ments in which fingerling chinook and coho salm- 

 on were immobilized by exposure to negative 

 pressure and by two items of indirect evidence: 

 (1) regions of negative pressure within turbines 

 and (2) immobilization of some fingerling salm- 

 on and trout after passage through turbines. 

 The assumption, however, cannot be tested in 

 situ, and some (if not all) of the fish may have 

 been immobilized by factors other than decom- 

 pression. 



Because of the limited sampling, the data are 

 of little analytical value but suggest that sig- 

 nificant numbers of fish passing through a tur- 

 bine are immobilized by physical forces in the 

 turbine. Those fish that experience sublethal 

 immobilization must surely contribute indirectly 

 to the total loss at dams. At a river velocity of 

 1 m per sec, 10 min of immobilization would 

 expose fish to predation for more than one-half 

 kilometer. An accurate measure of total mor- 

 tality due to turbines, then, requires an evalu- 

 ation of direct and indirect losses. It may best 

 be derived by determining the number of sur- 

 vivors passing a point several kilometers down- 

 stream from the dam. 



LITERATURE CITED 



CRAMER, F. K., and R. C. OLIGHER. 



1964. Passing fish through hydraulic tur- 

 bines. Trans. Am. Fish. Soc. 93: 243-259. 

 HARVEY, H. H. 



1963. Pressure in the early life history of 

 sockeye salmon. Ph.D. Thesis, Univ. Brit- 

 ish Columbia, Vancouver, Can., 222 p. 

 LONG, C. W., and W. M. MARQUETTE. 



1967. Research on fingerling mortality in 

 Kaplan turbines. Proc. 6th Bienn. Hy- 

 draul. Conf., Moscow, Idaho, Oct. 18-19, 

 1967, p. 11-36. Wash. State Univ., Pull- 

 man. [Processed.] 

 MUIR, J. F. 



1959. Passage of young fish through tur- 

 bines. Proc. Am. Soc. Civ. Eng., J. Power 

 Div. 80 (PO 1), Part 1: 23-46. 

 SCHOENEMAN, D. E., R. T. PRESSEY, and 

 C. 0. JUNGE, JR. 



1961. Mortalities of downstream migrant 

 salmon at McNary Dam. Trans. Am. 

 Fish. Soc. 90: 58-72. 



GPO 999-981 



