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Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration
Closed seasons are generally implemented on the presumption that they increase reproductive output of fished populations. This is.based on the assumption that the imposition of a closed season during the breed~· season allows more individuals to reproduce, as they are not being harvested.I evaluated...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2020
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| _version_ | 1867613165571801088 |
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| access_status_str | Open Access |
| author | Arendse, Clement |
| author2 | Govender, Anesh |
| author_browse | Arendse, Clement Govender, Anesh |
| author_facet | Govender, Anesh Arendse, Clement |
| author_sort | Arendse, Clement |
| collection | Thesis |
| description | Closed seasons are generally implemented on the presumption that they increase reproductive output of fished populations. This is.based on the assumption that the imposition of a closed season during the breed~· season allows more individuals to reproduce, as they are not being harvested.I evaluated the validity of imposing closed seasons during the breeding season creating a simulation model using the limpet Cymbula granatina as a test case and the compared following four scenarios: 1) an unharvested population; 2) no closed season imposed; 3) a closed season imposed during the breeding season; and 4) a closed season imposed outside the breeding season, to determine the effects of the latter three situations on the reproductive output and yield. From the outputs of the model it was determined that closed seasons do not significantly affect the reproductive output of the population and that the timing of closed seasons made no difference to the reproductive output of the population, as the output was the same for populations with closed seasons during the breeding season or outside the breeding season. Survivors, catch in numbers and yield in biomass were affected by the timing of closed seasons, with higher outputs for each obtained when the closed season was closer to the month when individuals become of harvestable size. It was thus concluded that the imposition of a closed season at any time of the year is an effective management measure if imposing the closed season can reduce annual fishing, but the imposition of a closed season specifically during the breeding season with a view to increase reproductive output brings no benefits relative to closure at any other time of the year. Moreover, any closure will be ineffective if it does not also bring about a reduction of annual fishing effort. The reasons for advocating closure of a fishery during the breeding season are thus based on false ground. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/32317 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:48.735Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/32317 Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration Arendse, Clement Govender, Anesh Branch, George Botany Closed seasons are generally implemented on the presumption that they increase reproductive output of fished populations. This is.based on the assumption that the imposition of a closed season during the breed~· season allows more individuals to reproduce, as they are not being harvested.I evaluated the validity of imposing closed seasons during the breeding season creating a simulation model using the limpet Cymbula granatina as a test case and the compared following four scenarios: 1) an unharvested population; 2) no closed season imposed; 3) a closed season imposed during the breeding season; and 4) a closed season imposed outside the breeding season, to determine the effects of the latter three situations on the reproductive output and yield. From the outputs of the model it was determined that closed seasons do not significantly affect the reproductive output of the population and that the timing of closed seasons made no difference to the reproductive output of the population, as the output was the same for populations with closed seasons during the breeding season or outside the breeding season. Survivors, catch in numbers and yield in biomass were affected by the timing of closed seasons, with higher outputs for each obtained when the closed season was closer to the month when individuals become of harvestable size. It was thus concluded that the imposition of a closed season at any time of the year is an effective management measure if imposing the closed season can reduce annual fishing, but the imposition of a closed season specifically during the breeding season with a view to increase reproductive output brings no benefits relative to closure at any other time of the year. Moreover, any closure will be ineffective if it does not also bring about a reduction of annual fishing effort. The reasons for advocating closure of a fishery during the breeding season are thus based on false ground. 2020-10-21T09:22:27Z 2020-10-21T09:22:27Z 2004 2020-10-20T05:03:17Z Thesis Other BSc (Hons) http://hdl.handle.net/11427/32317 eng application/pdf Department of Biological Sciences Faculty of Science |
| spellingShingle | Botany Arendse, Clement Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration |
| title | Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration |
| title_full | Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration |
| title_fullStr | Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration |
| title_full_unstemmed | Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration |
| title_short | Does the implementation of a closed Fishing Season during the breeding Season benefit a Species? A per-recruit-based approach using Cymbula Granatina as an Illustration |
| title_sort | does the implementation of a closed fishing season during the breeding season benefit a species a per recruit based approach using cymbula granatina as an illustration |
| topic | Botany |
| url | http://hdl.handle.net/11427/32317 |
| work_keys_str_mv | AT arendseclement doestheimplementationofaclosedfishingseasonduringthebreedingseasonbenefitaspeciesaperrecruitbasedapproachusingcymbulagranatinaasanillustration |