FISHERY BULLETIN: VOL. 71, NO. 4 

 Table 4. — Stomach contents of yellowfin tuna and spotted porpoise taken in a single net haul: Haul 3. 



Food item 



Yellowfin tuna, Thiiniuis cilhacare\ . 



20 stomachs 



(13 full, 3 with traces, 4 empty) 



Volume Number Occurrence 



Spotted Porpoise, Sicin-IUi iiiwiuitiui, 



20 stomachs 



(none full, 19 with trace, 1 empty) 



Number Occurrence 



ml 



No. 



No. % 



No. 



Total 



Fish 



Exocoetidae 



E\()Coein'< Villi tans 

 Unid. exocoetid 



Scombridae: 

 Auxis sp. 



Unid. fish 



Cephalopods 



Ommastrephidae 



Ommastrephid A (probably 



D(>sidicii\ ,i,'(>,'(/v) 

 Ommastrephid B (probably 



SyiuplcciiiU'iiihis sp.) 



Enoploteuthidae: 

 Ahruliopsi\ af finis 



Unid. Octopod 



Unid. Cephalopod fragments 

 Unid. Cephalopod beaks 



Crustaceans: 

 Portunidae: 



EuphyUix ilovii 



837 100.0 112 100.0 16 100.0 



379 45.3 12 10.7 



2 

 2 



tr. 



tr. 



37.5 



20 2.4 3 2.7 3 18.8 



18 2.2 1 0.9 1 6.3 



2 0.2 2 1.8 2 12.5 



320 38.2 4 3.6 1 6.3 



39 4.7 2 1.8 2 12.5 



3 0.4 78 69.6 8 50.0 



0.2 68 60.7 8 50.0 

 0.2 53 47.3 8 50.0 



14.3 



37.5 



0.1 — 



455 54.4 22 19.6 10 62.5 



75 100.0 — 100.0 



'75 100.0 



66 88.0 



32 42.7 



34 45.3 



19 100.0 



2 100.0 



2 100.0 



2 100.0 



— 



Specimens were preserved from two stomachs only; therefore the sample size for the cephalopod taxa is two. 



A striking difference between the data for 

 tuna and spotted porpoise on one hand and the 

 spinner porpoise on the other involved the rel- 

 ative number of empty stomachs encountered. 

 Only 1 tuna stomach of 14 and 3 spotted por- 

 poise stomachs of 25 were empty, whereas 15 

 spinner porpoise stomachs of 23 contained no 

 food remains. The chance of this difference 

 occurring by chance due to sampling error, 

 based on chi-square analysis and assuming 

 commonality of tuna and spotted porpoise, is 

 less than 0.001, indicating that in the aggrega- 

 tion fewer spinner porpoise than spotted por- 

 poise and tuna had been recently feeding or that 

 the spinner porpoise had regurgitated their 

 stomach contents during the fishing operation. 



The spinner porpoise had eaten smaller squid 

 than had the spotted porpoise and tuna. Clarke 



(1962) demonstrated that beak size within a 

 species is closely correlated with total body 

 weight. The sample of beaks of ommastrephid 

 A (probably Dosidicus gigas) collected from the 

 spinner porpoise clearly belong to a different 

 size distribution than those taken from the 

 spotted porpoise and the tuna (Figure 1), indi- 

 cating that the spinner porpoise on the average 

 had been feeding on smaller squid. 



Haul 3 



Only yellowfin tuna and spotted porpoise 

 were examined in Haul 3 (Table 4). The por- 

 poise stomachs were all nearly empty, contain- 

 ing only hard parts of squid. Except for the 

 complete absence of fish in the porpoise stom- 

 achs, the results for the two species were similar 



1084 



