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Fishery Bulletin 100(3) 



Figure 1 



Map of the study area showing location of the dive sites and bathymetry. Numbers 

 represent Jago dive numbers. 



the common demersal nekton from these videotapes and 

 examine fish behaviors and demersal fish assemblages. 



Materials and methods 



Field sampling 



Videotapes of 44 diving sites in the Orange River delta 

 area between 28°15'S and 29°40'S were analyzed. Surveys 

 were conducted at depths between 100 and 140 m in the 

 middle shelf (Fig. 1). Twenty-six dives were conducted 

 north of the river mouth, and 18 were conducted to the 

 south. 



The submersible was launched from a support ship 

 (MV Zealous) and towed by an inflatable dinghy to the 

 first way-point of each dive survey. The position of the 

 submersible was tracked every 31 seconds by using an 

 acoustic transponder array. Accuracy of the positioning 

 system was within approximately 5.0 m. A fairly detailed 

 track-chart of the dive was produced and overlaid onto 

 maps of underlying bathymetry. 



Videotapes were recorded as the submersible cruised 

 along the seabed (generally at speeds of 0.25 knots) by 

 using a digital video camera. The camera usually faced 

 forward and downward through the front acrylic dome- 

 window and was only occasionally panned or moved dur- 

 ing the survey. The submersible stopped at times, either so 



