The tuna reaourcea of the weatern tropical Pacific are of great intereat to the 

 Japaneae people, who before the war had begun to exploit them; to the people of the Phlllpplnea, 

 Indoneaia, and New Guinea, who would like to exploit them; and to the people of Mlcroneaia, 

 who may find In them one of the few thinga that they can aell. Theae tuna atocka are alao of 

 Intereat to Americana becauae aome of the lalanda of the area are preaently under U. S. truatee- 

 ahip and It la contlnguoua to portlona of the central Pacific now being explored by the U. S. Fiah 

 and WUdlife Service. 



Moat of the knowledge of theae weatern Pacific reaourcea haa been reported in 

 acattered Japaneae flahery literature on the prewar activitiea of Japaneae fiahermen. Following 

 the war, tuna motherahlp flahlng operatlona in the equatorial weatern Pacific (fig. 1) were 

 authorized by the Allied Governmenta in control in Japan. There were nine of theae expedltiona 

 between Jxine 1950 and October 1951. Each took the form of a motherahlp that atored the catch 

 and aupplied loglatic aupport to a fleet of relatively amall catcher veaaela that flahed with long- 

 llnea. Obaervera from the Pacific Oceanic Flahery Ipveatlgationa of the U. S. Fiah and Wild- 

 life Service accompanied aix of these expedltiona and the general observationa on the methoda, 

 catch, and area flahed during theae voyagea have been publiahed (Shinnada 1951a and b, Ego and 

 Otau 1952, and Van Campen 1952). 



In addition to the recorda obtained by the. American obaervera with the expeditions, 

 the operatora were required to maintain a dally log on each of the longline Catcher veaaela. 

 Theae loga contain obaervationa on the weather and aea, the number of hooka aet each day, the 

 kind of bait uaed, and the numbera and weighta of each of the principal speciea in the daily 

 catchea. Moat of the obaervationa were recorded with reaaonable accuracy excepting the weighta 

 of the flahea, which perforce were eatimatea on the part of the captalna. 



The purpoae of thia paper la to aummarize the recorda with regard to the abundance 

 of the principal apeciea compriaing the catch (yellcwfin, bigeye, and black marlin), and to 

 examine the relation of abundance to factora in the environment. Since thia type of consideration 

 involvea Interpreting catch ratea (usually expreaaed aa catch per 100 hooks) as indexes of 

 abundance, we also examine the possibility that the catch rates might be affected by factora other 

 than abundance, such aa the type of bait uaed and veaael efficiency. 



SPECIES OF FISH IN THE CATCHES 



The vernacular namea of the various species of fish in the catches are used in the 

 text. Theae are Hated below with their uaually accepted scientific names. 



Yellowfin tuna - Neothunnua macropterua (Temminck and Schlegel) 

 Bigeye tuna - Parathunnus sibi (Temminck and Schlegel) 

 Skipjack - Katsuwonus pelajnis (Linn^) 

 Albacore - Germo alalunga (Bonnaterre) 

 Black nriarlin - Makadra nnazara (Jordan and Snyder) 

 Pacific white marlin - Makaira marllna (Jordan and Hill) 

 Striped marlin - Makaira mitsukurii (Jordan and Snyder) 

 Pacific sailfish - Istiophorus orientalis (Schlegel) 

 Broadbill swordfish - Xiphias gladius (Linne) 



Sharks - These are not listed specifically becauae of inadequate identification in the 

 records. 



