FOOD OF BIGEYE AND YELLOWFIN TUNA 



79 



Table 9. — Distribution of the volume of stomarh contents of /,S9 yelloivjin and 166 bigeye caught by longline fishing in the 



central Pacific 



T.\BLE 10. — Summary of data relating average volume of stomach contents to condition of fish, whether dead or alive, at time 



of landing 



SUMMARY AND CONCLUSIONS 



1. This study is based on the quantitative 

 analysis of the stomacii contents of 166 bigeye 

 tuna {Parathunnus sibi) and of 439 yellowfiii tuna 

 {Neothunnus macropterus) caught at tlie same 

 time or nearly the same time as the bigeye. 



2. These tuna were captured in the central 

 Pacific during the period October 1950-Juiic 1953 

 by means of longline-gear fishing at deptlis of 

 150 to 500 feet. 



3. The food of the yellowfin consisted of fish 

 (62 percent by volume), squid (29 percent), other 

 moilusks (7 percent), and crustaceans (1 percent); 



the food of bigeye consisted of fish (62 percent), 

 squid (33 percent), other moilusks (3 percent), 

 and crustaceans (2 percent). 



4. Both species of tuna apj)ear to utilize a great 

 variety of animal food, ranging from small plank- 

 ton organisms to large squid and fish. Food items 

 of major importance to both spt^cies were pomfret 

 {Collybus drachme), snake mackerel (Gempylus ser- 

 pens), and squid of the families Ommastrephidae 

 and Loliginidae. 



5. This great diversity of diet suggests that 

 many forms of fish, squid, and shrimp — if available 

 through culture or capture might be eflTective as 

 live i)ait or longline bait in tuna fishing. 



