Sun et al Age and growth of XIphias gladius 



829 



ference in size ranges of LJFL sampled for studying the 

 sex ratio (Mejuto, et al.. 199.5). Most of the LJFL in our 

 sample ranged between 100 and 18.5 cm, close to Arocha 

 and Lee's (1995) middle size range within which the sex 

 ratio was also almost 1:1 (Arocha and Lee, 1995). Besides 

 the size range difference, the differences in geographical 

 areas and seasons can also affect the sex ratio (Hoey, 

 1991; Mejuto et al., 1991). The proportion of females in our 

 study, which increased to 100% at 210 cm and thereafter, 

 was similar to those described by Turner et al. (1996). 

 Stone and Porter (1997), and DeMartini et al. (2000). 



Several genetic studies (Grijalva-Chon et al., 1994; 

 Rosel and Block, 1996; Chow et al., 1997; Chow, 1998) 

 have been unable to reject the hypothesis that swordfish 

 comprise a single, homogenous population in the Pa- 

 cific. However, from recent analyses of mtDNA, Reeb et 

 al. (2000) concluded that swordfish are not homogenous 

 in the Pacific. They found significantly different northern 

 and southern populations in the western Pacific and sev- 

 eral overlapping swordfish populations may occur in the 

 eastern Pacific, making swordfish genetically continuous 

 there. Gene flow between the populations occurs through 



