





















































lalla nl ] Telhalhc)| lel Paral 
1 i) | 1 Yi | | | | 
35 KIPJACK Y - + eae loa foul ie ai 
| N=48 g | | 
30 leet Y) +t ical 1 
| ZY | | | 
25/4 Yy a ad = | 
20} VW sop esi 
Ly lial l | 
15 i = i 
| YY | | | Wall 
10 i Y / t E 
Af YZ 
5 V _ a 
o& AEA! | | je [ie] 
5 35 qr TIP 
i) | 
© 30\—ALBACORE Lapse 
a] N=46 [ 
imal lial 
20} | q dette 
Y) | 
15} ++ ! | | 
| 
10;— | 
T | | AV | | 
| | | | ZA\ T 
ot AAA_|_| L 
BO SSP 
] ] 
io ___BIGEYE | 3 
N:97 7A A 
el jae VA g 
o | T ~ Y ] 
7 y 
ou +! Z Z G as FA ler emai 
50 62 74 86 98 110 122 134 146 158 170 192 194 
539 659 +779 «2899 1019 1139 
LENGTH (CM.) 
Figure 10.--Length-frequency 

distributions of 






















1259 1379 M499 1619 1739 1859 1979 
skipjack tuna, 
albacore, and bigeye tuna. 
2. Yellowfin tuna were the most abundant and 
widely distributed species of deep-swimming 
tunas in the oceanic areas, Where areal and 
seasonal comparisons could be made, they were 
more abundant on long. 132° W,. than on 150° W., 
and during the Southern Hemisphere summer 
than during winter. The concentrations also 
showed apparent north-south shifts. Yellowfin 
tuna also were more abundant in the inshore 
waters of the Marquesas than in oceanic waters 
south of lat. 7° S, 
3. The abundance of yellowfin tuna around 
the Marquesas varied seasonally. The presence 
of greater numbers of larger, and presumably 
more mature, fish and the occurrence of greater 
numbers of the larvae during the summer, sug- 
gest that they gather in this area to spawn. 
4, Although bigeye tuna were not as abundant 
or widely distributed, their distribution, in gen- 
eral, was somewhat similar to that of yellowfin 
tuna, The greatest relative abundance of bigeye 
tuna was to the east (long. 132° W.) and during 
the Southern Hemisphere summer; they also 
showed north-south shifts in centers of concen- 
tration. Only small numbers of this species 
were taken near the Marquesas. 
5. No albacore were caught north of lat. 
7° S. on long. 132° and 150° W. There are indi- 
cations that an east-west discontinuity of the 
oceanic structure around lat. 10° S, somehow 
may restrict the distribution, Like bigeye tuna, 
albacore were not very abundant at the inshore 
stations around the Marquesas. 
6. Longlines did not fish as deep between 
lat. 2°N, and 2°S, as they did farther to the 
north and south. This fact was ascribed to 
shearing between the westerly flowing South 
Equatorial Current at the surface and the east- 
erly flowing Equatorial Undercurrent beneath. 
7. No conclusive statement could be made of 
the depths at which oceanic yellowfin and bigeye 
tunas were most abundant. Both species, how- 
ever, were caught at all depths fished by the 
longlines. Oceanic albacore south of lat. 7° S, 
were evenly distributed between 105 and 164 m. 
Near the Marquesas Islands catches of yellowfin 
tuna were often greater when the longlines 
fished deeper. Catches of bigeye tuna were 
greatest between150 and 164 m. Albacore were 
deeper than yellowfin or bigeye tunas. 
8. The length-frequency distributions of 
yellowfin tuna caught at oceanic stations and at 
stations near the Marquesas Islands were sim- 
ilar; yellowfin tuna from 90 to 130 cm. long 
were sparsely represented in catches near the 
Marquesas. Fish in this size range possibly 
