Inventaire Et Profil Epidémiologique Des Parasites De Cinq Espèces De Poissons A Potentiel Piscicole Dans Le Cours Supérieur Du Fleuve NKAM (Littoral-Cameroun)

Résumé – La présente étude a été conduite de mai à septembre  2019 en amont du fleuve Nkam, dans la plaine des Mbô en vue de  contribuer à la connaissance de la biodiversité et de l’écologie des parasites des poissons. Ainsi, un total de 130 spécimens de poissons (13 Clarias gariepinus, 34 Clarias jaensis, 24 Labeobarbus batesii, 29 Oreochromis niloticus et 30 Parachanna obscura) a été collecté de manière aléatoire auprès des pêcheurs. L’examen parasitologique a permis de déterminer la prévalence et l’intensité moyenne d’infestation. Les résultats ont un montré un polyparasitisme chez toutes les espèces de poissons avec un total de six taxons de parasites (monogènes, myxosporidies, nématodes, cestodes, copépodes, trématodes). La prévalence générale (48%) a été faible. Indépendamment de l’espèce hôte, la prévalence a été faible pour les monogènes (49,23%), trématodes (28,46%) et myxosporidies (24,62%) pendant que les cestodes (1,53%), copépodes (5,38%) et nématodes (6,92%) ont enregistré une prévalence très faible. Les paramètres espèce, sexe, taille et poids n’ont pas significativement affecté la prévalence et l’intensité d’infestation des poissons. Par ailleurs, la prévalence des monogènes a été maximale (100%) chez Oreochromis niloticus suivis de Clarias gariepinus (76,92%). En outre, 75% de poisson Labeobarbus batesii a été parasité par les trématodes. Globalement, l’intensité d’infestation a varié de très faible à faible.  Au terme de la présente étude, il ressort un polyparasitisme par une faune parasitaire composée de six groupes parmi lesquels les monogènes ont été les plus représentés. Dans l’ensemble, la prévalence et l’intensité d’infestation ont été affectées par l’espèce, le sexe, les classes de taille et poids de poissons du fleuve Nkam sans toutefois montrer de grande différence.Motsclés – Polyparasitisme ; Prévalence; Intensité ; Biodiversité, Ecologie.Abstract – This study was conducted from May to September 2019 uptream of the Nkam river, in the “plaine des Mbô” in order to contribute to the knowledge of fish parasites biodiversity and ecology.  So, a total of 130 fish specimens (13 Clarias gariepinus, 34 Clarias jaensis, 24 Labeobarbus batesii, 29 Oreochromis niloticus and 30 Parachanna obscura) randomly collected from the fishermen were parasitologically examined so as to determine the prevalence and mean intensity of infestation. Results revealed the polyparasitism of all the fish species with six taxa of parasites (monogeneans, myxosporeans, nematodes, cestodes, copepods, trematodes). The overall prevalence (48%) was low. Irrespective of the host species, the prevalence was low with monogeneans (49.23%), trematodes (28.46%) and myxosporeans (24.62%) while cestodes (1.53%), copepods (5.38%) and nematodes (6.92%) recorded a very low prevalence. Fish species, sex, size classes and weights did not significantly influence the prevalence and intensity of infestation. In addition, the prevalence of monogeneans was maximum (100%) in Oreochromis niloticus followed by Clarias gariepinus (76.92%). On the other hand, 75% of the fish Labeobarbus batesii was infested by trematodes. The overall intensity varied from very low to low. This study finally reveals the polyparasitism of fishes by a parasitic fauna composed of six groups of parasites among which monogeneans were the most represented. Overall, the prevalence and the intensity of infestation was affected by the species, sex, sizes and weight classes of fishes from the Nkam river with no significant difference.Keywords – Polyparasitism, Prevalence; Intensity; Biodiversity, Ecology

Automatic Extraction and Geospatial Analysis of Lineaments and their Tectonic Significance in South Cameroon Area using Remote Sensing Techniques and GIS

This study investigates the dominant orientations of lineament features and the relationship between these trends and the spatial orientation of tectonic structures in the transition zone of the Congo craton and the Pan African belt in South Cameroon area. Landsat 8 OLI/TIRS and hill-shaded images, constructed from 30 m-resolution SRTM-DEM data, were used for automatically extracting and mapping geological lineaments. Lineament features were analyzed by means of azimuth frequency and length density distributions. Three major sets of lineaments trending W–E, ENE-WSW and WNW-ESE are identified in the South Cameroon area. These trends are probably related to repeated reactivation of pre-existing crustal structures during Eburnean and Pan-African tectonic episodes. The lineaments were formed under the compressional tectonic stress regimes generated during these tectonic events

Comparing Smoked Fish Quality of Traditional and Improved Modern Ovens Using Dendro-Energy from Mangrove and Tropical Forest Woods and Implications for Conservation in Central African Atlantic Coast, Cameroon

Smoked fish qualitative organoleptic parameters (color, smell, texture and taste) and quantitative proximate parameters (protein and ash content and salt mineral: Ca, Iron, Mg, Zn content in ash) of two species (Ethmalosa fimbriata and Pseudotolithus elongatus) smoked in traditional and modern ovens with wood from mangrove (Rhizophora racemosa) and two tropical forest (Sacoglottis gabonensis and Albizia glaberrina) species in Douala-Edea Atlantic coast, Cameroon are presented. Women processors significantly spend more time, consume more wood and consequently release significant amount of carbon dioxide (CO2) to the environment with traditional smoking system. Organoleptic characteristics were significantly different with ovens types but not with different wood species except color (black and marron from inland forest wood species and preferred brownish and golden brown colored smoked fish from mangrove wood). Fish food constituents yielded for improved smoked oven:  Protein content (65.52%; 69.45%), ash content (6.21%; 5.57%) and traditional oven: Protein content (70.65%; 75.00%), ash content (5.73%; 6.33%) for Ethmalosa fimbriata and Pseudotolithus elongatus respectively. Results also confirmed good dietary quality of fish samples (source of calcium, iron and magnesium). Some energy efficient management techniques and conservation implications were proposed regarding qualitative and quantitative improvement of smoked fish

Effect of the Incorporation Level of Ripe Avocado Pulp Powder Persea americana on the Zootechnical Performances of Clarias jaensis Juveniles (Boulanger, 1909)

In order to contribute to the valorization of agricultural by-products in fish feed, the effect of the incorporation level of the ripe avocado pulp powder persea americana on the zootechnical performance of Clarias jaensis Juveniles (Boulanger, 1909), was studied between February and July 2019 in the highland zone of West Cameroon. To attend the aims, 156 juvenile Clarias jaensis (25.82 ± 7.43g) settled in triplicates in floating tanks were fed four iso-protein rations (40% crude protein) corresponding to 0, 8, 12 and 16% incorporation of ripe avocado. Feed were distributed twice daily (8 am and 6 pm) at 5% of the fish biomass for 63 days. The following results were as follows: Survival rate, final mean weight, daily mean weight gain, specific growth rate and condition factor K were higher and non-significant in batches receiving 8% of ripe avocado pulp powder with a lower feed conversion ratio (99,14 ± 0,50% ; 40,22 ± 10,5g; 0,14 ± 0,44 g/d, 0,41 ± 1,07 %g/d; 0,70 ± 0,09 %g/cm3 and 1,87 ± 0,09) and lower with a highest feed conversion ratio at 16% incorporation (93,67 ± 8,47 %; 30,02 ± 8,00g; 0,08 ± 0,22 g/d; 0,28 ± 0,77 % g /d; 0,68 ± 0,15 %g/cm3 and 2,018 ± 017). Body composition varied with the level of pulp meal incorporation, water content was high with 0% (79.14%), and dry matter (23.87%), crude protein (15.35%) and fat (5.23%). It was higher with 16%, while ash was higher (3.45%) in batches fed with 12% incorporation. The feed cost was lower at 8% incorporation (734.89Fcfa/kg of fish produced). The incorporation of 8% avocado pulp meal was found to improve the growth of Clarias jaensis juveniles and reduce the feed cost. Producers can use spoiled avocados as fish feed to reduce production costs, without negative impact on the final product

Co-culture Clarias gariepinus-Oreochromis niloticus : quels avantages pour l’amélioration des performances zootechniques et économiques des poissons élevés dans les « whedos » du delta de l’Ouémé au Bénin ?

L’alimentation des poissons est la contrainte majeure pour l’émergence de la pisciculture tropicale. Dans le but d’évaluer l’effet de la co-culture Clarias gariepinus - Oreochromis niloticus sur la croissance de ces deux espèces élevées dans les whedos, une expérience a été conduite durant 56 jours dans le village Aïzè à Ouinhi (Bénin). Des alevins de C. gariepinus (6,74 ± 0,27 g) et de O. niloticus (8,11 ± 0,14 g) ont été placés respectivement dans des happas de 1 m2 (30 alevins / m2) et de 6,25 m2 (30 alevins / happa), les happas contenant C. gariepinus étant insérés dans les happas contenant O. niloticus. Trois types d’aliments ont été testés: aliment importé Sckretting (45% de protéines), aliment local (37% de protéines), et aliment mixte (50% aliment local et 50% aliment importé). Seuls les alevins de C. gariepinus ont été nourris, les alevins de O. niloticus se nourrissant de la production primaire produite par les déjections de C. gariepinus. Les meilleures performances zootechniques et d’utilisation alimentaire ont été obtenues avec l’aliment mixte suivi de l’aliment importé chez les deux espèces. Chez C. gariepinus, le poids moyen final a varié de 20,95 ± 1,12 g à 42,56 ± 2,26 g tandis que chez O. niloticus il a varié de 17,00 ± 1,84 g à 19,63 ± 0,83 g. La présente étude a clairement montré que la co-culture Clarias gariepinus – Oreochromis niloticus avec nourrissage seulement de C. gariepinus est une forme d’élevage de plusieurs espèces de poissons à la fois à coût réduit.© 2015 International Formulae Group. All rights reserved.Mots clés: Co-culture, whedos, happas, delta de l’Ouémé, SckrettingEnglish AbstractThe fish feeding is the major constraint to the emergence of tropical fish farm. In order to assess the effect of co-culture Clarias gariepinus - Oreochromis niloticuson on the growth of these two species bred in whedos, an experiment was conducted during 56 days in the village Aїzè in Ouinhi (Benin). Fingerlings of C. gariepinus (6.74 ± 0.27 g) and O. niloticus (8.11 ± 0.14 g) were placed respectively in happas 1 m2 (30 fingerlings / m2) and 6 25 m2 (30 fingerlings / happa), the happas containing C. gariepinus being inserted into the happas containing O. niloticus. Three kinds of foods were tested: imported food Sckretting (45% protein), local food (37% protein), and mixed food (50% imported and 50% local food). Only C. gariepinus fingerlings were fed, O. niloticus fingerlings feeding on primary production produced by the manure of C. gariepinus. The best growth performance and feed utilization were obtained with the mixed food followed by imported food in both species. In C. gariepinus, the final average weight ranged from 20.95± 1.12 g to 42.56 ± 2.26 g, while in O. niloticus it ranged from 17.00 ± 1.84 to 19 g, 63 ± 0.83 g. This study clearly demonstrated that co-culture Clarias gariepinus - Oreochromis niloticus with only C. gariepinus feeding is a form of rearing several species of fish both at reduced cost.© 2015 International Formulae Group. All rights reserved.Keywords: Co-culture, whedos, happas, Ouémé Delta, Sckretting

Performances de reproduction du poisson chat endogène du Cameroun Clarias jaensis (Boulenger, 1909) en milieu contrôlé

Les performances de reproduction de Clarias jaensis ont été évaluées entre mai et octobre 2014 à Batié (Ouest-Cameroun). A cet effet, 30 femelles de poids moyen 199, 52 ± 34,85 g ont été réparties en 5 lots comparables. Chaque lot choisi au hasard a été soumis à l’Hormone Chorionique Gonadotrophine (HCG) aux doses de 3500, 4000 et 4500 Unités Internationales (UI) / kg et aux extraits hypophysaires des mâles et des femelles. Le poids et le diamètre des ovocytes, les taux de fécondation et d’éclosion ont été évalués. Les principaux résultats ont montré que: le poids des ovocytes a été le plus élevé (p < 0, 05) avec l’extrait hypophysaire femelle (39,33±17,08g) ; le diamètre des ovocytes a été comparable entre les traitements. Le taux de fécondation a été le plus élevé pour la dose de 4000 UI / kg de HCG (87, 50 ± 12,45%) suivi de l’extrait hypophysaire femelle (85,08 ± 14,29%). Cependant aucune différence significative (p ˃ 0,05) n’a été obtenue. Le taux d’éclosion a été plus élevé avec l’extrait hypophysaire femelle (19, 38 ± 6,58%). La reproduction artificielle chez Clarias jaensis est possible avec l’hormone HCG à 4000 UI / kg ou des extraits hypophysaires femelles.© 2016 International Formulae Group. All rights reserved.Mots clés: Clarias jaensis, espèce endogène, performances de reproduction, captivité, CamerounEnglish Title:  Reproductive performances of indigenous catfish of Cameroon Clarias jaensis (Boulenger, 1909) in captivityEnglish AbstractIn order to improve local biodiversity and number of fishes in aquaculture in Cameroon, reproductive performances in captivity of Clarias jaensis have been studied between Mai and October 2014 in Batié (West Cameroon). In fact, 30 females with 199, 52 ± 34, 85 g were divided randomly into five comparable treatments. Each was submitted to a Human Chorionic Gonatropin Hormon at 3500, 4000 and 4500 Internationals Units (UI) / kg of body weight, males and female’s pituitary extracts. The main results obtained were: The oocyte weight was significantly higher (p < 0, 05) with females’ pituitary extracts (39, 33 ± 17,08g), the oocyte diameter mean was comparable within the treatments. The higher fecundity rate was obtained with the Human Chorionic Gonadotropin Hormon at 4000 UI / kg of body weight (85, 08 ± 14, 29%). However, no significant differences (p ˃ 0, 05) were found. The hatching rate was significantly higher (p < 0, 05) with the pituitary extracts of females (19, 38 ± 6, 58%). Clarias jaensis can be reproduced artificially using Human Chorionic Gonadotropin Hormon at 4000 UI / kg of body weight or female’s pituitary extracts.© 2016 International Formulae Group. All rights reserved.Keywords: Clarias jaensis, reproductive performances, indigenous species, captivity, Cameroo