7. 



avoid the net. Additionally, the uncertainty of the actual 

 configuration of the net with respect to the bottom is a 

 problem that excludes trawling as a valid quantitative sampling 

 technique. 



The photographic sled "Cheep Tow" used in this survey 

 consists of a welded aluminum channel frame with four glass 

 buoyancy spheres mounted on top (Fig. 4). This configuration 

 results in the sled being almost neutrally buoyant with the 

 ability to right itself. A camera, strobe, Aandera current 

 meter and pinger were mounted on the frame. Either a 35 mm 

 EG & G or a 70 mm Hydroproducts camera was used for each tow. 

 Both cameras were oriented facing front and tilted slightly 

 downward. Exposures were taken at automatic 15 second inter- 

 vals, with the time being marked adjacent to each frame. 



The camera sled was towed at speeds between 0.8 to 1.2 

 knots, resulting in an average of 8 meters between successive 

 frames (Appendix E) . The triggering of a flash approximately 

 8 meters away may cause avoidance by some of the more mobile 

 components of the epi fauna. Uzmann et al. (19 77) compared 

 various sampling techniques and found that siobmersible and 

 camera sled photographic techniques tended to underestimate 

 the abundance of pelagic species. They suggest that a photo- 

 negative response in pelagic forms may account for some of the 

 differences observed, between photographic sampling and 

 trawling, in estimating the abundance of these organisms. 



