jacent oceanic areas; catch rates differed little 
during winter (fig. 4 and table 2). In the equa- 
torial Pacific Ocean, near the Line Islands, 
yellowfin tuna also tend to be more abundant 
near land than in the open ocean (Shomura and 
Murphy. 1955; Iversen and Yoshida, 1957). 

WINTER 









CATCH PER 100 HOOKS 
Figure 4.--Catch rates (number of fish per 
100 hooks) for yellowfin tuna in the Mar- 
quesas Islands (inshore stations) and adja- 
cent oceanic areas south of lat. 7° S. 
Bigeye Tuna 
The distribution of bigeye tuna differed from 
that of yellowfin tuna on long. 132° W. in the 
winter of 1956 (fig. 5), Their distribution was 
relatively limited along this meridian (between 
lat. 4° and 11° S.). whereas yellowfin tuna were 
found from about lat. 2°N. to 13°S, In the 
summer of 1957, however, bigeye tuna were 
more abundant and more widely distributed (lat. 
4°29’ N, to 14°02’ S.) than they were in the win- 
ter of 1956 and their distribution closely paral- 
leled that of yellowfin tuna (figs. 2, 5, and table 
3). 
Farther west, on long. 150° W., bigeye tuna 
were not as abundant nor as widely distributed 
as they were on long. 132° W. (fig. 5 and table 
3). They were taken in small numbers between 
lat. 5°51’ S. and 3°01’ N. on this transect but 
were distributed discontinuously within these 
latitudes. In contrast, yellowfin tuna were found 
from lat, 16°34’ S, to 3°01’ N. on this meridian 
during the same period. Along long. 150° W. 
from lat, 4°44’ N. to 0°45’ S, the following sum - 
mer, the distributions of bigeye and yellowfin 
tunas were similar, except that the peak catch 
of bigeye tuna was at lat. 0°53’ N. and the peak 
catch of yellowfin tuna was at lat. 2°57’ N. 
Only small numbers of bigeye tuna were 
caught near the Marquesas Islands in both sum- 
mer and winter. The catch rates varied from 
0 to 0.8 fish per 100 hooks and, unlike the rates 
for yellowfin tuna, displayed no marked season- 
al difference, 
Other Tunas 
Small numbers of skipjack tuna and albacore 
were caught along with yellowfin and bigeye 
tunas. Deep-fishing longlines do not effectively 
sample the skipjack tuna, which is a small, 
3 

° W. | | 
WINTER 1956 

tr 



o 









ida} 
<4 1 7 
S | 
2 0 ZA wEOENEO D A 
i] 
ee cS} 
a 
a 150° W. 
= 2 SUMMER 1957 
& 
S 












3 | 
150° W. | 
4 SUMMER 1958 
1 
0 Was 0 
15%S? 10° Se o° 5°N. 
LATITUDE 
Figure 5.--Oceanic catch rates for bigeye 
tuna (number of fish per 100 hooks) on 
long. 132° W., winter 1956 and summer 1957, 
and on long. 150° W., summers 1957 and 
1958. 
Table 3.--Catch rates of bigeye tuna by season and area 

Area or season Comparison of catch rates 
Long. 132° W. Between summer 1957 and 
winter 1956 
Summer 1957 Between long. 132° and 
150° W. 





Test Result 
Mann-Whitney U = 60, ny iis ny = 13; p <0.002 
do U=" 43); n, = 135 ny = 15; p <0.002 

