Growth and Mortality of the Red-Spot Prawn (Metapenaeopsis Barbata) in the Northeastern Coast off Taiwan

Abstract

Seasonal growth parameters, mortalities and exploitation rate of red-spot prawn (Metapenaeopsis barbata) in the northeastern coast off Taiwan were examined using 12 monthly length-frequency data (February 1995 to February 1996) and analyzed with the ELEFAN methods. Parameters of the von Bertalanffy growth equation with seasonal fluctuations obtained are (1) K (growth coefficient)=1.5 year^(-1), L(subscript ∞)(asymptotic length) = 27.4 mm carapace length (CL), C (amplitude of seasonal growth oscillation) = 0.95, WP (winter point) = 0.25 of year, and Rn = 0.575 for females; and (2) K = 1.14 year^(-1), L(subscript ∞)= 23 mm CL, C = 0.95, WP = 0.59, and Rn = 0.556 for males. The instantaneous rate of total mortality obtained through seasonalized length-converted catch curve for females and males are 4.80 and 4.10 year^(-1), respectively. The instantaneous rate of natural mortality is 2.69 year^(-1) in females and 2.32 year^(-1) in males. The instantaneous rate of fishing mortality is 2.11 year^(-1) in females and 1.78 year^(-1) in males. The exploitation rate, E = 0.44 in females and 0.43 in males, implies that the stock is slight under-exploited.