International Journal of Fisheries and Aquatic Research 43 International Journal of Fisheries and Aquatic Research ISSN: 2456-7248, Impact Factor: RJIF 5.44 www.fishjournals.com Volume 2; Issue 2; March 2017; Page No. 43-49 Growth, Mortality and Exploitation rates of Lesser African threadfin, Galeoides decadactylus (Bloch,1795) within the coastal waters of Liberia 1 Austin Saye Wehye, * 2 Samuel KK Amponsah 1 Bureau of National Fisheries, Ministry of Agriculture, Liberia. 2 CSIR-Food Research Institute, Box M 20, Accra, Ghana. 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 and analyzed using FiSAT II software. 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 (Φ′) = 2.745. The length first capture (Lc50 = 9.41 cm) was 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) and maximum exploitation rate (E max) were 0.46 and 0.45 respectively. Galeoides decadactylus fishery in Liberian coastal waters was found to be experiencing unsustainable exploitation as well as growth overfishing. 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. Keywords: Liberia, Galeoides decadactylus, Growth, Mortality, Exploitation rate Introduction Galeoides decadactylus (Bloch, 1795), commonly known as ‘Lesser African threadfin’ of the family Polynemidae is primarily a demersal species, common to 30 cm total length, inhabits sandy and muddy bottoms in shallow coastal waters [1] . Galeoides decadactylus is well distributed from the south of Mauritania to Angola including the nearshore waters of Liberia. Its body is fusiform, grayish with two dorsal fins widely speared [2] , Descriptively, the caudal fin is large and forked with the pectoral fin inserted above the lateral line and the mouth short and inferior [3] , [4] . The Lesser African threadfin is carnivorous and scavenging in nature, preying on shellfish, little fish, crayfish and crabs [5] , [6] . Galeoides decadactylus species often portray negative allometric growth, thus its length grows faster than the corresponding weight [7] , [8] . Proximate analysis by [9] concluded that Galeoides decadactylus has higher moisture content thus vulnerable to a faster rate of post-harvest loss due to spoilage. However, one of the adopted control strategies in reducing post-harvest loss in Galeoides decadactylus fishery includes fermentation and drying of Galeoides decadactylus into lanhouin [10] . [11] defines lanhouin as a salted, fermented dried fish often consumed in southern Benin. ‘Butternose’ as it is locally known in Liberia is a significant marine fish resource with regards to Liberia’s coastal fishing as it is well appreciated by the consumers because of the quality of its flesh. Galeoides decadactylus is primarily harvested by fishermen who operate with beach seines and gillnets along the nine coastal counties of Liberia. However, in Liberia, information on population parameters and population position of important commercial fishes are not readily accessible, despite the importance of fish to food security and nutrition, particularly in fishing households. Limitation of scientific information on fish population assessment renders fisheries management options geared toward sustainable exploitation of commercially important fishes in Liberia ineffective. In view of this, the objective of the study was to evaluate some population parameters of Galeoides decadactylus. Information gained from this study will not only fill knowledge gap but ensure sustainable management of this commercially important fish species resident in Liberia’s coastal waters. 2. Materials and Methods 2.1 Study area Liberia is a relatively small coastal state located in West Africa with geographical coordinates as 6.4281 o N, 9.4295 o W. The coastline of Liberia is 570 kilometers comprising of relatively warm waters and low nutrient contents [12] . However, the study focused on eight fish landing sampling stations within eight coastal counties along the coastline of Liberia (Figure 1). These fish landing sampling coastal counties included Maryland, Rivercess, Sinoe, Margibi, Montserrado, Grand cape Mount, GrandKru and Grand Bassa. Selection of the eight fish landing sampling sites was based on the level of fishing activity and geographical location. The main source of livelihood for the majority of the inhabitants residing within the selected eight fish landing sampling stations is fishing and its related activities such as fish processing and fish trade. However, a few of the indigenes are engaged in alternative forms of livelihoods including farming, driving and others.