Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery

In South Africa, linefishing increased in the mid-1800s and eventually reached a peak in the 1980s/90s. A legal linefishery emergency was declared in 2000 in accordance with the Marine Living Resources Act of 1998. This was a large blow for the commercially important industry. Nonetheless, the carpe...

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Main Author: Rousseau, Meghan
Other Authors: Attwood, Colin
Format: Others
Language:English
Published: University of Cape Town 2014
Online Access:http://hdl.handle.net/11427/7645
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spelling ndltd-netd.ac.za-oai-union.ndltd.org-uct-oai-localhost-11427-76452020-07-22T05:08:04Z Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery Rousseau, Meghan Attwood, Colin In South Africa, linefishing increased in the mid-1800s and eventually reached a peak in the 1980s/90s. A legal linefishery emergency was declared in 2000 in accordance with the Marine Living Resources Act of 1998. This was a large blow for the commercially important industry. Nonetheless, the carpenter stocks had already been overexploited to such a high degree by linefishing, and also as part of trawling bycatch, that even at an effort less than half of the effort that produces a maximum sustainable yield, carpenter stocks were still found below the biomass found at the maximum sustainable yield. In order to explore three different management strategies for the carpenter stock on the offshore Central Agulhas Bank, an agestructured, non-stochastic model was set up. The influences of the following strategies - Total Allowable Catch (TAC), as well as revised minimum size limit and closed season – on a stock found at a dismal 19.2% of carrying capacity, are projected using this model on a monthly time-step. The objectives of this fishery are to achieve a biomass in the final year equal to the biomass found at a maximum sustainable yield (7243 t) and to maximise effort (employment) and catch. The overall recommendation for this stock was a reduction in minimum size limit from 35 cm to 30.48 cm in combination with a flexible TAC starting at 790 t. It is also recommended that even though models are important for fisheries management, no model should be taken in isolation without first considering life history traits and other important information about a stock. 2014-09-22T12:00:27Z 2014-09-22T12:00:27Z 2013 Bachelor Thesis Honours BSc http://hdl.handle.net/11427/7645 eng application/pdf University of Cape Town Faculty of Science Department of Biological Sciences
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language English
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description In South Africa, linefishing increased in the mid-1800s and eventually reached a peak in the 1980s/90s. A legal linefishery emergency was declared in 2000 in accordance with the Marine Living Resources Act of 1998. This was a large blow for the commercially important industry. Nonetheless, the carpenter stocks had already been overexploited to such a high degree by linefishing, and also as part of trawling bycatch, that even at an effort less than half of the effort that produces a maximum sustainable yield, carpenter stocks were still found below the biomass found at the maximum sustainable yield. In order to explore three different management strategies for the carpenter stock on the offshore Central Agulhas Bank, an agestructured, non-stochastic model was set up. The influences of the following strategies - Total Allowable Catch (TAC), as well as revised minimum size limit and closed season – on a stock found at a dismal 19.2% of carrying capacity, are projected using this model on a monthly time-step. The objectives of this fishery are to achieve a biomass in the final year equal to the biomass found at a maximum sustainable yield (7243 t) and to maximise effort (employment) and catch. The overall recommendation for this stock was a reduction in minimum size limit from 35 cm to 30.48 cm in combination with a flexible TAC starting at 790 t. It is also recommended that even though models are important for fisheries management, no model should be taken in isolation without first considering life history traits and other important information about a stock.
author2 Attwood, Colin
author_facet Attwood, Colin
Rousseau, Meghan
author Rousseau, Meghan
spellingShingle Rousseau, Meghan
Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery
author_sort Rousseau, Meghan
title Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery
title_short Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery
title_full Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery
title_fullStr Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery
title_full_unstemmed Modelling the effect of alternative management strategies on the catch and effort in the carpenter (Argyrozona argyrozona) linefishery
title_sort modelling the effect of alternative management strategies on the catch and effort in the carpenter (argyrozona argyrozona) linefishery
publisher University of Cape Town
publishDate 2014
url http://hdl.handle.net/11427/7645
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