6. 



meters with limited coverage below 1600 meters (Fig. 3). The 

 lack of adequate shallow water photographic coverage for the 

 two northern canyons, Lydonia and Oceanographer, results from 

 the presence of numerous lobster pot arrays along the walls and 

 in the heads of these canyons. Thus, in order to avoid physical 

 entanglement of the camera sled, as well as the resulting legal 

 ramifications, it was necessary to restrict the photographic 

 survey to the deeper parts of both canyons. 



The photographic method for estimating abundance and dis- 

 tribution of epibenthos has various advantages over trawling 

 or motion pictures. Both of these other methods tend to under- 

 estimate epifaunal density, while direct visual observation 

 tends to overestimate it (Grassle et al., 1975). Barham, Ayer 

 and Boyce (19 67) compared measures of epifaunal density 

 obtained by still photographs and 16 mm cinemaphotography 

 along a transect in the San Diego Trough. The densities 

 obtained from examination of the still photographs were nearly 

 twice as high as those obtained from a study of the motion 

 pictures. The investigators attributed this difference to the 

 more critical examination possible with camera stills. A 

 comparison of densities estimated from trawls versus still 

 photographs shows that photographs yield densities an order of 

 magnitude greater than those obtained from trawls (Haedrich, 

 Rowe and Polloni, 1975) . This is probably due to the fact 



that the more mobile components of the epifauna can readily 



