INTRODUCTION 



This is an interim progress report on one phase of a group 

 of investigations by the Fish and Wildlife Service conducted through 

 its Pacific Oceanic Fishery Investigations located in Hawaii o These 

 investigations are designed to insure the maximum development and 

 utilization of the high-seas fishery resources in the central Pacifico 

 Considered herein are the first results of a longline fishing survey 

 not yet completedo Widespread interest in these initial findings 

 calls for their publication without delay. Owing to parallel studies 

 in the physical,, chemical,, and biological oceanography of the region, 

 it is possible to relate the results of the fishing survey to environ^ 

 mental causes, but no exhaustive treatment of this subject is intended 

 hereo 



On the American west coastj, tuna are generally taken by 

 live-bait fishing, trolling, or pxirse seiningo For a number of 

 reasons apparent from extensive trials, these methods are suited 

 neither to large-scale commercial development in the region nor to 

 use as a survey methodo The Japanese have long used the longline 

 method commercially,. This same method is proving useful in inves- 

 tigating the distribution and abundance of deep=swiraming tunas and 

 may have commercial possibilities in the central Pacific areao 



In planning the research program, cognizance was taken 

 of the vast area under consideration and the relatively limited 

 resources available by confining the exploratory fishing to areas 

 that appeared to offer a favorable environment for tunaso The general 

 region from the Countercurrent south to the Equator seemed to be a 

 potentially favorable environment because upwelling was known to 

 occur there (Sverdrup etc alo 1942) and because POFI hydrographic 

 surveys had encountered more abundant queintities of plankton at 

 those latitudes than to the north and southo Accordingly, cruises 

 7 and 11 of the ^gh Mp Smith (figo l) were designed to ascertain 

 whether this potentially favorable environment was in fact more 

 heavily populated with tunas.-. Smith Cruise 5 was primarily devoted 

 to hydrographic studies, but it included 1 week of longlining to 

 test the practicability of the methodo Incidentally it provided 

 some data on the abundance of deep-swimming tunas in the vicinity 

 of Canton Island in the Phoenix groupo 



This report contains the results of the longline fishing 

 for these three cruisesl/together with such related material as 

 is available and pertinent to an understanding of the relationship 

 of the tunas to their environment„ The possibilities of commercial 

 exploitation are also consideredo Attention has been devoted to 



_/ The period covered by these cruises is roughly July to November o 

 A sequal to this report will deal with the subsequent winter 

 and spring crtiiseso 



