This indicates that the species which occurs at the greatest depths 

 is the big-eyed tuna, followed by the albacore, and that the yellowfin 

 lives in the shallowest levels, fe have no results from any such study on 

 the spearfishes, but they are known to be generally distributed in the 

 shallow strata. The vertical distribution of these fishes differs between 

 night and day, it being thought that they generally go deep during the 

 day and swim at shallow levels at night. 



The present author has shown, in the results of the surveys of the 

 Shonan Maru, that these fishes occur at far greater depths than was indi- 

 cated by Dr. Kishinouye, however, these data were from the warm seas of 

 the south while Dr. Kishinouye 's observations were made in the coastal 

 waters of Japan proper so the differences of environment must be fully 

 taken into consideration. 



Our discussion of vertical distribution is, after all, based on the 

 construction of the fishing gear, so I will here present a brief descrip- 

 tion of this gear. 



In the longline gear in general use, as is shown in Figure U, there 

 are no floats attached to the branch lines. The gear used by the Shonan 

 Maru, as shown in Figure /ib, had floats attached to each branch line. The 

 number and lengths of the branch lines and the lengths of the float lines 

 are not uniform but vary as between regions and individuals. If we com- 

 pare the two sets of gear in the figure, we see that the tyoe used by the 

 Shonan Maru is always subject to one limit, that is, the hook cannot go 

 any deeper than the float line plus the branch line (including the sekiyama 

 and the vdre leader) , while the other gear has two limits, one when two 

 floats are right together and the other when the trunk line is at full 

 stretch, however, in any other case it is not easily possible to determine 

 the depths at which the hooks are. 



The results of the experimental fishing carried on in the waters 

 east of Formosa v/ere qs follows: 



Table 11 Catch at Various Depths (1935, Shonan Maru) 



33 



