spearfish some specimens which are about to spawn or are engaged in spawning are discovered. 

 The author has previously made some observations in the South SeasJLi' on the ripe eggs of the 

 sailfish. The juvenile sailfish have a strongly marked positive phototropism, and in the waters 

 east and south of the island they are taken from time to tinne with night-lights. The fishery 

 experiment stations of both Takao Province and Taihoku Province have specimens under 20 cm. 

 in length which were taken in this manner, and in this laboratory several specimens of about 

 30 cm. are preserved that were taken in the same manner off Hong Kong. Among the sailfish 

 that are taken in set nets along the coast of eastern Taiwan in the summer there are individuals 

 with highly developed gonads. Of course, they are still quite a way from having ripe eggs, but 

 it is thought that they are not too far off from spawning. Considering the appearances of juveniles 

 and the degree of ripeness of these ovaries, it is possible to imagine that the sailfish spawn 

 sonnewhere not very far from Taiwan. 



Among the spearfishes which migrate into the waters east of Taiwan in the winter, the 

 gonads are very immature and in many cases it is difficult to distinguish the males and females 

 with the naked eye, but it is clear that spawning is being carried on by the shortnosed spearfish 

 occurring farther off shorel"/. 



The research vessel Shonan Maru of this laboratory on November 22, 1936, fished a 

 station at 21 46i30"N., 124°22'30"E. , and at 2:00 P.M. one shortnosed spearfish was brought 

 aboard still alive. When lifted out of the water, the fish released eggs all over the deck. This 

 fish was captured on a branch line 60 m. long, and since wooden floats had been placed above 

 each of the branch lines, the depth at which the fish was hooked was not greater than 60 m. Since 

 it is probable that because of the force of the current the branch lines hang at sonnewhat of an 

 cingle in the water, in actuality the depth at which the fish bit was probably 10 or 20 percent less 

 than 60 m. The observations recorded in the field notebook were as follows: 



The air temperature at the station at noon that day was 24.6 C, atmospheric pressure 

 was 763 nnm. , the sky was clear, surface water temperature was 25.8 C. , as was that at the 

 60 m. level. A thermometer inserted into the anus of the shortnosed spearfish showed a body 

 temperature of 25.4 C. The snout of the fish was slightly broken, but the distance from the tip 

 of the snout to the keels on the caudal peduncle was 1, 524 mm. and the weight of the fish was 

 12.3 kg. 



The eggs that were released were preserved in alcohol and brought back, but as they had 

 already become white and opaque it was not possible to see their internal structure. The size of 

 the eggs was about 1 mm. The ovarian eggs of this specimen were preserved by freezing together 

 with the fish and when they were looked at later it was found that they were very poorly developed, 

 the eggs were small, and the oil globules were clustered like grapes (plate 11). At the same time 

 a number of other specimens captured were investigated and the majority of them had the gonads 

 either ripe or nearly ripe so that it was possible to nnaike observations of a large number of ripe 

 eggs. The eggs in the ovaries that were thought to be nearly mature were almost colorless and 

 translucent zmd the yellowish-brown oil globules had united until there were only two of them 

 (plate 11). The eggs at this stage of development had a diameter of about 0.8 mm. According to 

 the observer who witnessed the release of the eggs they were released in a whitish mucus and 

 were almost colorless and clear. 



The gonads of both males and females are of a peculiar form as was pointed out in section 

 I (plate 11). 



There is thus no doubt that spawning of the shortnosed spearfish takes place off the eastern 

 side of the island, but we may consider further that the spawning of the spearfishes probably does 

 not, as in other fishes, take place in great groups over a very short period of time, but probably 

 continues over a long period and over a broad area of the sea. The reason for this belief, 



15/ 

 — Nakamura, Hiroshi. Zool. Mag. 44, 244, 1932 



16/ 



Nakamura, Hiroshi. Zool. Mag. 49, 233-238, 1937 



36 



