thermocline or the measured depth of the line. However, summaries of the catches of the four 

 cruises by station and relative hook depth indicate that on three cruises ( Manning cruises 12 and 

 13 and Smith cruise 18; tables 13, 15, and 16) there were no significant differences in the catch 

 of yellowfin among the three hook levels, although the shallower hooks caught fewer fish. On 

 two of these cruises Bendix depth recorder records (tables 11 and 12) indicate there was consider- 

 able current-induced streaming of the line. This would, of course, reduce the depth differential 

 between shallow and deep hooks, and less difference in catch should be expected. On the Cava - 

 lieri cruise (table 14) yellowfin were taken in significantly greater numbers on the deep hooks, 

 but there are no records of the depths fished by the line. 



On all four cruises more bigeye were taken on the deeper hooks, but the differences 

 were statistically significant on only two (Cavalieri and Manning cruise 13). The only cruise on 

 which albacore were taken in any number ( Manning cruise 13, table 15) indicated a much greater 

 catch on the deepest hooks. 



Table 1 1. --Measurements of buoy interval and line depth. Smith cruise 18 



\_l Based on the mean setting buoy distance as estimated from t 

 time. 



he setting speed and 



23 



