A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource
| dc.contributor.advisor | ||
| dc.contributor.advisor | ||
| dc.contributor.author | Plagányi, Éva E | |
| dc.contributor.author | Butterworth, Doug S | |
| dc.date.accessioned | 2016-03-10T07:58:48Z | |
| dc.date.available | 2016-03-10T07:58:48Z | |
| dc.date.issued | 2010 | |
| dc.date.updated | 2016-03-10T07:44:45Z | |
| dc.description.abstract | The management of abalone stocks worldwide is complicated by factors such as illegal fishing combined with the difficulties of assessing a sedentary (but not immobile) resource that is often patchily distributed. The South African abalone Haliotis midaefishery is faced with an additional problem in the form of a relatively recent movement of rock lobsters Jasus lalandii into much of the range of the abalone. The lobsters have heavily reduced sea urchin Parechinus angulosus populations, thereby indirectly negatively impacting juvenile abalone which rely on the urchins for shelter. A model is developed for abalone that is an extension of more standard age-structured assessment models because it explicitly takes spatial effects into account, incorporates the ecosystem change effect described above and estimates the magnitude of substantial illegal (‘poached’) catches. The model is simultaneously fitted to catch per unit effort and Fishery-Independent Abalone Survey abundance data, as well as to several years of catch-at-age (cohort-sliced from catch-at-size) data for the various components of the fishery and different spatial strata. It constitutes the first quantitative approach applied to the management of this commercially valuable resource in South Africa and has provided a basis for management advice over recent years by projecting abundance trends under alternative future catch levels. | en_ZA |
| dc.identifier | http://dx.doi.org/10.2989/1814232X.2010.501561 | |
| dc.identifier.apacitation | Plagányi, É. E., & Butterworth, D. S. (2010). A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource. <i>African Journal of Marine Science</i>, http://hdl.handle.net/11427/17625 | en_ZA |
| dc.identifier.chicagocitation | Plagányi, Éva E, and Doug S Butterworth "A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource." <i>African Journal of Marine Science</i> (2010) http://hdl.handle.net/11427/17625 | en_ZA |
| dc.identifier.citation | Plagányi, É. E., & Butterworth, D. S. (2010). A spatial-and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource. African Journal of Marine Science, 32(2), 207-236. | en_ZA |
| dc.identifier.issn | 1814-232X | en_ZA |
| dc.identifier.ris | TY - Journal Article AU - Plagányi, Éva E AU - Butterworth, Doug S AB - The management of abalone stocks worldwide is complicated by factors such as illegal fishing combined with the difficulties of assessing a sedentary (but not immobile) resource that is often patchily distributed. The South African abalone Haliotis midaefishery is faced with an additional problem in the form of a relatively recent movement of rock lobsters Jasus lalandii into much of the range of the abalone. The lobsters have heavily reduced sea urchin Parechinus angulosus populations, thereby indirectly negatively impacting juvenile abalone which rely on the urchins for shelter. A model is developed for abalone that is an extension of more standard age-structured assessment models because it explicitly takes spatial effects into account, incorporates the ecosystem change effect described above and estimates the magnitude of substantial illegal (‘poached’) catches. The model is simultaneously fitted to catch per unit effort and Fishery-Independent Abalone Survey abundance data, as well as to several years of catch-at-age (cohort-sliced from catch-at-size) data for the various components of the fishery and different spatial strata. It constitutes the first quantitative approach applied to the management of this commercially valuable resource in South Africa and has provided a basis for management advice over recent years by projecting abundance trends under alternative future catch levels. DA - 2010 DB - OpenUCT DP - University of Cape Town J1 - African Journal of Marine Science LK - https://open.uct.ac.za PB - University of Cape Town PY - 2010 SM - 1814-232X T1 - A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource TI - A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource UR - http://hdl.handle.net/11427/17625 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/17625 | |
| dc.identifier.uri | http://www.tandfonline.com/doi/abs/10.2989/1814232X.2010.501561 | |
| dc.identifier.vancouvercitation | Plagányi ÉE, Butterworth DS. A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource. African Journal of Marine Science. 2010; http://hdl.handle.net/11427/17625. | en_ZA |
| dc.language | eng | en_ZA |
| dc.publisher | National Inquiry Services Centre | en_ZA |
| dc.publisher.department | Marine Resource Assessment and Management Group | en_ZA |
| dc.publisher.faculty | Faculty of Science | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.source | African Journal of Marine Science | en_ZA |
| dc.source.uri | http://www.tandfonline.com/toc/tams20/current | |
| dc.subject.other | abalone | |
| dc.subject.other | ecosystem change | |
| dc.subject.other | fisheries management | |
| dc.subject.other | Haliotis midae | |
| dc.subject.other | illegal catches | |
| dc.subject.other | poaching | |
| dc.subject.other | spatial modelling | |
| dc.subject.other | stock assessment | |
| dc.subject.other | TURF | |
| dc.title | A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource | en_ZA |
| dc.type | Journal Article | en_ZA |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Article | en_ZA |