Diversity and abundance of cichlids in Ikere Gorge Reservoir, Iseyin, Oyo State, Nigeria

Cichlids are highly abundant and commercially important fish in freshwater ecosystems in Nigeria. This study examined the diversity and abundance of cichlids in Ikere Gorge Reservoir. Four fishing villages were randomly selected from 12 fishing villages in Ikere Gorge Reservoir as sampling sites. Cichlids were sampled randomly and examined from fishermen catch in each selected fishing village; were identified with appropriate keys; the weight and abundance of the catches were recorded. The data obtained was subjected to descriptive statistical analysis using SPSS (Version 20.0) software to determine the abundance of fish species. Fish species diversity was carried out by using Palaeontological Statistics (PAST). Eight species of cichlids were sampled in Ikere Gorge but Sarotherodon galilaeus was the most abundant species while the least abundant species was Pelmatolapia mariae. It was observed that, cichlids were abundant in rainy season than in the dry season. Likewise, cichlids were abundant in Ikere-gorge reservoir but they have low diversity. This may be as a result of unsustainable fishing pressure and deforestation of riparian forest and sedimentation in Ikere-gorge reservoir. Therefore, to maintain sustainable fishing activities and improve cichlids population in Ikeregorge reservoir, unsustainable activities in and around Ikere Gorge reservoir should be put under control. Keywords: Cichlidae; freshwater species; dominant; Sarotherodon galilaeus; Pelmatolapia mariae.

Recent status of exotic tilapia species in Turkey

One of the most controversial issues in Turkey about the occurrence of the exotic fish species belonging to the family Cichlidae. Up to date, starting the 1970’s a total of seven species including Coptodon rendalli, C. zillii, Oreochromis aureus, O. mossambicus, O. niloticus, Sarotherodon galilaeus and Tristramella simonis introduced to Turkey for aquaculture purposes or accidently. Then these species have deliberately released or escaped from research and aquaculture facilities establishing themselves into natural environment of Turkey. In other cases, tilapia have been introduced into new aquatic habitats via aquarists or ornamental fish farmers. There was not any reliable record about establishment of O. mossambicus, S. galilaeus and T. simonis in Turkey. It is observed that now C. rendalli, C. zillii, O. aureus, and O. niloticus and/or hybrids of them exist in the wild water system of Turkey. Another problematic issue is that species identification of specimens found in nature is impossible due to the fact that hybridization of different species of Cichlidae. By the way, the range of the species belonging to the family Cichlidae in Turkey is determined that a need for detailed genetic studies to assess the current status.

Morphological characterization of natural populations of Sarotherodon galilaeus (Linnaeus, 1758) from three selected reservoirs in South Western, Nigeria

Morphological characterization of Sarotherodon galilaeus (Linnaeus, 1758)from Opa, Asejire and Ero reservoirs in southwest, Nigeria was carried out with a view to determining the morphological heterogeneity or homogeneity among the three different populations and to determine whether there are morphotypes of this species in the selected study areas. Twenty five morphometric measurements and six meristic counts were recorded on 150 specimens; fifty from each reservoir population. Principal Component Analysis (PCA) and Canonical Variate Analysis (CVA) were performed on the morphometric and meristic data using PAST software. All the clusters produced by the PCA and CVA analyses on the morphometric and meristic data overlapped widely; indicating a low level of morphological differentiation among the three populations of Sarotherodon galilaeus. The study concluded that the Sarotherodon galilaeus populations from Opa, Asejire and Ero reservoirs are morphologically similar and phenotypically inseparable. Keywords: Morphometric, Meristic, Morphological differentiation, Reservoirs in south-western Nigeria, Sarotherodon galilaeus

Scanning morphology, prevalence and histopathology of some acanthocephalans infecting some River Nile fish

Acanthocephalan morphology and their adverse pathological impact on fish are of great concern. Two species of acanthocephalans were recorded from 800 samples of live freshwater fish collected randomly during 2017–2018 from Lake Nasser, Aswan, Egypt. The recovered species were identified morphologically as Acanthogyrus (Acanthosentis) tilapiae from three Tilapia spp. (Sarotherodon galilaeus, Oreochromis niloticus and Tilapia zillii) and Rhadinorhynchus niloticus from Lates niloticus. The intensity of parasitic infection and the seasonal prevalence were higher in L. niloticus than in Tilapia spp. The clinical signs and post mortem lesions of infected fish were reported. Morphological description of the detected parasites using light microscope was then confirmed by electron microscopy to amplify ambiguous details. The histopathological findings of the intestine of naturally infected fish with acanthocephalan parasites were investigated and described. The main damage caused by them is destruction of the mucosal epithelium of the villi, necrosis and degeneration of intestinal epithelial cells.

Diversité piscicole et paramètres démographiques des principales espèces de poisson du réservoir de Samandeni, Burkina Faso

La gestion de la pêcherie du réservoir de Samandeni au Burkina Faso, nouvellement mise en eau en 2017 nécessite des informations fiables qui sont pour l’instant éparses, insuffisantes voire inexistantes. Ce travail vise à combler ce gap à travers une analyse de la diversité, des paramètres de croissance et d’exploitabilité de la faune piscicole de ce réservoir. Pour ce faire, les poissons ont été échantillonnés au filet maillant et épervier entre avril 2018 et janvier 2019. Les espèces ont été identifiées et chaque poisson a été pesé puis mesuré. Au total 39 espèces ont été recensées et regroupées en 29 genres et 14 familles. Les familles les plus représentées sont Cichlidae, Mormyridae et Mochokidae. Les espèces dominantes sont Sarotherodon galilaeus Siluranodon auratus, Schilbe intermedius, Coptodon zillii et Oreochromis niloticus. L'étude suggère que les poissons et cet écosystème aquatique sont dans de bonnes conditions. Les résultats de cette étude contribueront à mieux planifier la gestion de cette nouvelle pêcherie et constitueront une base pour comprendre les changements futurs.

Etat des lieux de la faune ichtyologique des pêcheries de la Sirba et de Sidi-Kompenga, Est du Burkina Faso

Cette étude a concerné les pêcheries des localité de Sidi-Kompenga et de Sirba situées à l’Est du Burkina Faso et a eu pour objectif de faire l’état des lieux de la faune ichtyologique. L’échantillonnage s’est déroulé durant les périodes de crue et d’étiage. Des pêches expérimentales combinant plusieurs engins de pêche ont été menées sur six stations. Quatre paramètres physico-chimiques ont été mesurés : la température, le pH, la conductivité et la transparence. La richesse taxinomique ainsi que les indices de diversité de Shannon, d’équitabilité de Pielou et de Simpson ont été déterminés. Les températures moyennes étaient comprises entre 27,8 et 31,2 °C et entre 28,6 et 30,9 °C respectivement au niveau de Sidi-Kompenga et de la Sirba. Quant aux pH moyens, ils étaient compris entre 7,3 et 8,3 et entre 7,04 et 8,24 respectivement au niveau de SidiKompenga et de la Sirba. Quant à la faune ichtyologique, on a dénombré 29 espèces regroupées en 22 genres et 11 familles au niveau de Sidi-kompenga et 28 espèces regroupées en 23 genres et 11 familes au niveau de Sirba. Les indices de Shannon H’, d’équitabilité de Pielou et de Simpson calculés ont été respectivement 2,67 ; 0,79 et 0,90 à Sidikompenga et 2,66 ; 0,80 et 0,91 à Sirba. Les familles des Alestidea et des Mormyridea ont été les plus diversifiées avec chacune 6 espèces dont Sarotherodon galilaeus, Oreochromis niloticus et Coptodon zillii ont été les 3 espèces les plus courantes dans les captures. Les résultats montrent que les deux pêcheries présentent une population piscicole diversité.