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Vol. 46 No. 1, 2007
Age and Growth Estimates of the Whitespotted Bamboo Shark,
Chiloscyllium plagiosum, in the Northern Waters of Taiwan
Wei-Ke
Chen1, Po-Chuan Chen2, Kwang-Ming Liu2,*, and Shyh-Bin Wang2
1Department
of Environmental Biology and Fisheries Science, Notional Taiwan Ocean
University, 2 Pei-Ning Road, Keelung 202, Taiwan
2Institute of Marine Resource Management, National
Taiwan Ocean University, 2 Pei-Ning Road, Keelung 202, Taiwan
Wei-Ke
Chen, Po-Chuan Chen, Kwang-Ming Liu, and Shyh-Bin Wang (2007)
Age and growth rates of the whitespotted bamboo shark, Chiloscyllium
plagiosum, were described from 481 specimens (313 females and 168
males, 35.5-85.0 cm in total length) collected from Feb. 2002 to Feb.
2003 in waters off northern Taiwan on bottom longlines or lobster trap
nets. The sex-specific relationships between weight (W) and total
length (TL) significantly differed and could be expressed as: W = 1.64
x 10-3 TL3.15 (n = 313, p < 0.05) for females and W = 5.09 x 10-3
TL2.87 (n = 168, p < 0.05) for males. Age was determined using
vertebral banding patterns. A single growth band (comprising
translucent and opaque zones) is formed each year, with up to 7 bands
observed for both sexes. A marginal increment ratio analysis indicated
that the translucent zone formed from June to Sept. Four growth
functions, the traditional von Bertalanffy (VBGF), VBGF with a fixed
size-at-birth (L0), Gompertz, and Robertson functions were used to
model the observed length-at-age data. The sex-specific growth
equations significantly differed. The traditional VBGF, based on
observed length-at-age data, predicted an asymptotic length (L∞) of
95.9 cm TL, a growth coefficient (k) of 0.205, a theoretical age at
zero length (t0) of -0.95 yr for females; and an L∞ of 100.9 cm TL, k
of 0.198, t0 of -0.90 yr for males. The parameters of VBGF with L0 set
to 15.0 cm were estimated to be an of L∞ 93.2 cm TL and k of 0.224 for
females; and an of L∞ 98.5 cm TL and k of 0.212 for males. Akaike's
information criterion showed that the VBGF with L0 had the best fit.
Ages at maturity estimated from the VBGF with L0 were 4.5 and 4.4 yr
for females and males, respectively.
Key words: Age
and growth, Chiloscyllium plagiosum, von Bertalanffy growth equation,
Northern Taiwan.
*Correspondence: Tel: 886-2-24622192 ext. 5018. Fax:
886-2-24620291. E-mail:kmliu@mail.ntou.edu.tw
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