Martin Hall

Sustainability of living resource exploitation relies on an ecosystem management approach. Within tropical tuna purse seine fisheries using fish aggregating devices (FADs), such an approach incorporates the reduction of bycatch, in particular vulnerable species such as elasmobranchs. The levels of total bycatch (in mass) from fishing operations using FADs is known to be five times higher than when tuna are caught in free-swimming schools. We intend to find practical solutions to reduce bycatch in FAD sets through the investigation of the relationships between the ratio of bycatch to target catch across different set size classes in all oceans. Ratios were always highest when catches were small, with the smallest class of catches responsible for the highest total portion of bycatch (23%–43%) while only contributing negligibly to the total target catch (3%–10%). Reducing the number of fishing sets (a part of the total effort) while maintaining the same total yield could contribute to ...

Conceptualizing community engagement as intertwined with teaching and long-established approaches to research requires a consideration of the epistemology of knowledge itself. What is accepted as legitimate knowledge? And what is the scope of the university’s role in recognizing and validating forms of knowledge and defining curriculum boundaries, understood as the ways in which the university disseminates knowledge that it has validated as authentic? A working understanding of community engagement would include service learning, problem-based teaching and research that addresses specific wants and needs, the pursuit of alternative forms of knowledge and challenges to established authorities that control and direct research systems and the allocation of qualifications. This article considers why this kind of engagement has remained on the margins of the traditional university in South Africa – via a case study of community engagement at the University of Cape Town – despite a decade...

The conventional selectivity paradigm is briefly reviewed and its performance examined from an ecosystem perspective. It is stressed that the overall (cumulative) selectivity of the harvest process in an ecosystem is the result of nested selection by fishers and fisheries of: (i) habitats; (ii) species assemblages; (iii) populations and (iv) individuals. A range of ecosystem models predict a strong impact of concentrated fishing (selective fishing) on the ecosystem structure stability, resilience and productivity. There seem to be advantages (in both yield and maintenance of ecosystem structure and functioning) to distribute fishing pressure broadly across available species and ecosystem compartments. Balanced harvesting was therefore defined by the workshop as a strategy that distributes fishing pressure across the wider possible range of trophic levels, sizes and species, in proportion to their natural productivity, reducing fishing pressure where it is excessive. The few attempts...

The conventional selectivity paradigm is briefly reviewed and its performance examined from an ecosystem perspective. It is stressed that the overall (cumulative) selectivity of the harvest process in an ecosystem is the result of nested selection by fishers and fisheries of:(i) habitats;(ii) species assemblages;(iii) populations and (iv) individuals. A range of ecosystem models predict a strong impact of concentrated fishing (selective fishing) on the ecosystem structure stability, resilience and productivity. There seem to be advantages (in ...