178 



U.S. NATIONAL MUSEUM BULLETIN 291 



2 ■! <> 



Figure 67. — a, c, Total number of 3-meter IKMT tows (clear area) and number of 

 successful tows (hatched area) at 250-meter increments in the Drake Passage (a) and 

 Drake Passage Convergence (c). b, d. Percentages (clear area) of total number of 

 3-meter IKMT tows (hatched area) that captured Bathyteuthis abyssicola at 250-meter 

 increments in the Drake Passage (b) and Drake Passage Convergence (d). 



In the Atlantic sector of the Antarctic Ocean 12 successful tows were 

 made from a total of 34 tows; the tows, 35.2% successful, averaged 

 0.82 specimens per total tow. Under the Convergence Zone only three 

 tows were attempted; all were successful and averaged 1.67 specimens 

 per tow (Table XII). Only 1 of 11 tows between 500-1000 m in 

 the Atlantic sector was successful , while 4 of the 8 tows between 1000- 

 1500 m were successful. The few deeper tows attained 100% success in 

 the 2000-2250 m range, but this was offset by the unproductive shallow 

 tows (Table XIII, fig. 66a, b). The combined success of Atlantic tows 

 was 40%. 



In the Drake Passage 16 (55%) of the 29 tows were successful in 

 catching B. ahyssicola for an average of 1.65 specimens per total tow. 

 Fifteen of eighteen tows (83.5%) in the Drake Passage Convergence 



