cor-cerning the cuy.jecb. In 1907, I made a tour of about two weeks aboard the 

 Ka^^-abusa f'iaru of the Fisheries College, which made a hydrobiological sui'vey of f5.sh- 

 dng £i'ounds centered around Izu Oshima, At that time, a small fish was obtained 

 from the stomach of a dolphin. This was reported as a young skipjack, but Dr. 

 Kishinouye late? stated that the specimen was probably a young frigate-jnackerel. 

 Dr. Kishinouye subsequently started to study skipjack young and requested all fish- 

 eries experimental stations in the coujitry to forward to him stomach contents of 

 skipjack. JuTfeniles were caught in larval nets used near the Toshima Islands of 

 Kagoshina, These specimens, said to be most likely the young of skipjack, have al- 

 ready been reported upon by Dr. Kishinouye at the Pan-Pacific Congress. I believe 

 it can be said that no further scientific studies have been conducted on skipjack 

 and tuna since Dr. Kishinouye' s work, 



I, too, was constantly on the lookout foi; young fish and had skipjack juve- 

 niles recovered from the stomachs of skipjack being processed into dried sticks un- 

 der the supervision of Mr. Kawakami of the Nanko Fishing Co., Ltd. About 20i4 

 specimens have been gathered to date and are repoaited with the Fisheries Experi- 

 mental Station in Tolcyo, 



These specimens (shown in figure) vere found in skipjack taken e t Amarai -Oshima 

 in 1922. About half of these were collected at the Nanko Fishing Co., Ltd. Juve- 

 niles of big-eyed tuna measuring 3.5 to 3.6 su n (4.2 to 4.3 inches) were found in- 

 side yellowfin tuna taken by longlines in the Tokobei area last year, while I was 

 in Palau, by a ship of the Fisheries Experimental Station. In May, 1934, a report 

 of a large school of blue-fin tuna was received from the Shoy5 Maru of the Kagoshima 

 Prefectural Fisheries Experimental Station. Eggs were collected with a plankton net 

 and samples were forwarded to us. These eggs were presumed to be those of tvina and 

 upon examination, were found to be pelagic eggs covered with an oily layer. A large 

 number of blue-fin tuna are caught in the Luzon Straits each year around May. The 

 fishing season is from April to June. When the stomachs of fish caught in May are 

 cut to remove the livers, careful observations of the reproductive organs reveal the 

 ovaries to be of considerable size. The ovaries are extremely well developed in the 

 early part of May, but are said to become smaller between the middle of May and the 

 early part of June together with a loss of weight in the fish. This is based on 

 statements made by members of the Foraosa Fisheries Experimental Station. In tVakasa 

 Bay, the gonads are large in June; in the Japan Sea, spawning probably takes place 

 in June. Technician Shimoda of the Ministry of Agriculture and Forestry visited 

 Java, the Sulu Sea, and the Celebes area eight years ago and returned fdth ovaries 

 of yellowfin tuna from this region. They measured from five to six sun (6 to 7.2 

 Inches) in length and from one and a half to two sun (1.8 to 2.4 inches) in diameter. 

 The fish from which these ovaries were taken were caught In May and June. I thought 

 that the ovaries were fairly well developed and this led me to wonder whether spawn- 

 ing takes place In May or June in the Java, Sulu, and Philippines area. In 1913 and 

 1914 the Fisheries College conducted an experiment using purse seines to catch tuna 

 near Hahajlma in the Benin Islands. At that time Mr. Kamishiro Kumada squeezed the 

 bellies of tuna caught by the net and obtained eggs, these were placed in a cup for 

 artificial fertilization, but the experiment failed because of the inability to cap- 

 ture a mature male. However, the eggs were retained and brought back. Mr. Kumada' s 

 experiment was the only attempt at artificial fertilization of mature eggs. It was 

 decided recently to conduct similar tests under Director Hatai, but I believe that 

 the experiment cannot be carried out without difficulty because of its complexities. 

 I am billing, however, to give all possible assistance to this project, I wanted to 

 go to Palau last year to study the spawning season of skipjack, but I arrived there 

 between November and January so that I was unable to find a mature ovary among those 

 which I examined. I requested Mr, Kawakami to gather data on the length of the fish, 

 the condition and size of the gonads, the number of vertebrae, etc. In addition, 1. 



