Sun et a\ Age and growth of Xiphias gladius 



831 



Table 4 



Results of the multivariate (Hotelling's T^) tests for difference between the estimated von Bertalanffy growth parameters of female 

 and male swordfish in the waters around Taiwan. 



Roy-Bose simultaneous confidence intervals around differences between parameter values. 



Indicates the parameter tested that significantly affects differences in growth between the females and the males at a significant level of 0.01. 



lem of multiple bands by determining whether the bands 

 were continuous around the circumference of the entire 

 ray section and by judging their distance from preceding 

 and following bands. In our study, 91 out of the 627 read- 

 able specimens had "multiple bands" that were read with- 

 out a problem by using these criteria. Of the 26 discarded 

 specimens that had multiple unreadable bands, most were 

 found in swordfish larger than 200 cm in size. The missing 

 first band in larger fish can be estimated from observa- 

 tions of its position on young specimens where the first 

 band is visible. Similar approaches for solving the problem 



of missing band have also been used for Atlantic swordfish 

 (Berkeley and Houde, 1983) and eastern Mediterranean 

 swordfish (Tserpes and Tsimenides, 1995). 



Results of marginal increment ratio analysis (Figs. 7 

 and 8) suggest one growth ring (annulus) is formed each 

 year from July to August, which is toward the end of the 

 spawning period for the swordfish in the north Pacific 

 (Yabe et al., 1959). Although the timing of annulus deposi- 

 tion coincides with the swordfish's spawning season in the 

 north Pacific, it may also be related to swordfish migration, 

 as suggested by Berkeley and Houde (1983) for Atlantic 



