This may in part be related to the relative inconspicuousness of the smaller fish, but more likely 

 is related to the speed of handling. Most shark damage occurs at the surface while a hooked fish 

 is being hauled in, and small fish like skipjack are landed with considerably more celerity than 

 large fish such as bigeye. This indicates that shark damage can be considerably lessened by re- 

 ducing the "playing time" in bringing fish aboard. 



Table 19. --Summary of shark-bitten tuna (by species), Manning cruises 11, 12, and 

 13, Gilbert cruise 1, Cavalieri cruise 1, Smith cruise 18 



SUMMARY 



1. During the period August to November 1952 there were four longline fishing cruises to the 

 equatorial Pacific between 120 W. and 170 W. longitude. 



2. Upwelling was very intense at the Equator on 120 W. longitude. Yellowfin catches were low 

 in this upwelled water, suggesting that the water had not been in the photosynthetic zone long 

 enough to have developed a favorable food supply. 



3. Along 130 W. longitude upwelling was somewhat less intense than on 120 W. , and in the zone 

 of upwelled water moderate quantities of yellowfin were taken. 



4. Two sections along 150 W. longitude and one along 140 W. gave evidence of moderate upwell- 

 ing. Along these sections there was a nnarked concentration of yellowfin tuna to the north of 

 the Equator. 



5. Compared with the results of other cruises, there was only moderately good fishing along 

 150 W. longitude in August and October, although good fishing was experienced during the in- 

 tervening month (September). This may be an indication of the magnitude of the ahort-terna 

 fluctuations to be expected in that region. 



o. Albacore were relatively abundant a few degrees south of the Equator on the western section 

 (169°W. longitude). 



7. Japanese commercial fishing in the region of 170 W. - 180 longitude showed bigeye relatively 

 abundant north of 5 N. latitude, and yellowfin relatively abundant south of that latitude. Catch 

 rates of the Japanese vessels were almost identical with catch rates of POFI experimental 

 fishing. 



29 



