When their movements are restricted hy their being placed 

 in a confined space or caught in a net or on a hookj, their 

 resistance is very weak and they die in a short timeo Ordinarily 

 just before they die they are seen to go into vxolent convulsionso 



They are fearful of nets and so forth, and they will not, 

 until danger threatens, try to get out of nets which have such 

 large meshes that they could easily pass through themo For this 

 reason even though the meshes may be very large in the leads of 

 trap nets, they are able to cut off the movements of the fish 

 and direct them into the trapo 



According to Dro Kishinouye, in their migrations the 

 males first appear most abundantly, then the females gradually 

 increase in numbers, and finally the females become most numerous. 



iio Food habits 



The tunas are carnivorous and are generally voracious,, As 

 fish which swim in the open seas, they have in general the 

 feeding habits of plankton-f eederso In many cases they feed on 

 planktonic crustaceans, argonauts, and the small fish which 

 accompany floating logs, and such things as jellyfish are also 

 found from time to time in the stomach contents, In the overall 

 picture squids are the most numerous, but in the last analysis 

 it is probably correct to consider that they feed on whatever 

 animals are most abundant and easiest to catch in the waters 

 in which they occuro Consequently, even assuming that they have 

 taste in foods and that they select what they eat, it is hard 

 to believe that these characteristics are very pronouncedc 



IThen it comes to large tuna, there are cases where they 

 have eaten mackerel and frigate mackerel up to 40 cmo in length, 

 and judging from their position in the stomach it is thought 

 that they are swallowed head firstc An examination of fish which 

 have been eaten in this fashion commonly shows scars from bites 

 on the trunk, and therefore it is thought that the tuna first 

 bites from the side and gives a fatal wound after which it 

 swallows its preyo 



In general they eat live food, but they are not limited 

 to such food, and in the case of bait used on hooks they will 

 take dead or even salted fisho When they are moving on the 

 surface of the water they will even bite on artificial lures„ 

 When they take the bait they are said to attack it at extremely 

 high speed and then to dive deep turning obliquely to the rearo 

 If we consider the manner in which the fish actually move when 

 they are hooked on longlines, the spearfishes and sharks for 

 the most part attempt to escape horizontally and in their 

 struggles they tangle the branch lines, but the tunas generally 

 try to escape in a vertical direction and thus rarely tangle 



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