Amo.ig the fii-hes those which appce.rod most commonly urere Engraulia. Ostracion, 

 Balistes , Sphy raena . Ty losunis , Stolepho i nig . Scombroid [sic], and Lsio gnathus . 



The above are all either pelagic, or, if they are shore-dwelling species, they 

 have the characteristic of moving about accompanying floating driftwood, so it is 

 not strange that they should form part of the food of yellowfin tuna. It can only 

 be said that on the score of the number of stomachs in which they appeared and the 

 number of specimens which vrere found the results were different from what had been 

 anticipated. 



It was said that in the course of investigations in the field flyingfish ap- 

 peared from time to time, but in ray investigation not a single specimen was found. 



Along with these food items were some crustaceans vAiich were plentiful both in 

 number of appearances and number of individuals and which were all bottom-dwelling 

 formSo This fact is probably related to some extent to the position of the fishing 

 grounds, but it can serve as evidence to show that yellowfin have the characteristic 

 of hunting food on the bottom at times. 



T?hen these demersal forms were found, as mentioned above, there were also 

 found a large number of pebbles of about one centimeter in diameter along with the 

 decayed leaves of trees. Prom this it is thought that the yellowfin migrates much 

 closer in to the shallow coastal waters than had been expected, however, it is not 

 difficult to imagine that this is true in the case of small islands far out in the 

 sea where the effect of the land mass on the sea water would be extremely slight. 



Among the purely planktonic forms found in the stomachs of the yellowfin there 

 were some Jellyfish, but the number of a^ipearances and the number of specimens were 

 small. Judging from the aforementioned point about the doubt which exists as to 

 the powers of food selectivity of this fish, it is a question irtiether or not the 

 yellowfin ate these jellyfish consciously. Perhaps they were swallowed accidentally 

 along with other small fish. 



It was mentioned above that there is probably some relation between the posi- 

 tion of the fishing ground and the food habits of the fish. This is what one would 

 naturally imagine, and in view of the fact that the yellowfin tuna is to begin with 

 a rather omnivorous animal, there is no room for doubting the truth of the assertion o 



On the first cruise there were five fishing stations at which the fish had 

 eaten large numbers of bottom-dwelling organisms; these were stations VIII, X, XII, 

 XIV, and XVI, The same was true of eight stations, I, II, III, VII, IX, XIX, and 

 XXIV, on the second cruise. It is unfortunate that there was no material from 

 stations IV, V, and VI of the second cruise, but the stations of the first cruise 

 ^rtiich are listed above and stations I - VI of the second cruise were all located 

 around Karakelong Island or close in to other islands. Furthermore, the rest of 

 the stations of the second ciniise for the most part present characteristics approxi- 

 mating these conditions. For this reason it may be said that the same sorts of 

 phenomena appeared in the same sea area or in sea areas presenting the same kinds 

 of conditions. In other words, one may regard food habits as being controlled by 

 geographical considerations. 



In this way it was possible through a study of its food habits to gain soae 

 knowledge of the yellowfin tuna's vertical movements (7). If it were possible to 

 ascertain the depths and environmental conditions in irtiich these demersal organisms 

 live, we could probably further enlarge our knowledge of the interesting habits of 

 the yellowfin tuna. 



