Table 7. --Percentages of small 



medium, and large albacore in 



o 

 the North Pacific catch at 140 - 



150 E. by nnonth and by latitude 



Fish under 75 cm. 



Fish over 95 cm. 



Note: Underlining shows where 

 more than half of the fish were 

 in that length group. 



Data are lacking for March 



from south of 28 N. , so it is not known 



to what extent the fish of 75 to 95 cm. 



o 

 have moved south. South of 28 N. in 



January and February, however, alba- 

 core above 95 cm. in length predominate 

 overwhelmingly, and in April and May 

 also in this area fish above 95 cm. 

 make up almost all of the catch, so it 

 seems likely that not many of the medium- 

 sized albacore come south of 28 N. Con- 

 sidering these various points together, 

 it is thought that the smaller the fish, 

 the farther north the position at which 

 the various size classes of albacore stop 

 their southward progress. Albacore 

 above 95 cm. in length are thought to 

 pass south of the Subtropical Convergence, 

 but more will be said about this later. 



The depth at which albacore are 

 caught is thought to be related to various 

 factors such as oceanographic conditions 

 and weather conditions (for example, the 

 amount of light in the water), but not 

 much is known because of the inadequacy 

 of the data. According to the data pre- 

 sented below, the efficiency is highest 

 on the branch lines which reach the 

 greatest depths. We find exceptionally 

 cases in which there is almost no diff- 

 erence in the number of fish taken by 

 the deepest hooks (145 to 150 m. ) ajid 

 those next deepest (120 to 125 m. ), but 

 in the Sagami Maru's case hooks num- 

 ber 3 and number 5 are at almost the 

 same depth. Catching efficiency appears 

 to drop considerably on the shallowest in 

 hooks (85 to 95 m. ). The data are given 

 in tables 8 and 9. 



Table 8. --Depth of capture of albacore. (a) Results of Sagami Maru's 



investigation, March 1950, at 28 -30 N. , 170 



175°E. 



Note: See table 6 for water 

 temperatures and size of 

 fish. Hooks 1 and 7 are 

 shallowest, 4 deepest. Actual 

 numbers of fish caught. 



107 



