FISHERY BULLETIN: VOL. 71, NO. t 



He found that juvenile fish, especially the acron- 

 urus larvae of Acanthuridae, were most impor- 

 tant in their diet. Also of importance were 

 members of the fish families Trichiuridae, Scom- 

 bridae, Triacanthidae, Holocentridae, Balistidae, 

 and Monacanthidae, and invertebrates such as 

 squids, larval and juvenile stomatopods, larval 

 crabs and shrimp. Hotta and Ogawa (1955) ex- 

 amined the stomach contents of skipjack tuna 

 caught to the east and south of the main Jap- 

 anese islands and reported that Scombridae, 

 Engraulidae, Exocoetidae, and Holocentridae 

 were major dietary items. Important inverte- 

 brates included squids, crab larvae, euphausiids, 

 and shrimp. Alverson (1963) examined the 

 stomach contents of skipjack and yellowfin tunas 

 caught in the eastern tropical Pacific. He found 

 euphausiids to be the main food items for skip- 

 jack tuna, followed by Gonostomatidae, Exocoeti- 

 idae, and the "red crab," Pleuroncodes planipes', 

 and for yellowfin tuna, the "red crab," the swim- 

 ming crab (Portunidae), Thunnidae, Ostraci- 

 dae, Exocoetidae, and Tetraodontidae. Wald- 

 ron and King (1963) studied the stomach 

 contents of skipjack tuna taken around the Ha- 

 waiian, Line, and Phoenix Islands and found that 

 common dietary items were Gempylidae, Scom- 

 bridae, Mullidae, Chaetodontidae, and Holocen- 

 tridae. Larval and juvenile skipjack tuna, 

 stomatopod larvae, shrimp, and crab megalops 

 were also important. E. Nakamura (1965), up- 

 on examination of the stomach contents of skip- 

 jack tuna from the Marquesas and Tuamotu 

 Islands, reported that scombrids, with skipjack 

 tuna constituting a high percentage, were com- 

 mon food items. Serranidae, Lutjanidae, and 

 Gempylidae were of importance as were stomato- 

 pods, crab megalops, and squids. It was con- 

 cluded by Hotta and Ogawa (1955) that the 

 tunas were nonselective in their feeding habits 

 and ate whatever was available in the area. 



Although these previous observations covered 

 broad areas of the Pacific, no mention was made 

 of any anchovy that may have been S. buccaneeri 

 occurring in the stomach contents. An exception 

 is a report by H. Nakamura (1936) on the food 

 of yellowfin tuna caught in the Celebes Sea that 

 mentioned an anchovy as one of the common food 

 items. The area in which he found tunas con- 



taining the anchovy, the frequency of occurrence 

 of the anchovy in tuna stomachs, and the num- 

 bers in which it occurred lead me to believe that 

 it may have been S. buccaneeri. 



METHODS 



The stomachs of the troll and pole-and-line 

 caught fish were removed after they were mea- 

 sured and sexed. Stomachs that appeared empty 

 and those of most male tunas were examined 

 in the field and their contents recorded. The 

 rest were placed in muslin bags and preserved 

 in 10% Formalin.' One of the objectives of the 

 cruises was to collect 50 skipjack tuna and/or 

 50 yellowfin tuna blood samples from each school. 

 Therefore, there were four occasions on which 

 50 stomach samples per school were collected. 



In the laboratory, counts were made of the 

 organisms in the stomachs whenever possible. 

 Many of the partially digested fishes were iden- 

 tified by their vertebrae which were prepared by 

 teasing away the muscles when necessary and 

 staining with alizarin red. Skipjack tuna re- 

 mains were identifiable by skeletons. Enough 

 of the external characters of the anchovy usually 

 remained for identification. Most of the other 

 fishes were identifiable only to family. The 

 stomach contents of the anchovy, which included 

 many crustaceans, were identified by staining the 

 organisms with methylene blue. Many of the 

 copepods were identified to species but other 

 invertebrates were identifiable only to major 

 groups such as the Chaetognatha, Amphipoda, 

 and shrimp, 



STOMACH CONTENTS 



EQUATORIAL EASTERN PACIFIC 



The results of examining 268 skipjack tuna, 

 44 bigeye tuna (Thunnus obesus) , 45 yellowfin 

 tuna, 2 common dolphin, and 7 little dolphin 

 (Coryphaena equiselis) caught on cruise 116 of 

 the Charles H. Gilbert are presented in Table 1. 

 The presence of S. buccaneeri in the stomach 



' Reference to trade names does not imply endorse- 

 ment by the National Marine Fisheries Service, NOAA. 



136 



