Table 9. — Chl-square analysis of five methods of baiting herring 

 and a summary of total catch, Cavallerl cruise (based 

 on a total of 120 hooks per method of baiting) 



Bal t re turn 



Total catch 



In summarizing the results of the baiting experiments. It appears that 

 the significantly higher returns of double-hooked sardines were due to loss of the 

 single-hooked baits during the hauling operation. The evidence for this statement 

 is the lack of difference in the catches by the two methods. In the case of the 

 herring the difference in returns is of a greater magnitude, almost 3 times as many 

 double-hooked as single-hooked herring have been retrieved, and furthermore it 

 appears that a portion of the differential loss of single-hooked herring occurs 

 during the soaking period, as Indicated in one experiment (table 7) by the lower 

 catches on single-hooked baits. Obviously this difficulty can be overcome by 

 double hooking the herring. 



KIND OP BAIT 



Food studies undertaken by various authors (Klshlnouye 1917, Nakamura 

 1950 and 1952, and Reintjes and King 1953) indicate that almost any pelagic marine 

 organism of a suitable size may become food for tuna. However, a survey of the 

 literature showed only a few experiments directed to a study of food preferences 

 of the tunas by using different kinds of bait. One experiment conducted in 1951 

 on the Japanese research vessel Sag ami Maru (Anonymous 1952) resulted in the gen- 

 eral conclusion that the various tunas and marllns do not discriminate between 

 frozen saury, Colalabis aaira (Brevoort), and salted sardine, S ardinia melanostlca 

 (Temminck and Schlegel) . Murphy and Otsu (1954), in their analysis of the catches 

 of Japanese mothershlp expeditions, reached the same conclusion from a comparative 

 study of the catch rates made by these two baits. 



Further experiments were carried out by POFI to determine whether there 

 were differences in catch rates with four kinds of bait, and if so to ascertain 

 whether the differences were due to preference on the part of the fish or to 

 superiority of the bait with respect to staying on the hook. The three experiments 

 compared mullet vs. herring, sardine vs. squid, and sardine vs. herring. 



10 



