United States Department of the Interior, Fred A. Seaton, Secretary 

 Fish and Wildlife Service, John L . Farley, Director 



SONIC EQUIPMENT FOR TRACKING INDIVIDUAL 



FISH 



by 



Parker S . Trefethen 

 Fishery Research Biologist 



Special Scientific Report- -Fisheries No. 179 



Washington, D.C 

 June 1956 



