Department of Aquaculture and Fisheries Management

Permanent URI for this collectionhttps://dspace.njala.edu.sl/handle/20.500.144402/158

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Start date: 2012Has files: No

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Now showing 1 - 10 of 14
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    Nutritional Evaluation of Defatted Groundnut Cake meal with Amino acid as Protein Supplement in African Catfish (Clarias gariepinus Burchell, 1822) Juveniles Diet
    (2018-12-15) Olapade, Olufemi Julius
    Background and Objective: Fish feed constitute about 60% of fish production costs and this is because fishmeal (FM) which is the major protein feedstuff in fish feed is in excessive demand by other agricultural production sectors thus leading to increase in its price.Researching into alternative way of attenuating FM in fish feed production becomes necessary.Consequently, in this paper, the effect of feeding Clarias gariepinus juveniles with diets supplemented with defatted groundnut cake (DGNC), lysine (L) and methionine (M) was studied for 56 days.Materials and Methods: Fish of an initial mean body weight of 34.4±0.548g were fed the trial diets at inclusion levels of 0, 25, 50, 75 and 100%.The diet with 0% DGNC and 100% fishmeal served as the control.The experimental fish held in 56 L troughs were fed treatment diets in triplicate group of 20 fish per replicate at 5% body weight twice daily.Water parameters measured according to standard methods were pH, temperature, conductivity and NH 3 .Dissolved oxygen was not determined because the experiment was completely flow-through.Results: At the end of the feeding trial, fish fed with the control diet recorded the highest mean weight gain (17.33±1.53),followed by fish fed diet 2 (14.33±0.58).Protein intake and survival rate were not significantly different (p<0.05) but protein efficiency ratio was significantly different among dietary treatments.Feed Conversion Ratio (FCR) was highest at diets 1, 2 and 3, respectively and were not statistically different (p<0.05).The water quality parameters monitored in the trial were within recommended range and were not affected by the supplemented diets.Conclusion: It can be concluded that, substituting FM with DGNC, L and M at 25 and 50% inclusion will not compromise growth performance and feed utilization of the fish and neither will it significantly lower the water quality of the culture environment.
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    Economic Assessment of Integrated Fish Farming (Fish-Rice-Piggery) in Sierra Leone
    (Science Publishing Group, 2015) Olapade, Olufemi Julius
    The present study evaluates the profitability and environmental effect of integrated fish cum rice and piggery production at Njala University, Sierra Leone. The research carried out between June and November, 2014 consists of the pigsty (2.5m × 11m), a maggoty and integrated pond (395.2m2) sown with 0.94kg NERICA 19 rice at spacing of 20cm inter - rows and 5cm intra - rows. The pond was stocked with Clarias gariepinus juveniles (mean weight 25.6± 1.78g) at the density of 4.8fish per m2.Water quality parameters viz., temperature, pH, Dissolved oxygen, NO3-N, NH3/NH4, hardness and alkalinity were determined in the pond and were found to be within the recommended range for the culture of tropical fish. Economic analysis of the adaptive research gave a negative incremental benefit and Net Present Value (NPV) in both the first and second year of production. The sensitivity analysis evaluation shows that the enterprise is fairly sensitive to price fluctuation (-46.02%) and highly sensitive to survival rate of the fish and the scale of production of the pigs. Increasing scale of production and selling at market price will greatly enhance profitability and short term payback of costs.
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    Growth Performance and Hematology of the African Catfish ( Clarias gariepinus Burchell, 1822) Juveniles Fed Graded Level of Anisophyllea Laurina R. Br. Ex. Sabine ( Monkey Plum ) Seed Meal
    (2015-04-14) Olapade, Olufemi Julius
    Anisophyllealaurina seed meal (ASM)in this study partially replacedfish meal(FM). Isonitrogenous and isocaloricdiets (40% crude protein) containing0%, 25%, 50%, 75%, 100% ASMwere formulated. Clariasgariepinus juveniles (32.72 ± 0.32) stocked at 10 fish/50L troughs fed twice daily for 98 daysutilized effectively the formulated diets for growth.Mean weight gained (MWG) washighest at 0%and 25% butdecreased as ASM increased.Specific growth rate (SGR), Protein efficiency ratio (PER), Protein intake (PI) were significant (p<0.05) at 0% and 25% inclusion. Survival rate (%SR)was unrelated totreatment - highest at 0% and 100% (97%SR)and least at 75% (90%SR).Carcass protein, packed cell volume and haemoglobin counts were statistically the same at 25%, 50%, 75% and 100% inclusion. Since C. gariepinusperform better at 25%ASM inclusion it is recommended as the level of replacement for FM in fish diets.
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    Influence of net cages on water quality and trophic status of Lake Victoria, Kenya: The case of Kadimu Bay
    (Wiley, 2023) Mawundu, Sellu
    Water quality is a critical component regulating ecosystem functioning in aquatic habitats, requiring regular monitoring for sustainable ecosystem services. Cage fish farming has the potential to affect water quality because of its rapid increase in many African waterbodies in response to dwindling wild fish stocks. Thus, there is a need for more studies to guide sustainable cage aquaculture in African lakes and reservoirs. This study evaluated the possible effects of cage farming of Nile tilapia (Oreochromis niloticus) on water quality parameters and the trophic state of Kadimu Bay, Lake Victoria, Kenya. Sampling for physicochemical and biological variables, including nutrient load, was conducted from January to October 2021, at five fish cage sites and a control site within the bay. In situ measurements of physical variables were undertaken in the field, while analysis of water samples for nutrient loads, biological and chemical variables was undertaken in the laboratory, following the methods described in APHA (American public health association standard methods for the examination of water and waste water. APHA‐AWWA‐WEF, 2005). The Carlson's Trophic State Index (CTSI) was used to classify the trophic state of the cage sites, while the total nitrogen:total phosphorus (TN:TP) ratio was used to determine the primary productivity limiting nutrient in the bay. The study results indicated electrical conductivity was significantly lower at the control (97.53 ± 4.17 μS/cm), compared to cage sites (105.42 ± 5.32 μS/cm at the Utonga cage site to 112.84 ± 1.94 μS/cm at the Oele cage site), indicating water of relatively lower quality at the cage sites. Similarly, the nitrite concentrations were higher at cage sites (6.35 ± .96 μg/L at the Uwaria cage site to 3.16 ± 2.25 μg/L at the Utonga cage site), and lower at the control site (2.68 ± 1.39 μg/L). In all, 14 physicochemical variables did not vary significantly between the cage and control sites, with nine variables (temperature, turbidity, electrical conductivity, total suspended solids, particulate organic matter, chlorophyll‐a, TP, nitrate and TN) being within the recommended thresholds for aquatic life processes. The bay was evaluated as being in a light eutrophic state, indicating moderate influence of the fish cages on the trophic state of the sites. There was a moderate relationship between chlorophyll‐a and TP concentration at the sampling sites (R2 = .50), compared to a stronger relationship with (R2 = .78). The TN:TP ratios were <10 at the sampling sites, indicating nitrogen was the limiting factor for primary production in the bay. The calculated CTSI suggests that the bay exhibited a light eutrophic state. Overall, although the results of this study showed cage aquaculture is not a current challenge to the water quality of the bay, regular monitoring is nevertheless recommended to inform sustainable aquaculture development in the bay and lake.
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    Environmental and Economic Impact of Fish cum Rice and Poultry Production Integration System
    (2015-04-14) Olapade, Olufemi Julius
    The economic viability and environmental friendliness of integrating fish with rice and poultry was evaluated in a fish pond (520m 2 ); a paddy platform (8 x 25m 2 ) sown with 1.00kg NERICA 19; a poultry house (3.5 x 11m in dimension) and a maggoty. Integrated pond was stocked at 1.923 fish per m 2 (25g mean weight) while 400 day-old broilers were housed. Water quality parameters determined were within recommended range for the culture of tropical fish species and statistically non-significant (p < 0.05). The synergy gave positive Net Present Value NPV of Le 18,520,661.51 (US\$4,161.95) in the third year; a benefit-cost ratio of 1.23 and two year payback. Sensitivity calculated was 23.6% an indication of the sensitivity of the investment to survival rate. Integrating fish with rice and poultry is environment friendly, and economically viable with potential to create employment, augment income and improve the living standard of sub Saharan poor population.
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    Sex ratio, gonad maturity and size-structure of Pagelus bellotti in Sierra Leone
    (2021-02-16) Mansaray, Alie Hindolo Dembeh
    A total of 135 specimens of Pagellus bellotti were randomly collected from artisanal boats in August 2018. Study of sex ratio, gonad maturity and size-structure of Pagellus bellottii is meagre in Sierra Leone, and forms the basis of the present study. The study will contribute to current knowledge and promote rational exploitation of the stock. Length and weight were measured using a fish measuring board (cm) and digital weight scale (g) respectively. Sex and gonad maturity were macroscopically assessed. Results showed dominant males (71.9%) and significant difference observed (1:2.6) and expected (1:1) female: male sex ratios (p 0.9). Indexes of condition were greater than 1.0 (K > 1) for all sex categories. Results portrayed a heterogeneous gender population of Pagelus bellottii and vast similarity in reproductive strategies by both sexes. The fish comprised of one size group and males may be growing larger than the females. Growth pattern was near-isometric for females and negative allometric for the males, and both sexes were in better condition (K >1.0). An annual study could provide further insight.
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    Harnessing light: innovative photodynamic therapy for controlling Aeromonas hydrophila in aquaculture
    (Springer Science+Business Media, 2025-02-28) Ayana, Gelana Urgesa