Relation Taille-Poids et Facteur de Condition de l’espèce Elops lacerta (Elopiformes : Elopidae) Valenciennes, 1847 dans le Golfe de Guinée, Côte d’Ivoire, Afrique de l’Ouest

La présente étude décrit la relation taille-poids et le facteur de condition de Elops lacerta dans la Zone Economique Exclusive (ZEE) Ivoirienne. Pour l’étude de ces paramètres, de janvier 2019 à décembre 2020 un échantillonnage mensuel a été réalisé lors des débarquements au port de pêche d’Abidjan (Côte d’Ivoire). La longueur de fourche (LF) a été utilisée dans cette étude. La relation taille-poids a été calculée en utilisant l’équation P = aLFb et le facteur de condition en utilisant l’équation K = (100P ⁄ LFb). Au total 865 poissons ont été collectés dont 494 mâles et 371 femelles avec une gamme de taille comprise entre 20 et 57 cm pour une masse totale oscillant entre 62,5g et 1500g. La valeur du coefficient d’allométrie est 3,06 pour les mâles, 3,11 pour les femelles et 3,09 pour les deux sexes confondus. Ces coefficients d’allométrie sont significativement différents de la valeur standard 3 (p < 0,05), traduisant une allométrie majorante chez l’espèce Elops lacerta.. Egalement, la variation saisonnière du coefficient d’allometrie révèle une allométrie majorante au cours de la saison froide chez les mâles (3,06), les femelles (3,16) et les deux sexes confondus (3,12). Par contre, au cours de la saison chaude une allometrie minorante a été obtenue uniquement chez les femelles (2,99). Le coeffieient de corrélation compris entre 0,90 et 0,98, indique une forte corrélation entre le poids et la taille des poissons. Le facteur de condition varie entre 0,76 ± 0,04 et 0,85 ± 0,08 chez les mâles et entre 0,63 ± 0,08 et 0,72 ± 0,05 chez les femelles. Les valeurs maximales de cet indice ont été observées pendant la grande saison froide précisément au mois d’août pour les mâles (0,85 ± 0,08) et en octobre chez les femelles (0,72 ± 0,05). Ces résultats fournissent une base de données sur la relation taille-poids et le coefficient de condition de l’espèce E. lacerta dans la ZEE ivoirienne.   The present study describes the length-weight relationship and the condition factorof Elops lacerta in the Ivorian Exclusive Economic Zone. For the study of these parameters, from January 2019 to December 2020 a monthly sampling was carried out during landings at the fishing port of Abidjan (Côte d’Ivoire). The fork length (LF) was used in this study. The length-weight relationship was calculated using the equation P = aLFb and the condition factor using the equation K = (100P ⁄ LFb). A total of 865 fish were collected of which 494 were males and 371 females with a size range between 20 and 57 cm with a weight varying from 62.5g and 1500g. The value of the allometry coefficient was 3.06 for males, 3.11 for females and 3.09 for both sexes combined. These allometry coefficients was significantly different from the standard value of 3 (p < 0.05), reflecting a major allometry in the Elops lacerta species. Also, the seasonal variation of the allometry coefficient revealed a major allometry during the cold season in males (3.06), females (3.16) and both sexes combined (3.12). In contrast, a minor allometry was obtained only in females (2.99) during the warm season. The correlation coefficient of 0.90 to 0.98 indicates a strong correlation between the weight and the size of the fish. The condition factor varies between 0.76 ± 0.04 and 0.85 ± 0.08 in males and between 0.63 ± 0.08 and 0.72 ± 0.05 in females. The maximum values of this index were observed during the long cold season, precisely in August for males (0.85 ± 0.08) and in October for females (0.72 ± 0.05). These results provide a database on the length-weight relationship and condition coefficient of the E. lacerta species in the Ivorian EEZ

The spatial distribution of coastal fish assemblage in Côte d’Ivoire’s Exclusive Economic Zone (EEZ), West Africa

Objectives: The interest of this study is double. Firstly, these results allow for the characterisation of species assemblages, to identify their spatial distribution boundaries. Secondly, these findings are relevant to define spatial or ecosystem units in order to provide background for fisheries management.Methodology and Results: Samples were collected and studied at a grid of three zones during the cruise of investigation on board the Oceanographic Vessel ITAF DEME in March 2012. Forty- seven taxa belonging to four orders (Cephalopoda, Malacostraca, Chondrichtyes and Osteichtyes) were selected for analysis. Spatial differences in fish structure were analysed through different multivariate routines from PRIMER including between-matrix analysis of similarities (ANOSIM), species contributions to similarity/dissimilarity (SIMPER), non-metric multidimensional scaling (MDS) and group average cluster analysis. Typical or abundant species from those zones included fishes from the families Sparidae, Haemulidae, Carangidae. The most abundant species were Ariomma bondi (Ariommidae), Selene dorsalis (Carangidae), Brachydeuterus auritus and Pomadasys incisus (Haemulidae), Pagellus bellottii (Sparidae). The species Sardinella maderensis, Brachydeuterus auritus, Trachurus trecae and Selene dorsalis had the highest frequencies of occurrence.Conclusion and application: The distribution of the species halieutics is not uniform along the coast of Côte d’Ivoire. This study pointed to the fish resources of Côte d’Ivoire’s Exclusive Economic Zone. These results will be used by the fishermen and for the development of adequate measures to prevent the loss of aquatic biodiversity.Keywords: Biodiversity, Indices of diversity, Coastal zone, Côte d’Ivoir

Abstracts of the 1st International Colloquium in Mine & Society

This book presents the abstracts of the selected contributions to the First International Colloquium on Mines and Society (CIMS) organized by The Higher Institute of Mining and Geology of Boke. The theme of this colloquium was "Mining and Sustainable Development, a major challenge for an Emerging Africa" which aims to bring together teachers, researchers, and Professionals from different backgrounds in order to exchange the results of their research work, share their points of view on the issue of mining and sustainable development. It also aims to define, in a collaborative and inclusive manner, research prospects or future projects between all the actors involved in this field. Colloquium Title: 1st International Colloquium in Mine & SocietyTheme: Mining and Sustainable Development, A Major Challenge for an Emerging AfricaColloquium Date: 20-22 May 2022Colloquium Location: A L’Hôtel Rio Nunez de BokeColloquium Organizer: The Higher Institute of Mining and Geology of Bok