The albacore, Genno alaltinga (Gmelln) , catch of 22 was almost equally 

 divided between sardine and squid baits, with catches of 10 and 12 respectively. 



Sardine vs. Herring 



Experiments were conducted on Manning cruise 14 and Smith cnilse 18 

 (October-November 1952) to test for differences between sardine and herring, the 

 most common baits available to U. S. fishermen. On the Manning cruise both types 

 of baits were single-hooked through the eyes, whereas on the Smith cruise the 

 herring were double -hooked. 



A summary of the analyses for the Manning experiment testing single- 

 hooked sardines and herring is given in table 12. The results are arranged in 

 accordance with the catch, i.e., when considering total catch the bait returns for 

 all stations are utilized, and the bait analyses for individual species are based 

 only on those stations at which the particular species were taken. Considering 

 the total catch, 95 fish were caught with sardine and only 77 with herring, but 

 the difference was statistically non-significant (P>0.05) even though 3.5 times 

 as many sardine as herring were retrieved. As in the previous experiment on sar- 

 dine and squid, there was a significant interaction chi-square (P<0.01). A study 

 of the individual tuna species shows that more yellowfin, blgeye, and albacore 

 were caught on sardine. However, the statistical tests showed that only in the 

 case of the albacore was the catch on sardine significantly higher thsm the catch 

 on herring (pooled x2 ■ 7.20, P<0.01). Of a total of 20 albacore caught, only 

 4 were taken on herring. The great difference in bait return at stations with 

 albacore catches (4.6 times as many sardine as herring) suggests that this dif- 

 ference in catch may be attributable to a differential availability of the two 

 baits during the fishing period, and that the nearly equal catch of yellowfin sind 

 bigeye was the result of a smaller aifferentlal in bait return. This then sug- 

 gests that the factor(s) responsible for the differential availability of oait 

 cheinged in intensity from station to station. 



The second experiment on sardine and herring ( Smith cruise 18) does not 

 parallel that carried out on the Manning , for in this trial the herring were 

 double-hooked and the sardine single -hooked. The similarity of the bait returns 

 in this instance (table 13) clearly indicates that double hooking overcomes the 

 differential loss of herring. The total catch and the catches of the individual 

 tuna species show virtually no differences between the two kinds of bait. 



It is evident that the bait return is a function of loss during fishing 

 plus loss during setting and hauling. It appears that at times differential loss 

 during hauling is responsible for differences in returns, e.g., in the single- 

 and double-hooked sardine experiment the differences in bait return are not 

 reflected in the catch. At other times, usually characterized by very high dif- 

 ferential returns, e.g., in the single- and double-hooked herring experiment, the 

 differential loss is reflected in the catch, indicating that part of the bait loss 

 occurred during the soaking period. Indication of a further confounding factor 

 in the experiments is the shift in relative return within an experiment (cruise). 

 This is shown, for instance, in the presence of interaction in bait return in some 

 of the groups of data in table 12, and Its absence in others. An explanation of 

 this phenomenon is advanced in the following section on environmental factors. 



ENVIRONMENTAL FACTORS 



Thus far only certain physical factors of baiting and the baits 

 themselves have been considered in determining bait loss. Bait stealers (tunas, 

 small fish, and invertebrates) and sea conditions also appear to affect the bait 

 during the soaking and retrieving periods. 



Bait Stealing 



The larger tunas themselves have been noted to take more than one bait, 

 as Indicated by the results of stomach examinations shown in table 14. Of a total 

 of 822 stomachs examined, 695 (84.5 percent) contained no bait fish, 112 (13.6 

 percent) contained one bait, and 15 (1.8 percent) held two or more baits. This 

 would Indicate that in most cases the bait is lost at the time of capture. Even 



13 



