Biology of WallQO — IVERSEN AND YOSHIDA 
identity of the more readily digestible forms 
could be lost during this time. Aside from 
these difficulties, it seems likely that the data 
in Table 2 provide a reasonably good picture 
of the food throughout the year. We do not 
believe there is much seasonal change in the 
fauna of the tropical Pacific. 
The results of other studies suggest the 
diet of wahoo is similar throughout its range. 
Welsh ( 19494 ; 22) made a preliminary exami- 
nation of the food of wahoo in the Hawaiian 
Islands, using a rating system which con- 
sidered total bulk of food, total number of 
food items, and the total number of times 
food was found in individual stomachs. Of 
the 17 stomachs he examined, 10 were empty. 
Those containing food held fish and squid. 
The food habits of the wahoo near Japan 
would seem to be nearly the same as in the 
Line Islands, for Kishinouye (1923: 412) 
states that they ”feed on calamaries [squid] 
and pelagic fish.” 
LENGTH FREQUENCY ANALYSIS 
An examination of the sizes of wahoo in 
our catches will contribute to our understand- 
ing of the biology of this species. In the Line 
Islands we sampled only a segment of the 
known size range of the species for small fish 
were not taken and much larger sizes have 
been recorded from other areas. Hosaka 
(1944: 69) reports a 124%-pound wahoo 
taken on sport fishing gear off the island of 
Oahu, and LaMonte (1952: 9) reports a world 
record for wahoo as 13314 pounds (6 ft., 11 
in.) caught in the Bahamas in 1943. 
The size distribution of longline-caught 
wahoo is similar in most respects to that of 
fish taken on trolling gear. The longline 
catches, most of which are from the open sea, 
were made over several years at all months 
of the year and show a prominent mode at 
128 cm. and a lesser mode at 146 cm. (Fig. 
4). These fish range from 54 to 198 cm,, with 
the majority between 106 and 162 cm. The 
measurements of troll-caught wahoo, taken 
mostly within 3 miles of land, during 1950, 
375 
Fig. 4. Size frequency distribution of longline- 
caught wahoo, October 1950 to March 1955. (Smoothed 
by a moving average of three.) 
1951, 1955, and 1956 show a similar size 
range, from 98 to 174 cm., and a similar 
distribution of sizes. It would appear then 
that both fishing methods sampled the same 
segments of a common population. 
Samples of wahoo from some islands show 
differences in length distribution between 
sexes. An example of this in distributions of 
wahoo taken at Christmas Island during 
March and April 1955 (Fig. 5) shows a slight 
displacement of modes. In the male distribu- 
tion there is a small mode at approximately 
114 cm. and a dominant mode at approxi- 
mately 134 cm.; in the female distribution 
there is a dominant mode at about 128 cm. 
LENGTH (CM.) 
Fig. 5. Size frequency distribution of troll-caught 
wahoo from Christmas Island during March -April 
1955. (Smoothed by a moving average of three.) 
