HIDA: FOOD OF TUNAS AND DOLPHINS 



FECUNDITY 



Ova of 32 specimens of S. buccaneeri obtained 

 from tuna stomach contents were measured: 

 Specimens were 38-55 mm SL. From each sub- 

 sample, diameters of 30 or more of the ova from 

 the most advanced mode were taken. Their dis- 

 tribution ranged from 0.4 to 0.8 mm and peaked 

 at 0.5 mm. The ova were opaque, granulated, 

 and classified as maturing. 



Since there are no previous estimates of fe- 

 cundity, ova from the most advanced mode from 

 two S. buccaneeri ovaries were counted. This 

 method was based on the assumption that all 

 of the ova in this mode constituted a single 

 spawning. A 44-mm specimen contained 595 

 ova in her left ovary and 830 in her right, a 

 total of 1,398. A 39-mm individual had 340 ova 

 in her left ovary and 454 in her right, a total 

 of 794. 



and in much better condition for identification 

 purposes. Hiatt (1951) examined the stomach 

 contents of the nehu, S. pitrpnreus, caught from 

 five major baiting areas in Hawaii and concluded 

 that nehu were selective feeders in that they took 

 the crustacean elements in the plankton. He 

 found important food items to be copepods, ghost 

 shrimp (Lucifer), barnacle nauplii, shrimp lar- 

 vae, and crab larvae. 



ACKNOWLEDGMENTS 



I am indebted to Peter Whitehead of the Brit- 

 ish Museum (Natural History) for his identifi- 

 cation and verification of S. buccaneeri samples. 

 Thanks are also due to the crew members and 

 scientific personnel of Charles H. Gilbert who 

 were instrumental in collecting the samples. 



FOOD STUDY 



The examination of 58 stomach contents of 

 S. buccaneeri recovered from tuna stomachs 

 showed that crustaceans w^ere important in their 

 diet, as shown in Table 3. Only one stomach was 

 found empty. The stomachs of S. buccaneeri 

 in this study contained primarily calanoid cope- 

 pods and other organisms. The copepods that 

 were abundant in one or more anchovy stomachs 

 from the equatorial eastern Pacific were Can- 

 dacia truncata and Euchaeta marina. The cy- 

 clopoid copepod, Oncaea vemista, was common 

 in one stomach. Copepods found in abundance 

 in one or more anchovy stomachs taken from 

 tunas caught from the Samoa Islands were Can- 

 dacia bispinosa ( ?) C. cahila, C. truncata, Cen- 

 tropages gracilis, Euchaeta marina and Temora 

 discaudata. C. truncata and E. marina were the 

 only two species that were abundant in both 

 areas. Not unexpectedly, the close-to-shore sam- 

 ples from Samoa were represented by more spe- 

 cies than those of the oceanic equatorial eastern 

 Pacific. It should be noted, however, that there 

 were many copepodites and badly digested spe- 

 cimens in the equatorial eastern Pacific samples, 

 while those from the Samoa Islands were larger 



LITERATURE CITED 



Alverson, F. G. 



1963. The food of yellowfin and skipjack tunas 

 in the Eastern Tropical Pacific Ocean. Bull. Inter- 

 Am. Trop. Tuna Comm. 7:293-396. 

 Hiatt, R. W. 



1951. Food and feeding habits of the nehu, Stoleph- 

 orus purpiirens Fowler. Pac. Sci. 5:347-358. 

 HiDA, T. S. 



1970a. Surface tuna schools located & fished in 

 equatorial eastern Pacific. Commer. Fish. Rev. 

 32(4) :34-37. 

 1970b. Surface tuna-school fishing & baiting around 

 Samoa Islands. Commer. Fish. Rev. 32(12) :37- 

 41. 

 HiGGINS, B. E. 



1970. Juvenile tunas collected by midwater trawl- 

 ing in Hawaiian waters, July-September 1967. 

 Trans. Am. Fish. Soc. 99:60-69. 



HOTTA, H., AND T. OGAWA. 



1955. On the stomach contents of the skipjack, 



Katsuwomis pelamis. Bull. Tohoku Reg. Fish. 



Res. Lab. 4:62-82. 

 Matsui, T. 



1963. Population of anchovy baitfish (Stolephorus) 



in the vicinity of Maui, Hawaiian Islands. M.S. 



Thesis, Univ. Hawaii, Honolulu, 98 p. 

 Nakamura, E. L. 



1965. Food and feeding habits of skipjack tuna 



(Katsuu'07ius pelamis) from the Marquesas and 



Tuamotu Islands. Trans. Am. Fish. Soc. 94:236- 



242. 



141 



