IS" 



lU^ lil 



Rj m 



m ^m. 



These inner and outer zones 

 were exchanged between observ- 

 ers each 20 minutes. The 

 observer scanning the outer 

 zone was also charged with the 

 responsibility of keeping the 

 team's records as well as mak- 

 ing periodic observations of 

 weather and sea conditions. 

 Unfortunately, communication 

 between observer and recorder 

 was a serious problem in the 

 noisy interior of the plane. 

 This problem was alleviated 

 when each observer was re- 

 quired to keep his own record. 

 During the last flight each ob- 

 s erver was also required to 

 measure and record the angle 

 from vertical of each object 

 sighted. 



The flights were about 

 4-1/2 hours long Eind covered a 

 distance of approximately 450 

 miles. The flight track was 

 usually laid out over aji area 

 which was being scouted by the 

 CHARLES H. GILBERT and. 

 in addition, covered areas 

 where skipjack were likelv to 

 occur (fig. 4). The plane flew 

 at altitudes between 500 and 

 2, 000 feet on the various flights, 

 but a constant altitude was main- 

 tained during each flight except 

 occasionally, when the plane 

 descended to lower elevations 

 to exajnine objects nnore closely 

 or repeatedly. On several flights a Navy photographer accompanied the pliine to photograph 

 objects of special interest. Records were maintained of the time and sighting of all fish, birds, 

 ctnd aquatic mammals and also the condition of the sea surface. Since frequent navigational fixes 

 were obtained by the Navy crew, it was possible to construct a detailed chart combining track 

 and sightings. 



Despite the minor differences in techniques, we believe that we maintained a very high 

 scanning efficiency on all flights. Usually the personnel included someone experienced in 

 searching for skipjack schools from a vessel. There was nnuch interest in making the flights 

 and they were short enough to avoid undue fatigue and eye strain. 



Behavior of Birds in Relation to Fish 



160° 



155° 



Figure 3. --Scouting plan for cruises 22, 23, and 24 of the 

 HUGH M. SMITH in September, October, and 

 November. 



Terns ajid shearwaters are most commonly seen in association with skipjack schools in 

 the Hawaiian waters and the fishermen consider both to be indicators of skipjack's presence 

 (table 2). Among the terns, the noddies and the sooty tern are the species nnost comnnonly seen. 

 The noddies are generally more abundant near the islands while the sooty terns range as far as 

 we have searched. The shearwaters and petrels are a difficult group of birds to identify in flight, 

 but the wedge-tailed shearwaters have been found to be very common. These also are found to 

 the limit of our scouting area. 



