ABSTRACT 



The results of 9 fishing cruises to the Line Islands area by POFI vessels during March 1955 

 to February 1956 are discussed. The catch rates obtained by longlining indicated that the abundance 

 of yellowfin, Neothunnus macropterus (Temminck and Schlegel), was low as compared with previous 

 years. 



Yellowfin caught by surface trolling close to the islands were smaller than the deep-swimming 

 yellowfin caught by longlining both near the islands and in the open ocean. Longline catch rates close 

 to the islands were generally higher th^ln their oceanic counterparts. 



Chemical sounding tubes were used to determine the depth fished by the longline. The data 

 indicated that the deepest hooks fished greater depths at 5° to 6*N. than near 1*N. latitude. There 

 was no significant relationship between the catch rates on the deepest hooks and the depth of fishing. 



From 1,056 yellowfin captured and tagged in the Line Islands area, there were 2 recoveries 

 prior to Septennber 1956, both from the same area in which they were released. 



NOTE 



After this paper was prepared for publication, a third tagged yellowfin (No. 3350) was recovered. 

 This fish was tagged at Christmas Island on October 8, 1955, and was retaken by a Japanese long- 

 liner, the No. 7 Sakura Maru, at02°45'N. latitude, 143°20'W. longitude, some 800 miles east of 

 Christmas Island on November 10, 1956. The fish had been at liberty for 13 months and during this 

 period grew from 111.0 cm. (58. 7 lb. ) to 139.0 cm. (95.8 1b.). Perhaps even more significant, 

 the fish had abandoned the island habitat for the open sea, and there is the implication that it had 

 changed its mode of life from surface- to deep-swimming. 



