Journal of Aquatic Sciences

A new methodology for the analysis of fish breeding seasonality

2023-06-22T14:31:23+00:00

The difficulty to dissect and weigh very tiny gonads and several fish specimens for the purpose of computing gonadosomatic indices (GSIs) due to non-availability of reliable electric power supply under field conditions, necessitated the study. This paper presents the performance of the gonad length indices vis-a-vis the traditional GSIs. The gonad elongation ratio (GER) (i.e. gonad length as a function of fish standard length expressed as a percentage) is here proposed for use in analyzing teleost fish breeding seasonality. The West African amphibious mudskipper, Periophthalmus barbarus (Linneaus, 1766) (Teleostei: Gobiidae) from the Imo River estuary, Nigeria, was used as the trial species. Monthly mean testicular and ovarian elongation ratios were examined vis–a–vis the classical testicular and ovarian gonadosomatic indices. The monthly mean gonad elongation ratios followed similar monthly mean sequences of the corresponding gonadosomatic indices. Mean GSI was 0.192 in males (range 0.097 – 0.347) and 1.197 in females (range 0.512 – 3.398); whereas mean GER was 16.5 for males (varied from 12.9 to 19.2) and 19.5 in females (ranged between 16.8 and 25.3). However, the gonad elongation ratios fluctuated more finely than the gonadosomatic indices. It is 2 - 3 times much easier and faster to determine gonad elongation ratio in the field than the gonadosomatic index. The determination of gonadosomatic indices require the use of sensitive electronic balance and reliable electric power supply while these are not necessities for the determination of gonad elongation ratios. Being a quantitative measure, the gonad elongation ratio can be subjected to statistical reliability estimates such as standard deviation, standard error and confidence intervals. The gonad elongation ratio which is quantitative and has biological interpretation that is analogous to the traditional gonadosomatic index, is recommended for use.

Assessment of fish distribution, composition and abundance in Otamiri River, Imo State, Nigeria

2023-06-22T17:12:53+00:00

Study on the fish distribution, composition and abundance in Otamiri River was carried out between January and December, 2021. Three sampling points (Stations 1, 2 & 3) were selected along the stretch of the river and used for the study. Fish population was assessed using different fishing gears such as hooks and lines, gillnets, cast nets and traps while one-man dugout and planked canoes were the crafts used. Species diversity indices were estimated using standard procedure. Results revealed a total of 757 fish samples comprising of 15 species, 10 genera, 9 families and 4 orders. The family Cichlidae ranked the highest as the most abundant fish species having 363 samples, while Distichodontidae ranked the lowest with just 5 fish specimen. The highest species richness (15) was recorded between the months of January and March while the least value (11) was obtained between April and June. Simpson`s Index (D) value ranged from 0.02 between July and September and 0.005 between the months of January and March. Results of Simpson`s Reciprocal Index (1/D) showed that fish species caught between May and August were not as diverse as those obtained between September and December. This may indicate that some anthropogenic activities (agricultural/crop farms, construction sites, sewage discharges, timber harvesting, industrial discharge, mining and sand dredging) observed at the study sites tended to increase during raining season which subsequently led to the decrease in fish diversity. These activities could be said to have some deleterious effects on fish distribution, composition and abundance in Otamiri River. Thus management strategies should be put in place by relevant authorities to check human activities in the area.

Effects of oyster mushroom, Lentinus sajor-caju on growth, gut histology and haematology of Clarias gariepinus

2023-06-23T05:19:18+00:00

There is need to reduce usage of antibiotics in favor of prebiotics and phytogenic in aquafeed production. The study evaluated effects of mushroom on growth, gut histology and haematological variables of Clarias gariepinus. Five treatment feeds were made to vary in inclusion of solvent extracted oyster mushrooms, Lentinus sajor-caju as follows: Feed 1, 0%; Feed 2, 4%; Feed 3, 8%; Feed 4, 12% and Feed 5, 16%. The diets were made isonitrogenous (42%) and isolipidic (6.0%). The growth performances, gut histology and haematological profile of the fish were estimated using standard procedures. The essential amino acid (EAA) contents of the mushroom and feeds were analyzed following standard methods. Ingredients were mixed according to proportions, preconditioned and steam pelleted. African catfish of average weight 9.48g were stocked in three replicates 20liter aquarium, at 113.76g/aquarium and fed with the experimental diets for 90days. Results showed that mushroom had good array of EAA especially lysine (7%). The haematobiochemical parameters and growth of the catfish were best at 8% mushroom extract inclusion. Histological sections showed significant increase in length and width of the mucosal fold microvilli as mushroom extract inclusion increased up to 8%. Similarly, red blood cell counts, packed cell volume, hemoglobin and total white blood cell counts of the catfish increased up to 8%. Fish fed Feed 3 had the best specific growth rate (3.00±0.06% day^-1), food conversion ratio (1.54±0.01), weight gain, (128.67±0.02g) and protein conversion ratio of 0.3±0.04. Catfish fed with higher than 8% inclusion of mushroom had reduced growth rates, hemato-biochemical and histological parameters. This may be probably due to the high polysaccharides and beta-glucans present in mushroom. Thus, mushroom extracts should be included in catfish feed but not beyond 8%.

Comparative study of harvested surface and ground water for aquaculture usage In Imo State.

2023-06-23T05:29:22+00:00

Comparative study of harvested surface (rain) and ground (borehole) water was carried out in the three agricultural zones of Imo State, namely: Okigwe, Orlu and Owerri. Water samples were collected using standard sampling methods from the different locations and examined for suitability for aquaculture use. Physico-chemical parameters (temperature, dissolved oxygen, pH, total dissolved solids, conductivity, hardness and chlorine were analyzed in-situ and in the laboratory using standard methods. Results obtained were analyzed statistically using ANOVA at 0.05 level of significance. Results obtained from the study showed that the physico-chemical parameters of surface and ground water were not significant (p>0.05) except conductivity which was higher in ground water samples. The ground water temperature recorded during the study period was within the range of 26.55±0.55oC (Okigwe) and 26.78±0.57oC (Owerri) and between 26.78±0.57oC (Okigwe) and 30.3±0.85oC (Owerri) for surface water. The overall mean water temperature for Okigwe was 28.18±1.87oC, 28.6±1.9oC fort Orlu and 28.8±2.21oC for Owerri. The highest dissolved oxygen content (6.9±0.50mg/l) was recorded in the surface water at Okigwe while the least DO value (5.3±0.33mg/l) was observed in the ground water at Orlu. The pH values for the different water samples varied between 6.63±0.15 and 6.96±0.11 for surface water and between 6.83±0.45 and 7.23±0.5 for ground water with an overall mean of 6.91±0.33 in Okigwe samples, 7.1±0.16 in samples from Orlu and 6.91±0.33 from Owerri. In general, all the water parameters tested were within the normal limits for use in aquaculture activities. Thus, fish farmers may utilize both borehole and rain water to grow fish in these different locations.

Bioaccumulation of heavy metals in gills and muscles of selected fish species from Owerrinta section of Imo River

2023-06-23T05:39:44+00:00

Bioaccumulation of heavy metals in aquatic organisms had been known to occur naturally. Over the years the levels of these accumulations keep increasing due to various human activities which make it detrimental to the life of aquatic organism and humans. The study assessed bioaccumulation of some heavy metals in the gills and muscles of some fish species. Fish samples were collected for a period of 4 months, identified and stored for further analysis. The following heavy metals: Zinc (Zn), Copper (Cu), Iron (Fe), Lead (Pb) and Cadnium (Cd) were assessed on the fish gills and muscles using standard procedure. Results showed that the fish species sampled (Clarias gariepinus, Tilapia zilli, Oreochromis niloticus, Alestes baremose and Pareutropius buffei) showed some levels of metal accumulation both in the gills and muscles. Levels of Zn in muscles of A. baremose, P. buffei, C. gariepinus, T. zilli and O. niloticus were 3.63±0.12, 1.45±0.26, 4.27±0.15, 4.03±1.42 and 2.00±0.15mg/kg respectively. The highest level of Zn (3.44±0.15mg/kg) in the gills was observed in T. zilli. Other results showed that P. buffei had the highest Pb concentrations (0.48±0.22mg/kg in muscle) and (0.17±2mg/kg in gills) while T. zilli had 2.24±0.54mg/kg and 1.46±0.65mg/l as the highest concentration of Fe in muscles and gills respectively. The levels of Zn, Cu, Fe and Pb recorded in the fish muscles where below the World Health Organization (WHO) and Food and Agricultural Organization (FAO) standards while Cadmium levels in all the fish sampled were above the recommended standard of 0.5mg/kg. This high cadmium accumulation in fish samples calls for concern considering the adverse effect it may cause if transferred to humans through fish consumption. There is therefore need to intensify efforts in mitigating some of the activities that amplify the levels of bioaccumulation of these metals in the aquatic environment towards a healthier environment.

Gas flaring-induced impacts on aquatic resources in the Niger Delta Region, Nigeria

2023-06-23T05:47:27+00:00

The Niger Delta is the Nigerian oil and gas province. About 10 – 40% of produced associated gas is underutilized and is flared into the environment. Gas flaring is the burning of natural gas and petroleum hydrocarbons in flare stacks by upstream oil companies in oil fields during operations. Flaring operations have adverse impacts on the environmental components and its aquatic resources. This paper reviewed the impacts of gas flaring on aquatic resources in the Niger Delta Region of Nigeria. The study revealed the induced thermal impacts on the aquatic environment to include alteration of ionic components, pH, temperature, conductivity, heavy metal concentration especially in rain water which could cause death of aquatic biota. Water toxicity from acid rain and heating from flare stacks had also caused some fish species to become extinct. Exposure to harmful air pollutants generated during incomplete combustion of gas had been linked to a variety of health hazards such as: cancer, neurological, reproductive and developmental consequences. It also affects vegetation leading to decrease in growth and productivity probably due to changes in soil quality parameters in the aquatic environment. Climate change has an impact on both physical and biological habitats, influencing biodiversity both directly and indirectly via interactions with other environmental factors. It is recommended that strict government legislations on how gas production projects may be conducted should be introduced and monitored. Regulatory agencies must fulfil their responsibilities of enforcing laws and regulregulations to check gas flaring activities in order to protect the aquatic resources of the Niger Delta Region.

Gastrointestinal parasite prevalence of cultured Clarias gariepinus in Port Harcourt, Rivers State, Nigeria

2023-06-23T05:58:38+00:00

Fish parasites are a key constraint to the production, sustainability and economic viability of aquaculture practices in Nigeria. Still, little has been documented on fish parasites and their associated risk factors. This study determined the prevalence of gastrointestinal parasites of Clarias gariepinus. One hundred and twenty (120) fish of different age groups in lengths, weights and sexes were randomly sampled from 3 fish farms (Station 1, Station 2 and Station 3) and examined for parasites. Of the 120 fishes examined, 83 (69.10%) were infected. Station 2 (33, 27.50%) recorded the highest overall prevalence percentage of parasitic fauna, followed by Station 1 (26, 21.60%) and Station 3 (24, 20%) the least. Sex-related prevalence of gastrointestinal parasites recorded a higher value (62, 51.59%) in males compared to female fishes (21, 16.0%). Age of fish based on lengths and weights indicated that smaller fishes harboured more parasites than bigger fishes. Observed parasites were nematodes, protozoan, trematodes and cestodes. Nematodes (33, 27.50%) recorded the highest abundance. In conclusion, smaller fishes were more infected than bigger ones in this study, suggesting best management practices to mitigate parasitic infection, especially in the smaller fishes.

Impacts of mycotoxin on cultured fish

2023-06-23T06:16:37+00:00

Mycotoxins are secondary metabolites produced by filamentous fungi that could cause toxic responses when ingested by animals. The extent of production varies with geographic location, feed storage practices and processing methods. In the tropics, improper bagging, transport, storage and use of feeds with inferior quality of ingredients are ways in which mycotoxin is produced and is a great challenge that threatens life of culture fish. Mycotoxins in feeds are a problem of significant concern as farmers are taking steps to overcome the challenge of feed supply. The effects result in teratogenic, carcinogenic, oestrogenic or immune-suppressive effects, poor growth, low apparent digestibility, physiological disorders, histological change and death. The expression of mycotoxin impacts is influenced by factors such as age, nutrition, sex, species and the possibility of concurrent exposure to other toxins. The main target organ in animals is the liver; therefore, mycotoxin disease is primarily hepatic. Conditions increasing the likelihood of mycotoxin impacts in aquatic organisms include limited feed availability, environmental conditions that favour mould growth on feedstuffs, and lack of regulatory systems for aflatoxin monitoring and control. Mycotoxin's effect on these organisms is not only on health problems in exposed fish but also represents a high risk to consumers through residues in fish musculature. Therefore, control and prevention measures are needed to sustain the aquatic resources. However, several effective ways to prevent and control hazardous fungi and their dangerous mycotoxins have been presented.

Growth responses of Clarias agboyiensis and C. macromystax fed foreign and indigenous commercial fish feed

2023-06-23T14:13:36+00:00

The study investigated growth responses of the small fish, Clarias agboyiensis and C. macromystax fed with foreign (Coppens and Al aqua) and indigenous (Vital and Blue crown) commercial catfish feed. Fish were grouped into four categories: AA1 to AA4 represented C. agboyiensis fed with Coppens; BB1 to BB4 represented C. macromystax fed with Al aqua; CC1 to CC4 represented C. agboyiensis fed with Vital while DD1 to DD4 represented C. macromystax fed with Blue crown. Fish on foreign feed were fed at 1% of their body weight once a day while those on indigenous feed were treated at 2% body weight twice daily. Each feed contained 60% crude protein. The experiment was laid out in a completely randomized block design with 16 fish in each 70 litre water container. Growth responses were estimated using standard procedure. Results showed that C. agboyiensis fed with Coppens at 1% body weight and once daily had the best average final weight of 337.37g, final length of 32.15cm, specific growth rate of 19.65%/day, condition factor of 2.95 and survival rate of 83.5 %. This was followed by C. macromystax fed Al aqua at the same frequency and duration having a final weight of 309.25g, final length of 30.85cm, specific growth rate of 19.40%/day, condition factor of 2.95 and survival rate of 80%. The least growth response was recorded in C. macromystax fed Blue crown. The study indicated that Coppens feed has the best nutrient utilization ability. Thus, fish fed this diet even at 1% biomass and once daily produced the best growth. Therefore, fish could actually be fed once a day for growth and improved meat quality provided the feed quality is adequate.

Effects of reproductive hormones on reproductive biology of commonly consumed fish in Akwa Ibom State, Nigeria

2023-06-23T14:25:16+00:00

Nutritionally proteinous food and feed are required for a balance healthy living. This study was designed to assess the efficacy of some reproductive hormones: human chorionic gonadotropin (HCG), Ovaprim (OVA), extract of carp pituitary (CPE) and deoxy- corticosterone acetate (DOCA) on some aspects of reproductive biology of gravid Heterobranchus longifilis and Clarias gariepinus. A 25 number each of gravid males and females H. longifilis and C. gariepinus were employed in this study. Five experimental set up were designed for the study. Each treatment group was dosed with the required amount of the four reproductive hormones while in the fifth treatment breeders were treated with normal saline. This served as the control experimental. All protocol followed standard procedure. Results showed the highest mean value of relative fecundity (148.177) recorded in H. longifilis treated with ovaprim. This was followed by HCG treated C. gariepinus (145.668). Egg fertility rate had the highest mean value of 61.4803 in C. gariepinus treated with ovaprim, followed by 55.583 mean value in H. longifilis with HCG treatment. Egg hatchability mean value of 70.9280 was the highest observed in H. longifilis with ovaprim treatment. The mean values of survival rate were high in both species with OVA and HCG treatment showing values of 61.86% and 61.00% respectively. Treatment of the species with these reproductive hormones yielded good outcomes, except in the case of DOCA. Thus, CPE, OVA and HCG are recommended for breeding of C. gariepinus and H. longifilis.

Total petroleum hydrocarbon analysis in water, tilapia and sediment samples from ARAC environment (Aluu), Rivers State

2023-06-23T17:42:48+00:00

The contamination of aquatic environments by Total Petroleum Hydrocarbons (TPHs) presents significant environmental and health concerns. This study aimed to assess the levels of TPHs in water, tilapia, and sediment samples collected from the African Regional Aquaculture Center in Aluu, Nigeria. Chromatographic techniques were employed for TPH extraction and detection. The results revealed elevated TPH concentrations in the study area, with the highest levels observed in sediment samples. The results revealed that the concentration of TPH was high during the dry season (September to November) compared to raining season (May to July). Also, the results indicated that TPH concentration was higher in sediment compared to fish and water with average concentration of 0.206667mg/kg, 0.17666mg/kg7, and 0.148333mg/kg in sediment, fish and water respectively. TPHs was observed to be in sediment from 0.18 – 0.25mg/kg, whereas in water it had variation of 0.11mg/kg making it the lowest. TPHs variation in fish was also observed to be between 0.15 – 0.22mg/kg. It was observed that the concentrations of TPHs in fish positively correlated with THPs in the aquatic water (y = 12.56x + 168.32). This correlation is statically significant (p <0.5). The results also revealed that concentration of TPH in sediments was positively correlated (y = 2.83 x 154.26) with the water at p< 0.5 significant level. There was a positive correlation between TPH concentrations in fish and water, as well as between TPH concentrations in sediment and water. The findings emphasized the need for prompt intervention to mitigate TPH pollution and protect the environment and human health.