Commercial production of natural freshwater fish food

A review is made of some of the methods that can be used for mass cultivation of natural fish food and the types of organisms that are cultured, which include various algae and zooplankton. Some examples are given of successful case histories in the mass cultivation of natural fish food in order to stimulate the interest of Nigerian scientists on research activities of live fish food for use by fish farmers in the country

Commercial production of fish meal from fish waste

The importance of fish meal production as a means of reducing fish waste currently being experienced in the fisheries subsector is discussed. Cost estimate for Nigeria establishing a fish meal manufacturing plant and suggestions on rational execution of the project are presented. If properly located and well managed, the project will serve to convert fish waste to cash in the industrial fishery

Investment in the training of technologists for commercial aquaculture

The protein shortage in Nigeria is noted and the role of aquaculture (=fish farming) as a complement in increasing the dwindling food supply is registered. In addition, the manpower shortage especially in the technology cadre is noted and attributed to the lack of co-ordination and standard curricula especially in aquaculture. An inventory of tasks performed in the aquaculture industry was taken and these were classified and validated, then their final priority level was used to assess which ones were critical, important or desirable and which ones would result in disaster or not with inadequate mastery. Based on the above, recommendations are made that all critical and important tasks be included in the teaching curriculum for aquaculture in both theory and practicals: while it is advocated that all tasks listed be undertaken in fish farm operations. This will raise the competence of technologists to run the commercial aquaculture projects

Commercial pond fish culture

Commercial pond fish culture practice is comparatively new in Nigeria. It is therefore very important that simple guidelines be provided for the establishment, development, and management of such projects. The objective of this paper is to fulfill this urgent need. All aspects of commercial pond fish culture are dealt with. Fish pond operations comprise of pond preparation, stocking, rearing, and harvesting. These have been highlighted in the text, bearing in mind that the most important principle of fish culture is the acquisition of maximum production of marketable-size pond fish from a given unit area

A review of recent advances in commercial tilapia culture

The paper introduces the tilapias as important culture fish; their classification, breeding habits and general ecology are discussed. The versatility and plasticity of their reproduction and growth are major advantages as well as draw backs in their use as culture species. The culture of tilapias in ponds, cages, pens and raceways are described and a comparison of extensive and intensive cultivation is made. The major factors in commercial cultivation of tilapias such as feeds, hatchery/fry production and disease control are discussed. Recommendation is made for the consideration of tilapia as the equivalent of the common carp in tropical African fish culture in either monoculture or in polyculture with other fish species

Commercial pond fish culture using waste water

Waste water from some National Electric Power Authority (NEPA) housing units in Nigeria was fed to a 0.4 ha pond which was stocked with 2,200 Sarotherodon galilaeus fingerlings with a mean weight of about 36.0gm and 1000 Cyprinus carpio fingerlings with a mean weight of 10gm. This yielded after 10 months, over 2300 kg of harvestable fish plus over 20,000 Sarotherodon galilaeus fingerlings. The growth rate of C. carpio was not very encouraging possibly because of the type of plankton that colonised the pond. The S. galilaeus became stunted because of overpopulation as there were no carnivores to control their excessive breeding. The physico-chemical parameters were favourable for the growth of fish food organisms

Some experiments on commercial pond fish culture in the tidal mangrove area of Niger delta of Nigeria

A pilot fish culture project was initiated by Shell Petroleum Development Company of Nigeria Limited in 1981 with specific aims and objectives. Site selection, survey, pond construction method and fish production with regards to experiences gathered and gained, problems and solutions so far obtained are discussed. Trials of freshwater fish species to check their adaptability to brackishwater ponds were carried out and the promising results of the growth rate of these species when compared with the traditional local brackishwater species selected for culture are reported. The extension programme so far carried out is briefly described

Commercial cage fish culture

With increasing emphasis in Nigeria on aquaculture as an alternative to dwindling artisanal fishing and scarce foreign exchange for fish import, cage fish culture, is a more profitable aquaculture practice than pond culture. It appears to be one of the most viable business ventures with minimum risks. It is a highly recommendable project

Commercial aquaculture in Nigeria: a vertically integrated approach in the commercial freshwater farming of tilapia in floating bamboo net-hapas and cages systems

Tilapia once termed "poor man's" fish, still remains as the highly-priced food fish in many developing countries. The good attributes of this fish prompt its use in intensive aquaculture vertically integrated systems (VIS) which embrace broodstock development, hatchery/nursery and growout phase. Based on the series of studies carried out at Kainji Lake Research Institute, in New Bussa, Nigeria using Oreochromis (Tilapia niloticus) in floating bamboo hapas/cages, the recommended intensive modular systems were estimated to be capable of producing 4 million Tilapia fingerlings and 729 tons fish (Market-size) annually. Cost-benefit analysis showed the venture to have high prospects. It is recommended that priority be given to Tilapia cage culture at the national level in order to contribute immensely towards increased fish production

A design for commercial production of catfish (Clarias lazera) in multiple cages

The findings are given of a preliminary study on the appropriate economical feeding rate which would enhance the growth of catfish (Clarias lazera) in cages in Lyi-ojoo Lake, Nike, Nigeria, providing also the details of the design of a practical floating platform that can be used for the culture of fish in multiple cages

Commercial mariculture of Oreochromis niloticus using net cages

The culture of tilapia has a long history in Africa. Fossil remains of members of the genus have been found which are about 18 million years old (Fryer and Iles, 1972). Oreochromis niloticus was the subject of detailed observations in Egypt of 5,000 years ago. A bas relief of 2,500B.C. depicts tilapia being reared in ponds in Egypt. However, despite this long history the prolific nature of this fish results in very high populations in pond culture systems. Consequently small size fish are harvested. Several methods have thus been tried to control the excessive reproduction of tilapia in captivity with only partial success. This paper reports how large size tilapia especially O. niloticus averaging at least 150g per piece can be commercially produced using floating net cages in the marine environment

Length-frequency estimation for yellowfin tuna (Thunnus albacares) caught by commercial fishing gear in the Eastern Pacific Ocean

ENGLISH: Methods of collecting samples for the purpose of estimating the numbers and weights of fish caught, by length interval, are described. Several models for two-stage sampling are described, and the equations for the estimators and their variances are given. The results from a brief simulation study are used to show the differences between estimates made with the different models. Estimators for the average weights of fish in the catch and their variances are also described. These average weights are used to provide improved estimates of the total annual catches of yellowfin taken from the eastern Pacific Ocean, east of 150°W, between 1955 and 1990. SPANISH: Se describen los métodos de recoger de muestreo para estimar el número o peso de peces capturados, por intervalo de talla. Se describen varios modelos para el muestreo de dos etapas, y se presentan las ecuaciones para los estimadores y sus varianzas. Se usan los resultados de un breve estudio de simulación para indicar las diferencias entre estimaciones realizadas con los distintosmodelos. También se describe un estimador para el peso promedio de peces en la captura y su varianza. Se usan estos estimadores para calcular estimaciones mejoradas de las capturas anuales totales de aleta amarilla tomadas del Océano Pacífico oriental, al este de 150°W, entre 1955 y 1990. (PDF contains 41 pages.)

Some aspects of the dynamics of populations important to the management of the commercial marine fisheries

(PDF contains 33 pages)

Iso-specific Ziegler-Natta polymerization of α-olefins with a single-component organoyttrium catalyst

The synthesis of a sterically tailored ligand array (M)_2((C_5H_2-2-Si(CH_3)_3-4-C(CH_3)_3)S_2i(CH_3)_2]("M_2Bp") (M = Li, 16; K, 19) is described. Transmetallation of Li_2Bp with YCl_3(THF)_3 affords exclusively the C_2 symmetric product rac-[BpY(µ_2-Cl)_2Li(THF)_2], 20. A X-ray crystal structure of 20 has been determined; triclinic, P1, a= 13.110 (8), b = 17.163 (15), c = 20.623 (14) Å, α = 104.02 (7), β = 99.38 (5), γ = 100.24 (6)° , Z = 4, R = 0.056. Transmetallation of K_2Bp with YCl_3(THF)_3 affords the halide free complex rac-BpYCl, 23. The corresponding rac-BpLaCl, 28, is prepared in an anlogous manner. In all cases the achiral meso isomer is not obtained since only for the racemic isomers are the unfavorable steric interactions between the Si(CH3)_3 groups in the narrow portion of the [Cp-M'-Cp] wedge avoided. Alkylation of 20 or 23 with LiCH(Si(CH_3)_3)_2 affords rac-BpYCH(Si(CH_3)_3)_2, 26 in good yield. Alkylation of 28 with LiCH(Si(CH_3)_3)_2 affords rac-BpLaCH(Si(CH_3)_3)_2 29. Hydrogenation of 26 cleanly affords the bridging hydride species [BpY(µ_2-H)]_2, 27, as the homochiral (R,R) and (S,S) dimeric pairs. 26 is an efficient initiator for the polymerization of ethylene to high molecular weight linear polyethylene. 27 catalyzes the polymerization of propylene (25% v/v in methylcyclohexane) and neat samples of 1-butene, 1-pentene, 1-hexene to moderately high molecular weight polymers: polypropylene (M_n = 4,200, PDI 2.32, T_m 157 °C); poly-1-butene (M_n = 8,500, PDI 3.44, T_m 105 °C); poly-1-pentene (M_n = 20,000, PDI 1.99, T_m 73 °C); poly-1-hexene (M_n = 24,000, PDI 1.75, T_m < 25 °C). ^(13)C NMR spectra at the pentad analysis level indicates that the degree of isotacticity is 99% mmmm for all polymer samples. 27 is the first single component iso-specific α-olefin polymerization catalyst. The presumed origins of the high isospecificity are presented.