FOOD OF ALBACORE TUNA, THUNNUS GERMO (LACEpEDE), 

 IN THE CENTRAL AND NORTHEASTERN PACIFIC 



By Robert T. B. Iversen, Fishery Biologist 

 Bureau of Commercial Fisheries 



The food study described in this report was un- 

 dertaken at the United States Bureau of Commer- 

 cial Fisheries Biological Laboratory, Honolulu,^ 

 as part of research studies on the highseas fishery 

 resources of the tropical, subtropical, and tem- 

 perate central Pacific. These studies have cen- 

 tered mainly on tunas since, as a source of human 

 food, they are the most widely exploited pelagic 

 species in this area. 



Investigations on the food and feeding habits of 

 tunas were initiated because other studies ha\'e in- 

 dicated that the availability of food is an impor- 

 tant factor in the abundance and distribution of 

 some fish (Hardy, Lucas, Henderson, and Fraser, 

 1936; Hansen, 1949). 



Albacore are widely distributed throughout the 

 tropical, subtropical, and temperate watei-s of the 

 Pacific. In temperate waters they are taken by 

 surface trolling, pole-and-line, gill netting, and by 

 longline fishing (Graham, 1957; Suda, 1954), 

 while in tropical watei-s they are found only sub- 

 surface and are captured by longlining (Murphy 

 and Shomura, 1953). Results of tagging experi- 

 ments have shown that albacore are capable of 

 extensive migrations. For example, two fish 

 tagged off the west coast of North America were 

 retaken in the vicinity of Japan; the distances 

 traveled were 4,230 and 4,300 miles respectively. 

 Such tagging results suggest that one population 

 of albacore in the North Pacific may be supporting 

 three fisheries (Otsu, 1960). In the temperate 

 North Pacific albacore ai'e fished by the Japanese 

 in the west mainly during the spring and sununer, 

 in midocean in the winter, and by North Ameri- 

 cans off the west coast during summer and fall. 

 Japanese also take albacore in a longline fisjicry in 

 tjie central and western Pacific from equatorial 

 waters to about latitude 30° S. 



The jiurposes of this study were : 



' Formerly tlip Pacific Oceanic FlRhery Investigations (POFI). 

 AppniviMl for iinlilic:iticiii. Aug. 11, 19«1. Fishery Bulletin 214. 



1. To describe the food of albacore tuna caught 

 in the central and northeastern Pacific. 



2. To determine whether the abundance and 

 distribution of albacore are related to the abun- 

 dance and distribution of their food. 



3. To determine whether feeding is related to 

 .such variables as method of capture of the alba- 

 core, their size, gcograpliic location, season, and 

 environmental factors. 



There are numerous accounts in the literature of 

 the food of albacore. Although reports for Pa- 

 cific albacore outnumber those (principally bj' 

 French workers) for the North Atlantic, most are 

 fragmentary. 



One of the earliest notes on the Pacific stocks 

 (Bennett, 1840) described albacore as "voracious 

 and miscellaneous feeders," and reported flying 

 fish, "calmars," and small .schooling fish as their 

 natural food. Bennett listed the following as hav- 

 ing been found in albacore stomachs : "Ostracions," 

 filefish, sucking fish, "janthina shells." pelagic 

 crabs, bonita, dolphin, and paper nautilus. Phyl- 

 losomas, larval sunfish, and pait of a bigeye tuna 

 had been eaten by albacore taken near the Bonin 

 Islands (Kishinouye, 1917). The Japanese Bu- 

 reau of Fisheries (1939, 1940) reported albacore 

 food as sardine, saury, pomfret, squid, octopus, 

 isopods, mysids, euphausiids, and heteropods. 

 Kanamura and Yazaki (1940) found squid, octo- 

 pus, stomatopo<ls, barracuda, "liairtail," "flat- 

 head," "ginkagami" (Mene macidata), and "sar- 

 dine" (Bathylagus nnk^zairai) in the stomachs of 

 albacore from the South China Sea. Hart, et al. 

 (1948) have presented a summary of albacore 

 stomach contents sampled off Vancoiner Island 

 and the coast of Washington from 1941 to 1947. 

 Saury, anchovy, lantern fish, pilchard, "red feed" 

 (i.e., euphausiids), and squid were frequently oc- 

 curring food items. Powell (1950) recorded 

 small rockcod as an important food of albacoi-e 

 taken in the nortiieasterii Pacific, with .'jquid, 

 saury, blackcod, and myctopliids also j)reseiit. 



4.'59 



