Sun el a\ Age and growth of Xiphias gladius 



823 



N 

 25 5- 



250- 



245- 



24.0- 



23,5- 



23 0- 



22 5- 



22 0- 



21.5- 



21 0- 



20 5- 





20 0- 







Tungkang" 



Shinkang. 



^<, 



Jt ^^ Taiwan 



Pacific Ocean 



CO 



E 120 140 160 



1J0 120 100 



119 



— I — 

 120 



121 



122 E 123 



Figure 1 



Three fishing ports in Taiwan where the swordfish anal-fin ray 

 samples were collected in this study. 



waters around Taiwan to be assessed by using yield-per- 

 recruit and sequential population analyses. 



Material and methods 



Data on lower jaw fork length (LJFL) and weight, and 

 samples of the first anal fin of male and female sword- 

 fish were collected from three offshore tuna longline and 

 harpoon fishing ports (Fig. 1) on a monthly basis between 

 September 1997 and March 1999. The fishing grounds for 

 those vessels are shown in Figure 2. In total, 769 LJFLs 

 and 685 anal fins were collected. The anal fins were frozen 

 for approximately one month before being thawed and 

 boiled to remove the tissue and to separate the second rays. 

 Three cross sections ranging in thickness from 0.5 to 0.75 

 to 1.0 mm were taken successively along the length of each 

 ray with a low-speed "ISOMET" saw (model no. 11-1280) 

 and diamond wafering blades, at a location equivalent 

 to 1/2 of the maximum width of the condyle base mea- 

 sured above the line of maximum condyle width (Fig. 3) 



(Ehrhardt, 1992; Ehrhardt et al., 1996). The sections were 

 immersed in 95% ethanol for several minutes, placed in a 

 labeled (with sampling date and a number) small plastic 

 case to air dry, and then stored for later reading. Anal- 

 fin ray sections were then taken from the small cases 

 randomly and examined under a dissecting microscope 

 (model: Leica MZ 6) with transmitted light at various 



