Environment

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Browsing Environment by Author "Acheampong, Emmanuel"

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    A fleet based surplus production model that accounts for increases in fishing power with application to two West African pelagic stocks
    (Fisheries Research, 2021-11) Cook, Robin; Acheampong, Emmanuel; Aggrey-Fynn, Joseph
    Assessments of many West African fish stocks rely on fishery dependent catch and effort data. Typically, these treat the catch data as error free and some assume that fishing power does not change over time. To address these issues we develop a fleet based surplus production model that accounts for increases in fishing power. It allows errors both in effort and catch data so avoiding the assumption that catch data are exact. Mean annual fleet fishing power increase can be estimated when data from multiple fleets are available provided it can be specified for at least one fleet. The model is tested using simulated data and then applied to western stocks of anchovy (Engraulis encrasicolus) and bonga shad (Ethmalosa fimbriata) in the Fishery Committee for the Eastern Central Atlantic (CECAF) area. Both stocks appear to be over-exploited and near to collapse. Corrections for fishing power are important in the anchovy assessment and help to explain conflicting trends in the data. Uncertainty in the assessments is explored with a range of sensitivity tests.
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    Human health risk assessment from heavy metals in three dominant fish species of the Ankobra river, Ghana
    (ELSEVIER, 2021-05-24) Effah, Elizabeth; Aheto, Denis Worlanyo; Acheampong, Emmanuel
    This study assessed heavy metal contamination of fish and its associated health risk to communities around the Ankobra River in the Western Region of Ghana. Species of fish randomly collected from different sections of the river were analyzed for Cd, Ni, Zn, Pb, Mn, Hg, As, Co and Cr using Atomic Absorption Spectrophotometry. Three commonly consumed fish species, Clarias gariepinus, Sarotherodon melanotheron and Pseudotolithus senegalensis, were analyzed. The health risks were assessed based on the potential non-carcinogenic effect associated with the daily consumption of fish by communities around the river. Concentrations of all the metals were higher in gills than the muscles of all three species. On average, levels of Mn (6.65 ± 7.30 mg.kg􀀀 1), Zn (2.24 ± 1.99 mg.kg􀀀 1) and Hg (3.06 ± 1.53 mg.kg􀀀 1) in all three species were above the permissible limits recommended by the World Health Organization. The health risk estimated for all the heavy metals was < 1, significantly below the ≥ 1 index associated with the incidence of cancer. This suggests that fish species examined in this study pose no significant non-carcinogenic risk and are safe for human consumption.