The future of tilapia culture in Nigeria

The culture of tilapia is assuming a greater importance globally. However, Nigeria's contribution to global production is insignificant. Although Egypt and Nigeria were the only African countries that had record of tilapia production in 1950, Egypt has left Nigeria far behind. The problem of prolific breeding still persists in our farm, making it difficult to raise tilapia to a good market size. The paper reviews Nigeria fish production, supply and demand forces and the contributions of leading tilapia producers; namely China, Thailand, Indonesia Egypt to mention a few. It reiterates some of the credentials of tilapia that makes it a good candidate for culture, the species for culture and the place of tilapia in the world fish market. The paper examines some of the limiting factor hindering the development of tilapia Industry and ways of mitigating such factors

PROTEIN PROFILE STUDY OF Sarotherodon melanotheron FROM SOUTH-WEST NIGERIAN WATER BODIES

Sarotherodon melanotheron is a Cichlid specie with good nutritional, economic and aquaculture potentials. Thegenetic difference among S. melanitheron populations in South-West Nigeria was investigated using 12%Sodium Dodecyl Sulphate- polyacrylamide Gel Electrophoresis (SDS-PAGE). Three populations from Pepe,Ugbonla, and Badagry were considered for the study. Thirty fish samples were analyzed; ten per location for theprotein profiling. The banding pattern from sarcoplasmic protein indicated variation among the populations.Molecular weight of the protein bands varied from 10-250kDa. Ninety eight (98%) of genetic variation that wasfound among populations reflects a high inter-population differentiation. The protein profile produced threeclusters, indicating divergence and also suggests high level of genetic variation among the studied populations ofS. melanotheron. The existence of genetic diversity among these populations has made them suitable for use infuture breeding programs for the development of improved S. melanotheron species

Tilapia sex reversal using methyl testosterone (MT) and its effect on fish, man and environment

Tilapia is the second leading aquatic crop globally, next to carps and its production has increased tremendously within the last decade. Its production is however affected by stunting, a phenomenon brought about by overpopulation due to precocious reproduction under mixed sex culture system. Several methods such as use of predatory fish, hybridization, polyploidy and sex reversal, using methyl testosterone have been employed w1th different degrees of success. This paper reviews the use of methyl testosterone in sex reversal of tilapia and its consequent effects on fish, man and environment. It established the preference of all-male tilapia due to better and more uniform growth under culture system. It has been demonstrated that the hormone does not have any adverse effect on fish flesh after cessation of treatment of tilapia fry. In like manner; ingestion of fish produced by sex reversal does not therefore harm man. However,one is not too sure of the effect of the hormone or its by- products on vital organs (liver, kidney, pancreas and gills), metabolic profile and nucleic acids. This may also affect muscle building and perceived libido-enhancement in man. On the environment, the steroid is either biodegraded or mineralized. It must be stated that escapee from tilapia hatchery into the natural water may, however, alter the dynamics of the environment due to unforeseen consequences

Genetic status of tilapia at Badore landing site using RAPD markers

Molecular technique based on Random Amplified Polymorphic DNA (RAPD) analysis was applied to study genetic status among tilapia species from Badore landing site of Lekki lagoon. Individual variations within species population were assessed using PCR-RAP analysis with five Operon primers (OPC04, OPA02, OPB08, OPE02 and OPF03, Operon Technologies Inc, USA) which revealed dif ferent banding patterns of varying primer reproducibility. Graphical representation using UPGMA cluster analysis produced a dendrogram chart with five clusters (~f, ~e, ~p ,~S, and ~W) indicating different degrees of variations and similarities. There were various levels of genetic similarity observed possibly due to hybridization. Nevertheless, few distinct variations among the samples were visible, show ing possible genetic variability. At 0.89 (89%) coefficient, cluster,~f is made up of 7 samples which are genetically similar. At 0.834 (83.1 %) coefficient, distinct sample BTl2 forms a cluster (~p) with cluster ~f which shows they are related at this coefficient. Cluster ~W (84% coefficient) comprising of 7 samples forms another cluster with a distinct sample BT06 at about 0.79 coefficients. At 78.6% coefficient (cluster ~e). All the samples are genetically similar except sample BT17. This distinct sample can increase genetic variability by a cross between it and other strains of tilapia. Therefore, care should be taken by fish farmers who buy or use the fish samples from this landing site for culture. Proper molecular characterization of this fish species before culture becomes necessary to avoid genetic problems

Genetic improvement of tilapia: challenges and prospects in Nigeria

The contribution of tilapia aquaculture in Nigeria to world output is negligible due to stunting, poor market value among others. This paper evaluates the aquacultural credentials of tilapia, some genetic improvement technology in cultured tilapia, namely, ploidy, hormonal sex reversal. transgenic, hybridization, and the necessity of Genetic Improvement in accelerating tilapia production in Nigeria. Investigation reveals the presence of O. niloticus with the highest growth perfermancc index (~h1=3.11) for Lake Kanji which indicates high growth potential in suitable culture environment and could serve as a good starting point for genetic development. The presence of ”wesafu”, an ecotype cichlid, endemic to Epe lagoon, Lagos, which grows to 1500g in the wild, appears to be an excellent candidate for genetic improvement of a commercial strain for the growing aquaculture industry. Tilapia Genetic improvement in Nigeria is faced with a number of setbacks. This includes short- term, scattered and disjointed funding, inadequate genetic research facilities, ecological risk, inadequate skilled manpower and poor documentation of tilapia genetic resources among others. Considering the growing importance of tilapia culture, the need to document, conserve, evaluate and utilize tilapia genetic resources is highlighted to enhance the success of food security in Nigeria

Hybridization and speciation among cichlids: the case of 'Wesafu', an ecotype cichlid

Fishes of the family Cichlidae are known for spectacular adaptive radiation and therefore serve as a model for evolutionary and ecological studies. They are highly speciated due to hybridization that frequently occur in the wild. The existence of an ecotype cichlid, ’wesafu’ in Epe Lagoon, Lagos, Nigeria appears to be the result of such hybridization. This paper reviews the profile of wesafu and compare the species with other cichlids, evaluate the probable causes of speciation which includes diversity in feeding morphology, mate choice, adaptation to changes in habitat arising from water level dynamics , eco-phenotypic variation, restricted migration to predation and introgressive hybridization. The implication of such speciation and hybridization were also highlighted

Comparative study of proximate composition of some wild tilapiine fishes in Epe Lagoon, Lagos, Nigeria

The proximate composition of some wild tilapiine fishes in Epe lagoon, Lagos, Nigeria was analyzed. The species were Sarotherodon melanotheron, Tilapia guineensis, Tilapia mariaei, Sarotherodon galileaus and an ecotype cichlid popularly called ‘wesafu’. Major nutrient compositions of raw muscles like protein, fat, moisture and ash were determined. Proximate compositions were found to be varied among the species. Protein was determined in Sarotherodon melanotheron (19.13%), T. guineensis (18.71%), T. mariae (18.08%), S. galileaus (18.34%) and ‘wesafu’ (21.80%) respectively. Lipid content was recorded as 0.82%, 0.40%, 0.60%, 0.65%, and 0.90% for the tilapia species. The highest level of moisture content was found in T. guineensis (81.70%) and the lowest was in ‘wesafu’ (78.50%). The percentage of ash content was highest in S. galileaus and S.melanotheron (1.75%) and lowest in T. guineensis (1.00%). The present study revealed highest protein content in the ecotype cichlid, wesafu (19.22%) and lowest value in T.mariae (18.08%) while fat was highest in ‘wesafu’ (0.90%). The results of this study reveal the nutritional significance of the ecotype cichlid, ‘wesafu’ above other cichlids of the lagoon

Growth performance of wild strains of Clarias gariepinus from Nigerian waters

The catfish (Clarias gariepinus) is the leading aquatic crop in Nigeria. Most of the strains used in aquaculture are suffering from in-breeding depression with its attendant poor egg and sperm quality. There is therefore the need to explore the natural population of the fish to improve performance. This study was carried out to evaluate the growth performance of strains of the catfish across the fresh water systems of Nigeria. Collections were made from the six geopolitical zones namely: North-Central (Kogi), Northeast (Adamawa), Northwest (Kebbi), South-West (Oyo), Southeast (Anambra), South-South (Delta) and domesticated strain obtained from Lagos. The fish were bred in the wet laboratory of the Department of Fish Technology/Biotechnology of the Institute for Oceanography and Marine Research, Lagos and fed for 12 weeks before subjected to growth study. The study involved allocation of 25 juveniles of each strain in lm hapas installed in a 0.4 ha at Badore fish farm, Lagos, Nigeria,fed 3% body weight twice daily while sampling forth-nightly. The results showed that the domesticated strain of C. gariepinus performed significantly better (a=0.05) than the six wild strains studied. This may be attributable to selective breeding which probably had been carried out by the farmers from which the broodstocks were purchased and mixture of the gene pool of improved Dutch strain commonly cultured. There was however no significant variation in the SGR and FCR among the strain. However, the growth study showed that the strain from North-West (Kebbi) did not perform as much as other strains in terms of these growth indices. Hoewever, it had the highest survival (96%). The strains from Oyo and Anambra however showed better growth over the rest strains from the wild. The implication of the breeding potentials of C. geriepinus strains from Kebbi, Oyo and Anambra is that if several selective breeding of these strains are carried out and the gene pool of Kebhi is combined with any of these two, we are likely to obtain fish seed of better growth and survival

Role of women in fisheries and fish processing: a global view

Women are the majority of the third World population. They are considered subservient to their male counterpart, even in Europe and America where women have greater basic human right. This paper evaluates the various roles of women in Fisheries and fish processing. Statistics from the European Union shows that, of the various fishing sectors, participation of women (in terms of number) was greatest in fish processing, followed by marine aquaculture, marine fishing and inland aquaculture, with no women involved in inland fishing. In Asia and Africa women are basically involved in fish processing and marketing. In Asia (Thailand and Philippines), women are involved in hatchery operations in aquaculture in addition to fish processing. The finding of the review shows that Fish processing in developing countries, principally Africa is not attracting young literate generation who may have better management competence. It further revealed that, in Nigeria women are directly involved in capture fishery, in addition to fish marketing and processing. This is aimed at empowering women economically to meet the pressing needs of the family. The paper further assesses the problems of women in fisheries and fish processing namely, access to financial resources, education, support services and the need to ensure food security. Possible ways of improving women’s participation in fisheries were highlighted

Role of women in fisheries and fish processing: a global view

Women are the majority of the third World population. They are considered subservient to their male counterpart, even in Europe and America where women have greater basic human right. This paper evaluates the various roles of women in Fisheries and fish processing. Statistics from the European Union shows that, of the various fishing sectors, participation of women (in terms of number) was greatest in fish processing, followed by marine aquaculture, marine fishing and inland aquaculture, with no women involved in inland fishing. In Asia and Africa women are basically involved in fish processing and marketing. In Asia (Thailand and Philippines), women are involved in hatchery operations in aquaculture in addition to fish processing. The finding of the review shows that Fish processing in developing countries, principally Africa is not attracting young literate generation who may have better management competence. It further revealed that, in Nigeria women are directly involved in capture fishery, in addition to fish marketing and processing. This is aimed at empowering women economically to meet the pressing needs of the family. The paper further assesses the problems of women in fisheries and fish processing namely, access to financial resources, education, support services and the need to ensure food security. Possible ways of improving women’s participation in fisheries were highlighted