Table 22. --Analysis of variance of bait return by kind of bait and sea 



condition, Hugh M. Smith cruise 18 (based on data in table 33) 



the sardine vs. squid experiment, visibility was considered to be the factor 

 responsible for the higher catch of yellowfin and bigeye with sardine baits. From 

 this it might be reasoned that albacore, considered to be a very deep-swimming 

 fish in equatorial waters, would be caught in greater nvunbers on sardine baits. 

 That this was not true is shown by the almost equally divided catch of 10 albacore 

 caxight with sardine baits and 12 with squid baits. The distribution of the skip- 

 jack catch also differed from those of yellowfin and bigeye, with a catch of 19 

 skipjack on squid and only 9 on sardine. However, viaibility is possibly not as 

 important a factor with this surface species as It is for the deeper swimming 

 tunas, and if this were true, differential bait retention on the shallow hooks may 

 have been the cause of the discrepancy. 



One of the objectives of this study was to determine whether the various 

 baits and baiting methods used in tuna longline fishing modify the catch rates 

 stifficiently to affect their comparability when used as indices of tuna abundance. 



24 



