Vol. 2, Issue 2 (2017)
Growth mortality and exploitation rates of butter nose, gale ides decadactylus ((Bloch, 1975) within the coastal waters of Liberia
Author(s): Austin Saye Wehye, Samuel KK Amponsah
Abstract: The study evaluated some population parameters of Galeoides decadactylus within Liberia’s coastal waters. A total of 1618 samples were collected from eight coastal counties of Liberia from April, 2013 to September, 2013. Total length of individual fish samples was measured for Total length and analysed using FiSAT II software. From the results, Von Bertalanffy parameters were estimated at asymptotic length (L∞) = 54.08 cm, growth rate (K) = 0.19 per year, the longevity (tmax) = 15.8 years, theoretical age at birth (t0) = −0.75 years and growth performance index (Ø) = 2.745. The length first capture (Lc50 = 9.41 cm) was found to be lower than the length at first maturity (Lm50 = 13.8 cm). Mortality parameters were calculated as total mortality rate (Z) = 0.91 per year, natural mortality rate (M) = 0.49 per year and fishing mortality rate (F) = 0.42 per year. The exploitation rate (E) of 0.46 and the maximum exploitation rate (Emax) was 0.45. Results from the study revealed that the Galeoides decadactylus fishery in Liberia is slightly overexploited as well as the presence of growth overfishing within the Galeoides decadactylus population with Liberian waters. Thus, to avert the consequences of growth overfishing, sustainable fisheries measures including monitoring of fishing efforts and increase in mesh size should be implemented and enforced.