grounds and the movements of the schools, but the movements of the 

 fishing boats are also based on econonnic considerations. Given the same 

 requirement of labor and capital, it is more profitable to fish for large 

 fish than for small fish as long as there are no great differences in the 

 catch rates. As stated above, the breadth of the fishing grounds from 

 north to south is from 200 to 250 miles, but there is a possibility that 

 schools of smaller fish are migrating farther to the north. To under- 

 write our estimate of this possibility, it is known that occasionally on 

 the northern extremity of the fishing grounds astonishingly high catch 

 rates are made on schools of small fish. 



There are almost no data on oceanographic conditions in this area 

 for October. There is a particular dearth of data regarding current boun- 

 daries and vortices, which are thought to have a particularly important 

 connection with fishing conditions. Tables 4 and 5 present postwar data 

 on surface water temperatures and fishing conditions from commercial 

 fishing vessels. 



Table 4. --Surface water temperature and catch rate (170°E. -175°E. ) 



Table 5. --Surface water temperature and catch rate (145 E.-150 E.) 



19 



