African Journal of Agricultural Economics and Rural Development

International Journal of Agricultural Extension and Rural Development Vol. 1 (4), pp. 094-100, December, 2013. © International Scholars Journals

Full Length Research Paper

Food and feeding habits of Ophiocephalus obscura (African snakehead in the Cross River estuary, Cross River State, Nigeria

George Ubong Uwem¹, Ekanem Albert P.¹* and George Eni²

¹Department of Fisheries and Aquaculture, University of Calabar, Cross River State, Nigeria. ²Department of Zoology and Environmental Biology, University of Calabar, Cross River State, Nigeria.

*Corresponding author. E-mail: [email protected].

Accepted 7 September, 2013

Abstract

Studies conducted on the food and feeding habits of Ophiocephalus obscura in the Cross River estuary, Cross River State, Nigeria, between February and April, 2009 revealed that the species feed mostly on food from animal origin, although diatoms and other plant materials were also identified. A total of 149 plant materials (15.95%) and 77 diatoms (8.24%) were consumed by the species. Food from animal origin consumed by the species included polychaete worm 110 (11.77%), shrimps 84 (8.99%), shrimp parts 33 (3.55%), juvenile fish 33 (3.33%), fish bones 44 (4.71%), fish scales 40 (4.28%), bivalves 61 (6.53%), insect larvae 2 (0.21%), adult insects 2 (0.21%), daphnia 62 (6.63%) and water snails 2 (0.21%). The condition factor calculated for the species varied during the study period with a mean value of 2.09 in February, 1.05 in March and 0.76 in April. Based on the food items isolated from the gut of the O. obscura, the species could be considered as a voracious carnivore in the Cross River system, while the variations in the condition factor of the species in the river system may indicate a period of high yield or otherwise of the species in the river system.

Key words: Food, feeding habits, Ophiocephalus obscura, Cross River estuary.

African Journal of Agricultural Economics and Rural Development Vol. 1 (3), pp. 070-078, November, 2013. © International Scholars Journals

Full Length Research Paper

Accumulation of some potentially toxic metals and polycyclic aromatic hydrocarbons (PAHs) in marine clam Liochoncha ornata collected from the Omani Sea

M.  Al-Busaidi, P. Yesudhason*, A. Al-Waili, W. Al-Rahbi, K. Al-Harthy, N. Al-Mazrooei and S.  Al-Habsi

Fishery Quality Control Center Ministry of Agriculture and Fisheries Wealth Post Box 427 Postal Code: 100 Muscat Sultanate of Oman.

*Corresponding author. E-mail: [email protected]. Tel: (968)24743528. Fax: +(968)24738222.

Accepted 31 July 2013

Abstract

Clam samples of Liochoncha ornata were collected for a period of one year from July 2009 to June 2010 at monthly interval. The soft tissue of clams was analyzed to detect some potentially toxic metals and polycyclic aromatic hydrocarbons (PAHs). Accumulation of Hg, Cd and Pb in the clam tissues showed variability with a mean concentration of 0.011±0.009, 1.769±0.942 and 0.015±0.039 µg/g wet weight for Hg, Cd and Pb, respectively. Cadmium had recorded a particularly high potential of accumulation in L. ornata. The bioaccumulation of PAHs in the clams appeared to be selective and ranged from 4.80 to 12.0 ng/g; wet weight. The most carcinogenic PAHs, such as benzo (a) pyrene and dibenz (a,h) anthracene, were in all cases below the limits of detection. No distinctive relationship was found between different size class and contaminant uptake by the clam. The concentrations of both of Pb and Hg in L. ornata, were found to be below the safe limits suggested by various authorities and thus gave no indication of pollution by such elements. However, continuous monitoring of these and other pollutants in the coastal marine ecosystem is advised.

Key words: Clam, Mercury, Cadmium, Pb, polycyclic aromatic hydrocarbons (PAHs), Oman.

African Journal of Agricultural Economics and Rural Development Vol. 1 (2), pp. 053-057, October, 2013. © International Scholars Journals

Full Length Research Paper

Effects of smoke-drying temperatures and time on physical and nutritional quality parameters of Tilapia (Oreochromis niloticus)

Idah, Peter Aba* and Nwankwo, Ifannyi

Department of Agricultural and Bioresources Engineering, Federal University of Technology, Minna, Niger State, Nigeria.

*Corresponding author. E-mail: [email protected].

Accepted 3 August, 2013

Abstract

Effects of smoke-drying temperatures and duration of drying on the quality of Nile tilapia (Oreochromis niloticus) samples were investigated by smoke–drying Tilapia fish under three different temperatures (50, 60 and 70°C) and three drying times (5, 10 and 15 h) using modified drum kiln dryer. The proximate compositions of the fresh and dried fish were evaluated and the sensory evaluation of the organoleptic parameters was assessed. The drying temperatures and duration of drying have different effects on the quality of the smoke-dried fish. The moisture contents of the samples were reduced from the initial value of 75.11% to average safe storage values of 15.30 and 17.95% after smoke-drying at 60°C for 15 h and at 70°C for 10 h, respectively. The results showed that the crude protein, crude fibre, crude lipid and ash contents of the dried fish generally increased from the initial values as the moisture content decreased. It can be concluded from the results of this study that the best smoked fish with good quality parameters in terms of nutrient and organoleptic parameters were the products dried at 60°C for 15 h and 70°C for 10 h.

Key words: Fish, smoke-drying, drying temperatures, drying time, proximate composition, organoleptic parameters.

African Journal of Agricultural Economics and Rural Development Vol. 1 (2), pp. 058-066, October, 2013. © International Scholars Journals

Full Length Research Paper

 Recent changes in fish communities of the equatorial Lake Naivasha, Kenya 

Aloo P. A.¹*, Oyugi D. O.², Morara G. N.³ and Owuor M. A.⁴

¹Department of Aquaculture and Fisheries Management, Karatina University, P. O. Box 1957-10101, Karatina, Kenya.

²Kenya Wildlife Service Training Institute, Kenyatta Avenue, P. O. Box 842, Naivasha, Kenya.

³Kenya Marine and Fisheries Research Institute, Mombasa Station, P. O. Box  81651-80100,  Mombasa , Kenya.

⁴Department of Applied Limnology and Marine Sciences, South Eastern University College, P. O. Box 170-90200 Kitui, Kenya.

*Corresponding author. E-mail: [email protected].

Accepted 15 September, 2013

Abstract

Changes in fish species composition and abundance in Lake Naivasha were investigated monthly for a period of 12 months. Data were obtained both from experimental surveys as well as commercial fish landings. The structure metrics considered included species abundance and composition, length-frequency and physico-chemical attributes. Results of the study showed that the fishery is currently dominated by the recently introduced common carp, Cyprinus carpio accounting for over 95% of the total fish landings, with the naturalized fish populations performing dismally both in terms of abundance as well as health conditions. The entry of the common carp into Lake Naivasha may have completely transformed the lake’s ecosystem integrity, driving the initially abundant tilapiine species to near local extinction. The study also confirms a restricted distribution of Micropterus salmoides to rocky-bottomed habitats of Hippo Point and Crescent Lake. Conversely, the long-fin barb, Barbus paludinosus, initially confined to the north swamp and the mouth of River Malewa, currently exhibits a lake-wide distribution. The changing climatic conditions as manifested in the lake level recessions may be a real threat to the fish stocks in the lake. Human activities in the catchment areas may also have contributed to the recent ecological changes witnessed in Lake Naivasha. This study proposes a number of recommendations with a view to ensuring ecosystem integrity and consequent sustainable fisheries of Lake Naivasha.

Key words: Ecosystem integrity, habitat preference, species introductions, sustainable fisheries, fish population, equatorial lake.

African Journal of Agricultural Economics and Rural Development Vol. 1 (1), pp. 035-041, September, 2013. © International Scholars Journals

Full Length Research Paper

Socio-economic and policy issues determining sustainable fish farming in Nigeria

Oluwasola Oluwemimo* and Ajayi Damilola

Department of Agricultural Economics, Faculty of Agriculture, Obafemi Awolowo University, Ile- Ife, Osun State, Nigeria.

*Corresponding author. E-mail: [email protected]. Tel: 234-(0)803-727-4784

Accepted 15 November, 2012

Abstract

A major agricultural sub-sector where achieving food security has become elusive in Nigeria is the fish production subsector. Demand for fish in Nigeria stands at about 1.5 million metric tonnes per annum while domestic production is just 511,700 metric tonnes. The nation spends about N150 billion (US$1billion) annually to bridge the gap between supply and demand. Consequently, several policy measures have been put in place to stimulate local fish farming. Till date, the results from the colossal investment and policy have not yielded the desired results. Hence, this study attempted to examine the factors determining the sustainability of fish farming in Nigeria with a view to stimulating private investment in the sector, meet national market demand through domestic production and export the excess to enhance the income of farmers. Regression and budgetary analyses were used to analyze data obtained from 100 fish farmers in ten local government areas of Osun State. The result showed that the average net income in the study area was N318,640.75 while the gross margin was N457,327.95. The benefit-cost ratio was 1.5 indicating that for every N100 invested, the enterprise yields additional N50. The regression analysis showed that experience of farmers in fish farming, quantity of feed used, access to credit and size of pond were significant determinants of fish farm production in Nigeria. Major challenges confronting fish farming in the study area are lack of access to credit, high cost of inputs and poor extension services.

Key words: Fish farming, inland waters, nutrition, employment, poverty, sustainable, pond.

Key words: Blood, exercise, portable meter, stress.