Population biology and stock status of planktonic shrimp Acetes indicus (Decapoda: Sergestidae) in the coastal waters of Malacca, Peninsular Malaysia

Reproductive cycle, growth, mortality and exploitation rate of Acetes indicus were examined in the coastal waters of Malacca, Malaysia between February 2005 and March 2007. Monthly length frequency data were analyzed using FiSAT software for estimating population parameters of A. indicus, including asymptotic length (L_∝), growth co-efficient (K) and exploitation rate (E) to assess the status of the stock. The annual mean L_∝ and K for males were estimated at 29.93 mm and 1.60 yr⁻¹, and for the females were 40.95 mm and 1.20 yr⁻¹. Mean growth performance index (φ′) was calculated as 3.15 and 3.31 for males and females, respectively. Maximum life span (t_max) of males and females was 1.88 and 2.50 years. Total mortality (Z) by length converted catch curve was estimated at 4.30 yr⁻¹ for males and 3.62 yr⁻¹ for females. The rate of natural mortality (M) for males and females was calculated as 2.54 yr⁻¹ and 1.93 yr⁻¹, and the fishing mortality (F) was 1.77 yr⁻¹ for males and 1.70 yr⁻¹ for females. Recruitment pattern of A. indicus was continuous throughout the year with two major peaks. The exploitation rate (E) of males was 0.41 and that of females was 0.47, though the exploitation rates were slightly less than the optimum level of exploitation (E = 0.50). Thus, the stock of A. indicus is under pressure in the coastal waters of Malacca, Malaysia.