Survey of the present and fast disappearing fish species along two rivers in the Niger Delta

Fisheries resources are on the decline in Nigeria due to over exploitation and inadequate management of her coastal waters. For sustainability of these resources, an adequate knowledge of species composition, diversity and relative abundance of her water bodies must be understood and vigorously pursued. A survey was conducted to determine fish species diversity in Brass and Nun River, Niger Delta, Nigeria and the socioeconomic studies carried out to determine the status of endanger or level of disappearance of fish species study area. The survey identified 53 species from 18 families caught from Brass and Nun stations respectively. The fish diversity from typically freshwater fishes such as Tilapia and Clarias to brackish species such as Chrysichthys nigrodigitatus and Penaeus species. The most abundant family within catch were the Scianidae, Cichlidae and Clariidae. A checklist of economically important fast disappearing fish species along the two water bodies was generated. Oil spillage, discharges from industries (industrialization) and the domestic wastes from boundaries settlements (urbanization) and farming activities along the tributaries were among the factors identified to have contributed to low species diversity and fast disappearance of certain species. Data generated from this study would serve as baseline information for fisheries resource management

Morphological Variation of Ten Tilapia guineensis Populations in Selected Rivers in Nigerian coastal waters

A morphological study was carried out on Tilapia guineensis, a fish species of considerable dietary importance commonly found in Nigerian coastal waters. Principal component analysis (PCA) revealed two principal components (PC-1 and PC-11) that accounted for 90.3% of observed variation in morphometric attributes; 58.1% and 58.8% in meristics and truss network system respectively. When compared to other locations, fish in Iwoama had the highest mean weight of 0.29+0.006kg with a mean total length of 0.24+0.002m (p<0.05). Truss network data showed that Brass location had the highest mean length of 0.149+0.001m. Among the thirteen morphometric variables considered, pre-anal length (PAL) and standard length were the most correlated (r = 0.96; p<0.01) while dorsal fin count (DFC) and anal fin count (AFC) were the most correlated (0.37; p<0.01) among the meristic variables. Cluster analysis revealed three clusters for meristic variables and two clusters for morphometric and truss network variables respectively. These findings could be attributed to gene flow between widely distributed sub-populations of T. guineensis. However, this fish still possess sufficient variability for possible genetic improvement through breeding

Physical losses could partially explain modest carotenoid retention in dried food products from biofortified cassava

Gari, a fermented and dried semolina made from cassava, is one of the most common foods in West Africa. Recently introduced biofortified yellow cassava containing provitamin A carotenoids could help tackle vitamin A deficiency prevalent in those areas. However there are concerns because of the low retention of carotenoids during gari processing compared to other processes (e.g. boiling). The aim of the study was to assess the levels of true retention in trans–β-carotene during gari processing and investigate the causes of low retention. Influence of processing step, processor (3 commercial processors) and variety (TMS 01/ 1371; 01/1368 and 01/1412) were assessed. It was shown that low true retention (46% on average) during gari processing may be explained by not only chemical losses (i.e. due to roasting temperature) but also by physical losses (i.e. due to leaching of carotenoids in discarded liquids): true retention in the liquid lost from grating negatively correlated with true retention retained in the mash (R = -0.914). Moreover, true retention followed the same pattern as lost water at the different processing steps (i.e. for the commercial processors). Variety had a significant influence on true retention, carotenoid content, and trans-cis isomerisation but the processor type had little effect. It is the first time that the importance of physical carotenoid losses was demonstrated during processing of biofortified crops

From cassava to gari: Mapping of quality characteristics and end-user preferences in Cameroon and Nigeria

User's preferences of cassava and cassava products along the value chain are supported by specific root quality characteristics that can be linked to root traits. Therefore, providing an evidence base of user preferred characteristics along the value chain, can help in the functional choice of cassava varieties. In this respect, the present paper presents the results from focus group discussions and individual interviews on user preferred quality characteristics of raw cassava roots and the derived product, gari, ‐ one of the major cassava products in Sub Saharan Africa ‐ in major production and consumption areas of Cameroon and Nigeria. Choice of cassava varieties for farming is mainly determined by the multiple end‐uses of the roots, their agricultural yield and the processing determinants of roots that support their major high‐quality characteristics: size, density, low water content, maturity, colour and safety. Processing of cassava roots into gari goes through different technological variants leading to a gari whose high‐quality characteristics are: dryness, colour, shiny/attractive appearance, uniform granules and taste. Eba, the major consumption form of gari in Cameroon and Nigeria is mainly characterized by its textural properties: smoothness, firmness, stickiness, elasticity, mouldability. Recommendations are made, suggesting that breeding will have to start evaluating cassava clones for brightness/shininess, as well as textural properties such as mouldability and elasticity of cassava food products, for the purpose of supporting decision‐making by breeders and the development of high‐throughput selection methods of cassava varieties. Women are identified as important beneficiaries of such initiatives giving their disadvantaged position and their prominent role in cassava processing and marketing of gari

Protein-Based Genetic Diversity Assessment of Tilapia guineensis and Sarotherodon melanotheron Populations from South-West Nigerian Coastal Waters

The present study was carried out to investigate the genetic differences in the Protein banding pattern of Tilapia guineensis and Sarotherodon melanotheron populations in Southwest Nigeria using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Four populations of Tilapia guineensis and three populations of Sarotherodon melanotheron from Ondo and Lagos states were considered for the study. The sarcoplasmic protein of the studied Cichlid species resolved on 12% SDS-PAGE revealed variations in their genetic diversity indices (number of alleles, shanon information index, heterozygosity and percentage polymorphism). T. guineensis had more proteins and higher genetic diversity as was revealed by the genetic diversity parameters and was found to be more polymorphic with a percentage polymorphism of 78.57% than S. melanotheron (57.14%). The two species had similarity coefficient of 0.82 indicating high genetic similarity between them. UPGMA (Unweighted Pair Group Method with Arithmetic Mean) dendrogram also revealed some level of genetic similarity between the studied populations and among the two species. Analysis of molecular variance (AMOVA) confirmed the low genetic variation among the populations of the cichlid species and demonstrated that genetic variation was mostly within populations in both species. It is established from the study that Tilapia guineensis had higher genetic diversity than Sarotherodon melanotheron and the two species are closely related. Further study involving molecular markers is encouraged to complement this finding