Conservation needs of fisheries resources and reorientation for sustainable captive and culture practices

A discussion is presented on the importance of conservation of fishery resources, considering in particular the situation in Nigeria and providing also an outline of various legislations made by government. Suggestions are given regarding the following: education on the importance of conservation; fish farming or aquaculture; restocking or rejuvenation of depleted water bodies; stock assessment; monitoring and surveillance; provision of fishing inputs; and, extension research linkag

On drift and diel vertical migration of bottom invertebrates of the Amur. [Translation from: Zoologicheskie Zhurnal 42 1601-1612, 1963.]

Planktobenthos was sampled in 1957-58 in the river Amur. A determination of the kind of organisms drifting in the mass of water of the Amur was carried out. Of special interest for the authors was the activity of drifting of benthic larvae

A class of Baker-Akhiezer arrangements

We study a class of arrangements of lines with multiplicities on the plane which admit the Chalykh–Veselov Baker–Akhiezer function. These arrangements are obtained by adding multiplicity one lines in an invariant way to any dihedral arrangement with invariant multiplicities. We describe all the Baker–Akhiezer arrangements when at most one line has multiplicity higher than 1. We study associated algebras of quasi-invariants which are isomorphic to the commutative algebras of quantum integrals for the generalized Calogero–Moser operators. We compute the Hilbert series of these algebras and we conclude that the algebras are Gorenstein. We also show that there are no other arrangements with Gorenstein algebras of quasi-invariants when at most one line has multiplicity bigger than 1

A comparative assessment of the methods of control of water hyacinth infestation with regards to fish production

Water hyacinth (Eichhornia crassipes) has been subject of three control methods since its arrival into the Nigerian freshwater lagoon system in 1984 - mechanical, chemical and biological. An assessment of these three methods seems to suggest that mechanical and chemical control methods, both of which being costly, must be applied either solely or integrated to combat the present level of considerable infestation in Nigeria. The biological control methods are advisable for slow, sustained control and can only cope with low levels of infestation. It is thus concluded that the preliminary control method should be mechanical or chemical to effectively abate the nuisance plant, followed by biological control once infestation levels have been sufficiently reduce

THE IMPLEMENTATION OF THE GAMBIAN RANGELAND AND WATER DEVELOPMENT PROJECT: LESSONS FOR SOUTHERN AFRICA

This article examines the conception, design, implementation and monitoring of The Gambian rangeland and water development project based in Niamina Dankunku and Niamina West districts of the country. It attempts to make a management evaluation of the project, gaining an insight into the nature of the development problem and the approach adopted by the project for its solution. It then seeks to examine the lessons that southern African countries could learn from this experience in the light of similarities in socio-economic circumstances. The conception of the project was sound in so far as it attempted to tackle the problem of environmental degradation by a system of controlled management of scarce range resources. However, the question of increasing cattle off-take which could have also reduced grazing pressure on range resources was not addressed. The project's initial focus on the relatively well off category of cattle owners was corrected by incorporating a food-aid component to address project's concern for the poorer segment of the society. While it was a good idea, the use of food-aid took away the expected financial contribution of the local community to project management and financed a significant part of project activities. The paper welcomes the conception of the income generation components but finds their introduction rather arbitrary. The project's flexibility and its approach of participatory management are recognised as its main strength, which could assure sustainability of project achievements. In addition, the project is a good example of strong co-operative involvement of a number of development agencies in jointly solving the development problem and co-ordinating development assistance.Land Economics/Use, Resource /Energy Economics and Policy,

Engineering initiatives for water hyacinth control with emphasis on the design, control and installation of the water hyacinth boom (barrier) across River Niger, north of Kainji Lake

(13 page document

Potential for the development of aquaculture in Africa

Aquaculture production in Africa has remained low despite the huge potential that exists on the continent. In order for this potential to be realized, it is necessary to refocus the direction of aquaculture development. This paper concludes that for further growth to occur it is necessary to: (i) widen the range of production systems; (ii) increase production intensities and efficiencies; (iii) develop management technologies for indigenous species that target local niche markets; (iv) put more emphasis on marketing and processing of high value products; (v) promote policy research on how aquaculture production can respond to changing macroeconomic policies; and (vi) accelerate the disengagement of government from activities that can best be done by the private sector