Wo Go Van Campen translated the Japanese fishing data included in the 

 reports Miss Jean Hailing assisted in processing the catch records 



OPERATIONAL DATA 



Longline fishing on the banning and Gilbert was done in 

 essentially the same manner as on the Hugh M, Smith (Murphy and Shomura 

 1953) with minor modifi cations-., Forty baskets of standard POFI long- 

 line gear (Niska 1953) were used at each station during the cruises under 

 consideration. Each of these baskets had a main line 1,260 feet long 

 with six evenly spaced hook droppers. Each dropper was 88 feet in 

 overall length. At certain stations on Cruise 11 of the Manning , 5 

 additional baskets of experimental gear were set.. These will be 

 discussed in a later section., Fresh frozen sardines, approximately 

 four to the pound, were used as bait Before use they were thawed 

 and packed in rock salt for from 1 to 3 days. The baits were hooked 

 through the eyes. 



Setting of the gear began about dawn and usually took an 

 hour* Retrieving the gear usually started at noon and finished 

 about U:00 P.M. Tables 1 and 2 give the exact working time for all 

 stations. These tables indicate that the stations were in general 

 comparable as regards the length of time the gear was fished and 

 the daily scheduling of the fishingo 



HORIZONTAL DISTRIBUTION OF YELLOWFIN TUNA 



The results of the first longline cruises to the equatorial 

 Pacific in the vicinity of 1$0°-160° HIT, longitude during the period 

 from August to November indicated a marked concentration of deep- 

 swimming yellowfin tuna in a zone north of the Equator (Murphy and 

 Shomura 1953)= These surveys were made during a period of predominant 

 southeast trades, which cause upwelling near the Equator and tend to 

 displace the upwelled water northward (Cromwellii ) It was tenta- 

 tively concluded that this enriched water, with its increased plankton 

 and presumably increased tuna forage, was directly linked with the 

 observed concentration of yellowfin,, 



Extrapolation of this theory to periods or areas charac- 

 terized by winds other than southeast indicates that the location 

 of the most productive zone should be somewhat different., Northeast 

 winds should create a mirror image of the circulation created by 

 southeast winds, with the zone of greatest productivity displaced 

 to the south of the Equator, Easterly or variable winds should 

 result in the zone of greatest productivity being symmetrically 

 arranged about the Equator 



2/ Cromwell, Townsend, MS, Circulation in a meridional plane in 

 the central equatorial Pacific 



