New Pacific Records of Juvenile Albacore 
Thunnus alalunga (Bonnaterre) from Stomach Contents 
Howard O. Yoshida 1 
Because the albacore, Thunnus alalunga 
(Bonnaterre), is commercially one of the more 
valuable species of tuna, a great deal of effort 
has been expended in investigating its biology. 
Although much has been learned in recent years 
about the albacore, its age and growth, move- 
ments and migrations (Otsu, I960; Clemens, 
1961; Otsu and Uchida, 1963), many facets of 
the biology of this species still need to be stud- 
ied. As part of the Albacore Ecology Program, 
staff members of the Bureau of Commercial 
Fisheries Biological Laboratory, Honolulu, Ha- 
waii, have been studying the early life history 
of albacore in order to fill the gaps in our 
knowledge. 
There is a paucity of information on the 
juvenile 2 and larval stages of albacore due in 
part to two factors. One is the limited success 
of efforts to collect the young, and the other 
is the difficulty of identifying them, sime adult 
morphological characters are often inadequate 
for identifying the young stages. Although there 
has been some success in collecting juvenile 
tunas with various types of midwater trawls 
(Matsumoto, 1961), most of the juvenile tunas 
recorded in the literature have come either from 
stomachs of predators or from dipnetting at 
nightlight stations. Yabe, Ueyanagi, Kikawa, 
and Watanabe (1958) reported on five juve- 
nile albacore less than 30 cm discovered in 
stomachs of predators caught in the western 
North and South Pacific Ocean. So far as I 
know, theirs is the only documented record of 
juvenile albacore in the Pacific Ocean, and it 
has positively demonstrated albacore spawning 
in these areas. 
In June I960, a program was initiated at the 
Biological Laboratory, Honolulu, to sample 
1 Bureau of Commercial Fisheries Biological Labo- 
ratory, Honolulu, Hawaii. Manuscript received Octo- 
ber 1, 1963. 
2 Unless otherwise noted, the term "juvenile” as 
used herein includes albacore up to 30 cm long. 
stomachs of large pelagic fishes for juvenile 
albacore. This paper presents the results of 
sampling through November 1962. Twelve 
juveniles were found in stomachs of predators 
caught in the central North and South Pacific, 
thereby extending known or demonstrating 
new spawning grounds for albacore. Although 
the number of specimens is small, I consider it 
important to report them promptly since juve- 
nile albacore are not very often collected and 
the information may be of value to other in- 
vestigators studying the biology of the albacore. 
SOURCE OF MATERIALS 
Two sources of stomach samples that were 
readily available to the author were the large 
fishes landed by the Hawaiian commercial long- 
line fishery and by exploratory fishing cruises 
of the Bureau of Commercial Fisheries’ research 
vessel "Charles H. Gilbert.” 
The Hawaiian longline fishery is usually con- 
ducted within 20 miles of the main islands, 
with most of the boats in the fleet operating 
out of Honolulu, while smaller numbers fish 
out of Hilo and Kona on the island of Hawaii, 
and from Port Allen on the island of Kauai 
(Otsu, 1954). The catch of this fishery con- 
sists of a variety of large pelagic fishes, includ- 
ing striped marlin ( Makaira audax) , blue mar- 
lin ( Makaira ampla ) , black marlin ( Istiompax 
marlina ), broadbill swordfish ( Xiphias gladius ), 
and shortnose spearfish ( Tetrapturus angusti- 
rostris ), among the spearfishes. Among the 
tunas, bigeye ( Thunnus ohesus ), yellowfin 
( Thunnus albacaves) , and small numbers of 
albacore and skipjack ( Euthynnus pelamis ) are 
taken. 
Stomachs were sampled at the auction mar- 
kets of the United Fishing Agency, Ltd., and 
the Hawaiian Fishing Co., Ltd., in Honolulu. 
Since it has been shown that juvenile tunas 
occur more frequently in stomachs of spearfishes 
442 
