The portion of the BLM document which explains how their data were derived is 

 reproduced in Section 5,4.2 of this report. The BLM investigators had to make 

 a number of assumptions in their data calculations, and there are obvious 

 limitations to the data collected from the sighting cards by this program. 

 Furthermore, one can question whether or not it is even valid to compare data 

 collected by such different methods. Still, it is felt that if enough data 

 can be gathered from the oil platforms the overall results derived from the 

 comparison will help to answer the question of whether the oil activities are 

 affecting marine mammal distributions. If densities around the platforms do 

 not fall within the range calculated by BLM, it will be necessary to question 

 whether the differences are simply due to a dissimilarity in methods. However, 

 the differences in marine mammal densities between the oil platform and the 

 quadrat as a whole will also alert NOSC scientists to a possible real effect 

 of the platforms on marine mammals. 



E-18 



