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Vol. 51 No. 3, 2012
Modeling the Growth of Silver Hatchet Chela Chela cachius (Cyprinidae) from the Old Brahmaputra River in Bangladesh Using Multiple Functions
Zoarder Faruque Ahmed1, Md. Yeamin Hossain2,3,*, and Jun Ohtomi2
1Department of Fisheries Management, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
2Faculty of Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima 890-0056, Japan
3Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh
Zoarder Faruque Ahmed, Md. Yeamin Hossain, and Jun Ohtomi (2012) The silver hatchet chela Chela cachius,
is a freshwater Cyprinidae commercially important for both subsistence
and artisanal fisheries in Bangladesh. This small, indigenous fish is
widely distributed in Bangladesh, India, Pakistan, and Myanmar. Ages
and growth patterns of male and female C. cachius
were separately estimated using monthly length-frequency distributions
through multiple functions. In total, 2396 specimens were captured from
the Old Brahmaputra River in Bangladesh from July 2007 to June 2008. A
birth date was assigned to the month when the peak mean gonadosomatic
index (GSI) occurred. The age of each cohort was estimated in weeks
from the assigned birth date to each sampling month. Growth patterns
for both males and females were modeled by fitting 3 different
equations between mean standard lengths and the corresponding ages. The
growth of C. cachius was best described by the von Bertalanffy model as
Lt ≡ 67.26 (1 - exp(-0.024 (t + 20.22))) for males and Lt ≡ 69.92 (1 - exp(-0.027 (t + 22.90))) for females based on the coefficient of determination (r2), Chi-squared (χ2 ) values, and Akaike’s information criterion (AIC), where Lt is the standard length (mm) at age t
(wk). Females grew faster than males, and their absolute growth was
larger than that of males at any age. The von Bertalanffy growth model,
in terms of body weight, provided equations as Wt ≡ 3.30 (1 - exp(-0.032 (t + 14.32)))3 for males and Wt ≡ 3.38 (1 - exp (-0.034 (t + 20.42)))3 for females, where Wt is the body weight (g) at age t (wk). The present study provides a new record of the maximum length of C. cachius from the Old Brahmaputra River and South Asia, which should be useful to fishery managers.
Key words: Chela cachius, Gonadosomatic index, von Bertalanffy, Old Brahmaputra River, Bangladesh.
*Correspondence: Tel/Fax: 81-99-2864152. E-mail:yeamin.fish@ru.ac.bd; yeamin2222@yahoo.com
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