A decade of exploitation and management of the Namibian hake stocks

The hake resource is the most important commercial fish species in the demersal sector of Namibia's fisheries, both in terms of annual catch and contribution to Gross Domestic Product (GDP). The fishery now spans four decades. In the 1960s and 1970s, hake were exploited heavily by mainly foreign fleets, total catches peaking at more than 800 000 tons in 1972. The first control measures, the use of a minimum mesh size of 110 mm and the allocation of quotas to each member country participating in the hake fishery, were implemented by the International Commission for the Southeast Atlantic Fisheries in 1975. In 1990, the Namibian Government took action to control fishing activities in Namibian waters, and the enactment of its Fisheries Policy (1991) and Sea Fisheries Act of 1992 provided for the control measures to be taken. The conservative management strategy adopted between 1990 and 1993 resulted in gradual increase in hake biomass, but thereafter the stock declined. The hake fishery is currently managed on the basis of a total allowable catch that takes into consideration the rate of increase or decrease in the size of the resource. Since 1990, the demersal trawl fishery has accounted for approximately 90% of the total hake catch. The resource is subjected to both directed fishing and bycatch, the latter taken in directed fisheries for species such as horse mackerel, monkfish and sole.Keywords: biomass, hake fishery, management, stock assessmentAfrican Journal of Marine Science 2001, 23: 307–31

Beplanning en die soeke na 'n nuwe ideaal

With the changing political dispensa­tion in South Africa, the ideological background of the profession (and therefore its legitimacy) was ques­tioned. The answer to the question why we plan, changed fundamentally with the advent of the ideal of an integrated new South Africa. Changing thinking about planning to accommo­date the dominant political ideology in South Africa, seems not to be in accordance with the world-wide trend to a more Small-scale Post-Modernistic society. The crisis in which planning thought finds itself world-wide, due to the detrimental effects of Large-scale Modernism, can and must be seen as an opportunity to re-evaluate the ideals of planning and to establish a small-scale alternative for the way in which man involves himself with his natural and cultural environment. Only if we succeed in this venture, will the planning profession be able to plan, in a sustainable way, the long-term future of our country and its people. Plan­ning will also be safeguarded against accusations of serving the ideal of a single political ideology.*This article is written in Afrikaans

Nitric oxide is an upstream signal involved in the multisignalling network during the Russian wheat aphid resistance response and its application enhances resistance

The Russian wheat aphid (RWA) is serious pest of wheat in South Africa since its discovery in 1978. Nitric oxide (NO) plays an essential role in the RWA resistance response of wheat. This study was conducted to establish whether NO acts upstream or downstream of salicylic acid (SA) during the RWA defence response and also to investigate the effect of NO application on RWA control. In addition, the involvement of peroxynitrite in the RWA resistance response of wheat was studied. Resistant and/or susceptible plants grown under controlled conditions (25 ± 2°C) were used. Using a NO donor, sodium nitroprusside (SNP), and a NO production inhibitor, sodium tungstate (NaWO4), it was proved that NO acts upstream of SA during the RWA resistance response of wheat. Furthermore, a significant decrease in RWA intrinsic increase rate (rm) and disease symptom development after SNP application emphasized the role of NO in the RWA resistance responses. High levels of peroxynitrite (by-product of NO) content in the RWA infested resistant plants and inhibition of secondary defence enzymes (β-1,3-glucanase and peroxidase) after urate (inhibitor of peroxynitrite production) application proposed the involvement of this molecule in the signalling events of the RWA resistance

The choice of technique in the brick making industry in the Western Cape: Opportunities for establishing worker controlled enterprises in this sector.

Magister Philosophiae - MPhilThe thesis focuses on the choice of technique as a key component in creating viable enterprises, including those controlled by their worker-members. A theoretical model of the choice of technique is presented, with its roots in the works of Pasinetti and others. Then a picture of the technological opportunities in the brick making industry is constructed through analyzing the actual technical choices made by a sample of firms in the industry. Implications for worker controlled enterprises are drawn throughout. The choice of technique function is shown to be more complex than is usually assumed. In the presence of uncertainty an enterprise has to search for a viable operating space rather than an optimum position.. The decision making criteria are firm specific decision rules built up over time. As such the enterprise can be viewed as 'embodied learning', with the power relations which characterise all social organisations. When making a choice, the enterprise has to reconcile the conflicting requirements of the technological system, the effective demand criteria and the the context in which the technique will operate. A key component of this context is the nature of the enterprise, the learning embodied in it, and the resources it possesses. The specific conditions within a worker controlled enterprise require changes to the institutional framework in which they can be successful. These are directly related to the distribution of income and the nature of the organisation of production. The former affects the capacity of a worker controlled enterprise to acquire human and physical resources required to invest in new techniques. The latter relates to the establishment of efficient management structures. The choice of technique in a sample of firms in the brick making industry in the Western Cape is investigated, and the technological opportunities and constraints analyzed. It is shown that smaller mechanised concrete masonry techniques seem to hold the most potential for a worker controlled enterprise under certain conditions. These conditions include particular state policies to foster the housing delivery systems geared towards small building contracts and squatter upgrading. These have to be supplemented with appropriate financing strategies and the provision of serviced land. The ability of worker controlled enterprises to attract efficient management skills will most probably depend on their capacity to integrate horizontally, and in so doing create economies of scale in the provision of managerial resources. The viability of an enterprise will ultimately depend on whether it is able to adopt a technique which can deliver the products wi th appropriate char act.erLst i cs , to a market segment which requires products of that nature at the cost required. In the Western Cape that growing market seems only to be possible in the sectors where housing is currently not affordable. Therefore, lack of effective demand places a limit on the viability of new enterprises until such time as state policies and the institutional context of land use and availability have been addressed

A holistic interdisciplinary approach towards environmental justice and youth empowerment

South African youth is described as marginalised and vulnerable because of, amongst others, high unemployment rates, a lack of access to opportunities and environmental degradation that threatens their and future generations’ well-being. Both social work and faith-based organisations place value on the empowerment of marginalised youth, as well as on the importance of participatory environmental initiatives. Practice guidelines to effectively empower youth in this regard are, however, lacking. This discussion was aimed at determining how environmental social work can take place in collaboration with faith-based organisations to contribute to both the empowerment of youth and environmental justice. A search of literature from 2010 onwards was conducted, focusing on the terms ‘sustainable development’, ‘marginalised youth’, ‘environmental and/or green social work’ and ‘faith-based organisations’. Central themes were identified through a thematic analysis. Four central themes were identified for youth empowerment through an interdisciplinary approach to contribute to environmental justice, namely environmental responsibility, attitude, knowledge and concern. It was concluded that the potential of an interdisciplinary environmental approach may be based on collaboration and an openness to include a renewed change orientation where disciplines work together across boundaries in multiple spaces to support environmental change and youth empowerment simultaneously

An Efficient Beam Steerable Antenna Array Concept for Airborne Applications

Deployment of a satellite borne, steerable antenna array with higher directivity and gain in Low Earth Orbit makes sense to reduce ground station complexity and cost, while still maintaining a reasonable link budget. The implementation comprises a digitally beam steerable phased array antenna integrated with a complete system, comprising the antenna, hosting platform, ground station, and aircraft based satellite emulator to facilitate convenient aircraft based testing of the antenna array and ground-space communication link. This paper describes the design, development and initial successful interim testing of the various subsystems. A two element prototype used in this increases the signal-to-noise ratio (SNR) by 3 dB which is corresponding to more than 10 times better bit error rate (BER)

Rate of inbreeding and effective population size in four major South African dairy cattle breeds

Pedigree information on the registered South African Ayrshire (n = 47 116), Guernsey (n = 18 766), Holstein (n = 892 458) and Jersey (n = 314 403) breeds was analyzed to determine the rate of inbreeding and effective population sizes for the period 1960 to 2003. Inbreeding coefficients were calculated using the Animal Breeder's Tool Kit. The mean inbreeding coefficients for 2003 were 2.02%, 2.04%, 2.30%, and 3.05% for the Ayrshire, Guernsey, Holstein and Jersey, respectively. The corresponding rates of inbreeding per year were 0.05%, 0.05%, 0.06%, and 0.07% indicating that inbreeding is accumulating at a slightly higher rate in Jersey compared to the other three breeds. However, the rates of inbreeding in the current study are still considerably lower than the acceptable rate of less than 0.5% per year. Estimates of effective population sizes were 148, 165, 137, and 108 for the Ayrshire, Guernsey, Holstein and Jersey, respectively. Results indicate that the impact of inbreeding on genetic variability is still minimal. However, the impact of inbreeding on phenotypic performance on traits of economic importance was not investigated in the current study and should therefore receive future consideration. South African Journal of Animal Science Vol. 36(1) 2006: 50-5

A new find of Megalotragus priscus (Alcelaphini, Bovidae) from the central Karoo, South Africa

Main articleWe document the occurrence of the Florisian, or late Quaternary, form of the giant alcelaphine, Megalotragus priscus, from dongas on the Ongers River, near Britstown in the central Karoo. This is significant as it confirms the occurrence of the species in the Karoo and it suggests significantly wetter environments and productive grasslands in the central Karoo in pre-Holocene times. The present-day Karoo environment did not maintain populations of large ruminant grazers similar to M. priscus, and other specialized Florisian grazers, prior to the advent of agriculture and pasture management. Aridification in recent times is the likely cause of changes in grassland quality and the local dissappearance of these animals, if not their extinction.Non