fishing (fig. 1). The seasons and areas of fish- 
ing are given in table 1. 
METHODS 
Mann (1955) described in detail longline gear 
Similar to that used for this study. The basic 
unit, the basket, was composed of a 384-m. 
mainline and eleven 5.5-m, hook droppers or 
branch lines attached to the mainline at 27.4-m. 
intervals. Forty-four to sixty of these baskets 
were joined to make a set. The set was buoyed 
by a series of floats attached to basket junc- 
tures by 18.3-m. float lines. The bait was fro- 
zen Pacific herring (Clupea harengus pallasi), 
Murphy and Shomura (19538a) described in some 
detail the manner in which longlines are set and 
retrieved. As a rule, they are set at dawn and 
retrieved at noon. 
To estimate the depths fished by the longline, 
five or six sounding tubes were used regularly 
at each fishing station. They were attached to 
the sixth dropper, the middle dropper of the 
11-hook basket, and were distributed evenly, 
throughout the set. For each longline station 
the depths indicated by these sounding tubes 
were averaged and the mean depths were used 
to represent the mean maximum depth of the 
longline. At many stations additional sounding 
tubes were attached to the third, sixth, and ninth 
droppers of one basket to get an estimate of the 
configuration of the mainline. 
The total lengths of all the tuna caught on the 
cruises were obtained by the method described 
by Marr and Schaefer (1949). 
For some sections of this paper it was con- 
venient to classify the fishing stations as 
““oceanic’’ or ‘‘inshore.’’ The division between 
oceanic and inshore fishing stations was made 
at a distance of 148 kilometers (80 nautical 

miles) from land (following Shomura and Murphy, 
1955). By this criterion, all of the stations 
fished on north-south transects on long. 132° 
and 150° W. were oceanic. The inshore stations 
were all near the Marquesas Islands. 

Ltt LONGLINE STATIONS 







eee: 
> 




/ ep 9p gh og 
[Ze 

Hareeetee . 
140° 

Figure 1.--Tracks of CHG (Charles H. Gilbert) 
cruises 30 and 38, and JRM (John R. Manning) 
cruise 34, 
Table 1.--Summary of fishing by season and area, Charles H. Gilbert cruises 30 and 38 and 
John R, Manning cruise 34 


Cruise 
Season 
Area fished 

Charles H. Gilbert 
cruise 30 
Winter (August- 
September 1956) 
Summer (January- 
March 1957) 
John R. Manning 
cruise 34 
Charles H. Gilbert Summer (February 
cruise 38 1958) 


ror Southern Hemisphere. 
Long. 132° W. from lat., 1°32 N.. topl2eO7mesre 
around Marquesas Islands and adjacent area. 
Long. 132° Wo from lat. 4°29. Ne vto: el 2 O2RaiSme 
around Marquesas Islands; long. 150° W. from 
Lat. 16°344/Se to ySsig0N IN 
Long. 150° W. from lat. 4°44' N. to 0°45' S. 

