FISHERY BULLETIN: VOL. 70, NO. 4 



De Jager, de V. Nepgen, and van Wyk (1963) , 

 de V. Nepgen (1970), and Penrith (1963) re- 

 ported that the food of yellowfin tuna caught off 

 South Africa consisted mainly of fish. De Jager, 

 de V. Nepgen, and van Wyk stated that lantern- 

 fish and anchovies occurred more frequently in 

 the diet of yellowfin tuna than in the diet of other 

 species of tunas; crab megalopae were by far 

 the highest ranking crustaceans. Fish in de V. 

 Nepgen's (1970) study consisted chiefly of gar- 

 fish, lanternfish, and mackerel (Scomber japon- 

 iciis). Most of the forage fishes reported by 

 Penrith (1963) were surface fishes (Scomhere- 

 sox saurus, Coryphaena hippurus, juvenile 

 Bramidae). Among crustaceans Penrith (1963) 

 found that yellowfin tuna fed chiefly on the deep- 

 living prawn, Funchalia woodwardii. Megalo- 

 pae also played an important role in the food 

 of yellowfin tuna and were more important than 

 amphipods. Mollusks consisted of unidentified 

 cephalopods (squid), heteropods, and pteropods. 

 In our study lanternfish and mackerel were un- 

 important as forage for yellowfin and skipjack 

 tunas, and anchovies were not eaten by yellowfin 

 tuna but occurred in great numbers in the diet 

 of skipjack tuna; megalopae were among the 

 highest ranking crustaceans. From a high num- 

 ber of forage fishes listed by Penrith (1963) only 

 unidentified Carangidae, Naucrates ductor, uni- 

 dentified Priacanthidae, Priacanthus sp., Acan- 

 thuridae, Scombridae, Balistidae, Blennidae, 

 Bramidae, Coryphaenidae, Coryphaena hippur- 

 us, and Syngnathidae were also observed by us. 

 Crustaceans common to Penrith's and our study 

 were stomatopods, amphipods {Phronima seden- 

 taria, Phrosina semilunata) , and megalopae 

 (Brachyura) . Molluscan food for the most part 

 was diflferent between our study and that of 

 Penrith (1963). 



On the basis of the studies discussed in this 

 section, it is evident that skipjack and yellowfin 

 tunas consume a great variety of forage organ- 

 isms. Fish, cephalopods, and crustaceans were 

 the principal foods of both species of tunas in 

 all investigations. The similarity in regard to 

 the taxonomic composition of forage between 

 different studies was greater when the investi- 

 gations were made in the same general area. 

 In each given area, only several types of food 



were important. Although occasionally bottom 

 organisms were found in the diet of a skipjack 

 and particularly yellowfin tunas, both of these 

 species primarily feed on juvenile pelagic or- 



ganisms. 



ACKNOWLEDGMENTS 



We wish to express sincere thanks to the fol- 

 lowing people for their assistance in the identi- 

 fication and verification of specimens: Thomas 



E. Bowman, Raymond B. Manning, and Clyde 



F. E. Roper of the Smithsonian Institution, 

 Washington, D.C.; L. B. Holthuis of the Rijks- 

 museum van Naturlijke Historie, Leiden, Hol- 

 land; Donald Moore, Anthony J. Provenzano, 

 Philip B. Robertson, Gilbert L. Voss, and Won 

 Tack Yang of the Rosenstiel School of Marine 

 and Atmospheric Sciences, University of Miami, 

 Miami, Fla. 



We also thank William W. Fox, Jr. of the Uni- 

 versity of Washington, Seattle, Wash., for ad- 

 vice on statistical procedures. Dr. George A. 

 Rounsefell of the University of Alabama re- 

 viewed the manuscript. 



LITERATURE CITED 



Alverson, F. G. 



1963. The food of yellowfin and skipjack tunas in 

 the eastern tropical Pacific Ocean. [In English 

 and Spanish.] Inter-Am. Trop. Tuna Comm., 

 Bull. 7:293-396. 

 Berrit, G. R. 



1961. Contribution a la connaissance des variations 

 saisonnieres dans le Golfe de Guinee. Observa- 

 tions de surface le long des lignes de navigation. 

 Cah. Oceanogr. Bull. Inf. Com. Cent. Oceanogr. 

 Etud. Cotes 13:715-727. 

 Blackburn, M. 



1965. Oceanography and the ecology of tunas. 

 Oceanogr. Mar. Biol. Annu. Rev. 3:299-322, 

 De Jager, B. V. D., C. S. de V. Nepgen, and 

 R. J. VAN Wyk. 



1963. A preliminary report on South African west 

 coast tuna. S. Afr. Div. Sea Fish., Invest. Rep. 

 47, 40 p. 

 Dragovich, A. 



1969. Review of studies of tuna food in the At- 



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