Environmental friendly aquaculture key to sustainable fish farming development in Nigeria

Aquaculture production in Nigeria has increased tremendously in recent times; along with this increase is the rise in the level of waste outputs from aquaculture practices. The discharge of waste from aquaculture operations on continuous basis leads to eutrophication and destruction of natural ecosystem in receiving water body. Controlled wastes production strategies is necessary to maintain sustainable aquaculture growth into the future, as long-term sustainability of fish culture systems depends on their ability to reduce their waste outputs. The release of solid wastes is mainly a function of the digestibility of various dietary components while the release of dissolved wastes is mainly a function of the metabolism of nutrients by the fish. This paper critically reviews the impacts of aquaculture wastes on the environment and the strategies to mitigate the effect of these impacts. Future trends and research needs on aquaculture induced effluents are outlined. As the amount of nutrient discharge is typically site and operation specific, effective farm management has been identified as the most important factor to avoid effluent pollution

Exploitable socio-economic benefits of mangrove oyster culture to the people of Niger Delta

The Niger Delta, a 30,000 km2 wetland of global ecological significance is located at the southernmost part of Nigeria. The Delta is dissected by a dense network of rivers and creeks of saline and freshwater surface bodies. The brackish water (saline) sector consists of estuaries and intertidal mangrove swamps; the total brackish water area for the Niger Delta estimated at about 7,415 km2. The mangrove oysters grow chiefly in brackish water creeks of Bayelsa, Delta and Rivers States, found attached to the aerial roots of the mangrove Rhizophora racemosa (Red mangrove). Mangroves are salt-tolerant evergreen forests found along sheltered coastlines, shallow-water lagoons, estuaries, rivers or deltas; stands stretching 30-40 km inland with an estimated area of 997, 700 ha in Nigeria. Aquaculture has an important role in the development of many national economies and plays a key role in rural development. The abundance of a natural population of mangrove oysters in the Niger Delta makes seed collectors and growing easier and inexpensive. The culture of mangrove oysters by the locals will contribute significantly to economic growth, increases income and food security, efficient utilization of surplus rural labour and reduced social problems, poverty alleviation, and social stability. This paper enumerates the culture and socio-economic benefits derivable from the practice of aquaculture through the sustainable culture of the native mangrove oysters

Growth of Clarias gariepinus juveniles fed five commercial feed

Clarias gariepinus juveniles 6.35 ~C 0.22 g weight were fed five different commercial diets for 105 days to determine growth rates. Diets were hand distributed in triplicate groups of 30 fish once daily. The diets used were Coppens, Multifeed, Eurogold, Vittal and Ajanla feeds. At the end of the experiment, the final mean weight for Coppens, Multifeed and Eurogold were 181.54 ~c 0.63 g, 179.92 ~c 0.95 g and 139.92 ~c 0.26 g respectively, while final mean weight for Vital and Ajanla were 110.11 ~c 0.23 g and 119.03 ~c 0.35 g respectively. The statistical analysis of the results showed that there were significant differences (P0.05) in the mean final weight between Coppens and Multifeed. The specific growth rates (SGR) were 3.19% day-1 3.18 % day-1 and 2.94% day-1 for Coppens Multifeed and Eurogold respectively and 2.71% day-1 and 2.78% day-1 respectively for Ajanla and Vital. There were significant differences (P0.05) between SGR of Coppens and Multifeed. Based on these findings, it was concluded that feed with macronutrient combinations of 45% CP, 12% crude fat, crude fiber, 1.5%, Ash 9.5% promoted better growth rates in C. gariepinus juveniles as compared with other combinations

The influence of stocking density on the growth performance and production of tilapia (Oreochromis niloticus) in earthen pond

An experiment was carried out to investigate the influence of stocking density on the growth of the initial stocked tilapia (O.niloticus) in earthen ponds, the effect on the reproductive performance of the fish and impact on the economy of production. Six African Regional Aquaculture Centre (ARAC), Aluu, Port Harcourt earthen genetic ponds split into three compartments representing three replicates were stocked with 666 fingerlings of 4.33g average initial weight and 6.06cm average initial length at 37 per replicate. They were fed with a 28%CP blood meal based diet for nine months. The size of the ponds and depth of water was such as to attain average stocking densities of 6.33, 6.45, 5.05, 3.60, 2.88 and 2.05 fish/m3. The result showed distinct increase in growth as the stocking densities decreased. Ponds 5,6 and 4 with lower densities 2.88, 2.05 and 3.60 fish/m3 having higher final weights of 146.10, 120.79 and 108.69g than ponds 3, 2 and 1 with 85.37, 74.36 and 59.68g respectively (P<0.05). Average final length was higher in ponds 5, 6 and 4 at 14.46, 13.86 and 13.79cm than ponds 3, 2 and 1 with 12.09, 10.62 and 11.36cm. Relative weight gain followed suit with 3274.13, 2689.61 and 2410.16% in ponds 5, 6 and 4 as against 1871.59, 1617.32 and 1277.83% in 3, 2 and 1. Percentage survival increased as stocking density decreased at 28.18, 35.45, 37.27, 40.91, 41.82 and 45.45% for the 6.33, 6.45, 5.05 , 3.60, 2.05 and 2.88 fish/m3 treatment respectively, with the 3.60, 2.05 and 2.88fish/m3 treatment significantly higher (P<0.05). The 2.88fish/m3treatment (treatment 5) also provided the cheapest cost of producing 1kg of fish at N178.74 as against N457.14, N351.44, N312.41, N242.81 and N217.25 per kg fish of treatments 1, 2, 3, 4 and 6 respectively. The total number of off-springs produced all in progressive sizes increased as the stocking density decreased at 1530, 1636, 1674, 2053, 3160 and 3234 for ponds 1-6. The experiment showed that tilapia fingerlings stocked in earthen pond at low densities grow and reproduce more and at a lower cost of production than those with higher stocking densities. The ideal appears to be between 2 and 3 fish/m