Population dynamics of Metapenaeus ensis (Decapoda: Penaeidae) in a coastal region of the Mekong Delta, Vietnam
2012
Tran, Van Viet | Sakuramoto, Kazumi
The greasyback shrimp, Metapenaeus ensis, was studied in the Ganh Hao River, in a coastal region of the Mekong Delta in Vietnam, between February and December 2010, at six stations extending 30 km from the estuary. The results are as follows for males and females. The carapace lengths were 14.5–33.5 mm and 14.4–35.5 mm, the asymptotic carapace lengths were 35.2 and 37.3 mm, growth coefficients were 1.6 year¯¹ and 1.5 year¯¹, and longevities were 1.8 and 2 years, respectively. Depending on the level of migration indices, for males and females, the total mortality coefficients were 3.7–5.0 year¯¹ and 4.1–4.9 year¯¹, fishing mortality coefficients were 1.4–2.7 and 2.4–3.2 year¯¹ , the exploitation rates ( Eα ) were 0.38–0.54 and 0.59–0.65, and the maximum exploitation rates ( E maxα ) were 0.4–0.70 and 0.6–0.8,respectively. The natural mortality coefficients were 2.3 year¯¹for males and 1.7 year¯¹ for females, respectively. Theseresults demonstrate that M. ensis is still underexploited ( Eₐ < E maxₐ ). However, large proportion of small shrimp is caught year round; it is a waste of natural resources and can deplete the resource in the future.
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