University of Cape Town
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Including quantitative ecosystem objectives in Management Strategy Evaluation with examples from South Africa's small pelagic fishery.

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posted on 2023-05-11, 07:52 authored by Carryn de MoorCarryn de Moor

Session Plenary at the PICES/ICES Symposium on Small Pelagic Fish: New Frontiers in Science and Sustainable Management, from 7-11 November 2022 in Lisbon, Portugal

Management Strategy Evaluation, which is the state of the art methodology used to simulation test Management Procedures (MPs), has been shown to be an effective means of managing small pelagic fisheries, despite the large uncertainties associated with modelling these short lived species with highly variable recruitment. In order to reconcile the key ecological role these species have within their ecosystems with the economic and social value gained from a fishery for small pelagic fish, six primary ways in which an ecosystem approach to fisheries can be explicitly considered in management strategy evaluation are explored. South Africa has a long history of using MPs to recommend quantitative catch limits for key commercial fisheries. The purse seine fishery for small pelagics is South Africa’s second most valuable fishery in monetary terms, with the highest volume landed. For the past three decades, MPs have been used to calculate directed and bycatch limit recommendations for anchovy and sardine, the two species forming the backbone of this fishery.  In addition to the fishery, many top predators in the Southern Benguela, including some of which are endangered, are highly dependent on these fish. The first of these MPs to explicitly consider ecosystem objectives in addition to objectives for the target resources and socio-economic objectives was OMP-14, used to set total allowable catches and bycatches from 2015 to 2018. Quantitative performance statistics were calculated to correspond to each objective. A tiered approach was used to assist with narrowing the selection of a candidate MP from the large set of performance statistics. Most performance statistics used to measure ecosystem objectives for the previous two MPs have been based on the endangered African penguin, given the data and quantitative functional relationships available at those times. The next MP for this fishery aims to include new performance statistics for a wider range of top predators, thus broadening the ability to measure candidate MP’s performance against ecosystem objectives. 



Department of Mathematics and Applied Mathematics, University of Cape Town