FISHERY BULLETIN: VOL. 85, NO. 3 



BEAUFORT 1 



ao-N 



20* 



10° 



o« 



10° 



20° S 



Northern 

 V Offshore 



Southern Offshore 

 Area 



Coastal band 



BEAUFORT 4 



30° N 



20° 



20°S 



Northern 

 Offshore 

 Area 



Southern Offshore 

 Area 



Coastal band 



160° 150° 140° 130° 120° 110° 100° 90° 80° 70°W 160° 150° 140° 130° 120° 110° 100° 90° 80° 70°W 



BEAUFORT 2 



30° N 



Northern 

 20° ] V Offshore 

 Area 



10° 



0'- 



10° 



20° S 



Southern Offshore oftshote. 

 Area band^ 



BEAUFORT 5 



30° N 



20°- 



0° 



10° 



20°S ■*• 



Northern 

 V Offshore 

 Area 



Southern Offshore 

 Area 



Coastal band 



160° 150° 140° 130° 120° 110° 100° 90° 80° 70° W 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° W 



BEAUFORT 3 



30° N 



20° 



10° 



20° S 



Northern 

 v Offshore 



Southern Offshore 

 Area 



Coastal band 



Figure 3.— Tracklines surveyed by airplanes during 1977 

 and 1979 in the coastal and offshore bands 

 stratified by Beaufort state. 



160° 150° 140° 130° 120° 110° 100° 90° 80° 70°W 



conditions occurred in the offshore band. This was 

 because the general searching pattern was to 

 begin searching on the westward, outbound leg in 

 the morning, and then to turn the aircraft near 

 noon and reach shore in late afternoon or night. 

 Thus the sun was directly overhead or in front of 

 the plane in the offshore reaches of the track and 

 behind the plane in the nearshore areas. 



Detection rates during good and poor sun condi- 

 tions were higher in the coastal band than in the 

 offshore band (Fig. 5), which was consistent with 



a hypothesized decreasing density gradient. 

 Within the coastal band, detection rates during 

 good sun conditions were greater than during 

 poor sun conditions, but most of the poor sun data 

 was gathered in the westward portion of the band 

 (Fig. 4). In the offshore band, trackline detection 

 rates during good and poor sun conditions were 

 similar, but the rate during good sun conditions 

 was based upon three sightings and only 8% of the 

 effort. 



Finally, I compared data collected by the ob- 



426 



