Gonadosomatic Index, Fecundity and Egg Size of Auchenoglanis occidentalis (Cuvier and Valenciennes) in River Rima, North-Western Nigeria

Study was carried out on Auchenoglanis occidentalis from River Rima, North-Western Nigeria to provide information on gonadosomatic index, fecundity and egg size. Eight hundred samples of the fish (398 females, 399 males and 3 with unidentified sexes were examined between November 2005 and December 2008. GSI, fecundity and diameter of the eggs were analysed. Linear regression analysis was used to determine therelationship between GSI, fecundity and egg size with total length (TL), total weight (TW), gonad weight (GW) and gonad maturation stages (MS). Six stages of gonad maturation were established. Mean gonadosomatic index (GSI) for female and males were 2.01±2.75SD and 0.17±0.32SD, respectively. It varied with sex, size class and gonad maturation stage, and exhibited significant (P<0.05) correlation with fish TL, TW and MS in females but not in males. Mean fecundity was 2834.45±2530.87SD and it correlated significantly (P<0.05) with GW, MS and inversely with egg diameter but not with TL and TW. Mean egg size was 1.31±0.33mm. It correlated significantly (P<0.05) with TL, TW and GW but not with MS. Egg size distribution was bimodal, with different sizes of egg in ovaries indicating multiple spawning. This study provided baseline information on some aspects of reproduction which is important in the management of A. occidentalis in River Rima.Keywords: Gonadosomatic index, fecundity, egg size, A. occidentali

Levels of some anions in Sokoto-Rima river system in north in western Nigeria

The level of some anions in Sokoto-Rima River system at the fishing site of the Argungu International Fishing and Cultural Festival (AIFCF) were analyzed. Water samples were collected for twelve months and analyzed for anions. Data generated was analyzed using ANOVA. Statistical analysis of the data was based on the months, wet and dry seasons and five sub-seasons namely early rainy (June and July), flood season (August and September), early dry season (October-December), mid dry Season (January and February) and late dry season (March-May). Chloride, nitrate, phosphorus, sulphate and nitrite ions were within the standard for aquatic life (Vezeau, 1989). Considering the concentrations of above ions obtained in this work, the river water is safe for the aquatic life therein.Key words: Sokoto-Rima River, anions, water, pollution status, Nigeria, AIFC

Length -weight relationship and condition factor in the Polyculture of Clarias and Tilapia in concrete tanks

The experiment was conducted to determine the length weight relationship and condition factor of Clariasgariepinus and Oreochromisniloticus in five different stocking combinations for a period of twelve weeks from 17th July – 9th October, 2009. A total of 1,509 juveniles of C. gariepinus withaverage weight of 24.88g and average length of 14.52cm, and 2,991 juveniles of O. niloticus with average weight of 24.90g and average length of 10.93cm were stocked at 30 fish/m2 in clarias:tilapia ratios of 0:1, 1:0, 1:2, 1:4, and 1:6. The fish were fed at 3% body weight per day (BWD) over a period of 84 days. The monoculture of the two species (Treatments 1 and 2) yielded the lowest growth indices (WG, %WG and SGR), while the performance of clarias at each of the three polyculture systems were higher than those of tilapia. For clarias Treatment 5 (1:6) had the maximum length (17.92±0.37cm) while the monoculture recorded the minimum of 16.60±0.29. The monoculture of tilapia gave the lowest length gain (4.83±0.41cm) while the highest (11.60±0.51cm) for tilapia was recorded in Treatment 4 (1:4). From the regression parameters and the associated statistics (r and SE) for the validation of the models, it is evident that there was a strong positive relationship between length and weight. Even though the relationship was curvilinear there were still higher percentages of regression coefficient in all the treatments and between the species. The SE was also low in all the treatments which further validated the logtransformed models. Therefore, the models are valid for estimating weight of the fishes from the length measurements without necessarily measuring the weight. Stocking ratio of 1:6 should be encouraged for better growth performance.Keywords: Polyculture, length – weight, condition factor, clarias, tilapia, juveniles

Carcass-waste yields and nutritional composition of strains of Clarias gariepinus (Burchell, 1822) as index traits for selective breeding

The role of carcass evaluation techniques in aquaculture genetics and breeding cannot be over-emphasized. Knowledge of growth potentials concerning carcass quality has improved genetic selection techniques and management. Therefore, this study was conducted on the carcass yields, by-yields, anatomical separation, and nutritional quality of Clarias gariepinus strains collected from river Rima and two other population groups from two different fish farms with records of a pure cultured strain of C. gariepinus and another farm with a pedigree of artificial crosses. The flesh weight (FW) of the river Rima (55.50±2.97) population strain was higher (p<0.05) than the two cultured population strains. Population strain C (47.79±1.17) recorded the lowest significant (p<0.05) flesh weight (FW). In comparison, B (49.12±2.68) population strain had an intermediately significant (p<0.05) flesh weight. The coefficients of variations (CV) were almost the same for all the three population groups except the gutted weight, where the river Rima (wild) population strains had the highest CV. This study recommended that attention be given to improving the cultured stock/strains in terms of resistance to diseases, heritability for improving healthy growth rate, feed conversion efficiency, and general hardiness, harnessing the diverse wild strains. In addition, this study recommended further investigation, including the amino acid profile and organoleptic characteristics of the wild fish population groups from river Rima for additional knowledge to the interest of Fish Nutritionists

Climate change effects on people’s livelihood

Generally climate is defined as the long-term average weather conditions of a particular place, region, or the world. Key climate variables include surface conditions such as temperature, precipitation, and wind. The Intergovernmental Panel on Climate Change (IPCC) broadly defined climate change as any change in the state of climate which persists for extended periods, usually for decades or longer (Allwood et al. 2014). Climate change may occur due to nature’s both internal and external processes. External process involves anthropogenic emission of greenhouse gases to the atmosphere, and volcanic eruptions. The United Nations Framework Convention on Climate Change (UNFCCC) made a distinction between climate change attributable to human contribution to atmospheric composition and natural climate variability. In its Article 1, the UNFCCC defines climate change as “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods” (United Nations 1992, p. 7)

Levels of some anions in Sokoto-Rima river system in north in western Nigeria

The level of some anions in Sokoto-Rima River system at the fishing site of the Argungu International Fishing and Cultural Festival (AIFCF) were analyzed. Water samples were collected for twelve months and analyzed for anions. Data generated was analyzed using ANOVA. Statistical analysis of the data was based on the months, wet and dry seasons and five sub-seasons namely early rainy (June and July), flood season (August and September), early dry season (October-December), mid dry Season (January and February) and late dry season (March-May). Chloride, nitrate, phosphorus, sulphate and nitrite ions were within the standard for aquatic life (Vezeau, 1989). Considering the concentrations of above ions obtained in this work, the river water is safe for the aquatic life therein.Key words: Sokoto-Rima River, anions, water, pollution status, Nigeria, AIFC