The same is true of anlnals which inhabl'-; waters of high constant temperature. 

 The kawanina . a hot springs form, always carries egps when found in hot springs, 

 but those at the periphery of the springs have definite egg-carrying periods. The 

 fact that the skipjack and tuna spawn over a long period even though they may have 

 an occasional prolific period is probably related to changes in water temperature. 

 Walford states that tunas spawn at 20- 100 fathoms and that following spawning, 

 the eggs float in the middle stratum of the sea. There may be some tuna which 

 spawn at the surface, as mentioned by Mr. Marukawa, but I believe that in search- 

 ing for eggs it is necessary to investigate the middle or lower strata. I also 

 believe that it is necessary in connection with a study on spawning habits that 

 the. food of large fish other than those which feed on young skipjack should be 

 studied. That tunas frequent deep waters is suggested by the fact that they eat 

 Splrula . a gastropod. 



Hatai : I wonder whether the fact that eggs are found throughout the year can be 

 interpreted to mean that the egg is carried in the ovary for a long time. Also, 

 If an oil layer envelops the egg they should float immediately aftor spawning. 

 What do you think of this? 



Amemiya : Such interpretations are possible, but they are still unconfirmed. If 

 one desires to seek small skipjack, I believe ha should look for other large fish 

 which prey upon the smaller ones. As Dr. Klshinouye uentloned, it is best to re- 

 cover Juveniles from natural collectors. 



Hatal ; However, in order to study this problem, wouldn't we have to restrict our- 

 selves to Juveniles; 



Amemiya t It would be a good idea to collect Juveniles by means of a jack-lamp. 



Marukawa ; The use of a Jack-lamp may be a good idea. The Hakuo W.-iru is collecting 

 small fish in the South Seas by means of a Jack-lamp. 



Amemiya ; It Is said that the skin of skipjack becomes coarse after spawning. 



Marukawa ; It is said that those which have spawned become reddish in color. 



Amemiya ; There are skipjack which follow those ^hich have been hooked. On one 

 occasion, a swordfish extruding eggs was caught. 



Takeda ; It seems that other fish accompany tl-e albacore when it is caught. 



Hatal ; f.5r, Takagi, have you anything to say? 



Takagl t I am definitely not acquainted with the subject of skipjack and tuna snawn- 

 Ing, I am, however. In support of this new program. On the basis of information 

 presented by individuals having practical experience, it seems that mature skipjack 

 are not difficult to catch and that artificial fertilization is a great possibility, 

 Embryological research on skipjack through selection and training of qualified per- 

 sonnel will not only be a great contribution to genetics, but I believe that it 

 will also be basic to the expansion of the fisher/. Therefore, I hope that this 

 project will be" Initiaterl immediately, whatever the cost. 



Hatal ; In regard to the question of steps to be taken on the study of skipjack 

 spawning grounds, I will read today's proceedings carefully and will draw un a 

 plan for your comments at the next meeting. We have heard a great deql on the 

 subject matter, but only a verv small part is clear so that the problem remains 



Itti 



