Hendershot, R. G., W. C. Acker and R. D. Sullivan (1984). Doppler techniques 
applied to fisheries hydroacoustics. Pages  15-20 in  Oceans '84 Conference 
Record: Industry, Government, Education. Designs for the Future, Washington, DC 
(USA).
	
Fisheries management agencies are in need of better technologies to monitor the 
runs of migratory species in free-flowing rivers. This paper describes a long-
pulse 420 kHz riverine Doppler sonar designed to detect upstream migrating fish 
in shallow waters and to reject false targets and large reverberations from the 
surface and bottom. The use of Hanning-shaped long pulses (30 msec) results in 
good spectral separation between reverberations and Doppler-shifted echoes from 
upstream migrants. A correlation detector rejects certain classes of false 
targets by comparing shapes of the transmit pulse and Doppler-shifted echoes. 
The correlation detector also improves the system's range resolution. In field 
tests the system has provided an accurate run timing index of the spring 1983 
sockeye salmon Oncorhynchus nerka run on the Quinault River in Washington State. 
Current research includes investigating bistatic configurations for monitoring 
fish passage through specific regions and the use of echo integration techniques 
to sum the total energy in the received signal.