62 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



few references pertaining specifically to the food 

 of bigeye. Suyehiro (1942) desciibes this species 

 as a very voracious fish and lists the following 

 items as appearing in its food: amphipods, shrimp, 

 cuttlefish, squid, sardines, sauries, bonitos, needle 

 fish, and a viper fish. In the report of the South 

 Seas Tuna Fishery Investigations for 1950 (,Kan- 

 agawa et al. 1951), the food of 27 bigeye is shown 

 to include the following: 7 squid, 1 octopod, 3 deca- 

 pod Crustacea, 1 fan fish, 15 needle fish, 1 file fish, 

 6 pomfret, and 4 lantern fish. This suggests that 

 the bigeye, like many other tunas, has a varied 

 diet. 



A large number of the tuna stomachs reported 

 on here were examined by John W. Reintjes, 

 Sueto Murai, and T. J. Roseberry, former em- 

 ployees of POFI. We appreciate their services 

 in a difficult and generally disagreeable task. We 

 are grateful to other staff members of POFI for 

 assistance in handling these large fish aboard the 

 vessels and in removing and preserving the 

 stomachs. 



SOURCE OF MATERIALS 



This report is based on examination of 439 

 yellowfin and 166 bigeye stomachs collected on 11 



cruises of Fish and Wildlife Service vessels during 

 the years 1950 to 1953 (table 1). The yellowfin 

 data include 125 stomachs collected in 1950 and 

 1951 and previously reported on by Reintjes and 

 King (1953). These collections and the additional 

 314 yellow^n stomachs obtained in 1952 and 1953 

 were obtained at the same stations, or near the 

 same stations, as furnished the bigeye stomachs 

 included in this report. The sampling area (fig^ 1), 

 extended along the Equator between M aufim^ 

 119° W. and 180° and approximately from lat- 

 itude 17° N. to latitude 14° S. at its greatest width. 



The tuna were captured by longline at depths 

 of about 150 to 500 feet. This method of fishing, 

 as practiced by POFI, has been reviewed by 

 Murphy and Shomura (1953a); the design and 

 construction of the gear was described by Niska 

 (1953). 



Only fish caught 25 miles or more from land are 

 considered in this study ; therefore local differences 

 due to reef faunas should be reduced to a mini- 

 mum. The sampled fish varied widely in size, 

 from 87 to 172 cm. fork length for the yellowfin, 

 and from 77 to 196 cm. fork length for the bigeye 

 (fig. 2). Weights of fish given in this paper were 



20° 



— 10° 



10° 



180° 



170° 



160° 



150° 



140° 



130° 



120° 



Figure 1. — Locations of the stomach collections of yellowfin and bigeye tuna captured by experimental longline fishing 



in the central Pacific, 1950-53. 



