Food Categories 



T. albocores 

 N= 215 



T. alolunqa 

 N= 34 



T. ihvnnus 

 N =27 



Aleoisourus 

 N = 81 



NEAR-SURFACE 

 Portunus sovi 

 Brachyurot larvae) 

 Anomura(larvae) 

 Ceratospis petiti 

 Stomatopoda (larvae) 

 Araonauta 



MIDWATER 



Phrosina semilunata 

 Phronimo sp 

 Other Hyperiidea 

 Soft-bodied squids 

 Other squids 

 AIIoposus mollis 

 Other octopods 

 Alciopidae 



100 X 50 100 X 



Percent Frequency of Occurrence 



Figure 4. — Frequency of occurrence of invertebrate forage categories in the stomachs of Thunnus and Alepisaurus. 

 gories are separated by their general location in the water column: near-surface or midwater. 



100% 



Cate- 



drachme, ranked high in number, volume, and frequency 

 (Reintjes and King 1953). Exocoetids, scombrids (mainly 

 Katsuwonus pelamis), and carangids (mainly 

 Decapterus sp.) were important in volume, but were in- 

 frequently consumed. The most important fishes in the 

 diet of central Pacific yellowfins were Collybus drachme 

 and Gempylus serpens (King and Ikehara 1956). Scom- 

 bridae and Mullidae were important in volume, though 

 infrequently eaten. In the southwest Pacific, the families 

 of fishes most frequently consumed by yellowfins were 

 midwater Sternoptychidae (mostly Argyropelecus spp.), 

 Paralepididae, and Bramidae, of which Collybus 

 drachme was most important (Fourmanoir 1971). From 

 the eastern tropical Pacific, Alverson (1963) reported 

 Scombridae as the most important by volume (12.2%) 

 followed in decreasing order of magnitude by Ex- 

 ocoetidae, Tetraodontidae, Carangidae, Myctophidae, 

 and Serranidae. 



Thunnus alalunga. — In stomachs of longline-caught 

 albacore from the central and northeastern Pacific, the 

 midwater families Gempylidae, Bramidae, Sternopty- 

 chidae, and Paralepididae were present most frequently 

 (Iversen 1962). Gempylus serpens was the most frequently 

 occurring species (9.9%) while Collybus drachme and 

 Sternoptyx sp. were both present in 4.9% of the stomachs. 

 In troll-caught albacore in California waters (Iversen 

 1971). however, the most important forage fishes in terms 

 of both volume and frequency of occurrence were ancho- 



vies and sauries, with certain deeper-occurring fishes 

 (Tarletonbeania crenularis, Paralepis atlantica, 

 Sebastes spp.) occurring less frequently. Albacore from 

 New Caledonia (Fourmanoir 1971) consumed Sternop- 

 tychidae, particularly Sternoptyx diaphana, and 

 Bramidae, especially Collybus drachme most frequently. 



Thunnus thynnus. — Dragovich (1970b) reported 

 Bramidae (Collybus drachme) and the epipelagic Scom- 

 bridae (particularly Scomber scombrus and Auxis sp.) 

 and Syngnathidae (Hippocampus erectus) as the most 

 frequently consumed fishes in western North Atlantic T. 

 t. thynnus. In the stomachs of the northern Pacific 

 bluefin, T. thynnus orientalis, however, Pinkas (1971) 

 found that Engraulis mordax was the primary forage 

 component (72.0% occurrence), followed by the red 

 swimmingcrab. Pleuroncodes planipes (13.5% occur- 

 rence), and the saury, Cololabis saira (11.9% occurrence). 



Thunnus obesus. — In her studies on the food of bigeye 

 tuna from the Gulf of Guinea, Borodulina (1974) found 

 midwater fishes, Paralepididae, Sternoptychidae, 

 Gonostomatidae, Omosudidae, Scopelarchidae, and 

 Alepisauridae most frequently consumed. Gempylidae 

 and Diretmidae were only occasionally utilized, but oc- 

 curred in large numbers when they were present. In the 

 eastern tropical Atlantic, Gempylidae, Trichiuridae, 

 Bramidae, Alepisauridae, and Myctophidae were most 



