International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-8, Issue-10, October- 2022] Page | 43 Morphological heterogeneity in the giant African River Prawn, Macrobrachium vollenhovenii from three rivers systems in the Niger Delta Region, Nigeria Nwafili, Sylvanus Anene 1* ; Akpoilih Benjamin Uzezi 2 University of Port Harcourt, Faculty of Agriculture, Department of Fisheries, P.M.B 5323, Choba, Rivers State, Nigeria *Corresponding Author Abstract— The study investigated morphological variations among samples of Macrobrachium vollenhovenii captured from Taylor Creek, Calabar Estuary and New Calabar River in the Niger Delta Region. A total of 76 individuals were caught using cone-shaped bamboo basket traps. The prawns were identified and 18 morphological characters were measured on each individual. All the data generated were analyzed using the PAST3 and JASP statistical software. The results of the study indicated that the morphometric measurements among the populations of M. vollenhovenii total length, rostrum length, third segment length, fifth segment length and abdominal length were significant different (p < .05) while telson length, telson width, caudal length, merus length and palm length were not different (p > 0.05). The coefficient of regression in the length-weight relationship were positively allometric (p < 0.05) for all populations with values of 3.5402, 4.6686 and 4.420. The condition factor varied from 0.668 to 2.729 averaging 1.498, 1.628 and 1.630 for New Calabar River, Calabar Estuary and Taylor Creek, respectively. Keywords— African River prawn, Macrobrachium vollenhovenii, morphological heterogeneity, length-weight relationship, condition factor. I. INTRODUCTION The genus Macrobrachium (Bate, 1868) belongs to a group of freshwater prawns (Crustacea, Decapoda, and Palaemonidae). They constitute one of the most diverse, abundant, and widespread crustacean genera (Murphy and Austin, 2005), occurring throughout the tropical and subtropical zones of the world with the exception of Europe (Holthuis, 1980; Fossati et al., 2002; March et al., 2002). Several studies have reported the existence of about 74 species (Chen et al., 2009; Holthuis and Ng, 2010; de Grave and Fransen, 2011). However, the number of species in the Niger Delta Region (NDR) of Nigeria are not well- understood and poorly known. The species that have been documented so far in the NDR include M. macrobrachion, M. vollenhovenii, M. dux, M. felicinum and the invasive species of M. equidens. The most economically important species for NDR are M. macrobrachion and M. vollenhovenii. The African river prawn, M. vollenhovenii is endemic to the west coast of Africa stretching from the Senegal River in the north to Angola in the south (Holthuis, 1980; Willfuhr-Nast et al., 1993; Paterson, 2007). In Nigeria, It does not, however, occur as plentiful in nature as M. macrobrachion even though it has a higher fecundity (Lawal-Are and Owolabi, 2012; George et al., 2013; Nwosu and Holzlöhner, 2016). In the Niger Delta, M. vollenhovenii is an important economic resource in the rural areas, supporting and sustaining viable artisanal fisheries in some rivers and estuaries within the region. Because it is the biggest of all the Macrobrachium species in West Africa (Konan et al., 2008) and grows at relatively fast rates in addition to a number of other favourable culture characteristics, it is considered a good candidate for aquaculture (Marioghae, 1987; Willfuhr-Nast et al., 1993; Niass and Fall, 2015). The African river prawn is also hardy in many parameters, it thrives in murky waters with dissolved oxygen as low as one part per million (Jimoh et al., 2011) To develop the culture of the species, knowledge of the degree of genetic variation is crucial and must be understood because it will provide information on the condition or status of a population with respect to long-term survival of a species and the fitness of the population to adapt to environmental dynamics (Dunham, 2002). Also, natural population are perhaps the best Received:- 01 October 2022/ Revised:- 10 October 2022/ Accepted:- 17 October 2022/ Published: 31-10-2022 Copyright @ 2022 International Journal of Environmental and Agriculture Research This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted Non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.