SARGA5SUM- 

 ASSOCIATE5 



Balisfidae 



Carangidae 



Tetroodontidae 



Syngnathidae 



Acanthuridae 



Chaetodontidae 



Priacanthidae 



Holocenfridae 



Antennariidae 



NEAR-SURFACE 

 Scombridae 

 Nomeidae 



T, al bacares 

 N = 209 



t 



t 



t 



MIDWATER 

 Bramidae 

 Alepisauridae 

 Paralepididae 

 Sternoptychidae 

 Gempylidae 

 Omosudidae 

 Chiasm odonridae 

 Anotopteridae 

 Gadidae 



100% 



50 100% 50 



Percent Frequency of Occurrence 



Figure 3.— Frequency of occurrence of the 20 most frequently occurring families of fishes in the stomachs of Thunnus and Alepisaurus. Families 

 are separated into three categories: Sargasa um-associates, near-surface, and midwater. 



somewhat deeper and may have broader depth ranges; 

 and T. obesus is recognized as the deepest swimming of 

 the tunas. The distribution of the lancetfishes may be far 

 broader than that of the tunas, although the lower depth 

 limit is not established. Large specimens have been 

 collected as shallow as 30 m, while small ones have been 

 caught in open nets fished as deep as 2,000 m (Gibbs and 

 Willimovsky 1966). Rancurel (1970) concluded that their 

 primary feeding area is in the upper 300 m. 



The following paragraphs summarize observations on 

 forage composition reported in major studies from both 

 the Atlantic and the Pacific for comparison with our 

 data. Forage composition in these studies may reflect 

 differences in the geographical distributions of prey, 

 local abundances of forage organisms, or local differences 

 in either predator or prey swimming depths but the tax- 

 onomic composition of the major food components is 

 similar in all of these studies. 



Thunnus albacares. — Dragovich (1970a) reported on 

 the food of yellowfin from the western North Atlantic. 



Auxis sp. (Scombridae) constituted 26.6% of the food 

 volume and occurred in 24.9% of the stomachs. Bramidae 

 and Gempylidae occurred frequently and were moderate- 

 ly important in volume and Balistidae were common. 

 Other surface organisms (Carangidae and 

 Priacanthidae), which were common in our study, were 

 surprisingly absent in the study by Dragovitch (1970a). 

 Serranids occurred frequently, 53.8%, and constituted 

 56.9% of the total volume. Other high-ranking families in 

 terms of occurrence and volume were Scombridae, 

 Carangidae (mainly Decapterus sp.), Dactylopteridae 

 (Dactylopterus volitans), and Chaetodontidae. 

 Dragovich and Potthoff (1972) reported that the fish 

 forage of yellowfins caught by live bait and trolling off 

 the coast of West Africa consisted by occurrence and 

 volume mainly of the epipelagic juveniles of 

 Acanthuridae, Carangidae, Dactylopteridae, Lutjanidae, 

 and Mullidae, and the midwater Gempylidae and 

 Gonostomatidae. 



In the diet of yellowfin tunas in the central Pacific, 

 acanthurids and bramids, particularly Collybus 



