Otsu (1956). Tubes were placed on dropper 7 

 (the middle dropper) in baskets 5, 15, and 35, 

 Manning (cruise 25); in baskets 5, 15, 26, and 

 35, Smith (cruise 29) and Manning (cruise 26). 

 An extra basket bearing sounding tubes on 

 droppers 4, 7, and 10 was placed b e t w e e n 

 baskets 25 and 26 on all longline cruises. 

 During the Gilbert's cruise 23, extra baskets 

 with tubes on droppers 4, 7, and 10 were placed 

 between baskets 5 and 6, 15 and 16, 25 and 26, 

 and 35 and 36. Droppers bearing sounding tubes 

 and all droppers in extra baskets were bookless. 

 This to some extent prevented excessively 

 deep readings due to the diving of captured 

 fish. 



Trolling was done usually with 5 to 8 

 lines bearing varieties of feathered, bone, and 

 plastic jigs (Shomura and Otsu 1956). Trolling 

 speeds varied from about 6 to 9 knots. When 

 in waters believed to contain albacore, trolling 

 was confined to speeds of 6 to 7 knots. This 

 general range of speed is thought to be optimum 

 (Powell et al. 1952) for catching albacore on 

 trolling gear. In addition to trolling on the runs 

 between longline and gill-net stations, 2 hours 

 were devoted to trolling on each longline station, 

 but little or no time was devoted to circling and 



"working" productive areas. All trolling was 

 carried out during daylight. 



Gill nets were used experimentally during 

 cruise 23 of the Gilbert as a supplement to sur- 

 face trolling. Their use was prompted by the 

 relatively good catches of albacore made by the 

 Pacific Seilmon Investigations (PSI) of the Fish 

 and Wildlife Service (Tester 1956). These 

 catches were nnade in salmon gill nets set in 

 the general area under investigation by POFI. 

 POFI's gear consisted of 6 shackles, each 300 

 fathoms long and 100 meshes deep. A set was 

 composed of 2 shackles each of 5-, 6-, and 7- 

 inch (stretched measure) mesh nets. The nets 

 were set at dusk and hauled at daybreak. 



DISTRIBUTION AND ABUNDANCE 



The Manning (cruise 25) and the Smith 

 (cruise 29) explored the late spring distribution 

 and abundance of albacore between 176°W. and 

 139°W. longitude (fig. 1). Surface -swimming 

 albacore were scarce in the area surveyed. A 

 single albacore was taken on each cruise or 

 less than 1 fish per 100 line hours' trolling at 

 speeds of 6 to 7 knots (table 2). 



O TROLL CATCH 



■ RELATIVELY LOW TRANSPARENCY 



Figure 1. --Spring cruises of the John R. Manning (cruise 25), May 2-June 7, 1955, and the Hugh M. 

 Smith (cruise 29), May 2-June 4, 1955. Tracks of each cruise are shown together with surface 

 temperature (°F.) and the distribution of water of relatively low transparency, in relation to sur- 

 face albacore catches. 



