Formula #3 . 90% sighting distance: 



N = density 



transect length x 90% sighting distance 



where N = number of animals observed; 



where L (transect length) = linear distance flown in nm; 



where 90% sighting distance = right angle distance within which 90% of 



sightings occur. This 90% distance is 

 obtained from records kept of right angle 

 distance to sighting. If both sides of 

 aircarft are manned, the distance is 

 doubled. In this study the 90% right angle 

 distance was determined to be 0.48 nm. 

 Therefore in this formula 0.96 nm was used 

 since both sides of the aircraft were 

 manned. 



Example: Let N = 350 



L = 2,034 nm 

 90% distance = 0.96 nm 



350 = 0.179/nm^ 

 2,034 X 0.96 



2 

 This density figure of 0. 1792animals/nm , when extrapolated to 



the area surveyed (25,000 nm ), yields an estimated abundance 



of 4,475 animals in the Bight. Note that the density figure in 



this formula does not differ greatly from that derived from 



formula #2. 



Formula #3 is an inhouse modification of Formula #1, adjusting the 

 path width downward, as a result of our review of the initial sighting 

 data. 



Formula #4 . Percent of area surveyed ratio: 



Ratio = % of Bight surveyed : N :: 100% of Bight : X 



where % of Bight surveyed = nm flown x 0.96 nm (path width when both 

 sides of aircraft are manned) divided by area of the Bight; 



where N = number of animals observed. 



B-72 



ee 



