there was, as is shown in Table 16, only 10 - 30$ mortality in an experi- 

 ment which continued for 3 hours at 30°C. As Table 17 shows, a mortality 

 rate approaching total destruction was obtained only as the result of an 

 experiment of an hour and a half's duration at the high temperature of 

 32°C. 



Looking at these results it can be seen that anchovies have greater 

 resistance to high water temperatures than have sardines,, 



2) Resistance to low temperatures 



According to Table 18 , when sardines which at the time of the 

 experiment were living in sea water with a temperature of about 22°C were 

 transferred directly into an experimental tank with sea water at the low 

 temperature of 8°C, there were no deaths even after three hours and a 

 half, andj as Table 19 shows, even when they were placed in a tank with 

 sea water at 6°C, there was only 5 - 10$ mortality after three and a 

 half hours o However, the anchovies which were taken at the same time 

 as these sardines and which were kept after capture in the same holding- 

 net, had a mortality, as shown in Table 20 and Table 21, of 25 - 30$ at a 

 water temperature of 8°C (which had caused no mortality at all among the 

 sardines) . 



Looking at these results it can be seen that sardines have greater 

 resistance to low water temperatures than have anchovies. 



According to these experiments, the anchovy can resist high tempera- 

 tures (sudden rises in water temperature) better than the sardine, and 

 the sardine can resist low water temperatures (sudden drops in water 

 temperature) better than the anchovy, Tne range of livable water tempera- 

 tures is about 7° - 29° for the sardine and 11° - 31° for the anchovy. 



These are the results of experiments with bait fish from the Pacific 

 coast of central Honshu made during early summer when the sea water 

 temperature was approximately 22°C, and it may not be possible to apply 

 them generally. At a different season, with fish from a different 

 locality, or with fish which had been adapted to gradual changes in 

 temperature, it is thought that, if we follow Loeb's theory of immuniza- 

 tion to temperature changes, the fish would be able to survive somewhat 

 higher and somewhat lower (the possibility is greater in the case of the 

 latter) temperatures than the results of these experiments indicate. At 

 any rate these results are well supported by the fact that the most 

 experienced operators say that sardines are weak at high temperatures and 

 strong at low ones while anchovies are just the opposite, and the fact 

 that generally sardines are distributed in the cold northern regions while 

 anchovies are found in the warm south. 



Next I shall attempt to say a word concerning the condition in which 

 bait fish die of such sudden changes in water temperature and the reasons 

 for this mortality. 



25 



