A Suirvey of Tuna Grounds in Equatorial 'teters 



1„ FNirpose. 



Good results were obtained from the previous survey of tuna fishing 

 grounds in the waters south of Palau, however, further attention must be 

 paid to the equatorial waters, which are considered as a continuation of 

 these fishing grounds, since they have been fished recently by tuna fishing 

 vessels from Japan and since they must be considered as future fishing 

 ground So For this reasonj an extensive area was siarveyed to determine 

 Ti^iether or not it has any value as a fishing groundo The findings are 

 submitted herein as reference data for the planning of commercial operations.. 

 (Note) The first fishing test was planned in accordance with the northward 

 shift of the Equatorial Counter^current at this seasono 



2„ Particulars of the survey, 



a„ Survey period=May 9 to May 24>, 194-1=16 days 



bo Area sarvey6d=From 6'^ N latitude to 1^ S latitude and from 129° 

 to 134o E longitude o 



Co Survey shlp„ Zuiho Kara, 133 tons, 360 HP 



do Fishing gear used in the survey=Tuna longlines (50 baskets^ 6 

 hooks per basket),, 



Brief description of one basket of tuna longline fishing gear. Main 

 line - cotton line 10- strand, 4-5 gr per £" 5-foot_J fathom; total length 175 

 fathoms (length of one section is 25 fathoms) » 



Branch lines^lO-strand cotton line, 37,5 gr per fathom, length 12,5 fathoms. 

 6 pieces 



Float lines=10=strand cotton line, 4-5 gr per fathom, length 12o 5 fathoms, 

 1 piece _ 



Cotton=covered wire=3 strands of 3 wires each, (eyes / ?_7 both ends) , length 

 4 fathoms, 6 pieces 

 Wire leader=length 1,5 fathoms, 6 pieces 



3o Resv.ltSc 



(l) Jesuit of each operation. 

 First fishing test, May 10 



This fishing ground is located about 100 -iiiles south of Palau 

 (5°40°N, 134°31'E) and due to the seasonal north/irard shift of the 

 Equatorial Counter-current, is believed to be in the Counter-current 

 area, Detaxls of the current, however, were not known. 



Lines were set in a southwesterly direction from 50 baskets. Since 

 the catch amounted to only 3 yellowfin and 1 blg^eyed tuna, it was 

 believed to be too early for the fishing season. 

 Second fishing test, May 12 



This fishing ground is located about 300 miles south of the first 

 fishing ground at 0°35" N latitude and 134-^26" E longitude near the Equator. 

 Lines from 50 baskets were set in a southerly direction. The current 

 flowed 'H^ at 1„6 knots^ The water temp^ratares of 29,6 degrees at the 

 surface, 28,6 degrees at the 50-meter layer and 24.,^ degrees at the 100- 

 meter layer were satisfactoryo 



