CABLE TO SOUNDER 



FIG. 8 Schematic diagram of the electronic sequencer. 



The sled is anchored underwater on a gently 

 sloping beach with the transducers "looking" up- 

 wards (Fig. 9). Cables from each transducer are 

 connected to the sequencer on the beach. A single 

 coaxial cable connects the sequencer to the sounder. 



After the gear is in position on the beach, the 

 sounder is set to record for 5 min once an hour. 

 Each transducer is gated on for 10 sec. The re- 

 sulting echogram is a series of "stair step" patterns 

 because of the different depth of each trans- 

 ducer (Fig. 10). The counter/printer system has 

 not been adapted for automatically recording data 

 from the transducer array and the fish echos must 

 be counted manually. 



This system proved to be reliable and relatively 

 trouble free. Data on the vertical distribution of fish 

 in a natural environment was collected and reported 

 on by the staff of the Prescott Facility (Blahm, 

 McConnell, and Snyder, 1974). 



SOUNDER 



f TIMER 



SEQUENCER 



SLOPING BEACH 



FIG. 9 Transducer array in position underwater with the elec- 

 tronics equipment on the beach. 



FIG. 10 An echogram from the transducer array installed 

 underwater on a sloping beach. 



REFERENCES 



Blahm, T. H. 1972. Gas Supersaturation Research. Report to 

 North Pacific Division, U.S. Army Corps of Engineers. 



Blahm, T. H., McConnell, R. ). and Snyder, G. R. 1974. Gas 

 Supersaturation Research 1972-1974. National Marine Fisheries 

 Service, Prescott Field Station. 



Monitoring Vertical Distribution 23 



