Aquaculture and Fisheries Management

SEX REVERSAL OF NILE TILAPIA Oreochromis niloticus (LINNEAUS, 1758) USING DIFFERENTLY PROCESSED Tribulus terrestris L. EXTRACTS

2022-03-02T11:13:34Z

SEX REVERSAL OF NILE TILAPIA Oreochromis niloticus (LINNEAUS, 1758) USING DIFFERENTLY PROCESSED Tribulus terrestris L. EXTRACTS SADIQ, HAUWA OHUNENE All male monosex culture in Oreochromis niloticus (ON) has been identified as a means of eliminating problem of stunted somatic growth caused by their prolific breeding habit. Production of all male ON populations through the use of synthetic steroid hormones has generated environmental and public health concerns, hence the need for natural alternatives. Phytochemicals from plants such as Tribulus terrestris (TT) has been reported as potential means of inducing sex reversal in fish. However, the efficacy of TT extracts for production of all male ON needs to be documented. Therefore, the effectiveness of TT extracts for sex reversal and growth enhancement of ON larvae was investigated. Extracts of TT obtained using ethanol (TTE), ethyl acetate (TTEA), aqueous (TTA100)at1000C and (TTA27) at 270C (room temperature) were assessed quantitatively for phytochemicals. Two extracts with highest saponin and steroid contents were used for the nutritional study. Each extract was added to isonitrogenous diets (Crude Protein 45%) at 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 g/kg while diet supplemented with 0.5mg/kg of 17-α-methyltestosterone (MT) served as control diet. Oreochromis niloticus larvae (n=3150; 0.02±0.001g) were randomly allotted to treatments in triplicates in a 2x7 factorial design. Fish were fed to satiation for 126 days. Percentage males (PM) in randomly selected fish (n=210) were determined using sex-linked markers. Growth performance indices such as Mean Weight Gain (MWG) and Specific Growth Rate (SGR) were determined. Blood (5mL) was sampled to evaluate Haematocrit, Aspartate aminotransferase (AST) and Serum Cholesterol (SC) using standard procedures. Data were analysed using descriptive statistics, ANOVA and Polynomial regression at α0.05. Flavonoid, saponins, anthraquinones, terpenoids and steroids were present in all TT extracts. Saponin was significantly highest in TTA27 (83±0.0mg/g) while steroid was highest in TTE (19±1.0mg/g). Least saponin (1±0.0mg/g) and steroid (3±0.00mg/g) were obtained in TTEA. Percentage males were 87.62±2.02% and 90.48±2.0% for TTE and TTA27 respectively. Least (53.33±11.6%) and highest (100.00±0.0%) PM were obtained in 0.0g/kg and 1.5g/kg TTA27,respectively. Least (3.56±0.4g; 4.110±0.1%/d) and highest (3.73±0.4g; 4.156±0.1%/d) MWG and SGR were recorded in TTE and TTA27, respectively. The MWG varied significantly from 2.26±0.2g (0.0g/kg) to 4.80±0.2g (2.5g/kg TTA27), while SGR were 3.79±0.1%/d and 4.39±0.03%/d in 0.0g/kg and 2.5g/kg TTA27, respectively. Optimum inclusion level of TTA27 relative to MWG was 2.05g/kg (R2=0.95). Haematocrit ranged from 25.36±0.1% (TTE) to 25.37±0.1% (TTA27) while AST was 64.14±0.1µ/L (TTE) to 64.30±0.1µ/L (TTA27). Highest (25.66±0.01%) and least (25.12±0.02%) haematocrit were recorded in 0.5g/kg TTA27 and 1.0g/kg TTE, respectively. The AST was highest (64.94±0.0µ/L) in 0.0g/kg and least (63.57±0.6µ/L) in 0.5g/kg TTE. The SC ranged from 141.34±0.1g/dL (TTA27) to 142.08±0.1g/dL (TTE). Significantly highest SC (162.60±0.3g/dL) was recorded in MT while 2.5g/kg TTA27 gave the least (134.44±0.16 g/dL). Tribulus terrestris water extract at 1.5g/kg could optimally reverse sex of Oreochromis niloticus larvae. Diets containing Tribulus terrestris water extracts at inclusion level of 2.05g/kg enhanced growth and health of Oreochromis niloticus larvae.

FISH COMPOSITION AND PRODUCTIVITY OF LOWER RIVER NIGER, AGENEBODE, NIGERIA

2022-03-02T11:06:49Z

FISH COMPOSITION AND PRODUCTIVITY OF LOWER RIVER NIGER, AGENEBODE, NIGERIA ADENIYI, OSAIMIANMIONMWANARASOMWAN Inland waterswhich are important sources of fish for food and economic security are gradually declining in productivity.Studies have shown that the fish production capacities of Nigeria’s inland water bodies such as Lower River Niger (LRN) are negatively impacted by habitat modifications and other anthropogenic activities. Restoration efforts for sustainable management of LRN require updated information on its fish resources composition and productivity which are currently limited. Therefore, fish resourcescomposition,distribution and productivity of LRN at Agenebodewere investigated. The LRN(46.4km) wasstratified spatially into downstream, midstream and upstream zones based on hydrological features. Two stations per zone were randomly selected.Water, phytoplankton and zooplankton samples were collectedbimonthly from each station for 24 months covering wet (April to October) and dry (November to March) seasons. Fish samples were obtained monthly fromthe fishers’ catches. Water samples were analysedfor Temperature (oC), Total Suspended Solids (TSS, mg/l), Conductivity(µS/cm), Dissolved Oxygen (DO, mg/l) and Gross Primary Productivity(GPP, g/O2/m3/d) using standard procedures. Phytoplankton, Zooplankton and fish samples were identified to species level. Length – Weight relationship (LWR, b >3 or <3 – allometric; b = 3 – isometric) of most dominant species was assessed. Species diversity was determined using Shannon-Weiner (H), species evenness(E) and Dominance (1–D) indices. Potential Fish Yield (PFY) was estimated. Data were analysed using descriptive statistics, ANOVA and canonical correspondence at α0.05. Temperature were 27.4±1.9 and 27.8±1.5, TSS 51.7±8.8; 69.9±23.8, Conductivity 43.6±4.5; 76.4±9.8, DO 4.3±0.4 and 6.1±10.0 and GPP 0.70.03; 1.10.3, for Downstream and Upstream, respectively.Temperature, varied from 25.3±1.8 to 27.5±1.5; TSS 43.1±6.1 to 89.7±17.6; Conductivity 58.7±6.5 to 60.3±6.1; DO 5.3±0.6 to 5.5±0.6and GPP 0.40.1 to 0.80.1 for wet and dry seasons, respectively. Six families of phytoplankton and nine of zooplankton were encountered. Bacillariophyta (44.0%) andcopepods(48.0%) werethe most abundant phytoplankton and zooplankton, respectively. A total of 1886 fish samples comprising 20 families, 30 genera and 45 species were identified. Cichlidae constituted highest fishsamples (18.1%), followed by Mochokidae (16.97%) and Alestidae (16.70%)while the least were Dasyatidae and Ichthyboridae (0.1% each).Oreochromisniloticus(11.3%), Synodontisclarias(10.4%) and Brycinus nurse (9.4%) dominated the catch. Significantly higher fish sampleswere encountered in dry season (1073) than wet season (813). All the species encountered showed allometric(b3) growth rate except Xenomystusnigri which was isometric (b = 3). The PFY was 565.7kg/ha. Fish diversity indices in wet season (H=3.2; E=0.6; 1-D=0.9) were higher than dry season (H=2.4; E=0.4; 1-D=0.9).Fish abundance was influenced by conductivity, pH, turbidity and GPP at 70.6% cumulative Eigen-values. Lower River Niger at Agenebodehas rich ichthyofauna diversity dominated by members of family Cichlidae. Conductivity, pH, turbidity and gross primary productivity are major environmental factors that impacted fish composition and productivity in Lower River Niger.

AQUATIC MACROPHYTES DYNAMICS AND ITS IMPACTS ON FISH PRODUCTIVITY IN ELEYELE LAKE, IBADAN, NIGERIA

2022-02-08T14:48:42Z

AQUATIC MACROPHYTES DYNAMICS AND ITS IMPACTS ON FISH PRODUCTIVITY IN ELEYELE LAKE, IBADAN, NIGERIA YEWANDE, ADETOKE SUNDAY Littoral zones invasion by macrophytes could facilitate major changes in lake ecosystem especially on the composition of other aquatic assemblages. It has been established that data on environmental interplay influencing macrophytes’ dynamics are needed for effective management of aquatic resources in lakes. However, information on macrophytes composition and other environmental variables required for sustainable management of fish production in Nigeria’s lakes, such as Eleyele Lake (EL), is limited. Therefore, environmental factors, macrophytes diversity and their effects on fish productivity in EL were investigated. Eleyele Lake was stratified into five zones (mouth Z1, upper Z2, middle Z3, lower Z4 and head Z5) based on the hydrological features. Three sampling points were randomly selected per zone. Water, sediment and macrophyte samples were collected from each sampling points bimonthly covering wet (May-November) and dry (December-April) seasons for 24 months. Fish samples were obtained from fishers’ catches. Water samples were analysed for Temperature (oC), Dissolved Oxygen (DO, mg/L) and Net Primary Productivity (NPP, mgO2/L/day). Organic carbon and silt in sediments were determined following standard methods. Macrophytes and fish samples were counted and identified to species level. Macrophyte species diversity were determined using Simpson’s (1-D) and Shannon-Weiner (H) indexes. Potential Fish Yield (PFY, Kg/ha) was calculated. Environmental Integrity (EI) and Vegetative Quality (VQ) of Macrophytes were evaluated using Aquatic Macrophytes Community Index (AMCI: 7 poorest EI to 70 highest EI) and Floristic Quality Assessment (FQA : 1-19 low VQ, 20-35 high VQ; > 35 natural VQ). Data were analyzed using descriptive statistics, ANOVA and canonical correspondence analysis, at α0.05. Temperature, DO and NPP ranged from 25.10±1.17 (Z1) to 25.40±1.15 (Z5); 4.25±0.93 (Z2) to 4.65±1.14 (Z5); 0.26±0.13 (Z3) to 0.53±0.21 (Z4), respectively. Temperature was (25.30±1.12, 25.29±1.19) DO (4.07±1.22; 4.51±1.08) and (NPP 0.55±0.31; 0.62±0.03) were for dry and wet seasons, respectively. Organic carbon and silt varied significantly from 4.66±1.61 (Z2) to 5.19±1.37 (Z4) and 18.97±3.92 (Z1) to 21.11±3.59 (Z2), respectively. Organic carbon and silt were 4.96±1.31, 5.02±1.35 and 20.52±4.14, 20.59±3.43 for dry and wet seasons, respectively. Ten families and 14 species of macrophytes were recorded with 7 and 14 species encountered during dry and wet seasons, respectively. Ipomoea aquatica was most dominant (15.4%) while Cyprerus rotundus had the least population (23.3%). A total of 3392 fishes belonging to 7 families and 9 species were recorded. Fish catch recorded in dry season was higher (1830) than wet season (1562). Macrophyte diversity were higher during wet season (1-D=0.90, H=2.4) than dry season (1-D=0.81, H=1.70). Highest and least PFY 536.72 and 367.04 were obtained in dry and wet seasons, respectively. Least AMCI (30) was recorded in Z1 while Z2, Z3 and Z4 had 37, each. Highest and least AMCI were 42 and 33 for dry and wet season, respectively while FQA was 16.05. Macrophyte composition and NPP impacted negatively on PFY with Eigen-value of 98.6%. Macrophyte composition in Eleyele lake is of low vegetative quality and had resulted in moderately poor environmental integrity. This has negatively impacted the aquatic diversity and fish productivity.

GROWTH PERFORMANCE AND PROTEIN DIGESTIBILITY IN Clarias gariepinus, BURCHELL, 1822 FED SOYABEAN MEAL BASED DIETS SUPPLEMENTED WITH AMINO ACID AND PROTEASE

2022-02-08T14:44:12Z

GROWTH PERFORMANCE AND PROTEIN DIGESTIBILITY IN Clarias gariepinus, BURCHELL, 1822 FED SOYABEAN MEAL BASED DIETS SUPPLEMENTED WITH AMINO ACID AND PROTEASE OYEDOKUN, JACOB OYELEYE Soyabean meal (SBM) could be a suitable replacement for the expensive fishmeal but for its low digestibility in fish. Appropriate dietary supplements of amino acid and protease can improve digestibility of SBM based diets. However, information on supplemental Dietary Amino Acid (DAA) and protease in such diets for optimum growth in cultured fish is limited. Therefore, growth performance and amino acid digestibility in Clarias gariepinus fed SBM based diets supplemented with DAA and protease were investigated. Soyabean grains processed by roasting and solvent (n-hexane) extraction were assessed for Crude Protein (CP), lysine and methionine content using standard methods. Six diets containing varied combinations of lysine+methionine (g/kg) supplementation were formulated for each of Roasted SBM (RS) and Solvent extracted SBM (SS): RS1, SS1 (Control: without supplementation), RS2, SS2 (0+10), RS3, SS3 (2.5+7.5), RS4, SS4 (5.0+5.0), RS5, SS5 (7.5+2.5) and RS6, SS6 (10+0) respectively. Furthermore, protease (ppm/kg) was supplemented in each of RS and SS: RS0, SS0: (control: without supplementation), RS100, SS100 (100), RS200, SS200 (200), RS300, SS300 (300), RS400, SS400 (400) and RS500, SS500 (500), respectively. Clarias gariepinus (n=1440; 19.70±0.20g) were fed to satiation with the diets for 12 weeks in triplicate in a completely randomised design. Final weight (FW, g) and Feed Conversion Ratio (FCR) were calculated. Blood (5mL) was sampled for Packed Cell Volume (PCV, %) and Alanine Amino Transaminase (ALT, IU/L). True Methionine (TM) and True Lysine (TL) digestibility were determined using standard procedures. Data were analysed using descriptive statistics, polynomial regression and ANOVA at α0.05¬¬¬. The CP, lysine and methionine were 52.5±2.8%, 58.5±2.5%; 2.3±0.0%, 2.8±0.1% and 0.5±0.0%, 0.6±0.01% in RS and SS, respectively. Least FW 32.60±3.59 and 34.8±1.2 were recorded in RS6 and SS2, respectively while RS5 (36.4±4.6) and SS1 (43.4±4.0) had the highest. The FCR ranged from 3.0±0.7 (RS5), 2.3±0.2 (SS3) to 3.8±0.5 (RS1) and 3.1±0.3 (SS2). The PCV were 21.0±1.7, 27.0±2.7 and ALT 19.3±5.0, in RS1 and RS5, respectively. The PCV and ALT ranged from 22.7±3.8, 23.0±2.0 to 25.7±1.5, 31.0±3.6 in SS1 and SS5, respectively. Significantly least (90.9±0.3) and highest (92.9±0.4) TL were obtained in RS2 and RS4, respectively while it ranged from 86.2±1.0 (SS4) to 95.9±0.2 (SS5). Optimal FW were 35.7 and 35.0g at 0.6+0.4g/100g supplementation in RS (R2=0.8) and SS (R2= 0.7). The FW were least in RS100 (31.2±3.4) and SS0 (32.0±0.7), highest in RS400 (46.9±9.25) and SS400 (44.6±2.9), FCR least in RS400 (1.4±0.3) and SS400 (1.6±0.2), highest in RS100 (2.8±0.6) and SS0 (2.8±0.0). The PCV were 23.5±5.0 (RS500) and 27.0±1.0 (RS0), ALT 20.3±0.6 (RS100), 34.7±13.3 (RS400) TM 77.8±0.2 (RS500), 93.5±0.0 (RS200) and TL 92.7±0.1, (RS300), 96.2±0.0 (RS100). In SS, PCV ranged from 22.7±4.6 (SS500) to 31.3±4.0 (SS0), ALT 20.0±1.0 (SS0) to 26.3±3.1 (SS400), TM 84.3±0.1 (SS100) to 95.8±0.2 (SS0) and TL 87.7±0.1 (SS100) to 95.9±0.1 (SS200). Optimal FW were 42.0 and 41.0g at 400 ppm/kg supplementation in RS (R2=0.6) and SS (R2=0.7), respectively. Lysine+methionine and protease supplementation at 0.6+0.4g/100g and 400ppm/kg could optimally improve growth and digestibility in Clarias gariepinus fed soyabean meal based diets without negative impact on fish health.