Fish In Ghana Research Articles

Managing reservoir fisheries: a critical look at reservoir physical environment

This short note follows a discussion on a study that assessed reservoir fisheries and ecosystem-based management approaches in Ghana. The main objectives of the study were to develop an understanding of how differences in reservoir morphometry and physicochemical characteristics influence ecosystem structures and fisheries productivity. This involved reviewing and updating empirical models for reservoir harvest estimations, relating morphometric characteristics of the reservoirs to fish production, assessing the exploitation levels and stock status of the reservoirs’ target species and providing a holistic description of the reservoirs’ biological interactions through a food web modelling approach. To manage reservoirs and associated riverine environments for the benefit of fish and fisheries, reservoirs' status and contribution to capture fisheries production have to be evaluated and addressed. Furthermore, the technical criteria and measures germane to assessment frameworks must be improved. Protecting and enhancing the physical environment of reservoirs for fish production requires considerations of ecosystem perspectives, optimal morphometric characteristics, duration of reservoir filling and development and prevention of critical nutrient enrichment. For enhancing Ghana's fish production, development strategies should focus on fisheries and aquaculture production in rivers, floodplains, lakes, reservoirs, and brackish water systems. Research, policy, and capacity-building issues related to developing these production systems must be addressed adequately. Moreover, to fully exploit their potential, the management requirements of the individual reservoir systems need to be assessed and appropriate regimes implemented with stakeholders.

Market women’s skills, constraints, and agency in supplying affordable, safe, and high-quality fish in Ghana

In Ghana, the role of female informal traders (“market women”) in making low-cost smoked and dried fish available in urban and rural marketplaces is the key to explaining the high consumption of fish in the country. However, market women’s contribution to food security and nutrition (FSN), as well as to fish quality and safety is underrated and poorly understood. Fish marketing requires proficient distribution and preservation skills, economic and sociocultural competence, and a high degree of mobility. Fish traders face numerous constraints related to fish supplies, credit access, hygiene, storage facilities, transport, and market governance, all of which affect their incomes and may affect the quality and safety of fish. The article, which is based on semi-structured interviews with fish traders and fish consumers in coastal and inland markets in Ghana, documents how traders operate and exhibit agency to deal with constraints by activating a range of skills in their profit-making and their fish quality and safety enhancement strategies. The authors argue that policies grounded in knowledge about fish traders’ activities, skills, and working conditions, with budgets that prioritize investment in public infrastructure that caters for market women’s professional and personal needs, can further enhance their ability to supply affordable, safe, and high-quality fish to Ghana’s population.

Prevalence of bacterial infections and the use of multiplex PCR assay for rapid detection of pathogens in cultured fish in Ghana.

The modern and rapid avenue for detecting pathogens provided by molecular genetic techniques including polymerase chain reaction (PCR) was explored in the present study to identify prevalent disease pathogens, from six aquaculture farms and in two commonly cultured fish in Ghana. The specific detection was carried out directly on clinical samples of naturally infected fish (O. niloticus and C. gariepinus) based on syber-mix reaction protocol in traditional PCR. Molecular diagnostic techniques allowed the detection of the six most common and important bacterial pathogens in aquaculture farms in Ghana. Also, three of the pathogens (Streptococcus agalactiae, Streptococcus iniae, and Staphylococcus aureus) were simultaneously isolated in a multiplex reaction. The results indicated 90-100% sensitivity and specificity for each of the six bacterial pathogens tested. Streptococcosis and motile aeromonad septicemia were found to be highly prevalent in most aquaculture farms in Ghana with severity in infections traced to the 85.7% and 14.9% co-infections with all six target pathogens in catfish and tilapia respectively. The prevalence rate of infections significantly correlated with variations in salinity, conductivity, and dissolved oxygen concentrations in the thermal stressed condition of the culture water. Multiplex techniques employed in this study represent one of the first to be used by a fish health laboratory in Ghana for rapid detection of pathogens in diseased fish and could be a useful alternative to the culture-based method for routine diagnosis of fish diseases in Ghana.

Nutrient and contaminant exposure from smoked European anchovy (Engraulis encrasicolus): Implications for children's health in Ghana

Inadequate nutrient intakes are frequent among young children in low- and middle-income countries, causing prevalent micronutrient deficiencies. In Ghana, small smoked fish are the most frequently consumed animal source foods, and both whole fish and different tissues of fish are commonly used in complementary foods. However, the risks and benefits associated with consumption of different tissues of smoked fish has not been explored. Samples of smoked European anchovy (Engraulis encrasicolus) were collected from five regions in Ghana and divided into subsamples of different tissues: whole fish, heads and skin, and samples without heads and skin. The different tissues were subsequently analyzed for selected nutrients (vitamins, minerals, trace elements and fatty acids), heavy metals and polycyclic aromatic hydrocarbons. A scenario referencing young children in Ghana (aged 6-23 months) was developed to assess the risks and benefits associated with daily consumption of different tissues of smoked European anchovy. We found that all tissues had the potential to substantially contribute to the recommended nutrient intakes of vitamins, minerals and essential fatty acids important for young child development. Samples of whole fish and of heads and skin contained levels of cadmium which exceeded the tolerable weekly intake greatly in the current scenario. All tissues contained elevated concentrations of BaP and PAH4 which exceeded the margin of exposure in the scenario, entailing potential consumer risk. A thorough assessment of dietary intakes of smoked fish products and refined risk-benefit assessments are therefore imperative to secure safe utilization of smoked fish in Ghana. • Different tissues of smoked European anchovy contain key nutrients for young children. • Whole fish or heads and skin combined exceeded the tolerable weekly intake for Cd. • All tissues contained elevated concentrations of PAHs, entailing potential consumer risk. • Refined risk-benefit assessments of smoked fish in Ghana are needed for safe utilization.

Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Smoked Sardinella sp. in Ghana: Impact of an Improved Oven on Public Health Protection.

An improved fish smoking oven called FAO-Thiaroye Technique (FTT) has been introduced in Ghana and other countries in the Global South as a technical intervention for the high levels of polycyclic aromatic hydrocarbons (PAHs) in traditionally smoked fish produced in those regions. This study evaluated the extent to which the intervention reduces consumer exposure to PAHs (considering benzo(a)pyrene [BaP] as a marker) in smoked fish, using Ghana as a case. Smoked Sardinella sp. were sampled from two traditional ovens (Chorkor smoker and metal drum oven) and the FTT and their PAH levels were determined by gas chromatography-mass spectrometry. Samples of the product were also purchased from informal markets in three selected regions of Ghana and analyzed for their PAH levels. Cross-sectional consumer surveys were conducted in the selected regions to determine intakes of the commodity. A probabilistic risk assessment of PAH was then done by the margin of exposure (MoE) approach. BaP MoE as low as 1,060 and 752 were obtained for products from the traditional ovens and the informal markets, respectively, whereas the lowest value for FTT products was approximately 161,000. MoE values less than 10,000 were considered to denote a serious public health concern requiring risk management action. Therefore, the findings suggest that there is a potential health concern of high consumer exposure to PAHs in traditionally smoked fish in Ghana, and that the FTT is a technically viable intervention for the problem.

Blue food demand across geographic and temporal scales

Numerous studies have focused on the need to expand production of ‘blue foods’, defined as aquatic foods captured or cultivated in marine and freshwater systems, to meet rising population- and income-driven demand. Here we analyze the roles of economic, demographic, and geographic factors and preferences in shaping blue food demand, using secondary data from FAO and The World Bank, parameters from published models, and case studies at national to sub-national scales. Our results show a weak cross-sectional relationship between per capita income and consumption globally when using an aggregate fish metric. Disaggregation by fish species group reveals distinct geographic patterns; for example, high consumption of freshwater fish in China and pelagic fish in Ghana and Peru where these fish are widely available, affordable, and traditionally eaten. We project a near doubling of global fish demand by mid-century assuming continued growth in aquaculture production and constant real prices for fish. Our study concludes that nutritional and environmental consequences of rising demand will depend on substitution among fish groups and other animal source foods in national diets.

Composition of nutrients, heavy metals, polycyclic aromatic hydrocarbons and microbiological quality in processed small indigenous fish species from Ghana: Implications for food security.

The triple burden of malnutrition is an incessant issue in low- and middle-income countries, and fish has the potential to mitigate this burden. In Ghana fish is a central part of the diet, but data on nutrients and contaminants in processed indigenous fish species, that are often eaten whole, are missing. Samples of smoked, dried or salted Engraulis encrasicolus (European anchovy), Brachydeuterus auritus (bigeye grunt), Sardinella aurita (round sardinella), Selene dorsalis (African moonfish), Sierrathrissa leonensis (West African (WA) pygmy herring) and Tilapia spp. (tilapia) were collected from five different regions in Ghana. Samples were analyzed for nutrients (crude protein, fat, fatty acids, several vitamins, minerals, and trace elements), microbiological quality (microbial loads of total colony counts, E. coli, coliforms, and Salmonella), and contaminants (PAH4 and heavy metals). Except for tilapia, the processed small fish species had the potential to significantly contribute to the nutrient intakes of vitamins, minerals, and essential fatty acids. High levels of iron, mercury and lead were detected in certain fish samples, which calls for further research and identification of anthropogenic sources along the value chains. The total cell counts in all samples were acceptable; Salmonella was not detected in any sample and E. coli only in one sample. However, high numbers of coliform bacteria were found. PAH4 in smoked samples reached high concentrations up to 1,300 μg/kg, but in contrast salted tilapia samples had a range of PAH4 concentration of 1 μg/kg to 24 μg/kg. This endpoint oriented study provides data for the nutritional value of small processed fish as food in Ghana and also provides information about potential food safety hazards. Future research is needed to determine potential sources of contamination along the value chains in different regions, identify critical points, and develop applicable mitigation strategies to improve the quality and safety of processed small fish in Ghana.

Risk of heavy metal ingestion from the consumption of two commercially valuable species of fish from the fresh and coastal waters of Ghana.

BackgroundThe need to evaluate the human health safety of fishery resources remain urgent in the mist of the ever-increasing fear of heavy metal toxicity from the consumption of Ghana’s fisheries resource, as a consequence of pollution from several anthropogenic activities including artisanal gold mining. Nevertheless, the bigeye grunt (Brachydeuterus auritus) and Bagrid catfish (Chrysichthys nigrodigitatus) remain commercially valuable fish species in West Africa and continue to attract high patronage.MethodForty-five specimens each of C. nigrodigitatus and B. auritus collected from the Weija Dam and the Tema Fishing Habour in Ghana, between June and September 2016, were analysed for seven heavy metals using Atomic Absorption Spectrometry.ResultLead and Cadmium were below detection in all samples while Cu was not detected in B. auritus. Levels of the remaining metals (mg kg-1) were below FAO/WHO maximum permissible limits in fish and occurred in the rank order Se (3.5) > Zn (2.34) > Cu (0.59) > As (0.37) > Hg (0.19) in C. nigrodigitatus and Se (2.97) > Zn (2.28) > Hg (0.31) > As (0.21) in B. auritus. Only As in C. nigrodigitatus recorded Estimated Weekly Intake (EWI) greater than FAO/WHO Provisional Tolerable Weekly Intake (PTWI). Also, As in C. nigrodigitatus and Hg in B. auritus had Targeted Hazard Quotient (THQ) greater than 1 for individuals consuming the fishes on daily basis and therefore, raising concerns. However, for both species of fish, cancer risk of As was 1 in 10,000,000,000 and modified Health Benefits values of Se (HBVSe) were positive indicating the health risks that might accompany Hg exposure would be negated. Since toxicity depends on the concentration and quantity of a pollutant consumed, safe maximum consumption rate of C. nigrodigitatus based on As concentrations was 0.21 mg per day and that of B. auritus was 0.058 mg per day for Hg. With an average of 0.227 kg fish per meal of an adult human, these translated into not more than 24 C. nigrodigitatus and nine (9) B. auritus meals in a month but because fish is consumed at 0.0685 kg per person per day in Ghana, these values respectively translates to 93 and 30 safe days of consumption per month.ConclusionAt the rate of 0.0685 kg fish per person per day that fish is consumed in Ghana, the consumption of the two species of fish in Ghana would essentially be of little or no consequence to consumers.

Assessment of Formaldehyde Levels in Local and Imported Fresh Fish in Ghana: A Case Study in the Tamale Metropolis of Ghana

Fish is an important source of protein all over the world, including in Ghana. The fishery sector plays a major role in meeting the domestic need of animal protein and also contributes greatly in foreign exchange earnings. The domestic supply of fish does not meet the demand, so Ghana imports fish and fish products from other countries. Media reports in Ghana have alleged the use of formaldehyde to preserve fish for increased shelf life and to maintain freshness. This research, therefore, sought to establish the levels of formaldehyde in imported and local fresh fish in the Tamale Metropolis by using a ChemSee formaldehyde and formalin detection test kit. Positive and negative controls were performed by using various concentrations of formalin (1, 10, 30, 50, 100, and 300 ppm) and sterile distilled water, respectively. Three times over a 6-month period, different fish species were obtained from five wholesale cold stores (where fish are sold in cartons) and some local sales points (where locally caught fish are sold). A total of 32 samples were taken during three different sampling sessions: 23 imported fish (mackerel, herring, horse mackerel, salmon, and redfish) and 9 local tilapia. The fish were cut, and 50 g was weighed and blended with an equal volume (50 ml) of sterile distilled water. Samples were transferred to test tubes and centrifuged. A test strip was dipped into the supernatant and observed for a color change. A change in color from white to pink or purple indicated the presence of formaldehyde in fish. The study showed that no formaldehyde was present in the imported and local fish obtained. The appropriate regulatory agencies should carry out this study regularly to ensure that fish consumed in Ghana is safe for consumption.

Cubic Fish Ventures: Fish for Friends, Financiers and Foreigners

This work describes a venture that will help meet the massively under-supplied market for fish in Ghana by attracting local entrepreneurs to become fish farmers. We'll sell a turnkey solution to the problem of entering the fish farming market by providing tank-systems, technical/business training, fingerlings, feed, and on-going maintenance. We plan to partner with either local or international financial organizations that can provide financing to interested parties.

Estimation of human health risk from exposure to methylmercury via fish consumption in Ghana

Background. Fish advisories have been established by some nations to protect the public from the potentially harmful health effects linked to eating contaminated fish. Advisories are based on estimations of the health risks associated with concentrations of contaminating chemicals found in fish, and the average levels of consumption of fish in the population. Fish is an important source of nutrition in Ghana; however, little is known about the possible health effects associated with metal concentrations found in fish. Objective. The overall aim of the present study was to estimate metal concentrations in fishery resources so as to inform guidelines on fish consumption. Methods. We collated previously published data on levels of metals in fish in Ghana. We also estimated the potential for adverse health effects by calculating a hazard quotient (HQ) based on the reported levels of mercury in fish and either the United States Environmental Protection Agency (USEPA) Reference Dose (RfD) or the FAO/WHO Expert ...

Polycyclic aromatic hydrocarbon (PAH) contamination in smoke-cured fish products

In this study, 108 fish samples of smoke cured fish Sardinella aurita (sardines/herrings) collected from 12 major fishing communities along the coastal belt of Ghana were extracted with Soxhlet apparatus using dichloromethane (DCM), and analyzed for sixteen polycyclic aromatic hydrocarbons (PAHs) using the GC/MS (Varian 3800 GC system with 8400 auto-sampler) to determine levels, distribution and the characterization of their sources. The mean total PAHs in the smoked sardines from the various communities ranged from 510.59μg/kg to 1461.79μg/kg for all seasons with a mean value of 716.84μg/kg. The benzo[a]pyrene (BaP) had a maximum mean level of 73.78μg/kg. The unit risk of carcinogenic PAHs for benzo[a]pyrene, chrysene, dibenz[a,h]anthracene, benzo[a]anthracene, benzo[k]fluoranthene, benzo[b]fluoranthene, and indenol[1,2,3-cd]pyrene associated with oral ingestion of smoked sardine was calculated to be 6.1×10−7 for adults and 1.6×10−7 for children. There is a significant correlation between the fish lipid content and the total PAH levels. The average lipid content of the smoked sardine samples collected varied among the various fishing seasons (3 seasons) in Ghana. A significantly high accumulation of PAHs was found in the smoke-cured fish as compared to the non-smoke-cured fish control samples, which showed PAH levels that were below detection (0.10–2.0μg/kg). This study highlights the increased danger of consuming smoke-cured fish in Ghana as some of the PAHs are known to be carcinogenic. These results indicate that there is a need to find alternative ways of curing fish other than the traditional smoking process.

A PRODUCTION FUNCTION ANALYSIS OF POND AQUACULTURE IN SOUTHERN GHANA

Aquaculture is considered an alternative to making up the shortfall in supply of fish in Ghana. The Cobb-Douglas production function, which relates production output to several independent input variables, was used to determine the inputs that affect productivity. A survey was conducted on pond farmers selected from four regions of Ghana. Empirical results show stocking rate as the most significant input that affected production. Aquaculture exhibited increasing returns to scale over the period of the study, meaning an increase in inputs will more than proportionately increase the output. Estimates of the marginal physical productivity of the inputs indicated stocking rate should be increased while decreasing feed and labor use in order to increase productivity.

Determination of methylmercury in marine and freshwater fish in Ghana using a combined technique of dithizone extraction and gas–liquid chromatography with electron capture detection

Concentrations of methylmercury (MeHg) residues were determined in different marine and freshwater fishes from Ghana. Samples were treated with ethanolic potassium hydroxide in water bath at 100 °C for 1 h. After neutralising with HCl and washing with hexane, MeHg was extracted with dithizone in toluene, cleaned up and determined by gas chromatography with electron capture detection (GC–ECD). The method was sensitive with good precision, detection limit of 0.0005 μg g −1 (0.5 μg kg −1) and provided good separation for organomercury compounds. The validity of the method was established using dogfish muscle certified reference material, DORM-2. The method was applied to different fish species. Concentration of MeHg in the edible muscle tissue of the tested fish ranged from 0.009 to 0.107 μg g −1 wet weight. The concentrations of MeHg in the fish samples obtained do not however, constitute any significant mercury exposure to the general population through consumption of the tested fish species.

Productivity of the hired and family labour and determinants of technical inefficiency in Ghana's fish farms

This paper examines the productivity of hired and family labour and determinants of technical inefficiency of fish farms in Ghana. A modified Cobb-Douglas stochastic frontier production function which accounts for zero usage of family and hired labour is employed on cross-sectional data of 150 farmers collected in 2007. The results reveal that family labour, hired labour, feed, seed, land, other costs and extension visit have a reasserting influence on fish farm production. Findings also show that family and hired labour used for fish farming production in Ghana may be equally productive. The combined effects of operational and farm specific factors (age, experience, land, gender, pond type and education) influence technical inefficiency although individual effects of some variables may not be significant. Mean technical efficiency is estimated to be 79 percent. Given the present state of technology and input level, the possibility of enhancing production can be achieved by reducing technical inefficiency by 21 percent through adoption of practices of the best fish farm.

Abundance, biomass and species composition of nearshore fish assemblages in Ghana, West Africa

Many of the world's fish populations are overexploited, including Ghana's fish resources. This study examines spatio-temporal trends in fish species composition in relation to biotic, abiotic and anthropogenic factors, towards achieving better-informed management of the beach-seine fisheries. Fishery-dependent data were collected between November 1999 and October 2001 from 94 beach-seine hauls fished at two stations along the Ghanaian coast. The catch consisted of fish, crustaceans, other invertebrates, and macroalgae. Generally, juveniles of species that are exploited by offshore fisheries were found in the catches. Species abundance and their occurrence generally peaked between November and January. Duration of solar radiation and tide level appeared to be important predictors of fish biomass. It is important to exploit the nearshore fish assemblage sustainably because of its nursery role. A co-managed (fishers and government) three-month ban on beach-seining (between May and July) is recommended as the most appropriate control measure towards the sustainability of Ghanaian fish stocks.

Iodine content of marine fish in Ghana

Iodine content of marine fish in Ghana

Quality attributes of cured fish in Ghana

Cured fish products were evaluated in terms of chemical composition and sensory quality. The moisture content of the smoked fish products ranged between 11.7 - 69.2 % (db), with salt content of 0.4 - 1.2 %, sodium content of 0.6 - 1.0 %, potassium content of 4.3 - 8.7 %, crude protein of 71.5 - 84.5 % and fat content of 7.2 - 19.0 % (all on dry matter basis). The salted-fermented fish products had moisture content of 48.4 - 58.3 % (db), salt content of 33.0 - 44.2 %, sodium content of 17.7 - 20.3 %, potassium content of 4.7 - 5.2 %, crude protein of 49.0 - 57.7 % and fat content of 2.1 - 3.7 %. Salted dried tilapia had moisture content of 45.8 %, salt content of 21.5 %, sodium content of 8.3 %, potassium content of 4.2 % , crude protein content of 67.2 % and fat content of 7.9 %, respectively. Consumer perceptions and expectations of desirable quality attributes were found to be dependent on the type of cured fish and how it was prepared before consumption. Both consumers and processors considered texture, flavour and colour as important quality attributes in the utilization of cured fish. Journal of Applied Science & Technology (JAST) , Vol.5, Nos. 1 & 2, 2000, pp. 148-155