Papers by Emmanuel T. Mensah
Lakes & Reservoirs: Science, Policy and Management for Sustainable Use, 2019
A mass balance model of trophic interactions among ten key functional producer and consumer group... more A mass balance model of trophic interactions among ten key functional producer and consumer groups in Lake Volta was constructed using the Ecopath model to study the energy flows and species interactions in the lake. The present study was based on secondary and primary data on fish catch, diet composition, phytoplankton and zooplankton biomasses, collected in 2015 and 2016. Additional information on growth parameters of major species required for balancing the Ecopath model was obtained from sampling and FishBase. The functional groups were detritus, phytoplankton, zooplankton, benthos, prey fish, Tilapia, Bagrus, Chrysichthys, Alestes and Synodontis species. Four trophic levels were identified in the Lake Volta ecosystem, with the energy flow occurring mainly within the first three trophic levels. The calculated ecotrophic efficiency value of the primary producers (phytoplankton: 0.17; detritus: 0.22) indicated they were least exploited, compared to the secondary producers, zooplan...
African Journal of Ecology, 2018
Fish species assemblage and selected environmental variables were monitored in Lake Volta from Se... more Fish species assemblage and selected environmental variables were monitored in Lake Volta from September 2014 to August 2016 to determine seasonal variability in species composition, catch and environmental variables that determine the structure of the fish community. A total of 1,557 individual fish belonging to 41 species, 25 genera and 13 families were recorded. The important fish species with respect to frequency of occurrence, abundance and weight, respectively, were as follows: Chrysichthys (100%; 43.03%; 17.93%), tilapias (100%; 28.97%; 17.86%), Alestes (100%; 14.13%; 32.10%) and Bagrus (91.67%; 5.65%; 12.80%) in that order. The composition of fish species and their temporal variation in experimental catches were similar to that of commercial catches. There were no significant differences (p > 0.05) in species abundance, weight and diversity indices between the dry and wet seasons. The modal class of length frequency distribution of the dominant species in the catch, Chrysichthys, reduced from 125 mm in 2006 to 95 mm in the current study indicating overfishing. Environmental variables considered showed little variation and within optimal ranges for fish survival and did not differ significantly between seasons. Canonical Correspondence Analysis showed that environmental variables explained 43.30% of the variation in species abundance with Lake water level, nitrite-nitrogen and total dissolved solids being the main environmental factors influencing the structure of the fish community. Entre septembre 2014 et août 2016, nous avons suivi des assemblages d'espèces de poissons et certaines variables environnementales dans le lac Volta afin de déterminer la variabilité saisonnière de la composition des espèces, des prises et des variables environnementales qui déterminent la structure de la communauté de poissons. Nous avons enregistré un total de 1557 individus appartenant à 41 espèces, 25 genres et 13 familles. Les espèces importantes au point de vue de leur fréquence, abondance et poids étaient respectivement Chrysichthys (100% ; 43,03% ; 17,93%), tilapias (100% ; 28,97% ; 17,86%), Alestes (100% ; 14,13% ; 32,10%) et Bagrus (91,67% ; 5,65% ; 12,80%). La composition des espèces de poissons et les variations dans le temps étaient comparables à celles des prises commerciales. Il n'y avait pas de différences significatives (p<0,05) dans l'abondance des espèces, leur poids et les indices de diversité entre les saisons sèches et les saisons des pluies. La classe modale de la distribution longueur-fréquence de l'espèce dominante des prises,
Aquaculture International, 2018
Globally, aquaculture production is faced with numerous challenges, notable among which is water ... more Globally, aquaculture production is faced with numerous challenges, notable among which is water quality. The study determined seasonal environmental changes in Lake Volta and its implications on cage production of Nile tilapia, Oreochromis niloticus in experimental and commercial farm (Sun Woo Farm) setups. For each setup , three cages were used, each measuring 81 and 162.5 m 3 for experimental and commercial, respectively. The cages were stocked with 22.5 g fingerlings at a rate of 40 and 80 m −3 in experimental and commercial cages, respectively, and fed commercial diet. The growth performance, yield, economics, and selected water quality parameters were monitored during the dry and wet seasons between November 2014 and July 2015. There were no differences in water quality parameters between dry and wet seasons (p > 0.05). Water quality for both seasons remained within limits required for good Tilapia growth in both setups. There were minimal variations in growth characteristics between seasons which were not significant; however, final mean weight and yields were high in the dry seasons in both setups. The cost of feed and fingerling accounting for about 80% of total costs were the major components identified to affect cost of production. A higher profit index and returns on investment were observed in the dry season in both setups and was linked to higher survival rates in the season. Production of Nile tilapia in cages can be cultured throughout the year without any adverse effects as exhibited in similar production patterns in both experimental and commercial setups .
Economic Research-Ekonomska Istraživanja, 2020
This paper sought to examine the pre-and post-IFRS adoption effects on the financial reporting qu... more This paper sought to examine the pre-and post-IFRS adoption effects on the financial reporting quality (FRQ) of manufacturing firms listed on the Ghana Stock Exchange (GSE) via means of correlation analysis, as well as regression analysis using a standard Fixed Effect (FE) model and the Ordinary Least Squares (OLS) technique. Data was sourced from the audited annual reports of eleven manufacturing firms observed over the period 2001 to 2006 for the pre-adoption era, and 2007 to 2014 for the post adoption era, making 148 firm-year observations. Using earnings management, measured by modified Jones' discretionary accruals, as a proxy for FRQ, the regression results showed a significant negative effect of IFRS adoption on earnings management, thus indicating an improvement in the FRQ. On the extent of earnings management practices both pre-and post-IFRS adoption, the study finds a decrease in the post-adoption era as against the pre-adoption era, also signifying an improvement in accounting quality after the adoption of IFRS. The findings of this study indicate that, IFRS adoption enhances the quality of firms' financial reports within the Ghanaian capital market, which is envisaged to boost investor confidence and attract more capital.
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Papers by Emmanuel T. Mensah