Maturation and Fecundity of Swordfish, 

 Xiphias gladius, from Hawaiian Waters 



JAMES H. UCHIYAMA and RICHARD S. SHOMURA' 



ABSTRACT 



Sixteen swordfish, Xiphias gladius, ovaries ranging in weight from 39 to 20,000 g were examined. Fish 

 size ranged from 47 to 246 kg. Based on the occurrence of ripe ovaries, spawning in Hawaiian waters was 

 estimated to extend from April through July. The developmental stages of ova are described; the most 

 advanced ova examined averaged 1.6 mm in diameter. The distribution of ova diameters within an ovary 

 was found to be heterogeneous. Fecundity was estimated for eight swordfish. Some variability in fecundity 

 was noted: a positive curvilinear relationship of mcrease in fecundity with increase in fish size was evident. 

 Best estimates suggest that an 80 kg swordfish has 3.0 million ova (early ripe or ripe stages) and a 200 kg 

 swordfish has 6.2 million ova. 



The occurrence in Hawaiian waters of mature 

 swordfish, Xiphias gladius, with ovaries in ad- 

 vanced stages of maturation has been observed in 

 the past by longline fishermen and other members 

 of the fishing industry. However, precise informa- 

 tion of the spawning period and the fecundity of 

 swordfish from the Hawaiian Islands area is lack- 

 ing. Although swordfish are not taken in large num- 

 bers by the longline fishery (Fig. 1), the absence of 

 studies on swordfish has been due principally to 

 difficulty in obtaining adequate data. The large 

 ovaries of swordfish along with ovaries of other bill- 

 fishes and tunas are commercially valuable and 

 considered as a food delicacy in Hawaii. Thus, in 

 order to prevent damage to the gonads, the auction 

 firms handling the sale of swordfish do not permit 

 the fish to be cut open prior to sale. Since fish are 

 often butchered outside of the auction area, we 

 were unable to obtain the needed information on 

 sex and maturity. Although very little data on 

 swordfish were available during our six years of 

 sampling (1961-66), we were able to collect 16 

 ovaries covering all seasons of the year. These 

 samples and related data on swordfish were consid- 

 ered adequate to permit us to make a preliminary 

 assessment of spawning and fecundity of swordfish; 

 the results are presented in this paper. 



OCCURRENCE OF SWORDFISH 

 IN HAWAIIAN WATERS 



Swordfish are taken exclusively with longline 

 fishing gear in Hawaiian waters. The swordfish 

 catch landed by the Hawaiian fishery is very small; 

 the total annual catch did not exceed 120 fish during 

 the six years of sampling (Fig. 1). Since fishing for 



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' Southwest Fisheries Center. Honolulu Laboratory, National 

 Marine Fisheries Service, NOAA, Honolulu, HI 96812. 



Figure 1.— Monthly landings of swordfish (upper panel) 

 and average size offish (lower panel) from 1961 to 1966. 



142 



