Growth Performance of the Nile Tilapia, Oreochromis Niloticusf Cultured in Cages in Two Dams in the Bongo District of Ghana

This study was carried out to compare the growth performance and survival rate of Nile tilapia, Oreochromis niloticus cultured in cages in two different dams in the Bongo District of the Upper East Region of Ghana. Three cages with the same structural characteristics were constructed in each of the dams as replicates. Each cage was stocked with 9500 all male O. niloticus fingerlings and fed with 48 % nourish plus feed thrice daily for a period of eight weeks. Twenty-five samples of the fishes were randomly collected bi-weekly from each cage and measurements such as standard length and body weight recorded. Other growth characteristics such as specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), mean weight gain (MWG), condition factor (K) and survival rate (SR) were estimated. The results revealed that, O. niloticus cultured in the Soe-Yidongo community dam recorded the highest growth performance in terms of final body weight, standard length, weight gain, specific growth rate, condition factor and protein efficiency ratio, and they were significantly different (p < 0.05) from those recorded in the Bon-Gurigo community dam which was attributed to the variations recorded in the physicochemical parameters of the two dams. It was concluded that tilapia cultured in cages might be an important alternative livelihood strategy for poor people in rural communities in Ghana

ORIGINAL ARTICLES Limnological Evaluation of the Fisheries Potentials of a Ghanaian Reservoir

ABSTRACT Morpho-edaphic Index (MEI), and total nutrient input have been applied to the Dawhenya reservoir in Ghana from August 2006 to July 2007 to estimate existing fish yield and future potential productivity. The estimated existing fish yield from the reservoir was about 38.44 kg/ha. In the Dawhenya reservoir, 12 species belonging to 8 genera were encountered out of which 7 genera were fin fishes while the remaining genus was a shell fish. During the dry season, eight fish species were sampled and Barbus macrops contributed the highest (71.6 %) and Oreochromis niloticus the lowest (0.2 %) by weight while in the wet season five fish species were collected and Barbus macrops contributed the highest (85.3 %) and Macrobrachium vollenhovenii the lowest (2.1 %) of total weight of fish in drag net catches. Estimates of b-values ranged from 2.793 in Sarotherodon galilaeus to 3.267 in Macrobrachium vollenhovenii. Only Barbus macrops growth pattern in the reservoir was isometric meaning there was an equal increase in length and weight during growth, while Macrobrachium vollenhovenii, Macrobrachium macrobrachion and Sarotherodon galilaeus growth patterns were allometric, meaning increases in length and weight of the species were not equal during growth. The general physicochemical parameters monitored during the study period fell within the ranges suitable for fisheries and aquatic life in reservoirs, except for phosphates which were outside recommended ranges. Observations of pH showed that the reservoir was slightly alkaline. Agricultural activities within the catchment area of the reservoir should be monitored and controlled to prevent nutrient enrichment since the inhabitants were predominantly peasant farmers

Determinants of Fisher’s Choice of Fishing Activity along the Volta Lake in Yeji, Ghana

The study examined factors that influence people’s decision to engage in the fishery-related activities in Yeji, a major inland fishing town in Ghana. A total of 304 respondents were randomly selected and interviewed using semi-structured questionnaire. The analysis was done using the Ordered Probit Model and descriptive statistics. The study revealed that fishers in Yeji depend on the small-scale fisheries as their source of livelihood. The Ordered Probit regression analysis showed that the likelihood to engage in the fishery-related activities was significantly influenced by factors such as fishers’ level of education, average daily catch, gear ownership (boat), credit access, fishing experience, income and household size. The study revealed that lack of credit access as affirmed by majority (82%) of the respondents as the major challenge faced in the study areas. It is concluded that the fisheries sub-sector has the potential to boost economic growth, reduce poverty and ensure household food security in Yeji. It is therefore recommended that Ghana government through the Fisheries Commission should put in place sustainable measures and strategies that would ensure availability of fishing nets and boats for rural poor fishers.Key words: Volta Lake, Determinants, Fishing Experience, Likelihood, Ordered Probit Mode

Pre-Impoundment Fish Stock Assessment of the Black Volta: A Contribution to Fisheries Management of Bui Reservoir in Ghana

A length-based fish stock assessment of the Black Volta River in Ghana was undertaken prior to its damming at Bui in 2011. The approach involved estimation of the population parameters and exploitation rates of dominant fish stocks using TropFish R. The targeted species were: Alestes baremoze, Hydrocynus forskalii, Hemisynodontis membranaceus and Labeo coubie. The estimated asymptotic length (L∞) ranged from 30.8 – 48.2 cm standard length (SL) with derived longevity of 11 – 27 years for the assessed species. The estimated growth coefficient (K) value ranged from 0.10 – 0.25 yr-1 which suggested slow growth rates. The estimated length at first capture (Lc50) was lower than the length at first maturity (Lm50) for all the assessed fish species which suggests the presence of recruitment overfishing within the fish stocks. The total mortality rate (Z) was relatively high ranging between 0.51 and 1.34 yr-1 suggesting that the stocks were over-exploited during the pre-impoundment period. The exploitation rate (E) for the assessed fish species were lower than the maximum exploitation rate (Emax) which indicates that the species are far from collapse. These estimates are baseline scientific information for designing a Fisheries Management Plan for the Bui reservoir. Meanwhile, alternative livelihood and employment opportunities such as cage fish culture are to be explored to reduce the fishing pressure on the reservoir

Propagation of nuclear data uncertainties for ELECTRA burn-up calculations

The European Lead-Cooled Training Reactor (ELECTRA) has been proposed as a training reactor for fast systems within the Swedish nuclear program. It is a low-power fast reactor cooled by pure liquid lead. In this work, we propagate the uncertainties in Pu-239 transport data to uncertainties in the fuel inventory of ELECTRA during the reactor life using the Total Monte Carlo approach (TMC). Within the TENDL project the nuclear models input parameters were randomized within their uncertainties and 740 Pu-239 nuclear data libraries were generated. These libraries are used as inputs to reactor codes, in our case SERPENT, to perform uncertainty analysis of nuclear reactor inventory during burn-up. The uncertainty in the inventory determines uncertainties in: the long-term radio-toxicity, the decay heat, the evolution of reactivity parameters, gas pressure and volatile fission product content. In this work, a methodology called fast TMC is utilized, which reduces the overall calculation time. The uncertainty in the long-term radiotoxicity, decay heat, gas pressure and volatile fission products were found to be insignificant. However, the uncertainty of some minor actinides were observed to be rather large and therefore their impact on multiple recycling should be investigated further. It was also found that, criticality benchmarks can be used to reduce inventory uncertainties due to nuclear data. Further studies are needed to include fission yield uncertainties, more isotopes, and a larger set of benchmarks.Comment: 4 pages, 4 figures, Proc. 2013 International Conference on Nuclear Data for Science & Technology (ND2013), March 4-8, 2013, New York, USA, to be published in Nuclear Data Sheet

Modelling the impact and cost-effectiveness of combination prevention amongst HIV serodiscordant couples in Nigeria

Objective: To estimate the impact and cost-effectiveness of treatment as prevention (TasP), pre-exposure prophylaxis (PrEP) and condom promotion for serodiscordant couples in Nigeria. / Design: Mathematical and cost modelling. / Methods: A deterministic model of HIV-1 transmission within a cohort of serodiscordant couples and to/from external partners was parameterized using data from Nigeria and other African settings. The impact and cost-effectiveness were estimated for condom promotion, PrEP and/or TasP, compared with a baseline where antiretroviral therapy (ART) was offered according to 2010 national guidelines (CD4+ <350 cells/μl) to all HIV-positive partners. The impact was additionally compared with a baseline of current ART coverage (35% of those with CD4+ <350 cells/μl). Full costs (in US $2012) of programme introduction and implementation were estimated from a provider perspective. / Results: Substantial benefits came from scaling up ART to all HIV-positive partners according to 2010 national guidelines, with additional smaller benefits of providing TasP, PrEP or condom promotion. Compared with a baseline of offering ART to all HIV-positive partners at the 2010 national guidelines, condom promotion was the most cost-effective strategy [US$1206/disability-adjusted-life-year (DALY)], the next most cost-effective intervention was to additionally give TasP to HIV-positive partners (incremental cost-effectiveness ratio US $1607/DALY), followed by additionally giving PrEP to HIV-negative partners until their HIV-positive partners initiate ART (US$7870/DALY). When impact was measured in terms of infections averted, PrEP with condom promotion prevented double the number of infections as condom promotion alone. / Conclusions: The first priority intervention for serodiscordant couples in Nigeria should be scaled up ART access for HIV-positive partners. Subsequent incremental benefits are greatest with condom promotion and TasP, followed by PrEP