Liu et al.: Age and growth of Atopias superciliosus 
489 
9-10 yr age class according to 
our estimations. We suggest 
that the results of Gruber and 
Compagno (1981), based on 
Holden’s method (1974), may 
not be an accurate estimate; 
we believe ours to be more 
reasonable. 
The size at maturity in dif- 
ferent areas were similar, i.e. 
females matured at 332-341 
cm TL in this area (Chen et 
al., 1997), 355 cm TL in the 
northwestern Atlantic (Still- 
well and Casey, 1976), and 
340 cm TL in the northeast- 
ern Atlantic (Moreno and 
Moron, 1992). Males ma- 
tured at 270.1-287.9 cm TL 
in this area (Chen et al., 
1997), 290-300 cm TL in the 
northwestern Atlantic (Still- 
well and Casey, 1976), and 
276 cm TL in the northeast- 
ern Atlantic (Moreno and 
Moron, 1992). Thus, size at 
maturity of the northwestern 
Pacific populations of A. 
superciliosus was very simi- 
lar to those of populations 
elsewhere (Chen et al., 1997). 
The maximum TL for fe- 
male bigeye thresher sharks 
was 450 cm in Florida waters 
(Gilmore, 1983), 452 cm in 
Cuba (Guitart, 1975), 458 cm 
in New Zealand (Grey, 1928), 
and 422 cm and 357 cm, fe- 
male and male, respectively, 
in this study. Possible rea- 
sons why this species is 
smaller in northeastern Tai- 
wan than in other waters 
may be due to different envi- 
ronments, genes, gear selec- 
tion, sampling bias, and fish- 
ing mortality. 
Age and growth assess- 
ment of sharks from hard 
parts has been verified by 
length-frequency analysis to 
increase accuracy (Stevens, 
1975; Pratt and Casey, 1983; 
Natanson et al., 1995). In 
this study, vertebral and 
C 
<D 
CT 
0 
Precaudal length (cm) 
Figure 8 
Length-frequency histograms for male Alopias superciliosus used in the analysis, and 
results of the best data fits. Horizontal bars indicate the constraints imposed to mean 
length at age. 
