FISHERY BULLETIN: VOL. 84, NO. 4 



variety of fishing gears, are needed to insure that 

 sampling biases do not exist; a wide range of skip- 

 jack tuna sizes or ages need to be sampled so that 

 the age-specific reproductive effort can be esti- 

 mated; and females with hydrated oocytes need to 

 be collected to verify that nearly all oocytes in the 

 most advanced mode are hydrated and spawned. 

 The last point seems particularly important because 

 our estimated body weight cost of reproduction is 

 high and is very sensitive to the estimate of batch 

 fecundity. It may never be practical to analyze histo- 

 logically sufficient numbers of specimens to estimate 

 spawning frequency for all months and ages since 

 some spawning occurs the year around (Nishikawa 

 et al. 1985). On the other hand, it may be practical 

 to calibrate the gonosomatic index (GSI) in peak 

 spawning months using histological criteria and to 

 use the GSI as a calibrated index of spawning fre- 

 quency during months of low spawning frequency. 

 We do not intend to continue this work but we en- 

 courage those working on the biology of tunas to 

 include such studies in their research plans. 



ACKNOWLEDGMENTS 



We thank the SWFC Honolulu Laboratory of the 

 National Marine Fisheries Service, and particular- 

 ly Christofer Boggs, for providing the samples of 

 recently spawned skipjack tuna from the Kewalo 

 Research Facility. We also thank Robert Gillett and 

 Richard Farman (South Pacific Commission) for col- 

 lecting the wild fish and Robert Kearney and Kurt 

 Schaefer (Inter- American Tropical Tuna Commis- 

 sion) for reading the manuscript. 



LITERATURE CITED 



Alheit, J., V. H. Alarcon, and B. J. Macewicz. 



1984. Spawning frequency and sex ratio in the Peruvian an- 

 chovy, Engraulis ringens. Calif. Coop. Oceanic Fish. In- 

 vest. Rep. 25:43-52. 

 Argue, A. W., F. Conand, and D. Whyman. 



1983. Spatial and temporal distributions of juvenile tunas 

 from the stomachs of tunas caught by pole-and-line gear in 

 the central and western Pacific Ocean. Tuna and Billfish 

 Assessment Programme, Tech. Rep. No. 9, 47 p. South 

 Pacific Commission, Noumea, New Caledonia. 

 Batts, B. S. 



1972. Sexual maturity, fecundity, and sex ratios of the skip- 

 jack tuna, Katsuwonus pelamis (Linnaeus), in North Carolina 

 waters. Trans. Am. Fish. Soc. 101:627-637. 

 Bretschneider, L. H., and J. J. Duyvene de Wit. 



1947. Sexual endocrinology of non-mammalian vertebrates. 

 Monographs on the Progress of Research in Holland Dur- 

 ing the War, Vol. 11, Elsevier, N.Y., 147 p. 

 Brock, V. E. 



1954. Some aspects of the biology of the aku, Katsuwonus 



-pelamis, in the Hawaiian Islands. Pac. Sci. 8:94-104. 



Bunag, D. M. 



1956. Spawning habits of some Philippine tuna based on 

 diameter measurements of the ovarian ova. Philipp. J. Fish. 

 4(2):145-177. 



Cayre, P. 



1981. Maturite sexuelle, fecondite et sex ratio du Listao {Kat- 

 suwonus pelamis) des cotes d'Afrique de l'ouest (20°N-0°N) 

 etudies a partir des debarquements thoniers (1977 a 1979) 

 au port de Dakar, (Senegal). Int. Comm. Conserv. Atl. 

 Tunas, Collect. Vol. Sci. Pap. 15:135-149. 



Cochran, W. G. 



1977. Sampling techniques. 3d ed. John Wiley & Sons, 

 N.Y., 428 p. 



DeMartini, E. E., and R. K. Fountain. 



1981. Ovarian cycling frequency and batch fecundity in the 

 queenfish, Seriphus politus: attributes representative of 

 serial spawning fishes. Fish. Bull., U.S. 79:547-560. 



Goldberg, S. R., and D. W. K. Au. 



In press. The spawning of skipjack tuna from southeastern 

 Brazil as determined from histological examination of 

 ovaries. In P.E. K. Symons, P. M. Miyake, and G. S. Saka- 

 gawa (editors), Proceedings of the ICCAT Conference on the 

 International Skipjack Year Program. Int. Comm. Conserv. 

 Atl. Tunas, Madrid, Spain. 



Hunter, J. R., and S. R. Goldberg. 



1980. Spawning incidence and batch fecundity in northern 

 anchovy, Engraulis mordax. Fish. Bull., U.S. 77:641-652. 



Hunter, J. R., and R. Leong. 



1981. The spawning energetics of female northern anchovy, 

 Engraulis mordax. Fish. Bull., U.S. 79:215-230. 



Hunter, J. R., and N. C. H. Lo, and R. J. H. Leong. 



1985. Batch fecundity in multiple spawning fishes. In R. 

 Lasker (editor), An egg production method for estimating 

 spawning biomass of pelagic fish: application to the north- 

 ern anchovy (Engraulis mordax), p. 67-78. U.S. Dep. Com- 

 mer., NOAA Tech. Rep. NMFS 36. 

 Hunter, J. R., and B. J. Macewicz. 



1980. Sexual maturity, batch fecundity, spawning frequen- 

 cy, and temporal pattern of spawning for the northern an- 

 chovy, Engraulis mordax, during the 1979 spawning season. 

 Calif. Coop. Oceanic Fish. Invest. Rep. 21:139-149. 

 1985a. Measurement of spawning frequency in multiple 

 spawning fishes. In R. Lasker (editor), An egg production 

 method for estimating spawning biomass of pelagic fish: ap- 

 plication to the northern anchovy (Engraulis mordax), p. 

 79-94. U.S. Dep. Commer., NOAA Tech. Rep. NMFS 36. 

 1985b. Rates of atresia in the ovary of captive and wild north- 

 ern anchovy, Engraulis mordax. Fish. Bull., U.S. 83:119- 

 136. 

 Isaac-Nahum, V. J., R. de D. Cardoso, G. Servo, and C. L. del 

 B. Rossi-Wongschowski. 

 1985. Some aspects of the spawning biology of the Brazilian 

 sardine, Sardinella brasiliensis, (Clupeidae). International 

 Council for the Exploration of the Sea. CM. 1985/H:63. 

 Pelagic Fish Comm. 12 p. (Mimeo.) 

 Iverson, R. T. B., E. L. Nakamura, and R. M. Gooding. 

 1970. Courting behavior in skipjack tuna, Katsuwonus 

 pelamis. Trans. Am. Fish. Soc. 99:93. 

 Joseph, J. 



1963. Fecundity of yellowfin tuna (Thunnus albacares) and 

 skipjack (Katsuwonus pelamis) from the eastern Pacific 

 Ocean. Inter-Am. Trop. Tuna Comm. 7:255-292. 

 Kaya, C. M., A. E. Dizon, S. D. Hendrix, T. K. Kazama, and 

 M. K. K. Queenth. 



1982. Rapid and spontaneous maturation, ovulation, and 



902 



