29-30).Literature cited.Summary and comments.Pathology.Resistence to stress.Reproduction.Residues.Growth.Mortality.Background.Introduction.Effects on cutthroat trout (Salmo clarki lewisi) of periodic exposure to different levels of DDT in bath and in food were determined over a 20-month period involving one spawning cycle. High dosages produced a marked increase in mortality, probably by reducing the resistance to nonspecific stressors; survivors fish in high-dosage lots were significantly larger than those in control and low-DDT lots. Intermediate and low dosages of DDT generally did not measurably affect mortality, growth, or reproductive potential, indicating that a threshold level exists around 0.1 p.p.m. monthly in contact form and around 0.3 mg. DDT per kg. of fish weekly in the diet for the toxic effects of DDT.Mode of access: Internet